creating hsNotifyc as a buffered channel

[AndrewK1273]

If two clients connect at the same time, an HS notification may be lost because writing to the channel is non-blocking and the channel is not buffered.

[fiorix]

Were you able to reproduce the problem and test with this change? Also I'm curious for what makes "10" the right size for the buffered channel here.

[AndrewK1273]

It depends on how robust it should be.

When I test it with 10 clients connecting simultaneously, which is probably not very likely in the real world, notifications stop being lost when the buffer set to 3 (see attachment).

It also depends on the way notifications are processed on the server side. During the test, I print out originHost.

func (f *FakePcrf) HandshakeNotifyHandler(hn <-chan diam.Conn) {
	for c := range hn {
		if meta, ok := smpeer.FromContext(c.Context()); ok {
			log.Printf("new peer OriginHost: %s", string(meta.OriginHost.Serialize()))
		}
	}
}

The value of 10 seemed like a sufficient reserve even for a very crazy case.
diam_hs_notif_tests.txt