ipn/proxies: force refresh protos conditionally

Author: ignoramous

intra/ipn/proxies.go

@@ -215,7 +215,7 @@ type Proxies interface {
 	ProxyProvider
 	Rpn
 	// RefreshProto broadcasts proto change to all active proxies.
-	RefreshProto(l3 string, mtu int)
+	RefreshProto(l3 string, mtu int, force bool)
 	// LiveProxies returns a csv of active proxies.
 	LiveProxies() string
 	// Reverser sets the reverse proxy for all proxies.
@@ -989,13 +989,13 @@ func (px *proxifier) LiveProxies() string {
 }
 
 // RefreshProto implements x.Proxies.
-func (px *proxifier) RefreshProto(l3 string, mtu int) {
+func (px *proxifier) RefreshProto(l3 string, mtu int, force bool) {
 	defer core.Recover(core.Exit11, "pxr.RefreshProto")
 	// must unlock from deferred since panics are recovered above
 	px.Lock()
 	defer px.Unlock()
 
-	if px.lp.l3 == l3 && px.lp.mtu == mtu {
+	if !force && px.lp.l3 == l3 && px.lp.mtu == mtu {
 		log.D("proxy: refreshProto (%s == %s & %d == %d) unchanged",
 			px.lp.l3, l3, px.lp.mtu, mtu)
 		return

intra/tunnel.go

@@ -239,7 +239,10 @@ func (t *rtunnel) SetLinkAndRoutes(fd, mtu, engine int) error {
 		if l3diff || mtudiff {
 			// dialers.IPProtos must always preced calls to other refreshes
 			// as it carries the global state for dialers and ipn/multihost
-			go t.proxies.RefreshProto(l3, mtu)
+			go t.proxies.RefreshProto(l3, mtu, false /*force*/)
+		}
+		if l3diff {
+			t.resolver.Add(newMDNSTransport(t.ctx, l3, t.proxies))
 		}
 		if l3diff {
 			t.resolver.Add(newMDNSTransport(t.ctx, l3, t.proxies))