From c8adaa45dac142262bdab2d27d51142591da021c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zolt=C3=A1n=20Papp?= <zoltan.pmail@gmail.com>
Date: Thu, 30 Jul 2026 12:32:12 +0200
Subject: [PATCH] [client] Serialize Android tunnel reconfiguration callbacks

The Android route notifier and the DNS search-domain notifier both
delivered OnNetworkChanged from a fire-and-forget goroutine per update.
Two updates in quick succession could reach the Java side reordered:
the TUN rebuild handler applies them in arrival order and compares
against the last applied parameters, so a stale route set delivered
last won as the final TUN state. This is the same reordering hazard
fixed for iOS in #6454.

Wrap the Android network change listener into the shared tunnelnotifier
FIFO introduced in #6870, the same way RunOniOS does, and deliver both
notifiers synchronously into it. Enqueueing is non-blocking, a single
delivery goroutine preserves order, and calls into Java never overlap.

Also stop hasRouteDiff from sorting the notifier's shared route slices
in place; compare sorted copies instead.
---
 client/internal/connect.go                    |  5 ++++-
 client/internal/dns/notifier.go               |  4 +---
 .../routemanager/notifier/notifier_android.go | 19 ++++++-------------
 3 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/client/internal/connect.go b/client/internal/connect.go
index 87126b222..ceb39419e 100644
--- a/client/internal/connect.go
+++ b/client/internal/connect.go
@@ -113,11 +113,14 @@ func (c *ConnectClient) RunOnAndroid(
 	stateFilePath string,
 	cacheDir string,
 ) error {
+	notifier := tunnelnotifier.New(networkChangeListener, nil)
+	defer notifier.Close()
+
 	// in case of non Android os these variables will be nil
 	mobileDependency := MobileDependency{
 		TunAdapter:            tunAdapter,
 		IFaceDiscover:         iFaceDiscover,
-		NetworkChangeListener: networkChangeListener,
+		NetworkChangeListener: notifier,
 		HostDNSAddresses:      dnsAddresses,
 		DnsReadyListener:      dnsReadyListener,
 		StateFilePath:         stateFilePath,
diff --git a/client/internal/dns/notifier.go b/client/internal/dns/notifier.go
index 35cb6ff82..79d924a78 100644
--- a/client/internal/dns/notifier.go
+++ b/client/internal/dns/notifier.go
@@ -51,7 +51,5 @@ func (n *notifier) notify() {
 		return
 	}
 
-	go func(l listener.NetworkChangeListener) {
-		l.OnNetworkChanged("")
-	}(n.listener)
+	n.listener.OnNetworkChanged("")
 }
diff --git a/client/internal/routemanager/notifier/notifier_android.go b/client/internal/routemanager/notifier/notifier_android.go
index 31f2a7aef..60e1d0a0f 100644
--- a/client/internal/routemanager/notifier/notifier_android.go
+++ b/client/internal/routemanager/notifier/notifier_android.go
@@ -79,9 +79,7 @@ func (n *Notifier) notify() {
 
 	routeStrings := n.routesToStrings(allRoutes)
 	sort.Strings(routeStrings)
-	go func(l listener.NetworkChangeListener) {
-		l.OnNetworkChanged(strings.Join(routeStrings, ","))
-	}(n.listener)
+	n.listener.OnNetworkChanged(strings.Join(routeStrings, ","))
 }
 
 func filterStatic(routes []*route.Route) []*route.Route {
@@ -103,16 +101,11 @@ func (n *Notifier) routesToStrings(routes []*route.Route) []string {
 }
 
 func (n *Notifier) hasRouteDiff(a []*route.Route, b []*route.Route) bool {
-	slices.SortFunc(a, func(x, y *route.Route) int {
-		return strings.Compare(x.NetString(), y.NetString())
-	})
-	slices.SortFunc(b, func(x, y *route.Route) int {
-		return strings.Compare(x.NetString(), y.NetString())
-	})
-
-	return !slices.EqualFunc(a, b, func(x, y *route.Route) bool {
-		return x.NetString() == y.NetString()
-	})
+	as := n.routesToStrings(a)
+	bs := n.routesToStrings(b)
+	sort.Strings(as)
+	sort.Strings(bs)
+	return !slices.Equal(as, bs)
 }
 
 func (n *Notifier) GetInitialRouteRanges() []string {