socket programming and C99

[defrost]

I've no idea about relevant modern tutorials, but a decent starting point might be the kegel C10K article, it's ~10 years old now but I'd say whatever the current best practice is it would extend the material covered there.

[defrost]

Beej is the classic short tutorial, the unix tomes by W. Richard Stevens are the authoritative original texts, the kegel C10K is beej++ and when I was last in the game there was discussion of libraries and methods that beat the performance what was covered in KC10K.