I updated the address parsing stuff to return a specific error for
unspecified hosts passed as empty strings, and look for that
when logging errors. I explicitly did not make parseAddress return a
netip.Addr containing an unspecified address because at this layer,
in the absence of any host, we don't necessarily know the address
family we're dealing with.
For the purposes of this code I think this is fine, at least until
we implement #12588.
Fixes#12979
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
This is implemented via GetBestInterfaceEx. Should we encounter errors
or fail to resolve a valid, non-Tailscale interface, we fall back to
returning the index for the default interface instead.
Fixes#12551
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
Aaron Klotz