I'm writing a mobile app that aggregates weather data and generates a push notification when certain criteria are met. The user has the option to change some of the variables (e.g. if the current temperature exceeds X degrees) which is stored both on the device, and on my server.
When my app opens, it requests the GCM (or APN) token and the user-defined variables and sends them to my server via POST. The endpoint would look something like this (if it were a GET):
type would be
apple if it were an iOS device)
On the server end,
registerPush.php takes the variables and stores them (via prepared statements) in a MySQL database. The requester is allowed 1 registration per 10 seconds (determined via PHP sessions) and if they exceed that, they get locked out for 2 minutes, to avoid one user trying to spam the database with bogus entries.
Every hour, a cron job runs and loops through all the items. If the temperature exceeds
maxtemp, the token is added to an array, and bulk-sent to those users via the correct push method (e.g. GCM or APN).
I'd like to keep this system "anonymous" (that is, not require a user to sign up), because creating an account simply to store push notifications is a bit overkill for the simplistic nature of my app, and things such as "Login with Facebook" are the same, because why should a user sign in with Facebook, just to get push notifications?
So my question is, short of throttling registration attempts via
$_SESSIONs, and perhaps storing the last time the token was sent to the server (and clearing out old tokens after X many units of time), what can I do to make this system more secure, short of asking people to create an account (for a simple weather app)?