The autoselection should pick sensible paths for all of:
- Windows (LocalAppData)
- Mac (Library/Caches)
- Unix user (XDG_CACHE_DIR)
- Linux systemd service (CACHE_DIRECTORY)
As a last resort, if cache dir lookup fails, plops sufficiently
uniquely named files into the current working directory.
Signed-off-by: David Anderson <dave@natulte.net>
* make RouterGen return an error, not take both tunname and tundev
* also remove RouteGen taking a wireguard/device.Device; currently unused
* remove derp parameter (it'll work differently)
* unexport NewUserspaceRouter in per-OS impls, add documented wrapper
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
