Re: [lwip-users] PPP

Hi Sylvain.

How I told you, I am facing problems with TCP-PPP in lwip scenario.

Then I decided use just a raw lwip code to reproduce the problem and, if it is possible, could you use it to reproduce in your environment.

I fetched my git repositoy today (15/jan). Hashs:

- lwip: e033866651903f4b12e6af074180272c5aadc553

- lwip-contrib: ddff8d34d0e7e5f417926aed032067e75c28a447

and I changed a little bit two files (attached).

- ports/unix/proj/unixsim/lwipopts.h

- ports/unix/proj/unixsim/simhost.c

The "simhost" then was compiled using the original makefile:

> cd .../lwip-contrib/ports/unix/proj/unixsim

> make

I have two VM´s (Ubuntu) in a Win-7 server. In the VM#1, I run the pppd (linux), passive mode. Just after, the simhost app is executed in VM#2. The link ppp is established, with no problem.

The simhost already implements a TCP echo server (reply). At VM#1, the echo client app (use the TCP linux stack, no lwip) is executed. The TCP connection is established.

After 3 or 4 string messages exchanged the lwip reports error and the TCP connection going to down. The client reports "Resource temporarily unavailable" and the simhost app sometimes shut down.

I apologize for my insistence, but we are in great need of a help.

Thanks.

2016-01-13 15:40 GMT-02:00 Norberto R. de Goes Jr. <address@hidden>:

Hi Sylvain, how are you?

Please, do you have any suggestion about my PPP-TCP problem reported?

Thanks.
Norberto

2016-01-08 7:53 GMT-02:00 Norberto R. de Goes Jr. <address@hidden>:
Hi Sylvain. I found the lwip HEAD in use:
409d7a99f95240e9188118d423dc88de5bf0a565

Thanks.

2016-01-06 9:45 GMT-02:00 Norberto R. de Goes Jr. <address@hidden>:
Hi Sylvain! Thanks for the prompt reply, much appreciated.

The version in use is HEAD - july/2015.
You asked about incoming bytestream level check. But I understand that the exception is happening at output level, in packets generated by the lwip core. Am I right?
Remembering that the UDP protocol use works fine what could validate the serial interface (connection between nodes).

Thanks again.

2016-01-05 17:51 GMT-02:00 Sylvain Rochet <address@hidden>:
Hi Norberto,

On Tue, Jan 05, 2016 at 11:26:35AM -0200, Norberto R. de Goes Jr. wrote:
> How are you doing?
>
> I am facing a problem in the use PPP-lwip.
> I have a application (app) using lwip stack. The app implements an echo
> message server (messages replier).
> The connection is through the PPP protocol (serial interface) no ethernet
> conection.
> When UDP messages are exchanged all is working fine. But when TCP is used,
> after the second message exchanged, the following error is throwed by the
> lwip:
>
> Assertion "RST not expected here!" failed at line 1033 in
> ../src/lwip_src/lwip/src/core/tcp_out.c

Which lwIP version are you using ? If Git, what's your HEAD hash ? We
don't assert on corrupted packets anymore (we try to remove all asserts
that can be remotely-triggered), it looks like an old code.

At first sight, I don't think PPP is related to the problem here, did
you check at the bytestream level that it is actually a wrongly
formatted incoming TCP packet ? If yes, there is not much we can do
except dropping the packet.

Sylvain

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--
Norberto R. de Goes Jr.
CPqD - DRC
Tel.: +55 19 3705-4241 / Fax: +55 19 3705-6125
address@hidden
www.cpqd.com.br

--
Norberto R. de Goes Jr.
CPqD - DRC
Tel.: +55 19 3705-4241 / Fax: +55 19 3705-6125
address@hidden
www.cpqd.com.br

--
Norberto R. de Goes Jr.
CPqD - DRC
Tel.: +55 19 3705-4241 / Fax: +55 19 3705-6125
address@hidden
www.cpqd.com.br

Norberto R. de Goes Jr.
CPqD - DRC
Tel.: +55 19 3705-4241 / Fax: +55 19 3705-6125
address@hidden
www.cpqd.com.br

From:	Norberto R. de Goes Jr.
Subject:	Re: [lwip-users] PPP - TCP
Date:	Fri, 15 Jan 2016 15:35:06 -0200

Re: [lwip-users] PPP - TCP