<?PHP

function generate_user_id()
{
	// this value is needed so nobody could steal a session from another use
	// putting in here the client IP would be best, but in fact ISPs like AOL
	// use their proxy and so client requests come from different IPs, even
	// if the same client requests stuff and worst of it, this might change
	// within seconds.
	// so yet we only check the HTTP_USER_AGENT, maybe someday there comes be more.
	
	return md5($_SERVER['HTTP_USER_AGENT']);
}

function kill_user_session()
{
	// empty the session array by filling it with an empty array
	
	$_SESSION = array();
	
	// use the function coming with PHP to destroy the session
	
	@session_destroy();
	
	return 0;
}

function user_session_start()
{
	session_start();
	$session_id = session_id();
	
	if(!session_is_registered('last_action'))
	 	$_SESSION['last_action']=time();
	 	
	if(!session_is_registered('session_unique_id'))	 
		$_SESSION['session_unique_id'] = md5(uniqid(rand(), true));
		
	//if(!session_is_registered('session_unique_id'))	 
	//	$_SESSION['session_unique_id'] = generate_user_id();
			
	return $session_id;
}

function user_session_store( $userdata, $cookie_name = "gframe" )
{
	// hash password so nobody can steal the password out of the local cookie file
	
	$password = md5($password);
	
	// put the cookie together, serialize the array so it can be handeled and make a simple encryption around it
	
	$cookie['username'] = $userdata['username'];
	$cookie['password'] = $userdata['password'];
	
	$cookie = serialize($cookie);
	$cookie = base64_encode($cookie);
	
	setcookie("$cookie_name", $cookie, time()+86400);	
}

function user_session_restore( $cookie_name = "gframe" )
{
	$cookie = $_COOKIE[$cookie_name];
	
	$cookie = unserialize(base64_decode($cookie));
	
	$userdata['username'] = $cookie['username'];
	$userdata['password'] = $cookie['password'];
	
	return $userdata;
}

function check_session($session_expire_time)
{
	if($_SESSION['session_unique_id'] != generate_user_id())
		$session = kill_user_session();
	if(($_SESSION['last_action'] + $session_expire_time) < time())
		$session = kill_user_session();	 
	else
		{
			$_SESSION['last_action']=time();
			$session = true;
		}
	return $session;	
}

function check_user_session($session_expire_time)
{
	// function get its parent function from check_session
	
	$result = check_session($session_expire_time);

	// check if the session is a 'admin session'
	
	if($_SESSION['session_type'] != 'user')
		$result = false;
		
	return $result;
}

function check_admin_session($session_expire_time)
{
	// function get its parent function from check_session
	
	$result = check_session($session_expire_time);

	// check if the session is a 'admin session'
	
	if($_SESSION['session_type'] != 'admin')
		$result = false;
		
	return $result;	
}

?>