plugin/forward: min and max for avgRTT (#1680)

* Move to readtimeout

* lets compile

* address comment

* comment from pr

* much smaller minimum

plugin/forward/connect.go

@@ -18,10 +18,14 @@ import (
 
 func (p *Proxy) readTimeout() time.Duration {
 	rtt := time.Duration(atomic.LoadInt64(&p.avgRtt))
-	if rtt < timeout/2 {
+
+	if rtt < minTimeout {
+		return minTimeout
+	}
+	if rtt < maxTimeout/2 {
 		return 2 * rtt
 	}
-	return timeout
+	return maxTimeout
 }
 
 func (p *Proxy) updateRtt(newRtt time.Duration) {

plugin/forward/proxy.go

@@ -91,5 +91,7 @@ func (p *Proxy) start(duration time.Duration) { p.probe.Start(duration) }
 const (
 	dialTimeout = 4 * time.Second
 	timeout     = 2 * time.Second
+	maxTimeout  = 2 * time.Second
+	minTimeout  = 10 * time.Millisecond
 	hcDuration  = 500 * time.Millisecond
 )