I'm writing a php page that will display user input from a form on a page.
Is there a program that I can run the user input through to make sure it
isn't malious:

<?
do_bad_stuff(now);
?>

or stupid html syntax errors that will mess up the look of the rest of the
page:

<H1>blah blah .H1>

I'd rather no block all html (ie just delete all < and >), but maybe only
allow color, size and bold type stuff (frames could be annoying :) )


Thanks,

Ben