Add Large Forward Open service

[nefethael]

Signed-off-by: Vincent Prince vincent.prince.fr@gmail.com

[nefethael]

Hi All,

This is my first contribution to OpENer, I'm not sure my PR takes care of everything (examples, doc, etc)?

Also, I only tried LFO feature with EIPScanner stack and wireshark (I don't own any CIP scanner equipment), so I'm not 100% confident about implementation.

Finally, I had to increase PC_OPENER_ETHERNET_BUFFER_SIZE value to fix buffer overflow here , nevertheless I'm not sure I did the right fix here.

Kind regards,
Vincent

[MartinMelikMerkumians]

Hi @nefethael ,
thanks for providing the Large Forward Open. I didn't have the time to properly check it, and the need for the large buffer is a little strange to me, but your contribution will be added as soon as I have everything checked.

Cheers,
Martin

[MartinMelikMerkumians]

Hi @nefethael,
first tests show, that this patch breaks the current ForwardOpen. Reply codes and reply lengths are wrong.

Best regards,
Martin

[MartinMelikMerkumians]

@nefethael already found the reason. You are only setting is_large_forward_open when calling LFO service. It is never reseted, and as a global variable is used, the flag stays true after the first LFO call.

[MartinMelikMerkumians]

Okay, I tried to push it back on this branch, but I failed miserably and created a new one

[MartinMelikMerkumians]

@nefethael I will again try to add this to your PR, so that you get proper credits for your contribution

[nefethael]

@CapXilinx Thanks for this quick integration.

For PC_OPENER_ETHERNET_BUFFER_SIZE manner, my sampleapp assemblies have g_assembly_data064 & g_assembly_data096 with more than 512 bytes, so I had to increase buffer size accordingly.

Maybe we could set assemblies size in opener_user_conf.h and calculate PC_OPENER_ETHERNET_BUFFER_SIZE from it?

[MartinMelikMerkumians]

@nefethael although the idea sounds nice, the problem is, that this calculation would be inherently bound to the specific sample application. A probably better solution would be to statically check if the created assembly fits into the PC_OPENER_ETHERNET_BUFFER_SIZE.
I checked the Internet on this, and there is a C11 feature which would accomplish that.
The problem is, that Microsoft is not updating their C Compiler to the new standard since years and I don't know if this would work with MSVC compilers or not