From mboxrd@z Thu Jan  1 00:00:00 1970
From: Florian Westphal <fw@strlen.de>
Subject: Re: [RFC] nftables: reverse path filtering for nft
Date: Mon, 12 Sep 2016 21:00:25 +0200
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 <20160912122107.GB27566@breakpoint.cc>
 <20160912185228.GA10862@salvia>
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Cc: Florian Westphal <fw@strlen.de>, netfilter-devel@vger.kernel.org
To: Pablo Neira Ayuso <pablo@netfilter.org>
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Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>         fib lookup ip daddr . oif
> 
> As you are basically looking for the route based on IPv4 address and
> the output interface, so this boils down to:
> 
>         fib lookup $expr $flags

How would the kernel disentangle the register data?
(i.e., how do i know where in the sreg e.g. the daddr is
 that i need to stuff in the flowi struct?)