WG: [En-Nut-Discussion] PPP/AHDLC logic problems...

[Ernst Stippl]

Hi!

I concentrated my testing in January on link establishing, using Eduardo's
CHAP implementation, which worked well for me. I did not look into link
disconnection, due to the nature of my app.

regards
Ernst

-----Ursprüngliche Nachricht-----
Von: en-nut-discussion-bounces at egnite.de
[mailto:en-nut-discussion-bounces at egnite.de] Im Auftrag von Brett Abbott
Gesendet: Samstag, 16. April 2005 23:54
An: Ethernut User Chat (English)
Betreff: Re: [En-Nut-Discussion] PPP/AHDLC logic problems...

Vesa, Harald

I think this is the same problem already resolved by Eduardo Serantes but
not released formally into NutOS.  He published his patch on 14th Jan 2005
to this discussion group for review.  Have a look at this, it is quite
thorough.

Ernst Stippl, Eduardo and I have tested this and in the words of Ernst (Jan
27), "In my opinion, it should be released".

I suspect there is still a minor memory leak associated with closing PPP
(which was there since ppp was first release) surrounding routes not being
removed - only an issue if you open and close it alot.

Im working (slowly) on a small mod to allow you to suspend PPP to issue
short AT commands without disconnecting the PPP session but this isnt
related to your issue.

It may pay for one of the three of us (Eduardo, Ernst or Me) to revise the
PPPC.c demo code to show how to close and subsequently reconnect from PPP.

Hope this helps.
Brett



Vesa Jääskeläinen wrote:

> Hi,
>
> I have been trying to solve problem with closing PPP connection and 
> then issuing hangup sequence and continuing using it for normal AT 
> commands and perhaps create another PPP connection.
>
> First problem I see here is to close PPP-connection. I am using 
> following to close it:
>
> _ioctl(pppcom, LCP_CLOSE, 0);
> //_ioctl(pppcom, LCP_LOWERDOWN, 0);
> if (pppcom != -1)
> {
>     _close(pppcom);
>     pppcom = -1;
> }
>
> // Reopen device
> // _open()...
> // hangup sequence here
>
> Now problem with _close() is that it only closes IPCP and not LCP. So 
> I need to shutdown LCP either by LCP_CLOSE/LCP_LOWERDOWN.
>
> After this ahdlc thread is still handling all characters from USART. 
> There is bug in this routine as it never allows leaving the loop. So 
> if I add following patch to ahdlcavr.c, ...
>
> -----
> diff -u -r1.8 ahdlcavr.c
> --- ahdlcavr.c  5 Apr 2005 17:44:56 -0000       1.8
> +++ ahdlcavr.c  16 Apr 2005 18:52:02 -0000
> @@ -438,6 +438,9 @@
>                  }
>              }
>
> +            if (dev->dev_icb == 0)
> +                break;
> +
>              ch = dcb->dcb_rx_buf[dcb->dcb_rd_idx++];
>
>              if (inframe) {
> -----
>
> ... there is even possibility that it gets out of that loop. After a 
> timeout or received character it would exit that loop, this waiting 
> could also be triggered in _ioctl HDLC_SETIFNET, but the problem is 
> that no-one is calling it...
>
> Is there someone with more knowledge where would be correct place to 
> fix this? I will continue to evaluate this myself, but if someone has 
> more information about it's internals I would be pleased to hear about 
> them. If I just call this ioctl myself, I get reboots and that ain't 
> nice.
>
> In my opinion there is at least a bug in PPP as it doesn't lower LCP 
> on closing and I need to manually to do that. There is one _ioctl(fd, 
> HDLC_SETIFNET, 0) in PPP's state machine, but that state is never 
> reached in my tests.
>
> Thanks,
> Vesa Jääskeläinen
> _______________________________________________
> En-Nut-Discussion mailing list
> En-Nut-Discussion at egnite.de
> http://www.egnite.de/mailman/listinfo.cgi/en-nut-discussion
>
>

--
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Brett Abbott, Managing Director, Digital Telemetry Limited
Email: Brett.Abbott at digital-telemetry.com
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