RE: SPAM? [lwip-users] Duplicate FINs and CLOSE_WAIT state

[Jan Ulvesten]

Hi

Thanks, it sounds like this is might be the solution. I will try it and
come back with a status-report. Likewise with the new checksum routine
(the old one never worked on Altera NIOS).

Jan

-----Original Message-----
From: Kelvin Lawson [mailto:address@hidden 
Sent: 14. desember 2005 11:10
To: address@hidden
Subject: SPAM? [lwip-users] Duplicate FINs and CLOSE_WAIT state

Hi,

Jan's earlier message reminded me of a problem I've seen in tcp_in.c:

When we receive a FIN, we do a +1 and send an ack as we should, and go 
into CLOSE_WAIT state. If we receive a duplicate FIN, however, we do 
another +1, and send another ack with the new ackno. This can lead to 
sticky situations - From memory, I think the effect I saw was a storm of

network traffic, where both ends are acking each other constantly, with 
the LWIP end erroneously upping the ackno every time.

The attached patch prevents the additional +1 if we receive duplicate
FINs.

Cheers,
Kelvin.