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 <?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';
 
 /**
  * NTP 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_Ntp extends Zend_TimeSync_Protocol
 {
     /**
      * NTP port number (123) assigned by the Internet Assigned Numbers Authority
      *
      * @var integer
      */
     protected $_port = 123;
 
     /**
      * NTP class constructor, sets the timeserver and port number
      *
      * @param string  $timeserver Adress of the timeserver to connect to
      * @param integer $port       (Optional) Port for this timeserver
      */
     public function __construct($timeserver, $port = 123)
     {
         $this->_timeserver = 'udp://' . $timeserver;
         if ($port !== null) {
             $this->_port = $port;
         }
     }
 
     /**
      * Prepare local timestamp for transmission in our request packet
      *
      * NTP timestamps are represented as a 64-bit fixed-point number, in
      * seconds relative to 0000 UT on 1 January 1900.  The integer part is
      * in the first 32 bits and the fraction part in the last 32 bits
      *
      * @return string
      */
     protected function _prepare()
     {
         $frac   = microtime();
         $fracba = ($frac & 0xff000000) >> 24;
         $fracbb = ($frac & 0x00ff0000) >> 16;
         $fracbc = ($frac & 0x0000ff00) >> 8;
         $fracbd = ($frac & 0x000000ff);
 
         $sec   = (time() + 2208988800);
         $secba = ($sec & 0xff000000) >> 24;
         $secbb = ($sec & 0x00ff0000) >> 16;
         $secbc = ($sec & 0x0000ff00) >> 8;
         $secbd = ($sec & 0x000000ff);
 
         // Flags
         $nul       = chr(0x00);
         $nulbyte   = $nul . $nul . $nul . $nul;
         $ntppacket = chr(0xd9) . $nul . chr(0x0a) . chr(0xfa);
 
         /*
          * Root delay
          *
          * Indicates the total roundtrip delay to the primary reference
          * source at the root of the synchronization subnet, in seconds
          */
         $ntppacket .= $nul . $nul . chr(0x1c) . chr(0x9b);
 
         /*
          * Clock Dispersion
          *
          * Indicates the maximum error relative to the primary reference source at the
          * root of the synchronization subnet, in seconds
          */
         $ntppacket .= $nul . chr(0x08) . chr(0xd7) . chr(0xff);
 
         /*
          * ReferenceClockID
          *
          * Identifying the particular reference clock
          */
         $ntppacket .= $nulbyte;
 
         /*
          * The local time, in timestamp format, at the peer when its latest NTP message
          * was sent. Contanis an integer and a fractional part
          */
         $ntppacket .= chr($secba)  . chr($secbb)  . chr($secbc)  . chr($secbd);
         $ntppacket .= chr($fracba) . chr($fracbb) . chr($fracbc) . chr($fracbd);
 
         /*
          * The local time, in timestamp format, at the peer. Contains an integer
          * and a fractional part.
          */
         $ntppacket .= $nulbyte;
         $ntppacket .= $nulbyte;
 
         /*
          * This is the local time, in timestamp format, when the latest NTP message from
          * the peer arrived. Contanis an integer and a fractional part.
          */
         $ntppacket .= $nulbyte;
         $ntppacket .= $nulbyte;
 
         /*
          * The local time, in timestamp format, at which the
          * NTP message departed the sender. Contanis an integer
          * and a fractional part.
          */
         $ntppacket .= chr($secba)  . chr($secbb)  . chr($secbc)  . chr($secbd);
         $ntppacket .= chr($fracba) . chr($fracbb) . chr($fracbc) . chr($fracbd);
 
         return $ntppacket;
     }
 
     /**
      * Calculates a 32bit integer
      *
      * @param string $input
      * @return integer
      */
     protected function _getInteger($input)
     {
         $f1  = str_pad(ord($input[0]), 2, '0', STR_PAD_LEFT);
         $f1 .= str_pad(ord($input[1]), 2, '0', STR_PAD_LEFT);
         $f1 .= str_pad(ord($input[2]), 2, '0', STR_PAD_LEFT);
         $f1 .= str_pad(ord($input[3]), 2, '0', STR_PAD_LEFT);
         return (int) $f1;
     }
 
     /**
      * Calculates a 32bit signed fixed point number
      *
      * @param string $input
      * @return float
      */
     protected function _getFloat($input)
     {
         $f1  = str_pad(ord($input[0]), 2, '0', STR_PAD_LEFT);
         $f1 .= str_pad(ord($input[1]), 2, '0', STR_PAD_LEFT);
         $f1 .= str_pad(ord($input[2]), 2, '0', STR_PAD_LEFT);
         $f1 .= str_pad(ord($input[3]), 2, '0', STR_PAD_LEFT);
         $f2  = $f1 >> 17;
         $f3  = ($f1 & 0x0001FFFF);
         $f1  = $f2 . '.' . $f3;
         return (float) $f1;
     }
 
     /**
      * Calculates a 64bit timestamp
      *
      * @param string $input
      * @return float
      */
     protected function _getTimestamp($input)
     {
         $f1  = (ord($input[0]) * pow(256, 3));
         $f1 += (ord($input[1]) * pow(256, 2));
         $f1 += (ord($input[2]) * pow(256, 1));
         $f1 += (ord($input[3]));
         $f1 -= 2208988800;
 
         $f2  = (ord($input[4]) * pow(256, 3));
         $f2 += (ord($input[5]) * pow(256, 2));
         $f2 += (ord($input[6]) * pow(256, 1));
         $f2 += (ord($input[7]));
 
         return (float) ($f1 . "." . $f2);
     }
 
     /**
      * Reads the data returned from the timeserver
      *
      * This will return an array with binary data listing:
      *
      * @return array
      * @throws Zend_TimeSync_Exception When timeserver can not be connected
      */
     protected function _read()
     {
         $flags = ord(fread($this->_socket, 1));
         $info  = stream_get_meta_data($this->_socket);
 
         if ($info['timed_out'] === true) {
             fclose($this->_socket);
             throw new Zend_TimeSync_Exception('could not connect to ' .
                 "'$this->_timeserver' on port '$this->_port', reason: 'server timed out'");
         }
 
         $result = array(
             'flags'          => $flags,
             'stratum'        => ord(fread($this->_socket, 1)),
             'poll'           => ord(fread($this->_socket, 1)),
             'precision'      => ord(fread($this->_socket, 1)),
             'rootdelay'      => $this->_getFloat(fread($this->_socket, 4)),
             'rootdispersion' => $this->_getFloat(fread($this->_socket, 4)),
             'referenceid'    => fread($this->_socket, 4),
             'referencestamp' => $this->_getTimestamp(fread($this->_socket, 8)),
             'originatestamp' => $this->_getTimestamp(fread($this->_socket, 8)),
             'receivestamp'   => $this->_getTimestamp(fread($this->_socket, 8)),
             'transmitstamp'  => $this->_getTimestamp(fread($this->_socket, 8)),
             'clientreceived' => microtime(true)
         );
 
         $this->_disconnect();
         return $result;
     }
 
     /**
      * Sends the NTP packet to the server
      *
      * @param  string $data Data to send to the timeserver
      * @return void
      */
     protected function _write($data)
     {
         $this->_connect();
 
         fwrite($this->_socket, $data);
         stream_set_timeout($this->_socket, Zend_TimeSync::$options['timeout']);
     }
 
     /**
      * Extracts the binary data returned from the timeserver
      *
      * @param  string|array $binary Data returned from the timeserver
      * @return integer Difference in seconds
      */
     protected function _extract($binary)
     {
         /*
          * Leap Indicator bit 1100 0000
          *
          * Code warning of impending leap-second to be inserted at the end of
          * the last day of the current month.
          */
         $leap = ($binary['flags'] & 0xc0) >> 6;
         switch($leap) {
             case 0:
                 $this->_info['leap'] = '0 - no warning';
                 break;
 
             case 1:
                 $this->_info['leap'] = '1 - last minute has 61 seconds';
                 break;
 
             case 2:
                 $this->_info['leap'] = '2 - last minute has 59 seconds';
                 break;
 
             default:
                 $this->_info['leap'] = '3 - not syncronised';
                 break;
         }
 
         /*
          * Version Number bit 0011 1000
          *
          * This should be 3 (RFC 1305)
          */
         $this->_info['version'] = ($binary['flags'] & 0x38) >> 3;
 
         /*
          * Mode bit 0000 0111
          *
          * Except in broadcast mode, an NTP association is formed when two peers
          * exchange messages and one or both of them create and maintain an
          * instantiation of the protocol machine, called an association.
          */
         $mode = ($binary['flags'] & 0x07);
         switch($mode) {
             case 1:
                 $this->_info['mode'] = 'symetric active';
                 break;
 
             case 2:
                 $this->_info['mode'] = 'symetric passive';
                 break;
 
             case 3:
                 $this->_info['mode'] = 'client';
                 break;
 
             case 4:
                 $this->_info['mode'] = 'server';
                 break;
 
             case 5:
                 $this->_info['mode'] = 'broadcast';
                 break;
 
             default:
                 $this->_info['mode'] = 'reserved';
                 break;
         }
 
         $ntpserviceid = 'Unknown Stratum ' . $binary['stratum'] . ' Service';
 
         /*
          * Reference Clock Identifier
          *
          * Identifies the particular reference clock.
          */
         $refid = strtoupper($binary['referenceid']);
         switch($binary['stratum']) {
             case 0:
                 if (substr($refid, 0, 3) === 'DCN') {
                     $ntpserviceid = 'DCN routing protocol';
                 } else if (substr($refid, 0, 4) === 'NIST') {
                     $ntpserviceid = 'NIST public modem';
                 } else if (substr($refid, 0, 3) === 'TSP') {
                     $ntpserviceid = 'TSP time protocol';
                 } else if (substr($refid, 0, 3) === 'DTS') {
                     $ntpserviceid = 'Digital Time Service';
                 }
                 break;
 
             case 1:
                 if (substr($refid, 0, 4) === 'ATOM') {
                     $ntpserviceid = 'Atomic Clock (calibrated)';
                 } else if (substr($refid, 0, 3) === 'VLF') {
                     $ntpserviceid = 'VLF radio';
                 } else if ($refid === 'CALLSIGN') {
                     $ntpserviceid = 'Generic radio';
                 } else if (substr($refid, 0, 4) === 'LORC') {
                     $ntpserviceid = 'LORAN-C radionavigation';
                 } else if (substr($refid, 0, 4) === 'GOES') {
                     $ntpserviceid = 'GOES UHF environment satellite';
                 } else if (substr($refid, 0, 3) === 'GPS') {
                     $ntpserviceid = 'GPS UHF satellite positioning';
                 }
                 break;
 
             default:
                 $ntpserviceid  = ord(substr($binary['referenceid'], 0, 1));
                 $ntpserviceid .= '.';
                 $ntpserviceid .= ord(substr($binary['referenceid'], 1, 1));
                 $ntpserviceid .= '.';
                 $ntpserviceid .= ord(substr($binary['referenceid'], 2, 1));
                 $ntpserviceid .= '.';
                 $ntpserviceid .= ord(substr($binary['referenceid'], 3, 1));
                 break;
         }
 
         $this->_info['ntpid'] = $ntpserviceid;
 
         /*
          * Stratum
          *
          * Indicates the stratum level of the local clock
          */
         switch($binary['stratum']) {
             case 0:
                 $this->_info['stratum'] = 'undefined';
                 break;
 
             case 1:
                 $this->_info['stratum'] = 'primary reference';
                 break;
 
             default:
                 $this->_info['stratum'] = 'secondary reference';
                 break;
         }
 
         /*
          * Indicates the total roundtrip delay to the primary reference source at the
          * root of the synchronization subnet, in seconds.
          *
          * Both positive and negative values, depending on clock precision and skew, are
          * possible.
          */
         $this->_info['rootdelay'] = $binary['rootdelay'];
 
         /*
          * Indicates the maximum error relative to the primary reference source at the
          * root of the synchronization subnet, in seconds.
          *
          * Only positive values greater than zero are possible.
          */
         $this->_info['rootdispersion'] = $binary['rootdispersion'];
 
         /*
          * The roundtrip delay of the peer clock relative to the local clock
          * over the network path between them, in seconds.
          *
          * Note that this variable can take on both positive and negative values,
          * depending on clock precision and skew-error accumulation.
          */
         $this->_info['roundtrip']  = $binary['receivestamp'];
         $this->_info['roundtrip'] -= $binary['originatestamp'];
         $this->_info['roundtrip'] -= $binary['transmitstamp'];
         $this->_info['roundtrip'] += $binary['clientreceived'];
         $this->_info['roundtrip'] /= 2;
 
         // The offset of the peer clock relative to the local clock, in seconds.
         $this->_info['offset']  = $binary['receivestamp'];
         $this->_info['offset'] -= $binary['originatestamp'];
         $this->_info['offset'] += $binary['transmitstamp'];
         $this->_info['offset'] -= $binary['clientreceived'];
         $this->_info['offset'] /= 2;
         $time = (time() - $this->_info['offset']);
 
         return $time;
     }
 }