Hacking pages for Guestbook

• hello-world.php (Source) - This file writes Hello World (normal) and also logs the user out of the guestbook if he/she was loged-in
• hello-someone.php (Source) - files says hello John when you say you are John. Plus it adds an input in the guestbook if you are logged in.
• hello-world2.php (Source) - This file writes Hello World (normal) and changes the password of any user in the guestbook if the user is logged-in.