Re: [nft PATCH RFC v2 3/4] Implement --echo option

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Thu, Jul 27, 2017 at 06:54:35PM +0200, Phil Sutter wrote:
> On Thu, Jul 27, 2017 at 06:43:00PM +0200, Pablo Neira Ayuso wrote:
> > On Thu, Jul 27, 2017 at 06:21:43PM +0200, Phil Sutter wrote:
> > > diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
> > > index 40096de04e963..70404f724808a 100644
> > > --- a/include/linux/netfilter/nf_tables.h
> > > +++ b/include/linux/netfilter/nf_tables.h
> > > @@ -114,6 +114,7 @@ enum nf_tables_msg_types {
> > >  	NFT_MSG_GETOBJ,
> > >  	NFT_MSG_DELOBJ,
> > >  	NFT_MSG_GETOBJ_RESET,
> > > +	NFT_MSG_META_ECHO,
> > 
> > Why this?
> 
> See netlink_echo_callback(): I want to reuse monitor code as much as
> possible, and therefore introduced that function as common callback
> dispatching to monitor callbacks. In order to make them print data like
> I want them to, I need to have an indicator. The simplest way was to
> introduce this fake type which in callbacks acts as third option to
> NFT_MSG_NEW* or NFT_MSG_DEL*.

Hm, there must be a way to reuse this code without adding a new
message type. From a netlink perspective, users should just set on the
NLM_ECHO flag to get echo reports. I don't want to have a new message
type for this.