以太坊交易信息及event、input、logs、topics等概念机制

以太坊交易信息及event、input、logs、topics等概念机制

一、交易信息获取

1.1 合约事件例子定义

举例,比如合约中事件如下:(以下内容均使用该事件例子)

event Transfer(address indexed from, address indexed to, uint256 value);
  • 事件名称:Transfer
  • 事件的参数:address, address, uint256
  • 注意:此事件的from和to参数前有indexed标记,value没有indexed标记

1.2 以太坊交易获取

当上述事件在合约中调用后,我们通过其交易hash获取交易信息。从以太坊得到一条交易信息的方式有两种:

  • eth_getTransactionByHash: :返回指定交易对应的交易信息
  • eth_getTransactionReceipt :返回指定交易对应的收据信息

eth_getTransactionByHash

返回的具体信息如下

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "blockHash": "0xb0d0e3b6c5e59b7b3e7e16701f6d6cb0c3c93487415b03839e88b3f7a241c528",
    "blockNumber": "0xd19505",
    "from": "0xb8262c6a2dcabd92a77df1d5bd074afd07fc5829",
    "gas": "0x10e3d",
    "gasPrice": "0x274daee580",
    "maxFeePerGas": "0x2d48ddd9f1",
    "maxPriorityFeePerGas": "0x6ccc91d0",
    "hash": "0xae2a33da8396a6bc40e874b0f32b9967113a3dbf071ab1290c44c62d86873d36",
    "input": "0xa9059cbb000000000000000000000000dac17f958d2ee523a2206206994597c13d831ec7000000000000000000000000000000000000000000000000000000016512c902",
    "nonce": "0x14",
    "to": "0xdac17f958d2ee523a2206206994597c13d831ec7",
    "transactionIndex": "0x71",
    "value": "0x0",
    "type": "0x2",
    "accessList": [],
    "chainId": "0x1",
    "v": "0x1",
    "r": "0xa1d7455286525df11602aab34e9e8ab21b092e2c7853a0d6beca0dfb2a78b2e8",
    "s": "0x75a485b8c378173a829b27a2e55312311fdb33c68ae65f4c74e5f9cc0a748e0d"
  }
}

web3调用中文文档:https://www.wenjiangs.com/doc/pr2nvcat

curl 调用:

curl -s -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","method":"eth_getTransactionByHash","params":["0xae2a33da8396a6bc40e874b0f32b9967113a3dbf071ab1290c44c62d86873d36"],"id":1}' http://127.0.0.1:8545

eth_getTransactionReceipt

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "blockHash": "0xb0d0e3b6c5e59b7b3e7e16701f6d6cb0c3c93487415b03839e88b3f7a241c528",
    "blockNumber": "0xd19505",
    "contractAddress": null,
    "cumulativeGasUsed": "0x6c847e",
    "effectiveGasPrice": "0x274daee580",
    "from": "0xb8262c6a2dcabd92a77df1d5bd074afd07fc5829",
    "gasUsed": "0xa169",
    "logs": [
      {
        "address": "0xdac17f958d2ee523a2206206994597c13d831ec7",
        "topics": [
          "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
          "0x000000000000000000000000b8262c6a2dcabd92a77df1d5bd074afd07fc5829",
          "0x000000000000000000000000dac17f958d2ee523a2206206994597c13d831ec7"
        ],
        "data": "0x000000000000000000000000000000000000000000000000000000016512c902",
        "blockNumber": "0xd19505",
        "transactionHash": "0xae2a33da8396a6bc40e874b0f32b9967113a3dbf071ab1290c44c62d86873d36",
        "transactionIndex": "0x71",
        "blockHash": "0xb0d0e3b6c5e59b7b3e7e16701f6d6cb0c3c93487415b03839e88b3f7a241c528",
        "logIndex": "0xa0",
        "removed": false
      }
    ],
    "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000010000000000000000000000000000000000000000000000000000000008000000000080000000000000000000000000000000000000000000000000000000000000000000200000000000000010000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000080000000000000000000000000000000000000004000000002000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000000000000000000000000200",
    "status": "0x1",
    "to": "0xdac17f958d2ee523a2206206994597c13d831ec7",
    "transactionHash": "0xae2a33da8396a6bc40e874b0f32b9967113a3dbf071ab1290c44c62d86873d36",
    "transactionIndex": "0x71",
    "type": "0x2"
  }
}

注意:getTransaction返回结果中包含input,而getTransactionReceipts返回结果中包含logs。

二、input解析

2.1 input内容解析

input=0x则为非合约调用,否则为合约方法调用。

以合约方法function transfer(address to, uint tokens) 为例;

input数据分为3个部分:

  • 第一部分: 4 字节,是方法名的哈希

例如:a9059cbb,具体可参见:以太坊智能合约各方法对应的签名编码

  • 第二部分: 32字节,以太坊地址,目前以太坊地址是20个字节,高位补0
例如:000000000000000000000000abcabcabcabcabcabcabcabcabcabcabcabcabca
  • 第三部分:32字节,是需要传输的代币数量,这里是1*10^18 GNT
例如:0000000000000000000000000000000000000000000000000de0b6b3a7640000

所有这些加在一起就是交易数据:

a9059cbb000000000000000000000000abcabcabcabcabcabcabcabcabcabcabcabcabca0000000000000000000000000000000000000000000000000de0b6b3a7640000

2.2 input处理逻辑

如下为处理input的逻辑(web3.js):

if(transanctionInput=='0x'){
        // 非合约调用
    return;
}else{
    retJson['function'] = {'funcName':null,'inputs':null,'outputs':null,'exeResult':null};
    var funcArr = mxxContractABI.filter(function (per) {
        return per.signature == funcHash ;
    });
    if(funcArr!==null&&funcArr.length>0){   // 得到方法名
        if(funcArr[0].hasOwnProperty("name") && funcArr[0].name!==null){
            retJson['function']['funcName'] = funcArr[0].name;
        }
        if(funcArr[0].hasOwnProperty("inputs") && funcArr[0].inputs!==null){
            funcArr[0].inputs.map(function (res) {  // 得到方法inputs(输入)
                inputs.push(res.type);
            });
            retJson['function']['inputs'] = inputs;
        }
        if(funcArr[0].hasOwnProperty("outputs")&& funcArr[0].outputs!==null){
            funcArr[0].outputs.map(function (res) {// 得到方法outputs(输出)
                outputs.push(res.type);
            });
            retJson['function']['outputs']= outputs;
        }

    }
    status = transanctionReceipt.status;
    if(status == '0x1'){
        //执行成功
        retJson['function']['exeResult'] = 'Successfully Executed';
    }else {
        retJson['function']['exeResult'] = 'Failed Executed';
    }

三、logs解析

智能合约通过【事件】来产生【日志】,日志存储的Gas费用要比合约的存储便宜很多(日志每个字节花费8个Gas,而合约存储是每32个字节20000个Gas)。想要通过合约向用户返回数据,则需将数据以事件的形式传给用户,用户拿到transactionReceipt后解析log,log.args.x拿到数据。Input只能拿到调用合约以及function的信息,而不能拿到function运行后内部产生的事件(事件不一定和function拥有相同名称和参数)。

3.1 logs解析代码

logs解析步骤代码(web3.js)

web3SolidityEvent = require('./node_modules/truffle-contract/node_modules/web3/lib/web3/event.js');
var transferErc20Json = {
    "anonymous": false,
    "inputs": [{
        "indexed": true,
        "name": "from",
        "type": "address"
    }, {
        "indexed": true,
        "name": "to",
        "type": "address"
    }, {
        "indexed": false,
        "name": "value",
        "type": "uint256"
    }],
    "name": "Transfer",
    "type": "event",
    "signature": "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
};
var transferEvent = new web3SolidityEvent(null, config.transferErc20Json, null);
async function processReceiptLogs(transactionReceipt){
        let ethErc20LogRecord = null;
        let logs = transactionReceipt.logs;

        for (let i = 0; i < logs.length; i++) {
            let isContractExists = await redis.contractExists(logs[i].address);

            if (isContractExists === true) {//判断redis中是否存在

//是否是ERC-20 transfer事件,用topics来判断
                if(logs[i].topics[0] === transferErc20Json.signature){ 

                    var log = await transferEvent.decode(logs[i]);
                    logger.debug(prefixOfLogger +'--'+'transferEvent decode result:',log);
                    ethErc20LogRecord = {
                        txHash: log.transactionHash,
                        logIndex: log.logIndex,
                        contractAddress: log.address,
                        fromAddress: log.args.from ,
                        toAddress: log.args.to,
                        value: log.args.value.div(Math.pow(10, 18)).toString(),
                        data: log.args.data,
                        blockNumber: log.blockNumber,
                        removed: log.removed
                    };
                    db.setCreateAndUpdateTime(ethErc20LogRecord);
                    let createLogRecord = await tables.EthErc20Log.create(ethErc20LogRecord);

                }
            }
}
  1. 取出transactionReceipt中logs;
  2. 取出logs中一条log;
  3. 使用event.js得到transferEvent,然后用transferEvent的decode方法解析log;

若是公链转币,以太坊转账,则交易回执转logs为空。

若是执行合约的事件,则logs不为空,故ERC-20代币转账,会执行合约Transfer方法,产生logs

四、topics

4.1 概念

Topics[]是一个数组

  • Topics[0] :指向特定的事件,是事件的签名,如ERC-20 Transfer方法:
sha3('Transfer(address,address,uint256)') => 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
  • Topics[1] :是address类型的from参数补齐64位结果(合约交易中真正的from地址)
  • Topics[2] :是address类型to参数补齐64位的结果(合约交易中真正的to地址)

由于value没有indexed标记,因此放在data中,将value的值转化为16进制并补齐64位

4.2 indexed

Transfer事件的第一个和第二个参数被标记为indexed, 因此他们的值被放在 topics array 中. 由于value参数没有标记为indexed, 所以value值被放在data字段. 如果事件中有多个字段未标记为indexed, 那么他们的值都会被记录在data字段中。

事件规则

  • topic[0] : keccak("Transfer(address,address,uint256)"),对事件的字符做keccak散列运算
  • topic[1] : address类型from参数补齐64位
  • topic[2] : address类型to参数补齐64位

data: 没有indexed标记的value的值转化为16进制,并补齐64位

注意:

事件中的参数类型需要写成完整的,如Transfer(address,address,uint)就不行,需要将uint改为uint256。

五、合约交易关键字段解释

{
  "jsonrpc": "2.0",   //RPC版本号,2.0
  "id": 1,      //RPC请求编号
  "result": {  //调用结果,为交易收据,主要包含如下字段:
    "blockHash": "0xb0d0e3b6c5e59b7b3e7e16701f6d6cb0c3c93487415b03839e88b3f7a241c528",  // 区块哈希
    "blockNumber": "0xd19505",   // 区块高度
    "contractAddress": null,    //合约地址
    "cumulativeGasUsed": "0x6c847e",  //当前交易执行后累计花费的gas总值
    "effectiveGasPrice": "0x274daee580",  //当前交易预计使用的gas总值
    "from": "0xb8262c6a2dcabd92a77df1d5bd074afd07fc5829",   //当前交易发送者的地址
    "gasUsed": "0xa169",    //执行当前这个交易单独花费的gas
    "logs": [   //这个交易产生的日志对象数组
      {
        "address": "0xdac17f958d2ee523a2206206994597c13d831ec7",   //当前交易被调用的合约地址
        "topics": [
          "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",  //keccak(Transfer(address,address,uint256)), //合约事件签名哈希值,对事件的字符做keccak散列运算
          "0x000000000000000000000000b8262c6a2dcabd92a77df1d5bd074afd07fc5829",  //当前交易from的地址
          "0x000000000000000000000000dac17f958d2ee523a2206206994597c13d831ec7"   //当前交易to的地址
        ], 
        "data": "0x000000000000000000000000000000000000000000000000000000016512c902",     //包含日志的非索引参数
        "blockNumber": "0xd19505",    // 区块高度
        "transactionHash": "0xae2a33da8396a6bc40e874b0f32b9967113a3dbf071ab1290c44c62d86873d36",   //交易的哈希值,32字节
        "transactionIndex": "0x71"   //交易在区块里面的序号,当交易为pending时为空
        "blockHash": "0xb0d0e3b6c5e59b7b3e7e16701f6d6cb0c3c93487415b03839e88b3f7a241c528",
        "logIndex": "0xa0",    //块中日志索引位置的整数,当交易为pending时日志为空。
        "removed": false   //当由于链重组而删除日志时,为True。 如果它是一个有效的日志则为False。  
      }
    ],
    //bloom过滤器,当交易为pending时日志为空
    "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000010000000000000000000000000000000000000000000000000000000008000000000080000000000000000000000000000000000000000000000000000000000000000000200000000000000010000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000080000000000000000000000000000000000000004000000002000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000000000000000000000000200",
    "status": "0x1",   //交易事务状态,1(成功)或0(失败)
    "to": "0xdac17f958d2ee523a2206206994597c13d831ec7",   //当前交易被调用的合约地址
    "transactionHash": "0xae2a33da8396a6bc40e874b0f32b9967113a3dbf071ab1290c44c62d86873d36",  //交易的哈希值,32字节
    "transactionIndex": "0x71",  //交易在区块里面的序号,当交易为pending时为空
    "type": "0x2"  
  }
}

getTransactionReceipt返回信息字段详情可参考:https://infura.io/docs/ethereum/json-rpc/eth-getTransactionReceipt


以上,就是今天分享的全部内容了,希望大家通过以上方式可以解决自己的实际需求,解决自己目前所遇到的问题。

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