ipn/auto: delay for 2s if rpn unhealthy

give it a few seconds to recover (typically, it may take around 5s for wg
handshakes to complete, but we do not have the luxury to wait that longer
given DNS53 timeouts may be shorter)

Author: ignoramous

intra/ipn/auto.go

@@ -20,8 +20,9 @@ import (
 )
 
 const (
-	ttl30s     = 30 * time.Second
-	shortdelay = 100 * time.Millisecond
+	ttl30s                   = 30 * time.Second
+	shortdelay               = 100 * time.Millisecond
+	delayForUnhealthyProxies = 2 * time.Second
 )
 
 // exit is a proxy that always dials out to the internet.
@@ -557,9 +558,10 @@ func (*auto) dialAlways(p Proxy, network, local, remote string) (net.Conn, error
 	return p.Dialer().Dial(network, remote)
 }
 
-func (*auto) dialIfHealthy(p Proxy, network, local, remote string) (net.Conn, error) {
+func (a *auto) dialIfHealthy(p Proxy, network, local, remote string) (net.Conn, error) {
 	if err := healthy(p); err != nil {
-		return nil, fmt.Errorf("auto dial; %s %s not ok; %v: %s", p.ID(), network, err, remote)
+		log.E("auto dial; %s %s not ok; %v: %s", p.ID(), network, err, remote)
+		time.Sleep(delayForUnhealthyProxies)
 	}
 	if len(local) > 0 {
 		return p.Dialer().DialBind(network, local, remote)