php與ethereum rpc server通信
一、Json RPC
Json RPC就是基于json的遠程過程調(diào)用，這么解釋比較抽象。簡單來說，就是post一個json格式的數(shù)據(jù)調(diào)用rpc server中的方法. 而這個json格式是固定的, 總的來說有這么幾項:
{ "method": "", "params": [], "id": idNumber}二、構建一個Json RPC客戶端
<?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 && $this->debug.='***** Request *****'."/n".$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; } }}?>比較簡單的代碼，如果比較懶，拿過去用就行了。也可以上packagist.org自己找一個rpc client.
三、調(diào)用RPC的兩類方法
有兩類方法需要調(diào)用. 一類是RPC server自帶方法，另一類就是合約方法.
RPC server方法調(diào)用json格式
{ "method": "eth_accounts", "params": [], "id": 1}RPC Server自帶方法的列表
調(diào)用自帶方法比較簡單，參考上述鏈接，大部分都有示例.
合約方法調(diào)用json格式
調(diào)用合約方法必須使用自帶方法中的eth_call. 而合約方法名稱和合約方法參數(shù)列表則使用params進行體現(xiàn), 比如: 我們要調(diào)用合約中的balanceOf方法, 則json數(shù)據(jù)應該如何構造呢?
首先看看getBalanace的函數(shù)實現(xiàn):
function balanceOf(address _owner) public view returns (uint256 balance)
提煉出函數(shù)原型:
balanceOf(address)
在geth控制臺下運行命令:
web3.sha3("balanceOf(address)").substring(0, 10)得到函數(shù)hash "0x70a08231"
假設待查詢的地址 address _owner = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", 則去掉前面的"0x", 并在左邊補24個零(一般地址長度為42位, 去掉'0x'后為40位)，構成64位十六進制參數(shù).
最終得到的參數(shù)為 "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"
假設我們的合約地址為 "0xaeab4084194B2a425096fb583Fbcd67385210ac3".
則得到最終的json數(shù)據(jù)為:
{ "method": "eth_call", "params": [{"from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"}, "latest"], "id": 1}把以上json數(shù)據(jù)以post方式發(fā)送給服務器，就可以調(diào)用合約方法"balanceOf", 查詢給定的地址中的代幣余額.
調(diào)用合約中的其他方法也要新遵循上面的方式, 我們再分析一下transfer方法, 加深印象:
首先, 看看代碼中的函數(shù)實現(xiàn):
function transfer(address _to, uint256 _value) public returns (bool)
其次, 提煉出函數(shù)原型:
transfer(address,uint256) //注意逗號后面不能有空格
再次, 在控制臺運行sha3函數(shù):
web3.sha3("transfer(address,uint256)").substring(0, 10)得到函數(shù)hash "0xa9059cbb"
第一個參數(shù)假設 address _to = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", 則去"0x", 補零到64位.
第二個參數(shù)假設 uint256 _value = 43776, 則化為十六進制"0xab00"后, 去"0x", 補零到64位.
連接起來
"0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"
構建json數(shù)據(jù):
{ "method": "eth_call", "params": [{"from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"}, "latest"], "id": 1}把以上的步驟轉化為代碼.
構建一個以太坊RPC client
<?php require './jsonRPCClient.php';//php自帶的dechex無法把大整型轉換為十六進制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 $client = null; //布署合約的賬戶地址 const COINBASE = '0x38aabef4cd283ccd5091298dedc88d27c5ec5750'; //合約地址 const CONTRACT = '0xaeab4084194B2a425096fb583Fbcd67385210ac3'; public static function __callStatic($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]); }}代碼比較簡單, 要注意幾點:
測試:
<?php var_dump(EthereumRPCClient::personal_newAccount(['password']));var_dump(EthereumRPCClient::personal_unlockAccount([EthereumRPCClient::COINBASE, "password", 3600]);var_dump(EthereumRPCClient::getBalance("0x...."));新聞熱點
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