Re: [PATCH 16/22] fwd: Helpers to clarify what host addresses aren't guest accessible

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Aug 20, 2024 at 09:56:18PM +0200, Stefano Brivio wrote:
> On Fri, 16 Aug 2024 15:39:57 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > We usually avoid NAT, but in a few cases we need to apply address
> > translations.  For inbound connections that happens for addresses which
> > make sense to the host but are either inaccessible, or mean a different
> > location from the guest's point of view.
> > 
> > Add some helper functions to determine such addresses, and use them in
> > fwd_nat_from_host().  In doing so clarify some of the reasons for the
> > logic.  We'll also have further use for these helpers in future.
> > 
> > While we're there fix one unneccessary inconsistency between IPv4 and IPv6.
> > We always translated the guest's observed address, but for IPv4 we didn't
> > translate the guest's assigned address, whereas for IPv6 we did.  Change
> > this to translate both in all cases for consistency.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  fwd.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++-------
> >  1 file changed, 87 insertions(+), 11 deletions(-)
> > 
> > diff --git a/fwd.c b/fwd.c
> > index 75dc0151..1baae338 100644
> > --- a/fwd.c
> > +++ b/fwd.c
> > @@ -170,6 +170,85 @@ static bool is_dns_flow(uint8_t proto, const struct flowside *ini)
> >  		((ini->oport == 53) || (ini->oport == 853));
> >  }
> >  
> > +/**
> > + * fwd_guest_accessible4() - Is IPv4 address guest accessible
> 
> Nit: I wonder if we should say "guest-accessible" in all these cases,
> it's a bit easier for me to decode, but not necessarily more correct.
> It's fine by me either way.

Just adding the hyphen?  Sure, done.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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