Re: [lwip-users] PCB states stay in FIN_WAIT_1

[Kieran Mansley]

On Fri, 2010-07-09 at 11:21 +0200, Theou Jean-Baptiste wrote:
> Hello everyone,
> 
> I've a problem with lwIP (1.3.2 on atmel) on TCP/IP transmission. I
> use lwIP in FreeRTOS. 
> In my project, web interface make an request (every 2 sec approx. ) to
> http server (who is on my embedded system) via
> http://192.168.0.120/CONFIG?blabla.
> Everything thing ok but after a while (seems random), request doesn't
> have answer anymore. 

If you're sure the connections are stuck in FIN_WAIT_1 then we need to
consider why.  TCP connections can move from there to FIN_WAIT_2 if we
receive the ACK of our FIN, or to CLOSING if we receive a FIN from the
other end.  It sounds like we're getting neither.  This suggests that
something else is preventing the reception or processing of TCP
segments.  Could there be a resource like packet buffers that has become
exhausted, or some threading issue that has resulted in deadlock?  I
would investigate this sort of thing, particularly if you can get a
packet capture showing the other end cooperating by ACKing the FIN or
sending its own FIN which should be allowing lwIP to move those
connections on to the next states.

Kieran