Re: [nft PATCH v3 3/4] Implement --echo option

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

On Wed, Aug 02, 2017 at 02:37:44PM +0200, Pablo Neira Ayuso wrote:
> On Fri, Jul 28, 2017 at 01:55:47PM +0200, Phil Sutter wrote:
> [...]
> > diff --git a/src/netlink.c b/src/netlink.c
> > index f13dfd3f9a021..35b52a3344f87 100644
> > --- a/src/netlink.c
> > +++ b/src/netlink.c
> > @@ -465,11 +465,11 @@ int netlink_replace_rule_batch(struct netlink_ctx *ctx, const struct handle *h,
> >  			       const struct location *loc)
> >  {
> >  	struct nftnl_rule *nlr;
> > -	int err;
> > +	int err, flags = ctx->octx->echo ? NLM_F_ECHO : 0;
> >  
> >  	nlr = alloc_nftnl_rule(&rule->handle);
> >  	netlink_linearize_rule(ctx, nlr, rule);
> > -	err = mnl_nft_rule_batch_replace(nlr, ctx->batch, 0, ctx->seqnum);
> > +	err = mnl_nft_rule_batch_replace(nlr, ctx->batch, flags, ctx->seqnum);
> >  	nftnl_rule_free(nlr);
> >  
> >  	if (err < 0)
> > @@ -2087,6 +2087,8 @@ static int netlink_events_table_cb(const struct nlmsghdr *nlh, int type,
> >  				printf("update table ");
> >  			else
> >  				printf("add table ");
> > +		} else if (type == -1) {
> > +			printf("table ");
> 
> Why do we need this '-1' case? Same question for other objects.

This is there just to skip the "add ..." part of the string, right?

I think this is relevant information. Semantically, this is just
exposing the netlink NLM_F_ECHO flag, so it should be possible to use
this flag in the future with 'delete' commands.

So if this -1 type is there just to skip the "add ...", I would simply
remove it.

Thanks!