Re: [PATCH 05/14] Add csum_ip4_header() helper to calculate IPv4 header checksums

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

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On Tue, Oct 18, 2022 at 05:03:49AM +0200, Stefano Brivio wrote:
> On Mon, 17 Oct 2022 19:57:58 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > We calculate IPv4 header checksums in at least two places, in dhcp() and
> > in tap_ip_send.  Add a helper to handle this calculation in both places.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  checksum.c | 6 ++++++
> >  checksum.h | 1 +
> >  dhcp.c     | 3 +--
> >  tap.c      | 3 +--
> >  4 files changed, 9 insertions(+), 4 deletions(-)
> > 
> > diff --git a/checksum.c b/checksum.c
> > index 72f1cfb..f25a96a 100644
> > --- a/checksum.c
> > +++ b/checksum.c
> > @@ -114,6 +114,12 @@ uint16_t csum_unaligned(const void *buf, size_t len, uint32_t init)
> >  	return (uint16_t)~csum_fold(sum_16b(buf, len) + init);
> >  }
> >  
> 
> /**
>  * csum_ip4_header() - Calculate and set IPv4 header checksum
>  * @iph:	IPv4 header
>  */
> 
> ...I just tried to run Doxygen, I think it would be nice to have
> eventually (especially for DOT call graphs), things don't look too bad.
> 
> > +void csum_ip4_header(struct iphdr *ip4hr)
> > +{
> > +	ip4hr->check = 0;
> > +	ip4hr->check = csum_unaligned(ip4hr, (size_t)ip4hr->ihl * 4, 0);
> 
> iph, for consistency.

As noted before, I'd prefer to avoid the implication that IPv4 is
normal and IPv6 is special.  I have changed to just ip4h, though.

-- 
David Gibson			| 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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