Re: [RFC] libnfnetlink and iface conversion to string

[Eric Leblond <eric@inl.fr>]

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Hi,

Le mardi 09 janvier 2007 à 01:53 +0100, Pablo Neira Ayuso a écrit :
> Eric Leblond wrote:
> > It is not correct to do a dump (and send a netlink message) for each
> > ifindex resolution. Thus, libnfnetlink needs to listen to netlink
> > interfaces message. A permanent "task" is thus needed to have the job
> > done : It can be a dedicated thread or a carefully hidden select.
> /* create a table ifindex to interface */
> struct nfnl_ifindex2name_table *nfnl_ifindex2name_open();
> /* destroy table */
> void nfnl_ifindex2name_close(struct nfnl_ifindex2name_table *);
> 
> /* returns a socket descriptor to listen to interface events */
> int nfnl_ifindex2name_events_open();

Speaking as NuFW's developper and thus libnetfilter_queue user, this
clearly mean that I need to modify select part of my code, not just add
some functions calls. It forces the developper to use directly
libnfnetlink. This goes against my way to see libnetfilter_queue and
other libnetfilter* libraries.

> /* process data available for the socket and update the table */
> int nfnl_ifindex2name_process_event(int, struct nfnl_ifindex2name_table *);
> /* close socket */
> void nfnl_ifindex2name_events_close(int); /* close the socket */
> 
> Another alternative could be the use of libnl, although this introduces
> a new library dependency for every libnetfilter_queue application.

I think that ifname resolution is necessary for an application if it is
a linked with wanted features. If it has to use it, application can link
to libnl (or something else) and have it done. If it don't need it then
libnetfilter_queue is enough.

route netlink message is not a part of Netfilter, we should'nt use it in
Netfilter code if it is not transparent :
      * It duplicates code
      * It changes the "spirit" of libnetfilter* libraries

BR,
-- 
Eric Leblond <eric@inl.fr>
INL

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