[En-Nut-Discussion] NutTcpConnect freeze

[Ole Reinhardt]

Hi Andras,

while searching for a problem in NutTcpConnect() I stumbled over your
following message to the Ethernut Mailing list.

I have exact the same problem with Nut/OS 4.9.8 running on a ethernut
3.1 board. But it does not take much more than 10 connect retries (with
a not connected network cable) to raise this condition.

Did you found a solution in the meantime?

Regards,

Ole Reinhardt


> I have a couple of AVR based modules with GPRS connection. There are a very rare cases ( It can be 3 weeks, or 3 months without a restart)
> when NutTcpConnect fails to return. Nut 4.3.3 is the base, there was a commit for such a bug, but that one is before this release.
> 
> Becouse it's very rare case, I cannot debug this easily, but in my opinion there must be something happen with the other side, strange network done etc..
> and what I seen before the socket will remain in SYN SENT state, and than nothing happens, that thread will be blocked forever.
> 
> I don't really know Nut tcp state machine internals, but could't these block come from here?
> 
> int NutTcpStateActiveOpenEvent(TCPSOCKET * sock)
> {
>     /*
>      * Switch state to SYN_SENT. This will
>      * transmit a SYN packet.
>      */
>     NutTcpStateChange(sock, TCPS_SYN_SENT);
> 
>     /*
>      * Block application.
>      */
> 	 if(sock->so_state == TCPS_SYN_SENT)
> 		NutEventWait(&sock->so_ac_tq, 0);
> 
>     if (sock->so_state != TCPS_ESTABLISHED)
>         return -1;
> 
>     return 0;
> }
> 
> 
> The NutEventWait will block forever.  It's safe to add a relative big timeout to event wait? Or there are other ideas?
> 
> 
> Best Regards,
> Andras
>  
> _______________________________________________
> http://lists.egnite.de/mailman/listinfo/en-nut-discussion

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