tp5获取真实ip地址

/*
* 获取用户真实IP地址
*/
public function get_ip()
{
if(!empty($_SERVER['HTTP_CLIENT_IP'])){
$cip = $_SERVER['HTTP_CLIENT_IP'];
}
else if(!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){
$cip = $_SERVER["HTTP_X_FORWARDED_FOR"];
}
else if(!empty($_SERVER["REMOTE_ADDR"])){
$cip = $_SERVER["REMOTE_ADDR"];
}else{
$cip = '';
}
preg_match("/[\d\.]{7,15}/", $cip, $cips);
$cip = isset($cips[0]) ? $cips[0] : 'unknown';
unset($cips);
return $cip;
}