详解php与ethereum客户端交互

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:

rush:PHP;"> { "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

rush: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($p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms)) {
  // no keys
  $p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms = $p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms[0];
} else {
  throw new Exception('P<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms 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,'p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms' => $p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms,'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 = <a href="https://www.jb51.cc/tag/fget/" target="_blank" class="keywords">fget</a>s($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

rush:PHP;"> { "method": "eth_accounts","id": 1 }

RPC Server自带方法的列表

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:

rush:PHP;"> function balanceOf(address _owner) public view returns (uint256 balance)

提炼出函数原型:

rush:PHP;"> balanceOf(address)

在geth控制台下运行命令:

rush:PHP;"> 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:

rush:PHP;"> { "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:

rush:PHP;"> function transfer(address _to,uint256 _value) public returns (bool)

其次,提炼出函数原型:

rush:PHP;"> 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:

rush:PHP;"> 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:

rush:PHP;"> { "method": "eth_call","data": "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"},"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

rush:PHP;"> 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],$p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms);

}

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;

$p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms = ['from' => $address,'to' => self::CONTRACT,'data' => $data];

$total_balance = self::eth_call([$p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms,"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';
$method_p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>m1_hex =str_pad(substr($to,STR_PAD_LEFT);  
$method_p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>m2_hex = str_pad(strval(bc_dechex($value)),STR_PAD_LEFT);

$data = $method_hash . $method_p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>m1_hex . $method_p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>m2_hex;
$p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms = ['from' => self::COINBASE,'data' => $data];

return self::eth_sendTransaction([$p<a href="https://www.jb51.cc/tag/ara/" target="_blank" class="keywords">ara</a>ms]);

}

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:

rush:PHP;"> PHP var_dump(EthereumRPcclient::personal_newAccount(['password'])); var_dump(EthereumRPcclient::personal_unlockAccount([EthereumRPcclient::COINBASE,"password",3600]); var_dump(EthereumRPcclient::getBalance("0x...."));

详解php与ethereum客户端交互

PHP与ethereum rpc server通信

一、Json RPC

二、构建一个Json RPC客户端

三、调用RPC的两类方法

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