support Frame.get with cffi backend

[minrk]

CFFI backend hasn't implemented Frame.get/set, which comes up mainly for the security metadata.

[subiol]

I was trying to access the user-id in a auth secured connection. Does this mean at the moment metadata information, and thus the user-id, can not be accessed with pyzmq?

[minrk]

When using the CFFI backend (i.e. in pypy), yes. The Cython backend does support this metadata, but you must use frames = socket.recv_multipart(copy=False) to access it.

[mattip]

Is this still actionable?

[minrk]

Yes, Frame.get/set (should wrap zmq_msg_get/set) is not implemented in the CFFI backend. Cython implementation is here