<?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) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license   http://framework.zend.com/license/new-bsd     New BSD License

 * @version   $Id: Sntp.php 20096 2010-01-06 02:05:09Z bkarwin $

 */

/**

 * Zend_TimeSync_Protocol

 */

require_once 'Zend/TimeSync/Protocol.php';

/**

 * SNTP Protocol handling class

 *

 * @category  Zend

 * @package   Zend_TimeSync

 * @copyright  Copyright (c) 2005-2010 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;

    }

}