Is there a definitive anti-XSS library for PHP?

Question

I already know how XSS works, but finding out all the many different ways to inject malicious input is not an option.

I saw a couple libraries out there, but most of them are very incomplete, ineficient, or GPL licensed (when will you guys learn that GPL is not good to share little libraries! Use MIT)

Answer 1

htmlspecialchars() is the only function you should know about.