[lwip-users] lwIP UDP echo server fails to send message

[Peter]

AFAIK there is no support forum or "community" for LWIP today. It is a
project which was at its height about 15 years ago and the devs have
generally moved on long ago.

This also means that if somebody develops a solution for something,
they have nowhere to post it.

Googling digs up lots of old stuff, mostly pre-2011. There is also a
lot of clickbait - sites which collate content from other sites.

I post questions all over the place (EEVBLOG, the ST forum) and
occassionally somebody bites, or I find someone who replies privately.

I doubt LWIP has any obvious bugs after all these years but there is
certainly some complex behaviour related to how much buffering has
been allocated. Like that business of broadcast packets messing stuff
up.


Peter


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>Today's Topics:
>
>   1. Re: lwIP UDP echo server fails to send message lengths of
>      4385 & 4386 (Dan Nygren)
>   2. Re: lwIP UDP echo server fails to send message lengths of
>      4385 & 4386 (Sylvain Rochet)
>   3. lwIP deInit (Thompson, Jeff)
>   4. Re: lwIP UDP echo server fails to send message lengths of
>      4385 & 4386 (Dan Nygren)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Fri, 3 Feb 2023 13:24:48 -0800
>From: Dan Nygren <dan.nygren@gmail.com>
>To: lwip-users@nongnu.org
>Subject: Re: [lwip-users] lwIP UDP echo server fails to send message
>       lengths of 4385 & 4386
>Message-ID:
>       <CAOX4Ohxnt_Pi1AA7K6mH5znb8DFStuRC_J7YHrUuh1F7-1Wdnw@mail.gmail.com>
>Content-Type: text/plain; charset="utf-8"
>
>Peter wrote:
>
>> 4385/4386 could be 3x MTU ? ...
>
>Peter, thanks for responding!
>Yes, it seems like I've hit some corner case.
>Is this the right place to notify the lwIP maintainers of problems? This is
>not a current problem for me as my messages are under the MTU size. I just
>hit this while developing some diagnostics for my board and I wanted to let
>others know about it.
>
>            Dan
>
>,
>On Wed, Feb 1, 2023 at 2:10 PM Dan Nygren <dan.nygren@gmail.com> wrote:
>
>> Hello fellow lwIP users. Can anyone point me in the right direction on how
>> to resolve or report to the right folks the below issue?
>>
>> I'm seeing rather bizarre behavior in that messages of length 4385 and
>> 4386 I send to a lwIP based UDP echo server are not received back.
>> udp_sendto() appears to be getting called and completing successfully.
>> Wireshark indicates there are "bogus, payload length" errors with these
>> lengths.
>>
>> I have a detailed write up showing the behavior here:
>> https://github.com/Xilinx/embeddedsw/issues/212
>>
>> I can copy the info above into an email for this mailing list if you
>> prefer.
>>
>> Let me know your suggestions on how to proceed. ...   Dan Nygren
>>
>> ,
>>
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>------------------------------
>
>Message: 2
>Date: Fri, 3 Feb 2023 22:39:15 +0100
>From: Sylvain Rochet <gradator@gradator.net>
>To: Mailing list for lwIP users <lwip-users@nongnu.org>
>Subject: Re: [lwip-users] lwIP UDP echo server fails to send message
>       lengths of 4385 & 4386
>Message-ID: <20230203213915.GA17368@gradator.net>
>Content-Type: text/plain; charset="utf-8"
>
>Hi,
>
>On Fri, Feb 03, 2023 at 01:24:48PM -0800, Dan Nygren wrote:
>> Peter wrote:
>> 
>> > 4385/4386 could be 3x MTU ? ...
>> 
>> Peter, thanks for responding!
>> Yes, it seems like I've hit some corner case.
>> Is this the right place to notify the lwIP maintainers of problems? This is
>> not a current problem for me as my messages are under the MTU size. I just
>> hit this while developing some diagnostics for my board and I wanted to let
>> others know about it.
>
>This kind of issues set all red lights to full brightness about a low 
>level driver issue or a buggy MAC offloader on fragmented IP packets.
>
>Anyway, basic rule about using fragmented IP packets: avoid (to not say 
>don't).
>
>Sylvain
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>------------------------------
>
>Message: 3
>Date: Fri, 3 Feb 2023 21:49:49 +0000
>From: "Thompson, Jeff" <JeffThompson@invue.com>
>To: "lwip-users@nongnu.org" <lwip-users@nongnu.org>
>Subject: [lwip-users] lwIP deInit
>Message-ID:
>       
> <BN8PR03MB46104630EA9C293B3040169DC7D79@BN8PR03MB4610.namprd03.prod.outlook.com>
>       
>Content-Type: text/plain; charset="utf-8"
>
>As part of a robust network recovery scheme, I need to take down the TCP/IP 
>stack, reset my Ethernet PHY, then bring it all back up again. I looked for a 
>de-init function but didn't see one. Is there a graceful way to accomplish 
>this? Right now, I just reboot to avoid issues with freeing up any allocated 
>memory and causing fragmentation or other problems.
>
>Jeff Thompson  |  Senior Electrical Engineer - Firmware
>+1 704 752 6513 x1394
>www.invue.com
>
>[cid:image001.gif@01D937EF.62713CC0]
>
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>------------------------------
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>Message: 4
>Date: Fri, 3 Feb 2023 14:57:24 -0800
>From: Dan Nygren <dan.nygren@gmail.com>
>To: lwip-users@nongnu.org
>Subject: Re: [lwip-users] lwIP UDP echo server fails to send message
>       lengths of 4385 & 4386
>Message-ID:
>       <CAOX4OhzrPTUtF8FK_VvvmiWMdEWr30Up-O_xVMdiBn8JhSYN3Q@mail.gmail.com>
>Content-Type: text/plain; charset="utf-8"
>
>Sylvain wrote > ... Anyway, basic rule about using fragmented IP packets:
>avoid (to not say
>don't).
>
>Thank you for the advice Sylvain. My design is keeping its packets under
>the Ethernet 1500 octet MTU. I had made a diagnostic command to have my
>design send back arbitrarily sized messages to prove everything was working
>correctly when I ran into the 4385/4386 message size problem.
>
>  Dan
>
>,
>
>On Fri, Feb 3, 2023 at 1:24 PM Dan Nygren <dan.nygren@gmail.com> wrote:
>
>> Peter wrote:
>>
>> > 4385/4386 could be 3x MTU ? ...
>>
>> Peter, thanks for responding!
>> Yes, it seems like I've hit some corner case.
>> Is this the right place to notify the lwIP maintainers of problems? This
>> is not a current problem for me as my messages are under the MTU size. I
>> just hit this while developing some diagnostics for my board and I wanted
>> to let others know about it.
>>
>>             Dan
>>
>> ,
>> On Wed, Feb 1, 2023 at 2:10 PM Dan Nygren <dan.nygren@gmail.com> wrote:
>>
>>> Hello fellow lwIP users. Can anyone point me in the right direction on
>>> how to resolve or report to the right folks the below issue?
>>>
>>> I'm seeing rather bizarre behavior in that messages of length 4385 and
>>> 4386 I send to a lwIP based UDP echo server are not received back.
>>> udp_sendto() appears to be getting called and completing successfully.
>>> Wireshark indicates there are "bogus, payload length" errors with these
>>> lengths.
>>>
>>> I have a detailed write up showing the behavior here:
>>> https://github.com/Xilinx/embeddedsw/issues/212
>>>
>>> I can copy the info above into an email for this mailing list if you
>>> prefer.
>>>
>>> Let me know your suggestions on how to proceed. ...   Dan Nygren
>>>
>>> ,
>>>
>>
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