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
<?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 = $url;// proxyempty($proxy) ? $this->proxy = '' : $this->proxy = $proxy;// debug stateempty($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,$params) {// checkif (!is_scalar($method)) {throw new Exception('Method name has no scalar value');}// checkif (is_array($params)) {// no keys$params = $params[0];} else {throw new Exception('Params must be given as array');}// sets notification or request taskif ($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 '.$this->url);}// debug outputif ($this->debug) {echo nl2br($debug);}// final checks and returnif (!$this->notification) {// checkif ($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}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...."));
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