php获取客户端真实IP

//获取客户端ip

public function getip(){ 
$onlineip=''; 
if(getenv('HTTP_CLIENT_IP')&&strcasecmp(getenv('HTTP_CLIENT_IP'),'unknown')){ 
$onlineip=getenv('HTTP_CLIENT_IP'); 
} elseif(getenv('HTTP_X_FORWARDED_FOR')&&strcasecmp(getenv('HTTP_X_FORWARDED_FOR'),'unknown')){ 
$onlineip=getenv('HTTP_X_FORWARDED_FOR'); 
} elseif(getenv('REMOTE_ADDR')&&strcasecmp(getenv('REMOTE_ADDR'),'unknown')){ 
$onlineip=getenv('REMOTE_ADDR'); 
} elseif(isset($_SERVER['REMOTE_ADDR'])&&$_SERVER['REMOTE_ADDR']&&strcasecmp($_SERVER['REMOTE_ADDR'],'unknown')){ 
$onlineip=$_SERVER['REMOTE_ADDR']; 
} 
return $onlineip; 

}