Add csum_icmp6() helper for calculating ICMPv6 checksums

At least two places in passt calculate ICMPv6 checksums, ndp() and
tap_ip_send().  Add a helper to handle this calculation in both places.
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 ICMPv6 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, 1 insertions, 4 deletions

diff --git a/ndp.c b/ndp.c
index dec36a9..03f1d06 100644
--- a/ndp.c
+++ b/ndp.c
@@ -189,10 +189,7 @@ dns_done:
 		ip6hr->saddr = c->ip6.addr_ll;
 
 	ip6hr->payload_len = htons(sizeof(*ihr) + len);
-	ip6hr->hop_limit = IPPROTO_ICMPV6;
-	ihr->icmp6_cksum = 0;
-	ihr->icmp6_cksum = csum_unaligned(ip6hr, sizeof(*ip6hr) +
-						 sizeof(*ihr) + len, 0);
+	csum_icmp6(ihr, &ip6hr->saddr, &ip6hr->daddr, ihr + 1, len);
 
 	ip6hr->version = 6;
 	ip6hr->nexthdr = IPPROTO_ICMPV6;