本文主要是介绍Michael.W基于Foundry精读Openzeppelin第59期——Proxy.sol，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
Michael.W基于Foundry精读Openzeppelin第59期——Proxy.sol
- 0. 版本
- 0.1 Proxy.sol
- 1. 目标合约
- 2. 代码精读
- 2.1 _delegate(address implementation) internal
- 2.2 _implementation() internal && _beforeFallback() internal
- 2.3 fallback() && receive()
0. 版本
[openzeppelin]：v4.8.3，[forge-std]：v1.5.6
0.1 Proxy.sol
Github: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.8.3/contracts/proxy/Proxy.sol
Proxy库对外只暴露了fallback和receive函数，是代理合约的基础实现。所有对Proxy合约的call都将被delegatecall到implement合约并且delegatecall的执行结果会原封不动地返还给Proxy合约的调用方。我们通常称implement合约为代理合约背后的逻辑合约。
1. 目标合约
继承Proxy合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/src/proxy/MockProxy.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;import "openzeppelin-contracts/contracts/proxy/Proxy.sol";contract MockProxy is Proxy {address immutable private _IMPLEMENTATION_ADDR;bool immutable private _ENABLE_BEFORE_FALLBACK;event ProxyBeforeFallback(uint value);constructor(address implementationAddress,bool enableBeforeFallback){_IMPLEMENTATION_ADDR = implementationAddress;_ENABLE_BEFORE_FALLBACK = enableBeforeFallback;}function _implementation() internal view override returns (address){return _IMPLEMENTATION_ADDR;}function _beforeFallback() internal override {if (_ENABLE_BEFORE_FALLBACK) {emit ProxyBeforeFallback(msg.value);}}
}
全部foundry测试合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/test/proxy/Proxy/Proxy.t.sol
测试使用的物料合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/test/proxy/Proxy/Implement.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;contract Implement {uint public i;address public addr;uint[3] public fixedArray;uint[] public dynamicArray;mapping(uint => uint) public map;event ImplementReceive(uint value);event ImplementFallback(uint value);function setUint(uint target) external {i = target;}function setUintPayable(uint target) external payable {i = target;}function setAddress(address target) external {addr = target;}function setAddressPayable(address target) external payable {addr = target;}function setFixedArray(uint[3] memory target) external {fixedArray = target;}function setFixedArrayPayable(uint[3] memory target) external payable {fixedArray = target;}function setDynamicArray(uint[] memory target) external {dynamicArray = target;}function setDynamicArrayPayable(uint[] memory target) external payable {dynamicArray = target;}function setMapping(uint key, uint value) external {map[key] = value;}function setMappingPayable(uint key, uint value) external payable {map[key] = value;}function triggerRevert() external pure {revert("Implement: revert");}function triggerRevertPayable() external payable {revert("Implement: revert");}function getPure() external pure returns (string memory){return "pure return value";}receive() external payable {emit ImplementReceive(msg.value);}fallback() external payable {emit ImplementFallback(msg.value);}
}
2. 代码精读
2.1 _delegate(address implementation) internal
将当前的call，委托调用到implementation地址。
注：通过内联汇编“黑魔法”，使得没有返回值的_delegate()函数可以动态返回delegatecall的返回值。
function _delegate(address implementation) internal virtual {// 内联汇编assembly {// 从当前calldata的position 0开始将全部calldata都复制到内存中。内存中的数据存储也是从位置0开始。// 为何此处使用内存的起始position不是从0x40处取空闲内存指针？原因见后文。calldatacopy(0, 0, calldatasize())// 使用delegatecall去调用逻辑合约。// 第一个参数：调用delegatecall的过程允许使用的gas上限。为gas()，即执行到此处剩余可用的全部gas;// 第二个参数：逻辑合约的地址;// 第三个参数：delegatecall所携带的calldata相关。calldata是从当前内存中获取，第三个参数为开始载入的内存position；// 第四个参数：delegatecall所携带的calldata相关。第四个参数为从内存中读取calldata的字节长度；// 综上可知，delegatecall所用的calldata就是进入_delegate(address implementation)时的calldata；// 第五个参数：delegatecall得到的返回数据存储在内存中，第五个参数为开始存储返回值的内存position；// 第六个参数：delegatecall得到的返回数据存储在内存中的字节长度。// 注：由于第五和第六个参数都设为0，即用来存储返回数据的内存长度为0。很明显delegatecall的返回数据长度（如有）要大于设定的存储空间，// 此时，全部的返回数据都要用returndatacopy()来复制到内存中。具体细则详见：https://learnblockchain.cn/article/6309let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)// 由于delegatecall()时设定的存储返回数据的空间为0，要用returndatacopy()和returndatasize()来获取全部的返回数据。// 第一个参数：内存中存储返回数据的起始position，即从position 0处开始存储；// 第二个参数：返回数据被复制的起始position，即从头开始复制返回数据；// 第三个参数：复制返回数据的字节长度。returndatasize()表示未存储到delegatecall()时设定的存储空间的返回数据字节长度，此时该// 值应该为全部返回数据字节长度。// 综上可知，delegatecall()得到的全部返回数据都存储到从0开始的内存空间中returndatacopy(0, 0, returndatasize())// 判断delegatecall是否成功调用switch resultcase 0 {// 如果delegatecall调用失败（例如gas不足），result为0// 那么就直接revert，revert携带的数据为内存中存储的delegatecall的全部返回数据revert(0, returndatasize())}default {// 如果非0（即1），表示delegatecall调用成功// 那么就进行函数返回，返回值为内存中存储的delegatecall的全部返回数据return(0, returndatasize())}}}
为何_delegate()中使用内存的起始position不是从0x40处取空闲内存指针，而是直接从position 0开始？
答：因为在该内联汇编代码块结束时直接进行函数返回，不会再有回到solidity代码逻辑的地方。全部内存都只供汇编代码块使用。只要在内联汇编中手动管理好内存指针，内存就是安全的。
2.2 _implementation() internal && _beforeFallback() internal
_implementation()：返回逻辑合约的地址。该函数未带实现体，需要在主合约中进行重写；_beforeFallback()：执行delegatecall之前会执行的hook函数，如果有需要可以重写该函数并在其中增添逻辑。
function _implementation() internal view virtual returns (address);function _beforeFallback() internal virtual {}
foundry代码验证：
contract ProxyTest is Test {Implement private _implement = new Implement();address payable private _testingAddress = payable(address(new MockProxy(address(_implement), false)));event ImplementFallback(uint value);event ImplementReceive(uint value);event ProxyBeforeFallback(uint value);function test_beforeFallback() external {_testingAddress = payable(address(new MockProxy(address(_implement), true)));Implement proxy = Implement(_testingAddress);uint proxyBalance = _testingAddress.balance;assertEq(proxyBalance, 0);uint ethValue = 1 wei;// case 1: test setUint()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);proxy.setUint(1024);// case 2:test setUintPayable()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);proxy.setUintPayable{value: ethValue}(1024);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 3: test setAddress()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);proxy.setAddress(address(1));// case 4: test setAddressPayable()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);proxy.setAddressPayable{value: ethValue}(address(1));assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 5: test setFixedArray()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);uint[3] memory targetFixedArray = [uint(1024), 2048, 4096];proxy.setFixedArray(targetFixedArray);// case 6: test setFixedArrayPayable()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);proxy.setFixedArrayPayable{value: ethValue}(targetFixedArray);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 7: test setDynamicArray()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);// build dynamic array as inputuint[] memory targetDynamicArray = new uint[](3);targetDynamicArray[0] = 1024;targetDynamicArray[1] = 2048;targetDynamicArray[2] = 4096;proxy.setDynamicArray(targetDynamicArray);// case 8: test setDynamicArrayPayable()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);proxy.setDynamicArrayPayable{value: ethValue}(targetDynamicArray);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 9: test setMapping()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);proxy.setMapping(1024, 2048);// case 10: test setMapping()vm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);proxy.setMappingPayable{value: ethValue}(1024, 2048);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 11: revert with any static call because it emits event in _beforeFallback()// and causes the evm error: "StateChangeDuringStaticCall"vm.expectRevert();proxy.i();vm.expectRevert();proxy.addr();vm.expectRevert();proxy.fixedArray(0);vm.expectRevert();proxy.dynamicArray(0);vm.expectRevert();proxy.map(1024);vm.expectRevert();proxy.triggerRevert();vm.expectRevert();proxy.getPure();// case 12: revert in the function of implement during a callvm.expectRevert("Implement: revert");proxy.triggerRevertPayable{value: ethValue}();// case 13: call the function not exists in the implement// and delegate call to the fallback function of implement// without valuevm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);emit ImplementFallback(0);bytes memory calldata_ = abi.encodeWithSignature("unknown()");(bool ok,) = _testingAddress.call(calldata_);assertTrue(ok);// with valuevm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);emit ImplementFallback(ethValue);(ok,) = _testingAddress.call{value: ethValue}(calldata_);assertTrue(ok);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 14: call the proxy with empty call data// and delegate call to the receive function of implement// without valuevm.expectEmit(_testingAddress);emit ProxyBeforeFallback(0);emit ImplementReceive(0);(ok,) = _testingAddress.call("");assertTrue(ok);// with valuevm.expectEmit(_testingAddress);emit ProxyBeforeFallback(ethValue);emit ImplementReceive(ethValue);(ok,) = _testingAddress.call{value: ethValue}("");assertTrue(ok);assertEq(_testingAddress.balance, proxyBalance + ethValue);}
}
2.3 fallback() && receive()
fallback()：当本合约被携带calldata的call调用时，进入该函数。随即将该call的calldata直接delegatecall到逻辑合约；receive()：当本合约被不携带任何calldata的call调用时，进入该函数。随即直接delegatecall到逻辑合约（不携带任何calldata）。
fallback() external payable virtual {// 调用_fallback()_fallback();}receive() external payable virtual {// 调用_fallback()_fallback();}// 携带当前对本合约的call的calldata，delegatecall到逻辑合约function _fallback() internal virtual {// delegatecall之前运行hook函数_beforeFallback();// 携带当前对本合约的call的calldata，delegatecall到逻辑合约_delegate(_implementation());}
foundry代码验证：
contract ProxyTest is Test {Implement private _implement = new Implement();address payable private _testingAddress = payable(address(new MockProxy(address(_implement), false)));event ImplementFallback(uint value);event ImplementReceive(uint value);function test_Call() external {Implement proxy = Implement(_testingAddress);// case 1: set uint256assertEq(proxy.i(), 0);assertEq(_implement.i(), 0);proxy.setUint(1024);// check storage by static callassertEq(proxy.i(), 1024);assertEq(_implement.i(), 0);// check storage by slot numberbytes32 slotNumber = bytes32(uint(0));assertEq(vm.load(_testingAddress, slotNumber), bytes32(uint(1024)));// case 2: set addressassertEq(proxy.addr(), address(0));assertEq(_implement.addr(), address(0));proxy.setAddress(address(2048));// check storage by static callassertEq(proxy.addr(), address(2048));assertEq(_implement.addr(), address(0));// check storage by slot numberslotNumber = bytes32(uint(1));assertEq(vm.load(_testingAddress, slotNumber), bytes32(uint(2048)));// case 3: set fixed arrayassertEq(proxy.fixedArray(0), 0);assertEq(_implement.fixedArray(0), 0);uint[3] memory targetFixedArray = [uint(1024), 2048, 4096];proxy.setFixedArray(targetFixedArray);for (uint i; i < 3; ++i) {// check storage by static callassertEq(proxy.fixedArray(i), targetFixedArray[i]);assertEq(_implement.fixedArray(i), 0);// check storage by slot numberslotNumber = bytes32(uint(2 + i));assertEq(vm.load(_testingAddress, slotNumber), bytes32(targetFixedArray[i]));}// case 4: set dynamic array// revert during static call because dynamic array isn't initializedvm.expectRevert();proxy.dynamicArray(0);vm.expectRevert();_implement.dynamicArray(0);// build dynamic array as inputuint[] memory targetDynamicArray = new uint[](3);targetDynamicArray[0] = 1024;targetDynamicArray[1] = 2048;targetDynamicArray[2] = 4096;proxy.setDynamicArray(targetDynamicArray);for (uint i; i < 3; ++i) {// check storage by static callassertEq(proxy.dynamicArray(i), targetDynamicArray[i]);vm.expectRevert();assertEq(_implement.dynamicArray(i), 0);// check storage by slot numberslotNumber = bytes32(uint(keccak256(abi.encodePacked(uint(5)))) + i);assertEq(vm.load(_testingAddress, slotNumber), bytes32(targetDynamicArray[i]));}// case 5: set mappinguint key = 1024;uint value = 2048;assertEq(proxy.map(key), 0);assertEq(_implement.map(key), 0);proxy.setMapping(key, value);// check storage by static callassertEq(proxy.map(key), value);assertEq(_implement.map(key), 0);// check storage by slot numberslotNumber = bytes32(uint(keccak256(abi.encodePacked(key, uint(6)))));assertEq(vm.load(_testingAddress, slotNumber), bytes32(value));// case 6: revert with msgvm.expectRevert("Implement: revert");proxy.triggerRevert();// case 7: call pure (staticcall)assertEq(proxy.getPure(), "pure return value");// case 8: call the function not exists in the implement// and delegate call to the fallback function of implementvm.expectEmit(_testingAddress);emit ImplementFallback(0);bytes memory calldata_ = abi.encodeWithSignature("unknown()");(bool ok,) = _testingAddress.call(calldata_);assertTrue(ok);// case 9: call without value and calldata// and delegate call to the receive function of implementvm.expectEmit(_testingAddress);emit ImplementReceive(0);(ok,) = _testingAddress.call("");assertTrue(ok);}function test_PayableCall() external {Implement proxy = Implement(_testingAddress);uint proxyBalance = _testingAddress.balance;assertEq(proxyBalance, 0);// case 1: set uint256 payableassertEq(proxy.i(), 0);assertEq(_implement.i(), 0);uint ethValue = 1 wei;proxy.setUintPayable{value: ethValue}(1024);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// check storage by static callassertEq(proxy.i(), 1024);assertEq(_implement.i(), 0);// check storage by slot numberbytes32 slotNumber = bytes32(uint(0));assertEq(vm.load(_testingAddress, slotNumber), bytes32(uint(1024)));// case 2: set address paybleassertEq(proxy.addr(), address(0));assertEq(_implement.addr(), address(0));proxy.setAddressPayable{value: ethValue}(address(2048));assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// check storage by static callassertEq(proxy.addr(), address(2048));assertEq(_implement.addr(), address(0));// check storage by slot numberslotNumber = bytes32(uint(1));assertEq(vm.load(_testingAddress, slotNumber), bytes32(uint(2048)));// case 3: set fixed array payableassertEq(proxy.fixedArray(0), 0);assertEq(_implement.fixedArray(0), 0);uint[3] memory targetFixedArray = [uint(1024), 2048, 4096];proxy.setFixedArrayPayable{value: ethValue}(targetFixedArray);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;for (uint i; i < 3; ++i) {// check storage by static callassertEq(proxy.fixedArray(i), targetFixedArray[i]);assertEq(_implement.fixedArray(i), 0);// check storage by slot numberslotNumber = bytes32(uint(2 + i));assertEq(vm.load(_testingAddress, slotNumber), bytes32(targetFixedArray[i]));}// case 4: set dynamic array payable// revert during static call because dynamic array isn't initializedvm.expectRevert();proxy.dynamicArray(0);vm.expectRevert();_implement.dynamicArray(0);// build dynamic array as inputuint[] memory targetDynamicArray = new uint[](3);targetDynamicArray[0] = 1024;targetDynamicArray[1] = 2048;targetDynamicArray[2] = 4096;proxy.setDynamicArrayPayable{value: ethValue}(targetDynamicArray);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;for (uint i; i < 3; ++i) {// check storage by static callassertEq(proxy.dynamicArray(i), targetDynamicArray[i]);vm.expectRevert();assertEq(_implement.dynamicArray(i), 0);// check storage by slot numberslotNumber = bytes32(uint(keccak256(abi.encodePacked(uint(5)))) + i);assertEq(vm.load(_testingAddress, slotNumber), bytes32(targetDynamicArray[i]));}// case 5: set mapping payableuint key = 1024;uint value = 2048;assertEq(proxy.map(key), 0);assertEq(_implement.map(key), 0);proxy.setMappingPayable{value: ethValue}(key, value);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// check storage by static callassertEq(proxy.map(key), value);assertEq(_implement.map(key), 0);// check storage by slot numberslotNumber = bytes32(uint(keccak256(abi.encodePacked(key, uint(6)))));assertEq(vm.load(_testingAddress, slotNumber), bytes32(value));// case 6: revert with msg payablevm.expectRevert("Implement: revert");proxy.triggerRevertPayable{value: ethValue}();// case 7: call the function not exists in the implement with value// and delegate call to the fallback function of implementvm.expectEmit(_testingAddress);emit ImplementFallback(ethValue);bytes memory calldata_ = abi.encodeWithSignature("unknown()");(bool ok,) = _testingAddress.call{value: ethValue}(calldata_);assertTrue(ok);assertEq(_testingAddress.balance, proxyBalance + ethValue);proxyBalance += ethValue;// case 8: call with value and empty callata// and delegate call to the receive function of implementvm.expectEmit(_testingAddress);emit ImplementReceive(ethValue);(ok,) = _testingAddress.call{value: ethValue}("");assertTrue(ok);assertEq(_testingAddress.balance, proxyBalance + ethValue);}
}
ps:
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