Re: [lwip-users] netconn/netbuf api with receiving timeout missing closed connection

[Dmitri Snejko]

Kieran Mansley wrote:
> On Fri, 2009-10-30 at 23:27 -0400, Dmitri Snejko wrote:
>   
> > I tried 1.3.1 and the last api_lib.c from SVC with a fix for
> > netconn_recv. It is still loosing closed conditions. 
> > I think there is something  more then just racing conditions in on
> > netconn->err. I found if i use 0 timeout  
> > closed remote side cached well but if i close the client side suddenly
> > on the middle of transition LwIP won't recover and close  
> > the connection  with a timeout. It still keep it opened.
> > Socket API build on netconn as well is doing well in all situations.  
> >     
>
> Can you get a packet capture to show the case where lwIP fails to spot
> the closed connection?
>
> Thanks
>
> Kieran
>
>
>
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Hello Kieran,

I have found the reason why the closed connection was missed with 
receiving timeout set to 0. It was my application problem. The remote 
side application was closed and windows stack sent RST. Netconn_recv set 
err to  ERR_RST. My application tried to close the netconn calling 
netconn_close, netconn_delete. Netconn_close nether returned back 
frizzing the receiving task. I removed netconn_close and left only 
netconn_delete, never missed ERR_RST or ERR_CLSD any more.
For timeout set >0 lwip is still missing  closed connections but it 
could be  the racing  you mentioned. I found the all  idea  doesn't work 
well and the application should follow  sockets select way to be really 
nonblocking on multiple netconns. 
Thanks
Dmitri.