Forwarding packets to the host stack in net map lb app

From: Kim Shrier <kim_at_westryn.net>
Date: Sun, 18 Sep 2022 21:47:30 UTC
I have a network monitoring program and I am using the lb app from
netmap to distribute packets to netmap pipes.  The monitor processes
are successfully receiving packets.

I would like to modify lb to send some packets to the host stack and
have packets coming from the host stack go out on the monitoring
ethernet interface.

I am relatively new to using netmap and it is not obvious to me how
to properly send/receive some packets to the host tx/rx rings while
still letting the the netmap pipes forward packets to my monitoring
application.

I have looked at the bridge app from netmap which opens 2 netmap
ports. It does not seem to me that that would be the right way to
deal with the host stack in the context of lb.

Should I just process the last tx/rx ring differently from the first ones
that are forwarding packets to the netmap pipes?

Thanks,
Kim