tunnel: remove kernel module downloader

Nathan Chance dropped the ball repeatedly and never maintained this in a
consistent way that anybody could use. With Android 12 out now, just
drop it all together. A bummer, but I don't see much of a choice.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui/src/main/java/com/wireguard/android/Application.kt

@@ -21,7 +21,6 @@ import com.wireguard.android.backend.GoBackend
 import com.wireguard.android.backend.WgQuickBackend
 import com.wireguard.android.configStore.FileConfigStore
 import com.wireguard.android.model.TunnelManager
-import com.wireguard.android.util.ModuleLoader
 import com.wireguard.android.util.RootShell
 import com.wireguard.android.util.ToolsInstaller
 import com.wireguard.android.util.UserKnobs
@@ -42,7 +41,6 @@ class Application : android.app.Application() {
     private val futureBackend = CompletableDeferred<Backend>()
     private val coroutineScope = CoroutineScope(Job() + Dispatchers.Main.immediate)
     private var backend: Backend? = null
-    private lateinit var moduleLoader: ModuleLoader
     private lateinit var rootShell: RootShell
     private lateinit var preferencesDataStore: DataStore<Preferences>
     private lateinit var toolsInstaller: ToolsInstaller
@@ -67,15 +65,7 @@ class Application : android.app.Application() {
     private suspend fun determineBackend(): Backend {
         var backend: Backend? = null
         var didStartRootShell = false
-        if (!ModuleLoader.isModuleLoaded() && moduleLoader.moduleMightExist()) {
-            try {
-                rootShell.start()
-                didStartRootShell = true
-                moduleLoader.loadModule()
-            } catch (ignored: Exception) {
-            }
-        }
-        if (!UserKnobs.disableKernelModule.first() && ModuleLoader.isModuleLoaded()) {
+        if (UserKnobs.enableKernelModule.first() && WgQuickBackend.hasKernelSupport()) {
             try {
                 if (!didStartRootShell)
                     rootShell.start()
@@ -100,7 +90,6 @@ class Application : android.app.Application() {
         super.onCreate()
         rootShell = RootShell(applicationContext)
         toolsInstaller = ToolsInstaller(applicationContext, rootShell)
-        moduleLoader = ModuleLoader(applicationContext, rootShell, USER_AGENT)
         preferencesDataStore = PreferenceDataStoreFactory.create { applicationContext.preferencesDataStoreFile("settings") }
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
             coroutineScope.launch {
@@ -140,9 +129,6 @@ class Application : android.app.Application() {
         @JvmStatic
         suspend fun getBackend() = get().futureBackend.await()
 
-        @JvmStatic
-        fun getModuleLoader() = get().moduleLoader
-
         @JvmStatic
         fun getRootShell() = get().rootShell