<?php
/**
* Zend Framework
*
* LICENSE
*
* This source file is subject to the new BSD license that is bundled
* with this package in the file LICENSE.txt.
* It is also available through the world-wide-web at this URL:
* http://framework.zend.com/license/new-bsd
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to license@zend.com so we can send you a copy immediately.
*
* @category Zend
* @package Zend_TimeSync
* @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @version $Id$
*/

/**
* Zend_TimeSync_Protocol
*/
#require_once 'Zend/TimeSync/Protocol.php';

/**
* SNTP Protocol handling class
*
* @category Zend
* @package Zend_TimeSync
* @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
*/
class Zend_TimeSync_Sntp extends Zend_TimeSync_Protocol
{
/**
* Port number for this timeserver
*
* @var integer
*/
protected $_port = 37;

/**
* Socket delay
*
* @var integer
*/
private $_delay;

/**
* Class constructor, sets the timeserver and port number
*
* @param string $timeserver Timeserver to connect to
* @param integer $port Port of the timeserver when it differs from the default port
*/
public function __construct($timeserver, $port)
{
$this->_timeserver = 'udp://' . $timeserver;
if ($port !== null) {
$this->_port = $port;
}
}

/**
* Prepares the data that will be send to the timeserver
*
* @return array
*/
protected function _prepare()
{
return "\n";
}

/**
* Reads the data returned from the timeserver
*
* @return string
*/
protected function _read()
{
$result = fread($this->_socket, 49);
$this->_delay = (($this->_delay - time()) / 2);

return $result;
}

/**
* Writes data to to the timeserver
*
* @param string $data Data to write to the timeserver
* @return void
*/
protected function _write($data)
{
$this->_connect();
$this->_delay = time();
fputs($this->_socket, $data);
}

/**
* Extracts the data returned from the timeserver
*
* @param string $result Data to extract
* @return integer
*/
protected function _extract($result)
{
$dec = hexdec('7fffffff');
$time = abs(($dec - hexdec(bin2hex($result))) - $dec);
$time -= 2208988800;
// Socket delay
$time -= $this->_delay;

$this->_info['offset'] = $this->_delay;

return $time;
}
}