Backend: abstract version information

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

app/src/main/java/com/wireguard/android/Application.java

@@ -46,6 +46,10 @@ public class Application extends android.app.Application {
         return get().asyncWorker;
     }
 
+    public static Backend getBackend() {
+        return get().backend;
+    }
+
     public static Class getBackendType() {
         return get().backend.getClass();
     }

app/src/main/java/com/wireguard/android/backend/Backend.java

@@ -62,4 +62,19 @@ public interface Backend {
      * @return The updated state of the tunnel.
      */
     State setState(Tunnel tunnel, State state) throws Exception;
+
+    /**
+     * Determine version of underlying backend.
+     *
+     * @return The version of the backend.
+     * @throws Exception
+     */
+    String getVersion() throws Exception;
+
+    /**
+     * Determine type name of underlying backend.
+     *
+     * @return Type name
+     */
+    String getTypeName();
 }

app/src/main/java/com/wireguard/android/backend/GoBackend.java

@@ -58,7 +58,11 @@ public final class GoBackend implements Backend {
 
     private static native String wgVersion();
 
-    public static String getVersion() { return wgVersion(); }
+    @Override
+    public String getVersion() { return wgVersion(); }
+
+    @Override
+    public String getTypeName() { return "Go userspace"; }
 
     @Override
     public Config applyConfig(final Tunnel tunnel, final Config config) throws Exception {

app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java

@@ -13,8 +13,6 @@ import com.wireguard.android.Application;
 import com.wireguard.android.model.Tunnel;
 import com.wireguard.android.model.Tunnel.State;
 import com.wireguard.android.model.Tunnel.Statistics;
-import com.wireguard.android.util.RootShell;
-import com.wireguard.android.util.ToolsInstaller;
 import com.wireguard.config.Config;
 
 import java.io.File;
@@ -41,6 +39,18 @@ public final class WgQuickBackend implements Backend {
         localTemporaryDir = new File(context.getCacheDir(), "tmp");
     }
 
+    @Override
+    public String getVersion() throws Exception {
+        final List<String> output = new ArrayList<>();
+        if (Application.getRootShell()
+                .run(output, "cat /sys/module/wireguard/version") != 0 || output.isEmpty())
+            throw new Exception("Unable to determine kernel module version");
+        return output.get(0);
+    }
+
+    @Override
+    public String getTypeName() { return "Kernel module"; }
+
     @Override
     public Config applyConfig(final Tunnel tunnel, final Config config) throws Exception {
         if (tunnel.getState() == State.UP) {

app/src/main/java/com/wireguard/android/preference/VersionPreference.java

@@ -14,6 +14,7 @@ import android.util.AttributeSet;
 import com.wireguard.android.Application;
 import com.wireguard.android.BuildConfig;
 import com.wireguard.android.R;
+import com.wireguard.android.backend.Backend;
 import com.wireguard.android.backend.GoBackend;
 import com.wireguard.android.backend.WgQuickBackend;
 
@@ -26,23 +27,14 @@ public class VersionPreference extends Preference {
     public VersionPreference(final Context context, final AttributeSet attrs) {
         super(context, attrs);
 
-        if (Application.getBackendType() == GoBackend.class) {
-            versionSummary = getContext().getString(R.string.version_userspace_summary, GoBackend.getVersion());
-        } else if (Application.getBackendType() == WgQuickBackend.class) {
-            versionSummary = getContext().getString(R.string.version_kernel_summary_checking);
-            Application.getAsyncWorker().supplyAsync(() -> {
-                final List<String> output = new ArrayList<>();
-                if (Application.getRootShell()
-                        .run(output, "cat /sys/module/wireguard/version") != 0 || output.isEmpty())
-                    throw new RuntimeException("Unable to determine kernel module version");
-                return output.get(0);
-            }).whenComplete((version, exception) -> {
-                versionSummary = exception == null
-                        ? getContext().getString(R.string.version_kernel_summary, version)
-                        : getContext().getString(R.string.version_kernel_summary_unknown);
-                notifyChanged();
-            });
-        }
+        final Backend backend = Application.getBackend();
+        versionSummary = getContext().getString(R.string.version_summary_checking, backend.getTypeName().toLowerCase());
+        Application.getAsyncWorker().supplyAsync(backend::getVersion).whenComplete((version, exception) -> {
+            versionSummary = exception == null
+                    ? getContext().getString(R.string.version_summary, backend.getTypeName(), version)
+                    : getContext().getString(R.string.version_summary_unknown, backend.getTypeName().toLowerCase());
+            notifyChanged();
+        });
     }
 
     @Override