Add csum_udp6() helper for calculating UDP over IPv6 checksums

Add a helper for calculating UDP checksums when used over IPv6
For future flexibility, the new helper takes parameters for the fields in
the IPv6 pseudo-header, so an IPv6 header or pseudo-header doesn't need to
be explicitly constructed.  It also allows the UDP header and payload to
be in separate buffers, although we don't use this yet.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/tap.c b/tap.c
index f082901..9c197cb 100644
--- a/tap.c
+++ b/tap.c
@@ -183,9 +183,8 @@ void tap_ip_send(const struct ctx *c, const struct in6_addr *src, uint8_t proto,
 		} else if (proto == IPPROTO_UDP) {
 			struct udphdr *uh = (struct udphdr *)(ip6h + 1);
 
-			uh->check = 0;
-			uh->check = csum_unaligned(ip6h, len + sizeof(*ip6h),
-						   0);
+			csum_udp6(uh, &ip6h->saddr, &ip6h->daddr,
+				  uh + 1, len - sizeof(*uh));
 		} else if (proto == IPPROTO_ICMPV6) {
 			struct icmp6hdr *ih = (struct icmp6hdr *)(ip6h + 1);