Remove the need for the caller to hold on to and call an unregister
function. Both two callers (one real, one test) already have a context
they can use. Use context.AfterFunc instead. There are no observable
side effects from scheduling too late if the goroutine doesn't run sync.
Updates #17148
Change-Id: Ie697dae0e797494fa8ef27fbafa193bfe5ceb307
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This adds a new helper to the netmon package that allows us to
rate-limit log messages, so that they only print once per (major)
LinkChange event. We then use this when constructing the portmapper, so
that we don't keep spamming logs forever on the same network.
Updates #13145
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I6e7162509148abea674f96efd76be9dffb373ae4
