[bityard]

Yes, it's called the GPL: https://en.wikipedia.org/wiki/GNU_General_Public_License

Under the GPL, a competitor can certainly take the code, rebrand it, and sell it as their own but they are required to provide the full source code of whatever "borrowed" GPL code they distribute to the end user. This ensures that the source (and whatever changes/additions are made) cannot be taken and locked up by someone else, which is possible with more permissive licenses like the BSD and MIT licenses.