[Bridge] Re: Bridge and PACKET-socket

Jason Lunz lunz at falooley.org
Mon Jan 12 14:24:05 PST 2004

luke at bluetail.com said:
> Still, I find the current semantics of packet sockets on bridged ports
> pretty confusing. It took me a full day to figure out why I wasn't
> receiving the packets I wanted, even though tcpdump did.
> I applied my proposed fix in my local tree: I have a separate clone of
> the ptype_base hashtable dev.c for specific-protocol handlers that
> want to run before the bridge, and an ioctl to move a packet-socket
> into that table. That way the user can choose whether he wants to get
> packets from enslaved interfaces or not.

I'm not sure you need to do that. On frame recieve, the loop over
ptype_base happens twice on a bridge, once before the bridging and once
after. For locally-destined packets, that is. (br_pass_frame_up() ends
up using netif_rx, sending the frame through dev.c again, right?)

If you want to see frames before the bridge has a chance to mess
w/ them, then bind your packet socket to the slave interface; otherwise,
bind to the virtual-bridge interface. Will this work? forwarded packets
will be hooked into open packet sockets somewhere in the TX path, iirc.

I may be misunderstanding you, but have you explored this?


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