The missing support prevents socket_wrapper from being used for fine-tunned applications using recvmmsg, like the Knot DNS server.
Let me know if I can assist somehow, I would be happy to test the support.
This is a glibc (gnu linux) only extension according to the manpage. If we add support for recvmmsg() we also need sendmmsg().
I do not have time to work on that right now, but I'm happy to review patches.
The standard implementation is normally not big deal. The hard part is msg_control handling ...