16ef88754d
We were previously not checking that the external IP that we got back from a UPnP portmap was a valid endpoint; add minimal validation that this endpoint is something that is routeable by another host. Updates tailscale/corp#23538 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: Id9649e7683394aced326d5348f4caa24d0efd532