PHP Decode

<?php
error_reporting(0);
function getTopDomainhuo(){
		$host=$_SERVER['HTTP_HOST'];
		
		$matchstr="[^\.]+\.(?:(".$str.")|\w{2}|((".$str.")\.\w{2}))$";
		if(preg_match("/".$matchstr."/ies",$host,$matchs)){
			$domain=$matchs['0'];
		}else{
			$domain=$host;
		}
		return $domain;

}
$domain=getTopDomainhuo();

$real_domain='baidu.com'; //  

$check_host = 'http://www.aijk.cc/update.php';
$client_check = $check_host . '?a=client_check&u=' . $_SERVER['HTTP_HOST'];
$check_message = $check_host . '?a=check_message&u=' . $_SERVER['HTTP_HOST'];
$check_info=file_get_contents($client_check);
$message = file_get_contents($check_message);



if($check_info=='1'){
   echo '<font color=red>' . $message . '</font>';
   die;
}elseif($check_info=='2'){
   echo '<font color=red>' . $message . '</font>';
   die;
}elseif($check_info=='3'){
   echo '<font color=red>' . $message . '</font>';
   die;
}

if($check_info!=='0'){ //  
   if($domain!==$real_domain){
      echo '';
	  die;
   }
}

unset($domain);

/**
 * 
**/
include("../includes/common.php");
if(isset($_POST['user']) && isset($_POST['pass'])){
	$user=daddslashes($_POST['user']);
	$pass=daddslashes($_POST['pass']);
	$code=daddslashes($_POST['code']);
	if (!$code || ($code != $_SESSION['vc_code'])) {
		unset($_SESSION['vc_code']);
		@header('Content-Type: text/html; charset=UTF-8');
		exit("<script language='javascript'>alert('');history.go(-1);</script>");
	}elseif($user==$conf['admin_user'] && $pass==$conf['admin_pass']) {
		unset($_SESSION['vc_code']);
		$session=md5($user.$pass.$password_hash);
		$token=authcode("{$user}\t{$session}", 'ENCODE', SYS_KEY);
		setcookie("admin_token", $token, time() + 604800);
		@header('Content-Type: text/html; charset=UTF-8');
		exit("<script language='javascript'>alert('');window.location.href='./classlist.php';</script>");
	}else {
		unset($_SESSION['vc_code']);
		@header('Content-Type: text/html; charset=UTF-8');
		exit("<script language='javascript'>alert('');history.go(-1);</script>");
	}
}elseif(isset($_GET['logout'])){
	setcookie("admin_token", "", time() - 604800);
	@header('Content-Type: text/html; charset=UTF-8');
	exit("<script language='javascript'>alert('');window.location.href='./login.php';</script>");
}elseif($islogin==1){
	@header('Content-Type: text/html; charset=UTF-8');
	exit("<script language='javascript'>alert('');window.location.href='./';</script>");
}
$title='';
include './head.php';
?>
  <nav class="navbar navbar-fixed-top navbar-default">
    <div class="container">
      <div class="navbar-header">
        <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
          <span class="sr-only"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
        </button>
        <a class="navbar-brand" href="./"></a>
      </div><!-- /.navbar-header -->
      <div id="navbar" class="collapse navbar-collapse">
        <ul class="nav navbar-nav navbar-right">
          <li class="active">
            <a href="./login.php"><span class="glyphicon glyphicon-user"></span> </a>
          </li>
        </ul>
      </div><!-- /.navbar-collapse -->
    </div><!-- /.container -->
  </nav><!-- /.navbar -->
  <div class="container" style="padding-top:70px;">
    <div class="col-xs-12 col-sm-10 col-md-8 col-lg-6 center-block" style="float: none;">
      <div class="panel panel-primary">
        <div class="panel-heading"><h3 class="panel-title"></h3></div>
        <div class="panel-body">
          <form action="./login.php" method="post" class="form-horizontal" role="form">
            <div class="input-group">
              <span class="input-group-addon"><span class="glyphicon glyphicon-user"></span></span>
              <input type="text" name="user" value="<?php echo @$_POST['user'];?>" class="form-control" placeholder="" required="required"/>
            </div><br/>
            <div class="input-group">
              <span class="input-group-addon"><span class="glyphicon glyphicon-lock"></span></span>
              <input type="password" name="pass" class="form-control" placeholder="" required="required"/>
            </div><br/>
			<div class="input-group">
				<span class="input-group-addon"><span class="glyphicon glyphicon-adjust"></span></span>
				<input type="number" class="form-control" name="code" placeholder="" autocomplete="off" required>
				<span class="input-group-addon" style="padding: 0">
					<img src="./code.php?r=<?php echo time();?>"height="32"onclick="this.src='./code.php?r='+Math.random();" title="">
				</span>
			</div><br/>
            <div class="form-group">
              <div class="col-xs-12"><input type="submit" value="" class="btn btn-primary form-control"/></div>
            </div>
          </form>
        </div>
      </div>
    </div>
  </div>