From 1d6a61506a7e27491ed6b7a5c74a897d50abafdf Mon Sep 17 00:00:00 2001
From: joshliebe <joshliebe@gmail.com>
Date: Mon, 6 Jul 2026 13:12:32 +0100
Subject: [PATCH] Fix AppTP unregister crash

---
 .../mobile/android/vpn/service/DnsChangeCallback.kt         | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/app-tracking-protection/vpn-impl/src/main/java/com/duckduckgo/mobile/android/vpn/service/DnsChangeCallback.kt b/app-tracking-protection/vpn-impl/src/main/java/com/duckduckgo/mobile/android/vpn/service/DnsChangeCallback.kt
index 135157d973bd..a840416c760b 100644
--- a/app-tracking-protection/vpn-impl/src/main/java/com/duckduckgo/mobile/android/vpn/service/DnsChangeCallback.kt
+++ b/app-tracking-protection/vpn-impl/src/main/java/com/duckduckgo/mobile/android/vpn/service/DnsChangeCallback.kt
@@ -44,6 +44,7 @@ class DnsChangeCallback @Inject constructor(
         context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager?
     }
     private var lastDns: List<InetAddress>? = null
+    private var registered: Boolean = false
 
     override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) {
         logcat { "onLinkPropertiesChanged: $linkProperties" }
@@ -68,22 +69,27 @@ class DnsChangeCallback @Inject constructor(
     }
 
     internal fun register() {
+        if (registered) return
         kotlin.runCatching {
             val request = NetworkRequest.Builder().apply {
                 addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
                 addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
             }.build()
             connectivityManager?.registerNetworkCallback(request, this)
+            registered = true
         }.onFailure {
             logcat(ERROR) { it.asLog() }
         }
     }
 
     internal fun unregister() {
+        if (!registered) return
         kotlin.runCatching {
             connectivityManager?.unregisterNetworkCallback(this)
         }.onFailure {
             logcat(ERROR) { it.asLog() }
+        }.also {
+            registered = false
         }
     }