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.

Test: ndp_test.TestDADResolveLoopback
PiperOrigin-RevId: 363224288

This is a cherry-pick of d81fac9.

Bug: 72768
Change-Id: Ia0471d045eae8aaf6dd974f14cfd6f988172c32e
8 files changed
tree: 4f0db01faa806766a8375e6708608c0e7aa536bf
  1. pkg/
  2. AUTHORS
  3. go.mod
  4. go.sum
  5. LICENSE