attempt to prevent incorrect idle notification in switch, needs testing

src/yggdrasil/link.go

@@ -64,6 +64,7 @@ type linkInterface struct {
 	closeTimer     *time.Timer // Fires when the link has been idle so long we need to close it
 	inSwitch       bool        // True if the switch is tracking this link
 	stalled        bool        // True if we haven't been receiving any response traffic
+	unstalled      bool        // False if an idle notification to the switch hasn't been sent because we stalled (or are first starting up)
 }
 
 func (l *link) init(c *Core) error {
@@ -324,13 +325,17 @@ func (intf *linkInterface) notifySent(size int, isLinkTraffic bool) {
 
 // Notify the switch that we're ready for more traffic, assuming we're not in a stalled state
 func (intf *linkInterface) _notifySwitch() {
-	if !intf.inSwitch && !intf.stalled {
+	if !intf.inSwitch {
+		if intf.stalled {
+			intf.unstalled = false
+		} else {
 			intf.inSwitch = true
 			intf.link.core.switchTable.Act(intf, func() {
 				intf.link.core.switchTable._idleIn(intf.peer.port)
 			})
 		}
 	}
+}
 
 // Set the peer as stalled, to prevent them from returning to the switch until a read succeeds
 func (intf *linkInterface) notifyStalled() {
@@ -362,7 +367,9 @@ func (intf *linkInterface) notifyRead(size int) {
 			intf.stallTimer = nil
 		}
 		intf.stalled = false
+		if !intf.unstalled {
 			intf._notifySwitch()
+		}
 		if size > 0 && intf.stallTimer == nil {
 			intf.stallTimer = time.AfterFunc(keepAliveTime, intf.notifyDoKeepAlive)
 		}