Clear dnsServers on establish and closeTun

Since we know the dnsServers are invalid after having invoked `closeTun` & `establish` this prevents the daemon from using DNS servers that are no longer valid.
mullvad · Feb 12, 2025 · a7ec806 · a7ec806
1 parent e70557a
commit a7ec806
Show file tree

Hide file tree

Showing 2 changed files with 21 additions and 5 deletions.
diff --git a/android/lib/talpid/src/main/kotlin/net/mullvad/talpid/ConnectivityListener.kt b/android/lib/talpid/src/main/kotlin/net/mullvad/talpid/ConnectivityListener.kt
@@ -14,6 +14,7 @@ import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.merge
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.scan
 import kotlinx.coroutines.flow.stateIn
@@ -23,7 +24,10 @@ import net.mullvad.talpid.util.RawNetworkState
 import net.mullvad.talpid.util.defaultRawNetworkStateFlow
 import net.mullvad.talpid.util.networkEvents
 
-class ConnectivityListener(private val connectivityManager: ConnectivityManager) {
+class ConnectivityListener(
+    private val connectivityManager: ConnectivityManager,
+    private val resetDnsFlow: Flow<Unit>,
+) {
     private lateinit var _isConnected: StateFlow<Boolean>
     // Used by JNI
     val isConnected
@@ -44,8 +48,7 @@ class ConnectivityListener(private val connectivityManager: ConnectivityManager)
         // the default network may fail if the network on Android 11
         // https://issuetracker.google.com/issues/175055271?pli=1
         _currentNetworkState =
-            connectivityManager
-                .defaultRawNetworkStateFlow()
+            merge(connectivityManager.defaultRawNetworkStateFlow(), resetDnsFlow.map { null })
                 .map { it?.toNetworkState() }
                 .onEach { notifyDefaultNetworkChange(it) }
                 .stateIn(scope, SharingStarted.Eagerly, null)

diff --git a/android/lib/talpid/src/main/kotlin/net/mullvad/talpid/TalpidVpnService.kt b/android/lib/talpid/src/main/kotlin/net/mullvad/talpid/TalpidVpnService.kt
@@ -15,6 +15,9 @@ import java.net.Inet4Address
 import java.net.Inet6Address
 import java.net.InetAddress
 import kotlin.properties.Delegates.observable
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.receiveAsFlow
+import kotlinx.coroutines.runBlocking
 import net.mullvad.mullvadvpn.lib.common.util.establishSafe
 import net.mullvad.mullvadvpn.lib.common.util.prepareVpnSafe
 import net.mullvad.mullvadvpn.lib.model.PrepareError
@@ -42,6 +45,7 @@ open class TalpidVpnService : LifecycleVpnService() {
             }
         }
 
+    private val resetDnsChannel = Channel<Unit>()
     private var currentTunConfig: TunConfig? = null
 
     // Used by JNI
@@ -50,7 +54,11 @@ open class TalpidVpnService : LifecycleVpnService() {
     @CallSuper
     override fun onCreate() {
         super.onCreate()
-        connectivityListener = ConnectivityListener(getSystemService<ConnectivityManager>()!!)
+        connectivityListener =
+            ConnectivityListener(
+                getSystemService<ConnectivityManager>()!!,
+                resetDnsChannel.receiveAsFlow(),
+            )
         connectivityListener.register(lifecycleScope)
     }
 
@@ -71,7 +79,11 @@ open class TalpidVpnService : LifecycleVpnService() {
         synchronized(this) { openTunImpl(config) }
 
     // Used by JNI
-    fun closeTun(): Unit = synchronized(this) { activeTunStatus = null }
+    fun closeTun(): Unit =
+        synchronized(this) {
+            runBlocking { resetDnsChannel.send(Unit) }
+            activeTunStatus = null
+        }
 
     // Used by JNI
     fun bypass(socket: Int): Boolean = protect(socket)
@@ -123,6 +135,7 @@ open class TalpidVpnService : LifecycleVpnService() {
             builder.addDnsServer(FALLBACK_DUMMY_DNS_SERVER)
         }
 
+        runBlocking { resetDnsChannel.send(Unit) }
         val vpnInterfaceFd =
             builder
                 .establishSafe()