From 05b950fbb3769f2eeb4d383aff1a091915d88ef7 Mon Sep 17 00:00:00 2001
From: Patryk <43276401+Zaptyp@users.noreply.github.com>
Date: Thu, 18 Dec 2025 16:25:31 +0100
Subject: [PATCH] fix: add check if kernel supports WG (#993)

---
 .../core/tunnel/KernelTunnel.kt                  |  3 +++
 .../domain/events/BackendCoreException.kt        |  4 ++++
 .../viewmodel/SharedAppViewModel.kt              | 16 +++++++++++++++-
 app/src/main/res/values-pl/strings.xml           |  1 +
 app/src/main/res/values/strings.xml              |  1 +
 5 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/com/zaneschepke/wireguardautotunnel/core/tunnel/KernelTunnel.kt b/app/src/main/java/com/zaneschepke/wireguardautotunnel/core/tunnel/KernelTunnel.kt
index 1b369089..b5fdf78c 100644
--- a/app/src/main/java/com/zaneschepke/wireguardautotunnel/core/tunnel/KernelTunnel.kt
+++ b/app/src/main/java/com/zaneschepke/wireguardautotunnel/core/tunnel/KernelTunnel.kt
@@ -2,6 +2,7 @@ package com.zaneschepke.wireguardautotunnel.core.tunnel
 
 import com.wireguard.android.backend.Backend
 import com.wireguard.android.backend.BackendException
+import com.wireguard.android.backend.WgQuickBackend
 import com.wireguard.android.backend.Tunnel as WgTunnel
 import com.zaneschepke.wireguardautotunnel.R
 import com.zaneschepke.wireguardautotunnel.di.ApplicationScope
@@ -9,6 +10,7 @@ import com.zaneschepke.wireguardautotunnel.di.IoDispatcher
 import com.zaneschepke.wireguardautotunnel.di.Kernel
 import com.zaneschepke.wireguardautotunnel.domain.enums.BackendMode
 import com.zaneschepke.wireguardautotunnel.domain.enums.TunnelStatus
+import com.zaneschepke.wireguardautotunnel.domain.events.KernelWireguardNotSupported
 import com.zaneschepke.wireguardautotunnel.domain.events.DnsFailure
 import com.zaneschepke.wireguardautotunnel.domain.events.InvalidConfig
 import com.zaneschepke.wireguardautotunnel.domain.events.KernelTunnelName
@@ -55,6 +57,7 @@ constructor(
     }
 
     override fun tunnelStateFlow(tunnelConfig: TunnelConfig): Flow<TunnelStatus> = callbackFlow {
+        if (!WgQuickBackend.hasKernelSupport()) close(KernelWireguardNotSupported())
         validateWireGuardInterfaceName(tunnelConfig.name).onFailure { close(it) }
 
         val stateChannel = Channel<WgTunnel.State>()
diff --git a/app/src/main/java/com/zaneschepke/wireguardautotunnel/domain/events/BackendCoreException.kt b/app/src/main/java/com/zaneschepke/wireguardautotunnel/domain/events/BackendCoreException.kt
index c2a6f800..0d878431 100644
--- a/app/src/main/java/com/zaneschepke/wireguardautotunnel/domain/events/BackendCoreException.kt
+++ b/app/src/main/java/com/zaneschepke/wireguardautotunnel/domain/events/BackendCoreException.kt
@@ -40,3 +40,7 @@ class UnknownError : BackendCoreException() {
 class UapiUpdateFailed : BackendCoreException() {
     override val stringRes = R.string.active_tunnel_update_failed
 }
+
+class KernelWireguardNotSupported : BackendCoreException() {
+    override val stringRes = R.string.kernel_wireguard_unsupported
+}
diff --git a/app/src/main/java/com/zaneschepke/wireguardautotunnel/viewmodel/SharedAppViewModel.kt b/app/src/main/java/com/zaneschepke/wireguardautotunnel/viewmodel/SharedAppViewModel.kt
index 414cc9f5..2e293807 100644
--- a/app/src/main/java/com/zaneschepke/wireguardautotunnel/viewmodel/SharedAppViewModel.kt
+++ b/app/src/main/java/com/zaneschepke/wireguardautotunnel/viewmodel/SharedAppViewModel.kt
@@ -3,7 +3,7 @@ package com.zaneschepke.wireguardautotunnel.viewmodel
 import android.net.Uri
 import androidx.core.net.toUri
 import androidx.lifecycle.ViewModel
-import com.zaneschepke.wireguardautotunnel.R
+import com.wireguard.android.backend.WgQuickBackend
 import com.zaneschepke.wireguardautotunnel.core.service.ServiceManager
 import com.zaneschepke.wireguardautotunnel.core.tunnel.TunnelManager
 import com.zaneschepke.wireguardautotunnel.data.model.AppMode
@@ -34,6 +34,7 @@ import kotlinx.coroutines.flow.map
 import org.amnezia.awg.config.BadConfigException
 import org.orbitmvi.orbit.ContainerHost
 import org.orbitmvi.orbit.viewmodel.container
+import timber.log.Timber
 import xyz.teamgravity.pin_lock_compose.PinManager
 
 @HiltViewModel
@@ -164,6 +165,19 @@ constructor(
                     else StringValue.StringResource(R.string.root_accepted)
                 postSideEffect(GlobalSideEffect.Snackbar(message))
                 if (!accepted) return@intent
+                if (WgQuickBackend.hasKernelSupport())
+                    Timber.i("Device supports kernel backend. WireGuard module is built in, switching to kernel backend.")
+                else {
+                    Timber.e("Device does not support kernel backend!")
+                    intent {
+                        postSideEffect(
+                            GlobalSideEffect.Snackbar(
+                                StringValue.StringResource(R.string.kernel_wireguard_unsupported)
+                            )
+                        )
+                    }
+                    return@intent
+                }
             }
         }
         settingsRepository.upsert(state.settings.copy(appMode = appMode))
diff --git a/app/src/main/res/values-pl/strings.xml b/app/src/main/res/values-pl/strings.xml
index 68f8a12d..42eeefdc 100644
--- a/app/src/main/res/values-pl/strings.xml
+++ b/app/src/main/res/values-pl/strings.xml
@@ -324,5 +324,6 @@
     <string name="donation_closing">Moim marzeniem jest praca nad tym projektem na pełen etat.</string>
     <string name="donation_signoff">Z wdzięcznością,</string>
     <string name="google_donation_message">Niestety, ze względu na politykę Google, linki do darowizn nie są dozwolone w wersji tej aplikacji dostępnej w Google Play. Aby dowiedzieć się, gdzie można przekazać darowiznę, odwiedź strony projektu.</string>
+    <string name="kernel_wireguard_unsupported">Kernel nie zawiera wsparcia dla WireGuard (brak modułu albo nie wbudowany w kernel)!</string>
     <string name="delete_active_message">Nie można usunąć aktywnego tunelu.</string>
 </resources>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index c62a14de..20f31585 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -377,6 +377,7 @@
     <string name="delete_active_message">Cannot delete active tunnel.</string>
     <string name="back">Back</string>
     <string name="configuration">Configuration</string>
+    <string name="kernel_wireguard_unsupported">Kernel does not include WireGuard support (module missing or not built-in into kernel)!</string>
     <string name="about">About</string>
     <string name="resources">Resources</string>
     <string name="website">App website</string>