bpf clatd.c - per RFC 6145 simply use bottom 16 bits of IPv6 frag id.
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ifac9ae3702b0fc54a02fcfcf05efb36c1299e8ec
diff --git a/bpf_progs/clatd.c b/bpf_progs/clatd.c
index b8c6131..22726ac 100644
--- a/bpf_progs/clatd.c
+++ b/bpf_progs/clatd.c
@@ -111,8 +111,8 @@
return TC_ACT_PIPE;
const struct frag_hdr *frag = (const struct frag_hdr *)(ip6 + 1);
proto = frag->nexthdr;
- // Trivial hash of 32-bit IPv6 ID field into 16-bit IPv4 field.
- ip_id = (frag->identification) ^ (frag->identification >> 16);
+ // Per RFC6145 use bottom 16-bits of 32-bit IPv6 ID field for 16-bit IPv4 field.
+ ip_id = frag->identification;
// Conversion of 16-bit IPv6 frag offset to 16-bit IPv4 frag offset field.
// IPv6 is '13 bits of offset in multiples of 8' + 2 zero bits + more fragment bit
// IPv4 is zero bit + don't frag bit + more frag bit + '13 bits of offset in multiples of 8'