CSRF protection

[andreakru]

hi

I have added a csrf protection to the class, you can see here:

https://github.com/macagoraga/form/commit/d0cad864f75de097fef2b47378d3bc5adeaaec4f

Usage:

<?php
$form = new Form();

// enable csrf passing key used for $_SESSION and $_POST
$form->enableCsrf('csrf_token');

// add csrf token into hidden field
$form->csrfToken();

$form->text('username');
$form->password('password');
$form->password('confirm_password');

$form->submit('submit_button', 'Click to Continue');

// when post is submit, check token
if($form->checkCsrf()) echo 'csrf passed';
else echo 'csrf failed';

// optional we can add timestamp, so token expire after X minutes
$timespan = 10; // 10 minutes
$onetime = false; // disable use token onetime, usefull when ajax 
$throwException = true; // trow an exception if failed
if($form->checkCsrf($timespan, $onetime, $throwException))
...

Inspired by https://github.com/BKcore/NoCSRF