<?php

function __start_session(){
	if(!defined('SESSION_START')){
		define('SESSION_START', true);
		session_set_cookie_params(86400*30);
		session_start();
	}
}
function set_session($key, $value, $maxage=2400){
	__start_session();
	$_SESSION[$key] = $value;
	$_SESSION[$key."__bccn__end_time"] = time()+$maxage;
}
function get_session($key){
	__start_session();
	if($_SESSION[$key."__bccn__end_time"] >= time()){
		return $_SESSION[$key];
	}else{
		del_session($key);
		del_session($key."__bccn__end_time");
		return null;
	}
}
function del_session($key){
	__start_session();
	unset($_SESSION[$key]);
}