Modify the pseudo-header checksum functions.

- Remove the initial checksum, which we don't use anywhere.
- Add the upper-layer protocol to the IPv6 function. Currently
  this is always the same as the next header field in the IPv6
  header, but technically it's the upper-layer header after all
  the extension headers. This is required to support fragments.

Bug: 11542311
Change-Id: Ie1a20fa74ee5bc933c1014bab74ae2957979b2b8

1 files changed, 2 insertions, 2 deletions

diff --git a/ipv4.c b/ipv4.c
index c828ffa..e2636b4 100644
--- a/ipv4.c
+++ b/ipv4.c
@@ -112,8 +112,8 @@ int ipv4_packet(clat_packet out, int pos, const char *packet, size_t len) {
   out[pos].iov_len = sizeof(struct ip6_hdr);
 
   // Calculate the pseudo-header checksum.
-  old_sum = ipv4_pseudo_header_checksum(0, header, len_left);
-  new_sum = ipv6_pseudo_header_checksum(0, ip6_targ, len_left);
+  old_sum = ipv4_pseudo_header_checksum(header, len_left);
+  new_sum = ipv6_pseudo_header_checksum(ip6_targ, len_left, nxthdr);
 
   if (nxthdr == IPPROTO_ICMPV6) {
     iov_len = icmp_packet(out, pos + 1, (const struct icmphdr *) next_header, new_sum, len_left);