Selecting an exit node that doesn't resolve to any current peer (a
nonexistent node, or MDM's "auto:any" placeholder before it is
resolved) installs the blackhole default routes, so internet traffic
is dropped rather than escaping to the local network. That behavior
is documented on ipn.Prefs.ExitNodeID and five-plus years old, but
nothing tested it. Lock it in ahead of an upcoming change that moves
OS route computation to net/routemanager and must preserve it.
Updates #12542
Change-Id: I0f63b0d5ce46061a74c69b75f7f83f115da7c3d4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Brad FitzpatrickandBrad Fitzpatrick
ce050f1ca1