Michael.W基于Foundry精读Openzeppelin第23期——ERC165Checker.sol
- 0. 版本
- 0.1 ERC165Checker.sol
- 1. 目标合约
- 2. 代码精读
- 2.1 supportsERC165InterfaceUnchecked(address account, bytes4 interfaceId)
- 2.2 supportsERC165(address account)
- 2.3 supportsInterface(address account, bytes4 interfaceId)
- 2.4 getSupportedInterfaces(address account, bytes4[] memory interfaceIds)
- 2.5 supportsAllInterfaces(address account, bytes4[] memory interfaceIds)
0. 版本
[openzeppelin]：v4.8.3，[forge-std]：v1.5.6
0.1 ERC165Checker.sol
Github: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.8.3/contracts/utils/introspection/ERC165Checker.sol
ERC165Checker库是用来查询已实现IERC165的目标合约自身实现了哪些interface的工具库。在使用时需要注意：利用ERC165Checker提供的查询方法进行查询的过程不会因为目标合约没有实现待查询interface而发生revert。而是通过bool变量来标识目标合约对待查询interface的实现情况，查询方可以通过该bool值进行判断从而进行下一步的逻辑处理。
1. 目标合约
封装ERC165Checker library成为一个可调用合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/src/utils/introspection/MockERC165Checker.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;import "openzeppelin-contracts/contracts/utils/introspection/ERC165Checker.sol";contract MockERC165Checker {using ERC165Checker for address;function supportsERC165(address account) external view returns (bool){return account.supportsERC165();}function supportsInterface(address account, bytes4 interfaceId) external view returns (bool){return account.supportsInterface(interfaceId);}function getSupportedInterfaces(address account, bytes4[] memory interfaceIds)externalviewreturns (bool[] memory){return account.getSupportedInterfaces(interfaceIds);}function supportsAllInterfaces(address account, bytes4[] memory interfaceIds) external view returns (bool){return account.supportsAllInterfaces(interfaceIds);}function supportsERC165InterfaceUnchecked(address account, bytes4 interfaceId) external view returns (bool){return account.supportsERC165InterfaceUnchecked(interfaceId);}
}
全部foundry测试合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/test/utils/introspection/ERC165Checker.t.sol
2. 代码精读
2.1 supportsERC165InterfaceUnchecked(address account, bytes4 interfaceId)
查询目标地址account是否继承了interface id对应的interface。即只做对应interface id的显式支持interface检查，而不做对IERC165 interface的支持检查。
注：方法内部使用了内联汇编的staticcall，如果account合约没有实现IERC165 interface 也不会revert。
function supportsERC165InterfaceUnchecked(address account, bytes4 interfaceId) internal view returns (bool) {// 拼接调用supportsInterface(bytes4 interfaceId)的calldatabytes memory encodedParams = abi.encodeWithSelector(IERC165.supportsInterface.selector, interfaceId);// 内联汇编中static call目标合约的supportsInterface方法bool success;uint256 returnSize;uint256 returnValue;assembly {// 内联汇编中的staticcall的参数为：staticcall(g, a, in, insize, out, outsize):// - g: 本次调用时设置的gas上限为30000// - a: call的合约地址为account// - in: memory中的staticcall的calldata的起始位置，即encodedParams指针+32个字节// - insize: memory中的staticcall的calldata的长度，即encodedParams指针指向内存中的值// - out: memory中存放返回数据的起始位置，即memory中第一个字位置0x00// - outsize: memory中存放返回数据的长度——0x20个字节（因为supportsInterface方法返回值为bool，内存中用一个字来存储）// 注： 内联汇编staticcall详解参见博文：https://blog.csdn.net/michael_wgy_/article/details/132196437success := staticcall(30000, account, add(encodedParams, 0x20), mload(encodedParams), 0x00, 0x20)// static call的returndata的字节长度returnSize := returndatasize()// 从memory中取出staticcall的返回值，即bool返回值内容returnValue := mload(0x00)}// 返回true的条件（与关系）：// 1. success为true —— static call成功调用;// 2. static call的return data字节长度>=32，即staticcall有返回数据;// 3. static call的返回值为truereturn success && returnSize >= 0x20 && returnValue > 0;}
foundry代码验证
import "openzeppelin-contracts/contracts/utils/introspection/ERC165.sol";
import "openzeppelin-contracts/contracts/token/ERC20/ERC20.sol";// all kinds of target contracts for test// no method `supportsInterface(bytes4 interfaceId)`
contract SupportNone {}contract SupportERC165 is ERC165 {}contract SupportERC165ButNotInvalidInterfaceId is ERC165 {function supportsInterface(bytes4 interfaceId) public view override returns (bool) {return interfaceId == 0xffffffff || super.supportsInterface(interfaceId);}
}interface ICustomized {function helloMichael() external view returns (string memory);
}contract SupportManyInterfacesButNotERC165 is ERC20, ICustomized {string _str = "michael.w";constructor()ERC20("", ""){}function helloMichael() external view returns (string memory){return _str;}function supportsInterface(bytes4 interfaceId) public pure returns (bool) {return interfaceId == type(IERC20).interfaceId ||interfaceId == type(IERC20Metadata).interfaceId ||interfaceId == type(ICustomized).interfaceId;}
}contract SupportManyInterfacesWithERC165 is ERC165, ERC20, ICustomized {string _str = "michael.w";constructor()ERC20("", ""){}function helloMichael() external view returns (string memory){return _str;}function supportsInterface(bytes4 interfaceId) public view override returns (bool) {return interfaceId == type(IERC20).interfaceId ||interfaceId == type(IERC20Metadata).interfaceId ||interfaceId == type(ICustomized).interfaceId ||super.supportsInterface(interfaceId);}
}contract ERC165CheckerTest is Test {MockERC165Checker testing = new MockERC165Checker();SupportNone supportNone = new SupportNone();SupportERC165 supportERC165 = new SupportERC165();SupportERC165ButNotInvalidInterfaceId supportERC165ButNotInvalidInterfaceId = new SupportERC165ButNotInvalidInterfaceId();SupportManyInterfacesButNotERC165 supportManyInterfacesButNotERC165 = new SupportManyInterfacesButNotERC165();SupportManyInterfacesWithERC165 supportManyInterfacesWithERC165 = new SupportManyInterfacesWithERC165();bytes4 constant INTERFACE_ID_INVALID = 0xffffffff;function test_SupportsERC165InterfaceUnchecked() external {// case 1: query to contract SupportNone without revert and return falseassertFalse(testing.supportsERC165InterfaceUnchecked(address(supportNone), type(IERC165).interfaceId));assertFalse(testing.supportsERC165InterfaceUnchecked(address(supportNone), INTERFACE_ID_INVALID));// case 2: query to contract SupportERC165assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportERC165), type(IERC165).interfaceId));assertFalse(testing.supportsERC165InterfaceUnchecked(address(supportERC165), INTERFACE_ID_INVALID));// case 3: query to contract SupportERC165ButNotInvalidInterfaceIdassertTrue(testing.supportsERC165InterfaceUnchecked(address(supportERC165ButNotInvalidInterfaceId), type(IERC165).interfaceId));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportERC165ButNotInvalidInterfaceId), INTERFACE_ID_INVALID));// case 4: query to contract SupportManyInterfacesButNotERC165assertFalse(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesButNotERC165), type(IERC165).interfaceId));assertFalse(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesButNotERC165), INTERFACE_ID_INVALID));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesButNotERC165), type(IERC20).interfaceId));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesButNotERC165), type(IERC20Metadata).interfaceId));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesButNotERC165), type(ICustomized).interfaceId));// case 5: query to contract SupportManyInterfacesWithERC165assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesWithERC165), type(IERC165).interfaceId));assertFalse(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesWithERC165), INTERFACE_ID_INVALID));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesWithERC165), type(IERC20).interfaceId));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesWithERC165), type(IERC20Metadata).interfaceId));assertTrue(testing.supportsERC165InterfaceUnchecked(address(supportManyInterfacesWithERC165), type(ICustomized).interfaceId));}
}
2.2 supportsERC165(address account)
检查目标地址account是否实现了IERC165 interface。
注：任何实现了IERC165的合约都必须支持对IERC165 interface id的显式支持查询和对invalid interface id （即0xffffffff）的显式不支持查询。
// 按照EIP-165规范，任何接口的interface id都不应该是0xffffffffbytes4 private constant _INTERFACE_ID_INVALID = 0xffffffff;function supportsERC165(address account) internal view returns (bool) {// 分别用IERC165 interface id和invalid interface id作为参数去static call目标合约的supportsInterface()方法。当返回值依次为true和false表示目标合约account完全支持IERC165 interfacereturnsupportsERC165InterfaceUnchecked(account, type(IERC165).interfaceId) &&!supportsERC165InterfaceUnchecked(account, _INTERFACE_ID_INVALID);}
foundry代码验证
contract ERC165CheckerTest is Test {MockERC165Checker testing = new MockERC165Checker();SupportNone supportNone = new SupportNone();SupportERC165 supportERC165 = new SupportERC165();SupportERC165ButNotInvalidInterfaceId supportERC165ButNotInvalidInterfaceId = new SupportERC165ButNotInvalidInterfaceId();SupportManyInterfacesButNotERC165 supportManyInterfacesButNotERC165 = new SupportManyInterfacesButNotERC165();SupportManyInterfacesWithERC165 supportManyInterfacesWithERC165 = new SupportManyInterfacesWithERC165();bytes4 constant INTERFACE_ID_INVALID = 0xffffffff;function test_SupportsERC165() external {// case 1: query to contract SupportNone without revert and return falseassertFalse(testing.supportsERC165(address(supportNone)));// case 2: query to contract SupportERC165assertTrue(testing.supportsERC165(address(supportERC165)));// case 3: query to contract SupportERC165ButNotInvalidInterfaceIdassertFalse(testing.supportsERC165(address(supportERC165ButNotInvalidInterfaceId)));// case 4: query to contract SupportManyInterfacesButNotERC165assertFalse(testing.supportsERC165(address(supportManyInterfacesButNotERC165)));// case 5: query to contract SupportManyInterfacesWithERC165assertTrue(testing.supportsERC165(address(supportManyInterfacesWithERC165)));}
}
2.3 supportsInterface(address account, bytes4 interfaceId)
检查目标地址account是否实现了输入interface id对应的interface。
注：该函数会同时检查目标地址是否支持IERC165 interface。
function supportsInterface(address account, bytes4 interfaceId) internal view returns (bool) {// 当目标地址同时支持IERC165 interface和对应interface id才被认为是已支持对应interface id对应的interfacereturn supportsERC165(account) && supportsERC165InterfaceUnchecked(account, interfaceId);}
foundry代码验证
contract ERC165CheckerTest is Test {MockERC165Checker testing = new MockERC165Checker();SupportNone supportNone = new SupportNone();SupportERC165 supportERC165 = new SupportERC165();SupportERC165ButNotInvalidInterfaceId supportERC165ButNotInvalidInterfaceId = new SupportERC165ButNotInvalidInterfaceId();SupportManyInterfacesButNotERC165 supportManyInterfacesButNotERC165 = new SupportManyInterfacesButNotERC165();SupportManyInterfacesWithERC165 supportManyInterfacesWithERC165 = new SupportManyInterfacesWithERC165();bytes4 constant INTERFACE_ID_INVALID = 0xffffffff;function test_SupportsInterface() external {// case 1: query to contract SupportNoneassertFalse(testing.supportsInterface(address(supportNone), INTERFACE_ID_INVALID));assertFalse(testing.supportsInterface(address(supportNone), type(IERC165).interfaceId));// case 2: query to contract SupportERC165assertFalse(testing.supportsInterface(address(supportERC165), INTERFACE_ID_INVALID));assertTrue(testing.supportsInterface(address(supportERC165), type(IERC165).interfaceId));// case 3: query to contract SupportERC165ButNotInvalidInterfaceIdassertFalse(testing.supportsInterface(address(supportERC165ButNotInvalidInterfaceId), INTERFACE_ID_INVALID));assertFalse(testing.supportsInterface(address(supportERC165ButNotInvalidInterfaceId), type(IERC165).interfaceId));// case 4: query to contract SupportManyInterfacesButNotERC165assertFalse(testing.supportsInterface(address(supportManyInterfacesButNotERC165), INTERFACE_ID_INVALID));assertFalse(testing.supportsInterface(address(supportManyInterfacesButNotERC165), type(IERC165).interfaceId));assertFalse(testing.supportsInterface(address(supportManyInterfacesButNotERC165), type(IERC20).interfaceId));assertFalse(testing.supportsInterface(address(supportManyInterfacesButNotERC165), type(IERC20Metadata).interfaceId));assertFalse(testing.supportsInterface(address(supportManyInterfacesButNotERC165), type(ICustomized).interfaceId));// case 5: query to contract SupportManyInterfacesWithERC165assertFalse(testing.supportsInterface(address(supportManyInterfacesWithERC165), INTERFACE_ID_INVALID));assertTrue(testing.supportsInterface(address(supportManyInterfacesWithERC165), type(IERC165).interfaceId));assertTrue(testing.supportsInterface(address(supportManyInterfacesWithERC165), type(IERC20).interfaceId));assertTrue(testing.supportsInterface(address(supportManyInterfacesWithERC165), type(IERC20Metadata).interfaceId));assertTrue(testing.supportsInterface(address(supportManyInterfacesWithERC165), type(ICustomized).interfaceId));}
}
2.4 getSupportedInterfaces(address account, bytes4[] memory interfaceIds)
批量检查目标地址account是否实现了输入interface ids对应的interface数组。返回值为一个bool数组，分别对应对相同index的interface ids数组成员的支持与否。
function getSupportedInterfaces(address account, bytes4[] memory interfaceIds)internalviewreturns (bool[] memory){// 在内存中创建与传入interface ids数组相同长度的bool数组bool[] memory interfaceIdsSupported = new bool[](interfaceIds.length);if (supportsERC165(account)) {// 如果目标地址account已经完全支持IERC165 interface，才会进一步去检查传入的interface ids数组的支持情况。否则，直接认作全不支持for (uint256 i = 0; i < interfaceIds.length; i++) {// 遍历查询目标account对各个interfaceId的支持情况，并将检查结果依次存入bool数组interfaceIdsSupported[i] = supportsERC165InterfaceUnchecked(account, interfaceIds[i]);}}// 返回bool数组return interfaceIdsSupported;}
foundry代码验证
contract ERC165CheckerTest is Test {MockERC165Checker testing = new MockERC165Checker();SupportNone supportNone = new SupportNone();SupportERC165 supportERC165 = new SupportERC165();SupportERC165ButNotInvalidInterfaceId supportERC165ButNotInvalidInterfaceId = new SupportERC165ButNotInvalidInterfaceId();SupportManyInterfacesButNotERC165 supportManyInterfacesButNotERC165 = new SupportManyInterfacesButNotERC165();SupportManyInterfacesWithERC165 supportManyInterfacesWithERC165 = new SupportManyInterfacesWithERC165();bytes4 constant INTERFACE_ID_INVALID = 0xffffffff;function test_GetSupportedInterfaces() external {bytes4[] memory interfaceIds = new bytes4[](4);interfaceIds[0] = type(IERC165).interfaceId;interfaceIds[1] = type(IERC20).interfaceId;interfaceIds[2] = type(IERC20Metadata).interfaceId;interfaceIds[3] = type(ICustomized).interfaceId;// case 1: query to contract SupportNonebool[] memory supported = testing.getSupportedInterfaces(address(supportNone), interfaceIds);assertEq(supported.length, 4);// all false because of not supporting ERC165 completelyassertFalse(supported[0]);assertFalse(supported[1]);assertFalse(supported[2]);assertFalse(supported[3]);// case 2: query to contract SupportERC165supported = testing.getSupportedInterfaces(address(supportERC165), interfaceIds);assertEq(supported.length, 4);assertTrue(supported[0]);assertFalse(supported[1]);assertFalse(supported[2]);assertFalse(supported[3]);// case 3: query to contract SupportERC165ButNotInvalidInterfaceIdsupported = testing.getSupportedInterfaces(address(supportERC165ButNotInvalidInterfaceId), interfaceIds);assertEq(supported.length, 4);// all false because of not supporting ERC165 completelyassertFalse(supported[0]);assertFalse(supported[1]);assertFalse(supported[2]);assertFalse(supported[3]);// case 4: query to contract SupportManyInterfacesButNotERC165supported = testing.getSupportedInterfaces(address(supportManyInterfacesButNotERC165), interfaceIds);assertEq(supported.length, 4);// all false because of not supporting ERC165 completelyassertFalse(supported[0]);assertFalse(supported[1]);assertFalse(supported[2]);assertFalse(supported[3]);// case 5: query to contract SupportManyInterfacesWithERC165supported = testing.getSupportedInterfaces(address(supportManyInterfacesWithERC165), interfaceIds);assertEq(supported.length, 4);// all trueassertTrue(supported[0]);assertTrue(supported[1]);assertTrue(supported[2]);assertTrue(supported[3]);}
}
2.5 supportsAllInterfaces(address account, bytes4[] memory interfaceIds)
检查目标地址account是否全部实现了输入interface ids对应的interface数组。如果全部实现返回true，否则返回false。
注：每次调用调用supportsInterface(address account, bytes4 interfaceId)检查目标地址account对某一interface id的支持情况都会进行一次对IERC165的支持检查。而本方法中无论数组interfaceIds的长度是多少都只会进行一次对IERC165的支持检查，非常节约gas。
function supportsAllInterfaces(address account, bytes4[] memory interfaceIds) internal view returns (bool) {// 如果目标地址account已经完全支持IERC165 interface，才会进一步去检查传入的interface ids数组的支持情况。否则，直接返回falseif (!supportsERC165(account)) {return false;}// 遍历查询目标地址account对各个interface id的支持情况。只要出现任意一个interface id不支持的情况就直接返回falsefor (uint256 i = 0; i < interfaceIds.length; i++) {if (!supportsERC165InterfaceUnchecked(account, interfaceIds[i])) {return false;}}// 当目标地址account对传入的各个interface id都支持时，返回truereturn true;}
foundry代码验证
contract ERC165CheckerTest is Test {MockERC165Checker testing = new MockERC165Checker();SupportNone supportNone = new SupportNone();SupportERC165 supportERC165 = new SupportERC165();SupportERC165ButNotInvalidInterfaceId supportERC165ButNotInvalidInterfaceId = new SupportERC165ButNotInvalidInterfaceId();SupportManyInterfacesButNotERC165 supportManyInterfacesButNotERC165 = new SupportManyInterfacesButNotERC165();SupportManyInterfacesWithERC165 supportManyInterfacesWithERC165 = new SupportManyInterfacesWithERC165();bytes4 constant INTERFACE_ID_INVALID = 0xffffffff;function test_SupportsAllInterfaces() external {bytes4[] memory interfaceIds = new bytes4[](4);interfaceIds[0] = type(IERC165).interfaceId;interfaceIds[1] = type(IERC20).interfaceId;interfaceIds[2] = type(IERC20Metadata).interfaceId;interfaceIds[3] = type(ICustomized).interfaceId;// case 1: query to contract SupportNoneassertFalse(testing.supportsAllInterfaces(address(supportNone), interfaceIds));// case 2: query to contract SupportERC165assertFalse(testing.supportsAllInterfaces(address(supportERC165), interfaceIds));// case 3: query to contract SupportERC165ButNotInvalidInterfaceIdassertFalse(testing.supportsAllInterfaces(address(supportERC165ButNotInvalidInterfaceId), interfaceIds));// case 4: query to contract SupportManyInterfacesButNotERC165assertFalse(testing.supportsAllInterfaces(address(supportManyInterfacesButNotERC165), interfaceIds));// case 5: query to contract SupportManyInterfacesWithERC165assertTrue(testing.supportsAllInterfaces(address(supportManyInterfacesWithERC165), interfaceIds));}
}
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