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

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(a)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(a)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