PHP 获取客户端IP地址

/**
 * 获取客户端IP地址
 * @param integer $type 返回类型 0 返回IP地址 1 返回IPV4地址数字
 * @return mixed
 */
public function getClientIp($type = 0) {
	$type = $type ? 1 : 0;
	static $ip = NULL;
	if ($ip !== NULL)
		return $ip[$type];
	if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
		$arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
		$pos = array_search('unknown', $arr);
		if (false !== $pos)
			unset($arr[$pos]);
		$ip = trim($arr[0]);
	}elseif (isset($_SERVER['HTTP_CLIENT_IP'])) {
		$ip = $_SERVER['HTTP_CLIENT_IP'];
	} elseif (isset($_SERVER['REMOTE_ADDR'])) {
		$ip = $_SERVER['REMOTE_ADDR'];
	}
	// IP地址合法验证
	$long = sprintf("%u", ip2long($ip));
	$ip = $long ? array($ip, $long) : array('0.0.0.0', 0);
	return $ip[$type];
}