force things to buffer in the switch if the best link is currently busy. note that other links can end up sending if they become non-idle for other reasons. this is a temporary workaround to packet reordering, until we can figure out a better solution

src/yggdrasil/switch.go

@@ -677,13 +677,10 @@ func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) boo
 	ports := t.core.peers.getPorts()
 	for _, cinfo := range closer {
 		to := ports[cinfo.elem.port]
-		_, isIdle := idle[cinfo.elem.port]
 		var update bool
 		switch {
 		case to == nil:
 			// no port was found, ignore it
-		case !isIdle:
-			// the port is busy, ignore it
 		case best == nil:
 			// this is the first idle port we've found, so select it until we find a
 			// better candidate port to use instead
@@ -713,6 +710,9 @@ func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) boo
 	}
 	if best != nil {
 		// Send to the best idle next hop
+		if _, isIdle := idle[best.elem.port]; !isIdle {
+			return false
+		}
 		delete(idle, best.elem.port)
 		ports[best.elem.port].sendPacketsFrom(t, [][]byte{packet})
 		return true