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}二、构建一个Json RPC客户端
<?phpclass 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 && $this->debug.="***** Request *****"."".$request.""."***** End Of request *****".""; // 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).""; } $this->debug && $this->debug.="***** Server response *****"."".$response."***** End of server response *****".""; $response = json_decode($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
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}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:
测试:
<?php var_dump(EthereumRPCClient::personal_newAccount(["password"]));var_dump(EthereumRPCClient::personal_unlockAccount([EthereumRPCClient::COINBASE, "password", 3600]);var_dump(EthereumRPCClient::getBalance("0x....")); 
