missing fin/ack server to client

[lumontec]

Describe the bug
rpc_server does not properly close connection after client requests for session termination. This will leave the client hanging waiting for a FIN/ACK packet that never arrives from server side.

To Reproduce
Steps to reproduce the behavior:
Tap connection with tcpdump or wireshark
./build/release/bin/smf_demo_server
./build/release/bin/smf_demo_client

Expected behavior

Observed behavior

Additional context
This happens w/o tls enabled.