PHPはMAC情報を取得する

class GetMacAddr{  
   var $return_array = array(); //     MAC         
   var $mac_addr;  
   function GetMacAddr($os_type){  
        switch ( strtolower($os_type) ){  
                 case "linux":  
                           $this->forLinux();  
                           break;  
                 case "solaris":  
                           break;  
                 case "unix":  
                            break;  
                  case "aix":  
                            break;  
                  default:  
                            $this->forWindows();  
                            break;  
    
         }  
         $temp_array = array();  
         foreach ($this->return_array as $value ){  
                  if (preg_match("/[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f][:-]"."[0-9a-f][0-9a-f]/i",$value,$temp_array ) ){  
                      $this->mac_addr = $temp_array[0];  
                      break;  
                  }  
    
         }  
         unset($temp_array);  
         return $this->mac_addr;  
    }  
    
    function forWindows(){  
         @exec("ipconfig /all", $this->return_array);  
         if ( $this->return_array )  
                  return $this->return_array;  
         else{  
                  $ipconfig = $_SERVER["WINDIR"]."\system32\ipconfig.exe";  
                  if ( is_file($ipconfig) )  
                     @exec($ipconfig." /all", $this->return_array);  
                  else 
                     @exec($_SERVER["WINDIR"]."\system\ipconfig.exe /all", $this->return_array);  
                  return $this->return_array;  
         }  
    }  
    
    function forLinux(){  
         @exec("ifconfig -a", $this->return_array);  
         return $this->return_array;  
    }  
         
   }  
 
$mac = new GetMacAddr(PHP_OS);  
 
echo $mac->mac_addr;