PHP get MAC address

<?php 
/** 
获取网卡的MAC地址原码；目前支持WIN/LINUX系统 
获取机器网卡的物理（MAC）地址 
**/
 
class GetMacAddr{ 
 
        var $return_array = array(); // 返回带有MAC地址的字串数组 
        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; 
         } 
 
} 
//方法使用 
//$mac = new GetMacAddr(PHP_OS); 
//echo $mac->mac_addr; 
?>