We have observed some clients with extremely large lists of IPv6
endpoints, in some cases from subnets where the machine also has the
zero address for a whole /48 with then arbitrary addresses additionally
assigned within that /48. It is in general unnecessary for reachability
to report all of these addresses, typically only one will be necessary
for reachability. We report two, to cover some other common cases such
as some styles of IPv6 private address rotations.
Updates tailscale/corp#25850
Signed-off-by: James Tucker <james@tailscale.com>
6364b5f1e0