Subject: nncp-xfer not respecting -seen

From: John Goerzen <[email-masked]>
Date: Sat, 05 Mar 2022 09:51:37 -0600

Hi Sergey,

In running this new code in 8.7.0, I've been observing the occasional
duplicate processing of a packet.  That's surprising to me, because I
use -seen with nncp-toss at every possible location.

Diving into it a bit, I see that:

1) An appropriate file is being created in seen/ after the first toss

2) When nncp-xfer -rx is used over a directory containing a packet that
has previously been seen, it generates an ACK for it (probably the right
thing to do) and but also the packet is placed into rx (probably not the
right thing to do)

3) nncp-toss will process it again despite the existence of seen/ for
it.

I looked at the code a bit, and it seems that the seen check is done
during the rx path of nncp-bundle and the tx path of nncp-xfer.  My
intuition says the nncp-bundle approach is correct but I may be
misunderstanding the code here.

Thanks!

- John