php與ethereum rpc server通信
一、Json RPC
Json RPC就是基于json的遠程過程調用，這么解釋比較抽象。簡單來說，就是post一個json格式的數據調用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
}
- method: 方法名
- params: 參數列表
- id: 對過程調用的唯一標識號
二、構建一個Json RPC客戶端
<?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、調用RPC的兩類方法
有兩類方法需要調用. 一類是RPC server自帶方法，另一類就是合約方法.
RPC server方法調用json格式
{
"method": "eth_accounts",
"params": [],
"id": 1
}
RPC Server自帶方法的列表
調用自帶方法比較簡單，參考上述鏈接，大部分都有示例.
合約方法調用json格式
調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列表則使用params進行體現, 比如: 我們要調用合約中的balanceOf方法, 則json數據應該如何構造呢?
首先看看getBalanace的函數實現:
function balanceOf(address _owner) public view returns (uint256 balance)
提煉出函數原型:
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.
最終得到的參數為 "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"
假設我們的合約地址為 "0xaeab4084194B2a425096fb583Fbcd67385210ac3".
則得到最終的json數據為:
{
"method": "eth_call",
"params": [{"from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"}, "latest"],
"id": 1
}
把以上json數據以post方式發送給服務器，就可以調用合約方法"balanceOf", 查詢給定的地址中的代幣余額.
調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, 看看代碼中的函數實現:
function transfer(address _to, uint256 _value) public returns (bool)
其次, 提煉出函數原型:
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:
web3.sha3("transfer(address,uint256)").substring(0, 10)
得到函數hash "0xa9059cbb"
第一個參數假設 address _to = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", 則去"0x", 補零到64位.
第二個參數假設 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數據:
{
"method": "eth_call",
"params": [{"from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"}, "latest"],
"id": 1
}
- from 轉出者地址
- to 合約地址
- data 上述操作得到的十六進制數
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:
- transfer函數的value單位很小, 是 10 ^ -18, 所以如果你想轉1000個，其實是要乘于 10的18次方, 這里的18是decimals.
- 由于第1點, 應該使用bcpow代替pow函數.
- 不能使用php自帶的dechex函數. 因為dechex要求整型不能大于 PHP_INT_MAX, 而這個數在32位機上為4294967295。由于第1 點, 所有的數都要乘于10的18次方, 所以得到的數要遠遠大于PHP_INT_MAX. 建議自己實現10進制轉16進制，如果你不知道如何實現，參考上述代碼。
- 在運行某些合約方法, 比如transfer時, 要先unlock用戶.
- 發送交易之后, 一定要在服務器端啟動挖礦, 這樣交易才會真的寫入到區塊, 比如你調用transfer之后，卻發現對方沒有到賬，先別吃驚，啟動挖礦試試。如果想啟用自動挖碼, 在geth --rpc ...最后加上 --mine.
測試:
<?php
var_dump(EthereumRPCClient::personal_newAccount(['password']));
var_dump(EthereumRPCClient::personal_unlockAccount([EthereumRPCClient::COINBASE, "password", 3600]);
var_dump(EthereumRPCClient::getBalance("0x...."));
