[libvirt] [libvirt PATCHv3 05/10] allow chain modification

[David Stevens]

Stefan Berger <stefanb at linux.vnet.ibm.com> wrote on 10/17/2011 09:07:12 
AM:

> On 10/12/2011 03:50 PM, David L Stevens wrote:
> >    This patch adds the internal capability to add rules to existing
> > chains instead of using temporary chains and to generate placeholders 
for
> > chains that are referenced without generating a rule for them 
immediately.
> > Finally, it includes variable matching for filter instantiation
> > (i.e., instantiate only when a given variable is present in a filter, 
or
> > only when it is not).
> >
> Following the above I am not sure what this will be used for as part of 
> this extension.

        This is used to add rules to existing chains when a new IP address 
is
discovered (i.e., a DHCP ACK from a server occurs). The existing code 
builds
the entire chain as a temporary chain and then swaps it in, which is only
appropriate at start-up. For DHCP snooping, we want to add and remove 
rules
that reference "IP" using a particular value (the address for the ACK or
lease expiration) without affecting other rules that don't reference IP or
have a different address value. "removeRules" was already there, but 
"addRules"
was not.

 +-DLS