[TEST/REVIEW] ng_ipfw: node to glue together ipfw(4) and netgraph(4)

Julian Elischer julian at elischer.org
Thu Jan 20 13:38:16 PST 2005

Gleb, as long as you have done enuogh work to evaluate other options (as 
you have,)
I have no objection to you committing your original idea.

Brooks Davis wrote:

>On Thu, Jan 20, 2005 at 04:45:53PM +0300, Gleb Smirnoff wrote:
>>  Julian,
>>On Wed, Jan 19, 2005 at 01:32:35AM -0800, Julian Elischer wrote:
>>J> I'm not sure they do two different things..  Each represents a place to 
>>J> send packets.
>>J> If each active divert socket number had a pointer to the module to which it
>>J> was attached then  you could divert to either in-kernel netgraph targets or
>>J> to userland socket based targets.  Currently of you divert to a divert
>>J> 'port number' and nothing is attached to it, the packet is dropped.
>>J> If a divert socket is attached to it, it is sent ot teh socket.
>>J> I would just suggest that is not a great leap of imagination that
>>J> attaching to a hook named 3245 would attach a netgrpah hook to the ipfw
>>J> code in the sam enamespace as the divert portnumber, and that a
>>J> subsequent attempt to attach a divert socket to that port number woild
>>J> fail. The packets diverted there would simply go to the netgraph hook
>>J> instead of going to a socket or being dropped.
>>Well, I've considered this. We are going to have these negatives with this change:
>>1) require divert loaded/compiled, when we are going to work with a completely
>>   different thing.
>>2) Acquire & drop lock on divert pcb info for each packet going into netgraph.
>>3) Extensively hack divert_packet()... Let me explain. The place where we can tell
>>whether we have a socket diversion or a netgraph diversion, is at the very end
>>of divert_packet(). Before this place many things are done, which does not apply
>>to a netgraph diversion.
>>This hacking may bring bugs into divert infrastructure, and add extra CPU cycles
>>for case of netgraph forwarding. I think saving one keyword for ipfw2 doesn't
>>worth this hacks.
>I think the code should be committed more or less as is.  I think the
>netgraph and divert features are relatively orthogonal.
>-- Brooks

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