[En-Nut-Discussion] Ethernet problem, application crash, problem in NutTcpReceive

[bon at elektron.ikp.physik.tu-darmstadt.de]

Michael Fischer writes:
> Hello List,
> 
> for the test I use the trunk version 6699 and a STM3240G-EVAL board.
> The application was compiled in debug mode with the GNU Arm Embedded Toolchain
> in version 7-2017-q4.

Strange, version 6699 is on Philips branch for lm3s.

> 
> The application is the iperf application for testing the Ethernet performance.
> Some more infos about JPerf can be find here on my page, which was done with lwIP:
> https://www.emb4fun.de/projects/tctsallwipuhttp/index.html
> 
> JPerf, version 2.0.2, can be find here:
> https://code.google.com/archive/p/xjperf/
> 
The link gives 404.

I tried iperf3 first, but could not get it to talk to the test
program. With much fiddling, I was able to find and setup iperf and
jperf in  version 2

> The application I used for NutOS was attached at the end of this description too.
> 
> The application does not use DHCP, it use a static IP-Adress, 192.168.1.200.
> With the JPerf GUI it is possible to use one or more stream to connect with the
> target. If the JPerf GUI is started with the "Run IPerf!" button it runs 10 seconds
> and stop automatically.
> 
> This makes no problem if one or more streams are used. The application can handle up
> to 4 streams in parallel.
> 
> How to produce the error?
> 
> Start the JPerf with the "Run IPerf!" button, do not wait the 10 seconds, it should
> not stop automatically. Stop manually with the "Stop IPerf" button.
> 
> Now the application crash, and stops in IntBusfaultHandler.
>

I tested on a Nucleo F767 with svn head and version 6700 and in no
situation could reproduce the error.

> The problem is a NULL pointer access in the while loop in NutTcpReceive:
> 
>          ab_cnt = 0;
>          while (ab_cnt < size) {
>              nb = sock->so_rx_buf;
>              nb_cnt = nb->nb_ap.sz - rd_cnt;
>              mv_cnt = size - ab_cnt;
>     
> nb is NULL here.
> 
> The problem can be fixed with the following code after the first while loop:
> 
>      /*
>       * Wait until any data arrived, a timeout occurs
>       * or the connection terminates.
>       */
>      while (sock->so_rx_cnt - sock->so_rd_cnt == 0) {
>          if (sock->so_state != TCPS_ESTABLISHED) {
>              sock->so_last_error = ENOTCONN;
>              return -1;
>          }
>          if (NutEventWait(&sock->so_rx_tq, sock->so_read_to))
>              return 0;
>      }
> 
>      /* @@MF start: Check for terminated connection with empty buffer */
>      if ((sock->so_state != TCPS_ESTABLISHED) && (NULL == sock->so_rx_buf)) {
>          sock->so_last_error = ENOTCONN;
>          printf(".");
>          return -1;
>      }
>      /*  @@MF end */
> 
Please, provide a diff. Textual descripton of what to change in some
code is error prone.

Even if I can not reproduces, I will consider applying.

I also consider to put your programm into the app directory as
iperf2_server. Does that naming sound right for you. I think, the
program implements an iperf server, and at the moment only for iperf2.


Bye
-- 
Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
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