[Twisted-Python] twisted linux netfilter_log protocol

[Phil Mayers]

On 02/10/13 09:25, David Stainton wrote:
>
> In examples of Twisted UDP clients they all do this:
>
> reactor.listenUDP(3000,MyProtocol())
>
> What would I do instead?
> reactor.addReader makes sense to me since what I have is a file descriptor,
> and the reactor loop and use select or epoll find out when there is data
> to read...
> and call our doRead() method of the Reader.
>
> I don't know about implementing this as a Protocol because I do not have any
> equivalent to ReactorUDP. ReactorUDP's listenUDP returns a ListeningPort.
> And I'm not sure how a Transport is related to my Reader... but it seems
> to me
> that there is some abstraction which sets callbacks for io and also
> calls buildProtocol...

Sorry, maybe I was unclear: you were asking about protocols, so I was 
merely pointing out that *if* you were to use a protocol, you should 
copy the approach DatagramProtocol and udp.Port take.

However as I noted, it *might not* make sense to do this, if there's 
only ever going to be one socket listening on this "thing", your current 
approach might be fine.

> If I am going to be using a Twisted Service to drop privileges after
> gaining access to the fd...
> How would I do this? Would I have startService() instantiate a Protocol
> instance?

As above, it depends. If you're using Protocol instances, then yes. If 
not, then no.

Services are just things which start and stop; they may or may not use 
objects implementing the transport/factory/protocol pattern.

>
> I don't know about the nflog file descriptor...
> but the nflog generator interface is non-blocking if used like this:

Ok. Weird API, but if it works...

> My nflog reader seems to work great.

If it works for you, and you're using documented Twisted interfaces, 
then there's probably no need to fiddle with it.