This is a open list challenge to help you learn to write real XDP programs. The playground requires you to input code and they get verdicted.
A running instance of the playground is available at http://playground.xdp.no/
If you'd like to submit a challenge for inclusion to the playground, please see Adding a challenge. Writing new challenges is welcomed and appreciated but other contributions like rewording or typo fixes are also very welcome. See Run XDP playground.