Fixes #1345 Updates golang/go#45736 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
We basically already had the RIB-parsing Go code for this in both net/interfaces and wgengine/monitor, for other reasons. Fixes #1426 Fixes #1471 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>