PHPCMS中用于获取客户端ip的函数

看了麦子哥博客发现了这个函数，记录下来以后备用吧

   function ip() {
	    if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) {
	        $ip = getenv('HTTP_CLIENT_IP');
	    } elseif(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')) {
	        $ip = getenv('HTTP_X_FORWARDED_FOR');
	    } elseif(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')) {
	        $ip = getenv('REMOTE_ADDR');
	    } elseif(isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')) {
	        $ip = $_SERVER['REMOTE_ADDR'];
	    }
	    return preg_match ( '/[\d\.]{7,15}/', $ip, $matches ) ? $matches [0] : '';
	}