ipn/local: differentiate Shields Up from Uninitialized in logs.

We were printing "Shields Up" when the netmap wasn't initialized yet,
which while technically effectively true, turned out to be confusing
when trying to debug things.

Signed-off-by: Avery Pennarun <apenwarr@tailscale.com>

ipn/local.go

@@ -354,17 +354,21 @@ func (b *LocalBackend) Start(opts Options) error {
 func (b *LocalBackend) updateFilter(netMap *controlclient.NetworkMap) {
 	// TODO(apenwarr): don't replace filter at all if unchanged.
 	// TODO(apenwarr): print a diff instead of full filter.
-	if netMap == nil || b.Prefs().ShieldsUp {
-		// Not configured yet or shields up, block everything
+	if netMap == nil {
+		// Not configured yet, block everything
+		b.logf("netmap packet filter: (not ready yet)")
+		b.e.SetFilter(filter.NewAllowNone())
+	} else if b.Prefs().ShieldsUp {
+		// Shields up, block everything
 		b.logf("netmap packet filter: (shields up)")
 		b.e.SetFilter(filter.NewAllowNone())
 	} else {
 		now := time.Now()
 		if now.Sub(b.lastFilterPrint) > 1*time.Minute {
-			b.logf("netmap packet filter: %v", b.netMapCache.PacketFilter)
+			b.logf("netmap packet filter: %v", netMap.PacketFilter)
 			b.lastFilterPrint = now
 		} else {
-			b.logf("netmap packet filter: (suppressed)")
+			b.logf("netmap packet filter: (length %d)", len(netMap.PacketFilter))
 		}
 		b.e.SetFilter(filter.New(netMap.PacketFilter, b.e.GetFilter()))
 	}