Detect looped-back NDP DAD messages

...as per RFC 7527.

If a looped-back DAD message is received, do not fail DAD since our own
DAD message does not indicate that a neighbor has the address assigned.

Note, this is not a cherry-pick of d81fac9 which makes the same fix on
the master branch as the `master` and `releases/f1` branches have
diverged.

Bug: 71187
Change-Id: I75b56359f5d32bd34bffb0d158a2550b3cd2a8a5
5 files changed
tree: 1c60c427f6e2f7843e08d9e95a1bfb6bf612f791
  1. AUTHORS
  2. LICENSE
  3. go.mod
  4. go.sum
  5. pkg/