[TYPO3] suggestions on form submit

[M.Couperus]

Hello all,

We created a simple extension with kickstarter and added custom code to it.
Everything seems to work fine except for one detail with which I'm not
happy. One of our PHP developers decided to submit the form to itself.
Normally I would post the form to a handler which checks the submitted data
and then submits this data (if the data adhered to specified rules) to the
database. As far as I know (in theory) this should be more secure. But how
to do this?  Personally I'm not that advanced in PHP programming and TYPO3
and so  I would post to -- for example--  'process.php'. This wouldn't work
in our case because I want to 'echo' the submitted data again to the user
without leaving the location in the CMS. In addition it would be vulnerable
to sql injections because it would be wide open to the internet i.e. (post
to www.domain.com/process.php)

 So the question: "How to process form data in typo3 effective and secure?"

Thanks in advance.

Regards,

Marco