Re: loopback problem with BCM, RAW using, Daniele Venzano

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 24.08.2012 06:47, Kurt Van Dijck wrote:

> On Thu, Aug 23, 2012 at 08:35:45PM +0200, Oliver Hartkopp wrote:
>> On 22.08.2012 10:57, Kurt Van Dijck wrote:
>>
>>> Oliver,
>>>
>>> I did not follow this thread in depth.
>>>
>>> The patch looks minimal, but I doubt its usefullness.
>>> In a proper designed CAN system, each node uses distinct CAN-ids.
>>> Therefore, filtering out local traffic can always be accomplished
>>> with the current filtering (RTR frames are an exception, but are
>>> irrelevant here).
>>>
>>> userspace can test flags (MSG_DONTROUTE) to decide if a received
>>> frame is from <localhost> or remote.
>>> So I don't see the problem that you're addressing with this patch.
>>
>>
>> Hello Kurt,
>>
>> this was a quick shot.
>>
>> After thinking a bit more on this idea, this sockopt is something like an
>> additional filter. But then i needs to have two bits:
>>
>> - receive rx frames (from the outside)
>> - receive tx frames (from the local host)
>>
>> Default is to receive both types of frames ...
>>
>> Btw. i don't know if this additional sockopt makes it even more complicated
>> for users ...
> 
> IMO, things get complicated.
> Example: what should I get when
> CAN_RAW_RECV_OWN_MSGS is set & CAN_RAW_RECV_HOST_MSGS is cleared?


Yep. That was also my thought. And putting CAN_RAW_RECV_OWN_MSGS into the new
sockopt in some way is misleading too.

Your original proposal to use the per-socket CAN-ID filters that are already
in place seems the appropriate solution for Maheshs request.

Regards,
Oliver