php与ethereum客户端交互

偏执的太偏执、 2022-05-21 10:27 240阅读 0赞

# php与ethereum rpc server通信 #

## 一、Json RPC ##

Json RPC就是基于json的远程过程调用，这么解释比较抽象。简单来说，就是post一个json格式的数据调用rpc server中的方法. 而这个json格式是固定的, 总的来说有这么几项:

{
        "method": "",
        "params": [],
        "id": idNumber
    }

*  method: 方法名
 *  params: 参数列表
 *  id: 对过程调用的唯一标识号

## 二、构建一个Json RPC客户端 ##

<?php
    
    class jsonRPCClient {
        
        /** * Debug state * * @var boolean */
        private $debug;
        
        /** * The server URL * * @var string */
        private $url;
        /** * The request id * * @var integer */
        private $id;
        /** * If true, notifications are performed instead of requests * * @var boolean */
        private $notification = false;
        
        /** * Takes the connection parameters * * @param string $url * @param boolean $debug */
        public function __construct($url,$debug = false) {
            // server URL
            $this->url = $url;
            // proxy
            empty($proxy) ? $this->proxy = '' : $this->proxy = $proxy;
            // debug state
            empty($debug) ? $this->debug = false : $this->debug = true;
            // message id
            $this->id = 1;
        }
        
        /** * Sets the notification state of the object. In this state, notifications are performed, instead of requests. * * @param boolean $notification */
        public function setRPCNotification($notification) {
            empty($notification) ?
                                $this->notification = false
                                :
                                $this->notification = true;
        }
        
        /** * Performs a jsonRCP request and gets the results as an array * * @param string $method * @param array $params * @return array */
        public function __call($method,$params) {
            
            // check
            if (!is_scalar($method)) {
                throw new Exception('Method name has no scalar value');
            }
            
            // check
            if (is_array($params)) {
                // no keys
                $params = $params[0];
            } else {
                throw new Exception('Params must be given as array');
            }
            
            // sets notification or request task
            if ($this->notification) {
                $currentId = NULL;
            } else {
                $currentId = $this->id;
            }
            
            // prepares the request
            $request = array(
                            'method' => $method,
                            'params' => $params,
                            'id' => $currentId
                            );
            $request = json_encode($request);
            $this->debug && $this->debug.='***** Request *****'."\n".$request."\n".'***** End Of request *****'."\n\n";
    
            // performs the HTTP POST
            $opts = array ('http' => array (
                                'method'  => 'POST',
                                'header'  => 'Content-type: application/json',
                                'content' => $request
                                ));
            $context  = stream_context_create($opts);
            if ($fp = fopen($this->url, 'r', false, $context)) {
                $response = '';
                while($row = fgets($fp)) {
                    $response.= trim($row)."\n";
                }
                $this->debug && $this->debug.='***** Server response *****'."\n".$response.'***** End of server response *****'."\n";
                $response = json_decode($response,true);
            } else {
                throw new Exception('Unable to connect to '.$this->url);
            }
            
            // debug output
            if ($this->debug) {
                echo nl2br($debug);
            }
            
            // final checks and return
            if (!$this->notification) {
                // check
                if ($response['id'] != $currentId) {
                    throw new Exception('Incorrect response id (request id: '.$currentId.', response id: '.$response['id'].')');
                }
                if (!is_null($response['error'])) {
                    throw new Exception('Request error: '. var_export($response['error'], true));
                }
                
                return $response['result'];
                
            } else {
                return true;
            }
        }
    }
    ?>

比较简单的代码，如果比较懒，拿过去用就行了。也可以上[packagist.org][]自己找一个rpc client.

## 三、调用RPC的两类方法 ##

有两类方法需要调用. 一类是RPC server自带方法，另一类就是合约方法.

### RPC server方法调用json格式 ###

{
        "method": "eth_accounts",
        "params": [],
        "id": 1
    }

[RPC Server自带方法的列表][RPC Server]

调用自带方法比较简单，参考上述链接，大部分都有示例.

### 合约方法调用json格式 ###

调用合约方法必须使用自带方法中的`eth_call`. 而合约方法名称和合约方法参数列表则使用params进行体现, 比如: 我们要调用合约中的`balanceOf`方法, 则`json`数据应该如何构造呢?

首先看看`getBalanace`的函数实现:

function balanceOf(address _owner) public view returns (uint256 balance)

提炼出函数原型:

balanceOf(address)

在`geth`控制台下运行命令:

web3.sha3("balanceOf(address)").substring(0, 10)

得到函数hash "0x70a08231"

假设待查询的地址 `address _owner = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750"`, 则去掉前面的"0x", 并在左边补24个零(一般地址长度为42位, 去掉'0x'后为40位)，构成64位十六进制参数.

最终得到的参数为 "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"

假设我们的合约地址为 "0xaeab4084194B2a425096fb583Fbcd67385210ac3".

则得到最终的json数据为:

{
        "method": "eth_call",
        "params": [{
       "from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"}, "latest"],
        "id": 1
    }

把以上json数据以post方式发送给服务器，就可以调用合约方法"balanceOf", 查询给定的地址中的代币余额.

调用合约中的其他方法也要新遵循上面的方式, 我们再分析一下`transfer`方法, 加深印象:

首先, 看看代码中的函数实现:

function transfer(address _to, uint256 _value) public returns (bool)

其次, 提炼出函数原型:

transfer(address,uint256) //注意逗号后面不能有空格

再次, 在控制台运行sha3函数:

web3.sha3("transfer(address,uint256)").substring(0, 10)

得到函数hash "0xa9059cbb"

第一个参数假设 `address _to = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750"`, 则去"0x", 补零到64位.  
第二个参数假设 `uint256 _value = 43776`, 则化为十六进制"0xab00"后, 去"0x", 补零到64位.

连接起来 "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"

构建json数据:

{
        "method": "eth_call",
        "params": [{
       "from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"}, "latest"],
        "id": 1
    }

*  from 转出者地址
 *  to 合约地址
 *  data 上述操作得到的十六进制数

把以上的步骤转化为代码.

### 构建一个以太坊RPC client ###

<?php 
    
    require './jsonRPCClient.php';
    
    //php自带的dechex无法把大整型转换为十六进制
    function bc_dechex($decimal) {
        $result = [];
    
        while ($decimal != 0) {
            $mod = $decimal % 16;
            $decimal = floor($decimal / 16);
            array_push($result, dechex($mod));        
        }
    
        return join(array_reverse($result));
    }
    
    class EthereumRPCClient {
        public static $client = null;
        
        //布署合约的账户地址
        const COINBASE = '0x38aabef4cd283ccd5091298dedc88d27c5ec5750';
        
        //合约地址
        const CONTRACT = '0xaeab4084194B2a425096fb583Fbcd67385210ac3';
    
        public static function __callStatic($method, $params) {
            $params = count($params) < 1 ? [] : $params[0];
    
            try {
                if (is_null(self::$client)) {
                    self::$client = new jsonRPCClient('http://127.0.0.1:8545', true);    
                }
            } catch (\Exception $e) {
                echo $e->getMessage();
            }
    
            return call_user_func([self::$client, $method], $params);
    
        }
    
        public static function getBalance($address) {
            $method_hash = '0x70a08231';
            $method_param1_hex = str_pad(substr($address, 2), 64, '0', STR_PAD_LEFT);
            $data = $method_hash . $method_param1_hex;
    
            $params = ['from' => $address, 'to' => self::CONTRACT, 'data' => $data];
    
            $total_balance = self::eth_call([$params, "latest"]);
    
            return hexdec($total_balance) / (pow(10, 18));
        }
    
        public static function transfer($to, $value) {
            self::personal_unlockAccount([self::COINBASE, "123456", 3600]);
    
            $value = bcpow(10, 18) * $value;
    
            $method_hash = '0xa9059cbb';
            $method_param1_hex =str_pad(substr($to, 2), 64, '0', STR_PAD_LEFT);    
            $method_param2_hex = str_pad(strval(bc_dechex($value)), 64, '0', STR_PAD_LEFT);
    
            $data = $method_hash . $method_param1_hex . $method_param2_hex;
            $params = ['from' => self::COINBASE, 'to' => self::CONTRACT, 'data' => $data];
    
            return self::eth_sendTransaction([$params]);
    
        }
    
    }

代码比较简单, 要注意几点:

*  **transfer函数的value单位很小, 是 10 ^ -18**, 所以如果你想转`1000`个，其实是要乘于 `10的18次方`, 这里的18是`decimals`.
 *  由于第1点, **应该使用bcpow代替pow函数**.
 *  **不能使用php自带的`dechex`函数**. 因为`dechex`要求整型不能大于 `PHP_INT_MAX`, 而这个数在32位机上为4294967295。由于第1 点, 所有的数都要乘于`10的18次方`, 所以得到的数要远远大于`PHP_INT_MAX`. 建议自己实现10进制转16进制，如果你不知道如何实现，参考上述代码。
 *  **在运行某些合约方法, 比如`transfer`时, 要先`unlock`用户**.
 *  **发送交易之后, 一定要在服务器端启动挖矿, 这样交易才会真的写入到区块**, 比如你调用`transfer`之后，却发现对方没有到账，先别吃惊，启动挖矿试试。如果想启用自动挖码, 在`geth --rpc ...`最后加上 `--mine`.

测试:

<?php 
    
    var_dump(EthereumRPCClient::personal_newAccount(['password']));
    var_dump(EthereumRPCClient::personal_unlockAccount([EthereumRPCClient::COINBASE, "password", 3600]);
    var_dump(EthereumRPCClient::getBalance("0x...."));

[packagist.org]: https://packagist.org/
[RPC Server]: https://github.com/ethereum/wiki/wiki/JSON-RPC