11Session和数据保持

session_start();
$_SESSION['visits']++;
print'You have visited here '.$_SESSION['visits'].' times.
';
echo'session id = '.$_COOKIE['PHPSESSID'];
echo"
";
echo"session name = ".session_name()."
";
?>

SessionID记录在全局变量_COOKIE中，SessionID的名字是PHPSESSID，PHPSESSID也可以通过session_name()获得。

2 预防Session劫持

ini_set('sessio.use_only_COOKIEs', true);
session_start();
$salt = 'YourSpecialValueHere';
$tokenstr = date('W').$salt;
$token = md5($tokenstr);
echo'token = '.$token.'
';

if(!isset($_REQUEST['token']) || $_REQUEST['token'] != $token)
{
    exit;
}
$_SESSION['token'] = $token;
output_add_rewrite_var('token', $token);
echo'link';
ob_flush();
output_reset_rewrite_vars();
?>

session_start();
output_add_rewrite_var('var', 'value');

echo'link';
ob_flush();

output_reset_rewrite_vars();
echo'link';
?>以上例程会输出：

<ahref="file.php?PHPSESSID=xxx&var=value">linka><ahref="file.php">linka>

3 预防Session定制

• 不会把session标志符附加到URL上的session COOKIE.
• 频繁的生成新的sessionID

ini_set('session.use_only_COOKIE', true);
session_start();
if(!isset($_SESSION['generated']) || $_SESSION['generated'] <(time() - 30))
{
    session_regenerate_id();
    $_SESSION['generated'] = time();
}
echo$_COOKIE['PHPSESSID']