长安链Solidity智能合约调用原理分析

你的名字 2024-05-08 07:12 78阅读 0赞

**目录**

ERC20智能合约案例

JAVA-SDK调用案例

调用分析

JAVA-SDK生成地址

合约部署

合约调用

msg.sender

--------------------

## ERC20智能合约案例 ##

pragma solidity ^0.4.11;
    
    contract Token {
    
        string public name = "token";      //  token name
        string public symbol = "TK";           //  token symbol
        uint256 public decimals = 6;            //  token digit
    
        mapping (address => uint256) public balanceOf;
        mapping (address => mapping (address => uint256)) public allowance;
    
        uint256 public totalSupply = 0;
        bool public stopped = false;
    
        uint256 constant valueFounder = 100000000000000000;
        address owner = 0x0;
    
        modifier isOwner {
            assert(owner == msg.sender);
            _;
        }
    
        modifier isRunning {
            assert (!stopped);
            _;
        }
    
        modifier validAddress {
            assert(0x0 != msg.sender);
            _;
        }
    
        constructor (address _addressFounder) public {
            owner = msg.sender;
            totalSupply = valueFounder;
            balanceOf[_addressFounder] = valueFounder;
            
            emit Transfer(0x0, _addressFounder, valueFounder);
        }
    
        function transfer(address _to, uint256 _value) public isRunning validAddress returns (bool success) {
            require(balanceOf[msg.sender] >= _value);
            require(balanceOf[_to] + _value >= balanceOf[_to]);
            balanceOf[msg.sender] -= _value;
            balanceOf[_to] += _value;
            emit Transfer(msg.sender, _to, _value);
            return true;
        }
    
        function transferFrom(address _from, address _to, uint256 _value) public isRunning validAddress returns (bool success) {
            require(balanceOf[_from] >= _value);
            require(balanceOf[_to] + _value >= balanceOf[_to]);
            require(allowance[_from][msg.sender] >= _value);
            balanceOf[_to] += _value;
            balanceOf[_from] -= _value;
            allowance[_from][msg.sender] -= _value;
            emit Transfer(_from, _to, _value);
            return true;
        }
    
        function approve(address _spender, uint256 _value) public isRunning validAddress returns (bool success) {
            require(_value == 0 || allowance[msg.sender][_spender] == 0);
            allowance[msg.sender][_spender] = _value;
            emit Approval(msg.sender, _spender, _value);
            return true;
        }
    
        function stop() public isOwner {
            stopped = true;
        }
    
        function start() public isOwner {
            stopped = false;
        }
    
        function setName(string _name) public isOwner {
            name = _name;
        }
    
        function burn(uint256 _value) public {
            require(balanceOf[msg.sender] >= _value);
            balanceOf[msg.sender] -= _value;
            balanceOf[0x0] += _value;
            emit Transfer(msg.sender, 0x0, _value);
        }
    
        event Transfer(address indexed _from, address indexed _to, uint256 _value);
        event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    }

## JAVA-SDK调用案例 ##

public class TestEvmContract extends TestBase {
    
        private static final String EVM_CONTRACT_FILE_PATH = "token.bin";
        private static final String CONTRACT_NAME = "token";
        private static final String CONTRACT_ARGS_EVM_PARAM = "data";
        private static String ADDRESS = "";
    
        private void makeAddrFromCert() {
            try {
                ADDRESS = CryptoUtils.makeAddrFromCert(chainClient.getClientUser().getCertificate());
            } catch (UtilsException e) {
                e.printStackTrace();
            }
        }
    
        @Test
        public void testCreateEvmContract() {
    
            //address根据用户证书生成
            makeAddrFromCert();
            //创建合约构造参数扽RLP编码值
            Function function = new Function( "" , Arrays.asList(new Address(ADDRESS)),
                    Collections.emptyList());
            String methodDataStr = FunctionEncoder.encode(function);
    
            Map<String, String> paramMap = new HashMap<>();
            paramMap.put(CONTRACT_ARGS_EVM_PARAM, methodDataStr.substring(10));
    
    
            ResponseInfo responseInfo = null;
            try {
                byte[] byteCode = FileUtils.getResourceFileBytes(EVM_CONTRACT_FILE_PATH);
                // 1. create payload
                byte[] payload = chainClient.createPayloadOfContractCreation(CONTRACT_NAME,
                        "1", ContractOuterClass.RuntimeType.EVM, paramMap, Hex.decode(new String(byteCode)));
    
                // 2. create payloads with endorsement
                byte[] payloadWithEndorsement1 = adminUser1.signPayloadOfContractMgmt(payload, chainClient.isEnabledCertHash());
    
                // 3. merge endorsements using payloadsWithEndorsement
                byte[][] payloadsWithEndorsement = new byte[1][];
                payloadsWithEndorsement[0] = payloadWithEndorsement1;
                byte[] payloadWithEndorsement = chainClient.mergeSignedPayloadsOfContractMgmt(payloadsWithEndorsement);
    
                // 4. create contract
                responseInfo = chainClient.createContract(payloadWithEndorsement, 10000, 10000);
            } catch (SdkException e) {
                e.printStackTrace();
                Assert.fail(e.getMessage());
            }
            Assert.assertNotNull(responseInfo);
        }
    
        @Test
        public void testInvokeTransferEvmContract() {
            Map<String, String> params = new HashMap<>();
            String add = "0x684a7b71376f6a28af5447516d2448dbe7d84460";
            String toAddress ="0x06ffc656405700dd26aa1b2f2f38f55935f69661";
            BigInteger amount = BigInteger.valueOf(600);
            Function function = new Function( "transfer" , Arrays.asList(new Address(toAddress), new Uint256(amount)),
                    Collections.emptyList());
    
            String methodDataStr = FunctionEncoder.encode(function);
    
            String method = methodDataStr.substring(0,10);
    
            params.put(CONTRACT_ARGS_EVM_PARAM, methodDataStr);
    
            ResponseInfo responseInfo = null;
            try {
                responseInfo = chainClient.invokeContract(CONTRACT_NAME, method, params, 10000, 10000);
            } catch (SdkException e) {
                e.printStackTrace();
                Assert.fail(e.getMessage());
            }
            Assert.assertNotNull(Numeric.toBigInt(responseInfo.getSyncResultTxInfo().getTransaction().getResult().getContractResult().getResult().toByteArray()));
            Assert.assertNotNull(responseInfo);
        }
    
        @Test
        public void testInvokeBalanceOfEvmContract() {
            Map<String, String> params = new HashMap<>();
            makeAddrFromCert();
    
            Function function = new Function( "balanceOf" , Arrays.asList(new Address(ADDRESS)),
                    Collections.emptyList());
    
            String methodDataStr = FunctionEncoder.encode(function);
    
            String method = methodDataStr.substring(0,10);
    
            params.put(CONTRACT_ARGS_EVM_PARAM, methodDataStr);
    
            ResponseInfo responseInfo = null;
            try {
                responseInfo = chainClient.invokeContract(CONTRACT_NAME, method, params, 10000, 10000);
            } catch (SdkException e) {
                e.printStackTrace();
                Assert.fail(e.getMessage());
            }
            Assert.assertNotNull(Numeric.toBigInt(responseInfo.getSyncResultTxInfo().getTransaction().getResult().getContractResult().getResult().toByteArray()));
            Assert.assertNotNull(responseInfo);
        }
    }

## 调用分析 ##

### JAVA-SDK生成地址 ###

ChainMaker目前已支持的证书模型与以太坊的公钥模型不相同，为此ChainMaker在SDK中支持通过证书的SKI字段转换为EVM中所支持的地址格式。主要流程为：

1.  通过证书获取其中的SKI信息
2.  将SKI进行HASH(Keccak256)并截取，生成address

### 合约部署 ###

1、合约部署需要先见token.sol编译成token.bin文件，编译方法详见官网：

[5. 智能合约开发 — chainmaker-docs v2.2.1 documentation][5. _ _ chainmaker-docs v2.2.1 documentation]

2、调用合约部署的方法中会遇到两个web3j的类。

Function function = new Function( "" , Arrays.asList(new Address(ADDRESS)),
                    Collections.emptyList());
            String methodDataStr = FunctionEncoder.encode(function);

Function里边主要构造的是合约方法名、合约请求参数（以集合形式传递）、合约响应参数（以集合形式传递）。

token.sol合约中的构造器方法需要一个初始化账户地址，并会在合约部署后给这个地址

100000000000000000的金额，故第二个参数即为此初始化账户。

FunctionEncoder当然就是编译abi码了。

3、部署合约与其他类型合约处理方法相同。

### 合约调用 ###

合约调用时主要注意如下几个细节。

1、调用合约的参数

Function function = new Function("transfer", Arrays.asList(new Address(toAddress), new Uint256(amount)),
                    Collections.emptyList());

“transfer”为token.sol里边的转账方法名，第二个集合中所传递的toAddress和amount即为转账方法的两个参数，注意类型需要完全匹配。

2、合约方法名和合约名称的取值

相对于其他类型的合约可以直接传递合约方法的字符串，Solidity智能合约需要传编码后的值，这个是所有Solidity智能合约的通用规则。详见

[Contract ABI Specification][]

String method = methodDataStr.substring(0,10);

这里的10是一个固定值。

Utils.calcContractName(CONTRACT_NAME)

3、params参数

params.put(CONTRACT_ARGS_EVM_PARAM, methodDataStr.getBytes());

相对于其他合约params里边传的都是自定义合约的参数，但是在长安链中针对Solidity智能合约这里是一个“data”的常量（不可变更）。如果你没见过evm合约的调用示例，估计自己琢磨，这里将是你一个难以逾越的鸿沟（O(∩\_∩)O）。要想找到这个data的出处还得去源码中找。长安链的evm有专门的开源项目。

[chainmaker / vm-evm · ChainMaker][chainmaker _ vm-evm _ ChainMaker]

这个“data”的出处就在runtime.go的invoke方法里边

func (r *RuntimeInstance) Invoke(contract *commonPb.Contract, method string, byteCode []byte,
    	parameters map[string][]byte, txSimContext protocol.TxSimContext, gasUsed uint64) (
    	contractResult *commonPb.ContractResult, specialTxType protocol.ExecOrderTxType)

params := string(parameters[protocol.ContractEvmParamKey])

这个protocol.ContractEvmParamKey的背后藏的就是data。

### msg.sender ###

了解完上边的好像差不多，合约也部署了，也能正常调用了。但是长安链还有一个比较坑的点就是这个msg.sender。这里处理不好很容易导致合约调用出现

message: "OK"
    contract_result {
      code: 1
      message: "revert instruction was encountered during execution"
    }
    tx_id: "89ee744e75ad9066f339aa4f49942e09a0692f30e48e1e03257adb2cce26839e"

1、首先通过SDK源码找到sender的到底是谁

源码位置在JAVA SDK的ChainClient.java中，详细如下：

private TxRequest createTxRequest(Payload payload, EndorsementEntry[] endorsementEntries) throws ChainMakerCryptoSuiteException {
            Member sender;
            org.chainmaker.pb.common.Request.EndorsementEntry.Builder endorsementEntryBuilder;
            if (this.clientUser.getAuthType().equals(AuthType.PermissionedWithCert.getMsg())) {
                if (this.isEnabledCertHash && this.clientUser.getCertHash() != null && this.clientUser.getCertHash().length > 0) {
                    sender = Member.newBuilder().setOrgId(this.clientUser.getOrgId()).setMemberInfo(ByteString.copyFrom(this.clientUser.getCertHash())).setMemberType(MemberType.CERT_HASH).build();
                } else if (this.isEnabledAlias && this.clientUser.getAlias() != null && this.clientUser.getAlias().length() > 0) {
                    sender = Member.newBuilder().setOrgId(this.clientUser.getOrgId()).setMemberInfo(ByteString.copyFrom(this.clientUser.getAlias().getBytes())).setMemberType(MemberType.ALIAS).build();
                } else {
                    sender = Member.newBuilder().setOrgId(this.clientUser.getOrgId()).setMemberInfo(ByteString.copyFrom(this.clientUser.getCertBytes())).setMemberType(MemberType.CERT).build();
                }
    
                endorsementEntryBuilder = EndorsementEntry.newBuilder().setSigner(sender).setSignature(ByteString.copyFrom(this.clientUser.getCryptoSuite().sign(this.clientUser.getPrivateKey(), payload.toByteArray())));
            } else {
                sender = Member.newBuilder().setOrgId(this.clientUser.getOrgId()).setMemberInfo(ByteString.copyFrom(this.clientUser.getPukBytes())).setMemberType(MemberType.PUBLIC_KEY).build();
                endorsementEntryBuilder = EndorsementEntry.newBuilder().setSigner(sender).setSignature(ByteString.copyFrom(this.clientUser.getCryptoSuite().rsaSign(this.clientUser.getPrivateKey(), payload.toByteArray())));
            }
    
            org.chainmaker.pb.common.Request.TxRequest.Builder txRequestBuilder = TxRequest.newBuilder().setPayload(payload).setSender(endorsementEntryBuilder);
            if (endorsementEntries != null) {
                txRequestBuilder.addAllEndorsers(Arrays.asList((Object[])endorsementEntries.clone()));
            }
    
            return txRequestBuilder.build();
        }

2、里边有个this.clientUser他又是谁

是我们节点的client用户吗，这里很容易让人产生误解，答案是不一定。这里的clientUser实际就是代表ChainClient里边的一个用户，这个用户怎么创建的，又得网上找谁创建的ChainClient，此时就找到ChainManager.java，里边有个createChainClient方法，如下：

public synchronized ChainClient createChainClient(SdkConfig sdkConfig) throws ChainClientException, RpcServiceClientException, UtilsException, ChainMakerCryptoSuiteException {
            this.checkConfig(sdkConfig.getChainClient());
            String chainId = sdkConfig.getChainClient().getChainId();
            ChainClientConfig chainClientConfig = sdkConfig.getChainClient();
            this.dealChainClientConfig(chainClientConfig);
            User clientUser;
            if (!chainClientConfig.getAuthType().equals(AuthType.PermissionedWithKey.getMsg()) && !chainClientConfig.getAuthType().equals(AuthType.Public.getMsg())) {
                clientUser = new User(sdkConfig.getChainClient().getOrgId(), chainClientConfig.getUserSignKeyBytes(), chainClientConfig.getUserSignCrtBytes(), chainClientConfig.getUserKeyBytes(), chainClientConfig.getUserCrtBytes());
                if (sdkConfig.getChainClient().getAlias() != null && sdkConfig.getChainClient().getAlias().length() > 0) {
                    clientUser.setAlias(sdkConfig.getChainClient().getAlias());
                }
            } else {
                clientUser = new User(sdkConfig.getChainClient().getOrgId());
                clientUser.setPukBytes(CryptoUtils.getPemStrFromPublicKey(chainClientConfig.getPublicKey()).getBytes());
                clientUser.setPublicKey(chainClientConfig.getPublicKey());
                clientUser.setPrivateKey(CryptoUtils.getPrivateKeyFromBytes(FileUtils.getFileBytes(chainClientConfig.getUserSignKeyFilePath())));
            }
    。。。。未截全。。。。

到这里相当于知道了是哪个用户，但是一个用户有几个证书，此时还得再看看User的构造方法和前边sender的创建时取的哪一个证书，最终确认为用户的签名证书，也就是sdk\_config.yaml配置的

user_sign_crt_file_path

只有梳理清楚后，后续在调用比如transferFrom、approve方法时才不容易报错。

[5. _ _ chainmaker-docs v2.2.1 documentation]: https://docs.chainmaker.org.cn/operation/%E6%99%BA%E8%83%BD%E5%90%88%E7%BA%A6.html#solidity
[Contract ABI Specification]: https://docs.soliditylang.org/en/latest/abi-spec.html
[chainmaker _ vm-evm _ ChainMaker]: https://git.chainmaker.org.cn/chainmaker/vm-evm.git