Re: [Qemu-devel] [PATCH] RFC/net: Add a net filter

[Jason Wang <jasowang@redhat.com>]

On 07/28/2015 05:19 PM, Yang Hongyang wrote:
> On 07/28/2015 12:00 PM, Yang Hongyang wrote:
>> On 07/28/2015 11:28 AM, Jason Wang wrote:
>>> On 07/27/2015 06:03 PM, Yang Hongyang wrote:
>>>> On 07/27/2015 05:16 PM, Jason Wang wrote:
>>>> [...]
>>>>>>>>>> I think this won't work for the buffer case? If we want the
>>>>>>>>>> buffer
>>>>>>>>>> case
>>>>>>>>>> to work under this, we should modify the generic netdev layer
>>>>>>>>>> code, to
>>>>>>>>>> check the return value of the filter function call.
>>>>>>>>>
>>>>>>>>> But checking return value is rather simpler than a new netdev
>>>>>>>>> type,
>>>>>>>>> isn't it?
>>>>>>>>
>>>>>>>> But how to implement a plugin which suppose to do the actual
>>>>>>>> work on
>>>>>>>> the packets?
>>>>>>>
>>>>>>> Well, the filter get the packets, so it can do everything it wants.
>>>>>>>
>>>>>>>> how to configure params related to the plugin? different
>>>>>>>> plugins may need different params, implement as another netdev?
>>>>>>>
>>>>>>> I belive qmp can do this? something like -filter
>>>>>>> dump,id=f0,len=10000?
>>>>>>
>>>>>> So you mean implement another object filter?
>>>>>
>>>>> Yes.
>>>>>
>>>>>> and the structure is like netdev?
>>>>>
>>>>> No, it is embedded in netdev.
>>>>
>>>> Ah, I see what you mean, thank you for the patience...
>>>> does the command line looks like:
>>>> -filter dump,id=f0,len=10000
>>>> -netdev tap,XXX,filter=dump
>>>>
>>>> If I need both dump and packets buffering, how will the qmp be?
>>>> -filter dump,id=f0,len=10000
>>>> -filter buffer,XXX
>>>> -netdev tap,XXX,filter=dump:buffer:XXX ?
>>>
>>> This is ok but we have several choices, e.g you may want to have a next
>>> field like:
>>>
>>> - filter buffer,id=f0
>>> - filter dump,id=f1,len=1000,next=f0
>>> - netdev tap,XXX,filter_root=f1
>>
>> This seems better, thank you!
>
> Sorry, when try to implement it, I found this qmp is not that good
> when it
> comes to dynamically add/remove filters, can I use below instead:
> -netdev tap,id=bn0
> -netfilter dump,id=f0,netdev=bn0
> -netfilter buffer,id=f1,netdev=bn0
>
> by this, I can introduce a QTAILQ of filters to NetClentState and
> netdev_{add|del}_filter to dynamically add/remove filters. 

This looks good.

Thanks