<?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

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

 */

/**

 * Zend_TimeSync_Protocol

 */

require_once 'Zend/TimeSync/Protocol.php';

/**

 * NTP Protocol handling class

 *

 * @category  Zend

 * @package   Zend_TimeSync

 * @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'];