You can fork the repo and submit a pull request on GitHub. For more information send us an email (p4-dev@lists.p4.org).
All developers must sign the P4.org CLA and return it to (membership@p4.org) before making contributions. The CLA is available here.
Any contribution to the C++ core code must respect the coding guidelines. We follow the Google C++ Style Guide. We provide a script to automatically format all code correctly.