PHP判断服务器端口是否打开的代码

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<?php $host = 'www.google.com'; //要ping的地址，也可以是IP  $port = '80'; //要ping的端口  $num = 3;  function microtime_float()  {  list($usec, $sec) = explode(" ", microtime());  return ((float)$usec + (float)$sec);  }  function ping($host,$port)  {  $time_start = microtime_float();  $ip = gethostbyname($host);  $fp = @fsockopen($host,$port,&$errno,&$errstr,1);  if(!$fp) return 'replay time out!';  $get = "GET / HTTP/1.1\r\nHost:".$host."\r\nConnection: Close\r\n\r\n";  @fputs($fp,$get);  @fclose($fp);  $time_end = microtime_float();  $time = $time_end - $time_start;  $time = ceil($time * 1000);  return 'Reply from '.$ip.': time='.$time.'ms<br />';  }  echo 'Pinging '.$host.' ['.gethostbyname($host).'] with Port:'.$port.' of data:<br /><br />'."\r\n";  for($i = 0;$i < $num;$i++)  {  ping($host,$port);  sleep(1);  ob_flush();  flush();  }  ?>