I’ve been trying to find some detailed information on the Quake 3 master server protocol without any luck. Reverse engineering dpmaster is not really an option since that code is very messy and contains lot’s of hacks for different engines. Do you guys have any lost tutorials laying around somewhere? 
The dpmaster master protocol is documented at https://hg.icculus.org/molivier/dpmaster/file/fafe4720af15/doc/techinfo.txt#l142. It’s nearly idential to the Q3A master protocol, differences are noted through out. “getserversExt” and “getserversExtResponse” (called extras there) were not part of Q3A master protocol.
It’s on id’s FTP. I assume someone from id wrote it.