New logic installs precise filters for subnet routes, plays nice with other users of netfilter, and lays the groundwork for fixing routing loops via policy routing. Signed-off-by: David Anderson <danderson@tailscale.com>
Signed-off-by: David Anderson <danderson@tailscale.com>
The router implementations are logically separate, with their own API. Signed-off-by: David Anderson <danderson@tailscale.com>