通过 PHP 从 NTP 服务器检索时间

问题描述 投票：0回答：3

我的虚拟机 (VMWare/Ubuntu) 遇到时间不同步的问题。我们认为最好的办法是直接从 NTP 服务器获取时间，所以我开始研究一个脚本来做到这一点，但到目前为止没有任何效果，这就是为什么我决定来这里看看是否有人可以指出我的正确方向方向。

为了澄清，我正在寻找一种通过 PHP 连接到时间服务器的方法，以直接检索时间并在我需要生成的时间戳上重用它，而不是同步服务器。

php ntp
3个回答
7
投票

我想从侦听端口 123 UDP rfc5905 的 ntp 服务器检索时间。我找到了解决方案here。 在我的工作页面 php 下方：

<!doctype html>  

<?php
session_start();
$please_wait = '';
$last = time();
if(isset($_SESSION['last'])) {
$last = $_SESSION['last'];
}
else {
$_SESSION['last'] = $last;
}
//wrap the whole thing in a test for the last hit-time on the page, to avoid abusing NTP servers
if (time() - $last < 15) {
  $wait = time() - $last;
  $please_wait = 'Request limit exceeded, please wait ' . (15 - $wait) . ' s.';
  $server = $vn_response = $mode_response = $stratum_response = $remote_originate = $remote_received
  = $remote_received = $remote_transmitted = $delay_ms = $ntp_time_formatted = $server_time_formatted = $please_wait;
}
else {
  $_SESSION['last'] = time();

  $bit_max = 4294967296;
  $epoch_convert = 2208988800;
  $vn = 3;
  
  $servers = array('0.uk.pool.ntp.org','1.uk.pool.ntp.org','2.uk.pool.ntp.org','3.uk.pool.ntp.org');
  $server_count = count($servers);
  
  //see rfc5905, page 20
  //first byte
  //LI (leap indicator), a 2-bit integer. 00 for 'no warning'
  $header = '00';
  //VN (version number), a 3-bit integer.  011 for version 3
  $header .= sprintf('%03d',decbin($vn));
  //Mode (association mode), a 3-bit integer. 011 for 'client'
  $header .= '011';
  
  //echo bindec($header);    
      
  //construct the packet header, byte 1
  $request_packet = chr(bindec($header));
  
  //we'll use a for loop to try additional servers should one fail to respond
  $i = 0;
  for($i; $i < $server_count; $i++) {
    $socket = @fsockopen('udp://'.$servers[$i], 123, $err_no, $err_str,1);
    if ($socket) {
      
      //add nulls to position 11 (the transmit timestamp, later to be returned as originate)
      //10 lots of 32 bits
      for ($j=1; $j<40; $j++) {
        $request_packet .= chr(0x0);
      }
      
      //the time our packet is sent from our server (returns a string in the form 'msec sec')
      $local_sent_explode = explode(' ',microtime());
      $local_sent = $local_sent_explode[1] + $local_sent_explode[0];
      
      //add 70 years to convert unix to ntp epoch
      $originate_seconds = $local_sent_explode[1] + $epoch_convert;
        
      //convert the float given by microtime to a fraction of 32 bits
      $originate_fractional = round($local_sent_explode[0] * $bit_max);
        
      //pad fractional seconds to 32-bit length
      $originate_fractional = sprintf('%010d',$originate_fractional);
        
      //pack to big endian binary string
      $packed_seconds = pack('N', $originate_seconds);
      $packed_fractional = pack("N", $originate_fractional);
  
      //add the packed transmit timestamp
      $request_packet .= $packed_seconds;
      $request_packet .= $packed_fractional;
      
      if (fwrite($socket, $request_packet)) {
        $data = NULL;
        stream_set_timeout($socket, 1);
        
        $response = fread($socket, 48);
        
        //the time the response was received
        $local_received = microtime(true);
        
        //echo 'response was: '.strlen($response).$response;
      }
      fclose($socket);
      
      if (strlen($response) == 48) {
        //the response was of the right length, assume it's valid and break out of the loop
        break;
      }
      else {
        if ($i == $server_count-1) {
          //this was the last server on the list, so give up
          die('unable to establish a connection');
        }
      }
    }
    else {
      if ($i == $server_count-1) {
        //this was the last server on the list, so give up
        die('unable to establish a connection');
      }
    }
  }
  
  //unpack the response to unsiged lonng for calculations
  $unpack0 = unpack("N12", $response);
  //print_r($unpack0);
  
  //present as a decimal number
  $remote_originate_seconds = sprintf('%u', $unpack0[7])-$epoch_convert;
  $remote_received_seconds = sprintf('%u', $unpack0[9])-$epoch_convert;
  $remote_transmitted_seconds = sprintf('%u', $unpack0[11])-$epoch_convert;
  
  $remote_originate_fraction = sprintf('%u', $unpack0[8]) / $bit_max;
  $remote_received_fraction = sprintf('%u', $unpack0[10]) / $bit_max;
  $remote_transmitted_fraction = sprintf('%u', $unpack0[12]) / $bit_max;
  
  $remote_originate = $remote_originate_seconds + $remote_originate_fraction;
  $remote_received = $remote_received_seconds + $remote_received_fraction;
  $remote_transmitted = $remote_transmitted_seconds + $remote_transmitted_fraction;
  
  //unpack to ascii characters for the header response
  $unpack1 = unpack("C12", $response);
  //print_r($unpack1);
  
  //echo 'byte 1: ' . $unpack1[1] . ' | ';
  
  //the header response in binary (base 2)
  $header_response =  base_convert($unpack1[1], 10, 2);
  
  //pad with zeros to 1 byte (8 bits)
  $header_response = sprintf('%08d',$header_response);
  
  //Mode (the last 3 bits of the first byte), converting to decimal for humans;
  $mode_response = bindec(substr($header_response, -3));
  
  //VN
  $vn_response = bindec(substr($header_response, -6, 3));
  
  //the header stratum response in binary (base 2)
  $stratum_response =  base_convert($unpack1[2], 10, 2);
  $stratum_response = bindec($stratum_response);
  //echo 'stratum: ' . bindec($stratum_response);
  
  //calculations assume a symmetrical delay, fixed point would give more accuracy
  $delay = (($local_received - $local_sent) / 2)  - ($remote_transmitted - $remote_received);
  $delay_ms = round($delay * 1000) . ' ms';
  //echo 'delay: ' . $delay * 1000 . 'ms';
  
  $server = $servers[$i];
  
  $ntp_time =  $remote_transmitted - $delay;
  $ntp_time_explode = explode('.',$ntp_time);
  
  $ntp_time_formatted = date('Y-m-d H:i:s', $ntp_time_explode[0]).'.'.$ntp_time_explode[1];
  
  //compare with the current server time
  $server_time =  microtime();
  $server_time_explode = explode(' ', $server_time);
  $server_time_micro = round($server_time_explode[0],4);
  
  $server_time_formatted = date('Y-m-d H:i:s', time()) .'.'. substr($server_time_micro,2);

}
?>

<html lang="en">  
<head>  
<meta charset="utf-8">
<title></title>  
<meta name="description" content="">  
<meta name="author" content="">
<style type="text/css">
td{
    width: 160px; height: 20px;
    padding: 4px;
    border: 1px solid #000;
    font-size: 12px;
}
.ntp_response{
    width: 240px;
}  
</style>
</head>
<body>
<table border="0">
<tr>
<td>Server:
<td class="ntp_response"><?php echo $server;?></td>
</tr>
<tr>
<td>VN (version number):</td>
<td class="ntp_response"><?php echo $vn_response;?></td>
</tr>
<tr>
<td>Mode:</td>
<td class="ntp_response"><?php echo $mode_response;?></td>
</tr>
<tr>
<td>Stratum:</td>
<td class="ntp_response"><?php echo $stratum_response;?></td>
</tr>
<tr>
<td>Origin time:</td>
<td class="ntp_response"><?php echo $remote_originate;?></td>
</tr>
<td>Received:</td>
<td class="ntp_response"><?php echo $remote_received;?></td>
</tr>
<td>Transmitted:</td>
<td class="ntp_response"><?php echo $remote_transmitted;?></td>
</tr>
<td>Delay:</td>
<td class="ntp_response"><?php echo $delay_ms;?></td>
</tr>
<td>NTP time:</td>
<td class="ntp_response"><?php echo $ntp_time_explode[0];?></td>
</tr>
<td>Server time:</td>
<td class="ntp_response"><?php echo $server_time_formatted;?></td>
</tr>
</table>
</body>
</html>
2
投票

答案中的代码似乎有点旧 - 它对我不起作用。 我编写了一个可与更现代的 NTP 版本配合使用的版本：

function ntp($server,$port=123){
  echo $server;
  $socket=@fsockopen("udp://$server",$port,$err_no,$err_str,1);
  if(!$socket)return;
  fwrite($socket,chr(0x1b).str_repeat("\0",47));
  $packetReceived=fread($socket,48);
  $unixTimestamp=unpack('N',$packetReceived,40)[1]-2208988800;
  $utcDate=date("Y-m-d H:i:s",$unixTimestamp);
  echo ":<b>$utcDate</b><br/>\n";
}

这是测试：

ntp('time.windows.com');
ntp('time.cloudflare.com');
ntp('time.facebook.com');
ntp('time.windows.com');
ntp('time.apple.com');
ntp('time.euro.apple.com');
ntp('ntp1.vniiftri.ru');
ntp('vniiftri.khv.ru');
ntp('ntp21.vniiftri.ru');
ntp('stratum1.net');
ntp('ntp.time.in.ua');
ntp('ts1.aco.net');
ntp('tick.usask.ca');
ntp('ntp.nict.jp');
ntp('pool.ntp.org');
0
投票

我想要一个总是返回结果的函数，所以我修改了函数递归。似乎当我使用虚拟服务器时，它返回“1899-12-31 19:00:00”，不确定这是否总是如此，但到目前为止它有效。我在华盛顿特区，当我尝试服务器“pool.ntp.org”时，它有时会返回一个空字符串。

我使用随机播放来确保我不会一直偏爱特定服务器，以免滥用资源。

function ntp(){
    $port=123;
    $servers = array(
        "dummy"=>"time.dummy.com",
        "windows"=>"time.windows.com",
        "cloudflare"=>"time.cloudflare.com",
        "facebook"=>"time.facebook.com",
        "apple"=>"time.apple.com",
        "pool"=>"pool.ntp.org",
        );
        
    shuffle($servers);
    
    $socket=@fsockopen("udp://$servers[0]",$port,$err_no,$err_str,1);
    if(!$socket){
        //ntp();  // Always seems to create socket in my testing, You can always try uncommenting this line for retry
        return;
    }
    stream_set_timeout($socket, 3);
    fwrite($socket,chr(0x1b).str_repeat("\0",47));
    $packetReceived=fread($socket,48);
    $unixTimestamp=unpack('N',$packetReceived,40)[1]-2208988800;
    $utcDate=date("Y-m-d H:i:s",$unixTimestamp);
    // contains: 1899 (server does not exist so get another sever recurse)
    //echo '^';
    //echo $utcDate;
    //echo '^';
    if( $utcDate === '' || $utcDate === '1899-12-31 19:00:00' ){
        //echo "retry";
        ntp();
    }
    else{
        echo "$servers[0]~$utcDate";
    }
}
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