Add csum_ip4_header() helper to calculate IPv4 header checksums

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>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/tap.c b/tap.c
index 58fc1de..de02c56 100644
--- a/tap.c
+++ b/tap.c
@@ -135,8 +135,7 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
 		iph->daddr = c->ip4.addr_seen;
 		memcpy(&iph->saddr, &src->s6_addr[12], 4);
 
-		iph->check = 0;
-		iph->check = csum_unaligned(iph, (size_t)iph->ihl * 4, 0);
+		csum_ip4_header(iph);
 
 		memcpy(data, in, len);