Settings: add version

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

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

@@ -56,6 +56,10 @@ public final class GoBackend implements Backend {
 
     private static native int wgTurnOn(String ifName, int tunFd, String settings);
 
+    private static native String wgVersion();
+
+    public static String getVersion() { return wgVersion(); }
+
     @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

@@ -0,0 +1,56 @@
+/*
+ * Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+package com.wireguard.android.preference;
+
+import android.content.Context;
+import android.content.Intent;
+import android.net.Uri;
+import android.support.v7.preference.Preference;
+import android.util.AttributeSet;
+
+import com.wireguard.android.Application;
+import com.wireguard.android.BuildConfig;
+import com.wireguard.android.R;
+import com.wireguard.android.backend.GoBackend;
+import com.wireguard.android.backend.WgQuickBackend;
+
+public class VersionPreference extends Preference {
+    private String versionSummary;
+
+    public VersionPreference(final Context context, final AttributeSet attrs) {
+        super(context, attrs);
+
+        if (Application.getComponent().getBackendType() == GoBackend.class) {
+            versionSummary = getContext().getString(R.string.version_userspace_summary, GoBackend.getVersion());
+        } else if (Application.getComponent().getBackendType() == WgQuickBackend.class) {
+            Application.getComponent().getToolsInstaller().getVersion().whenComplete((version, exception) -> {
+                if (exception == null)
+                    versionSummary = getContext().getString(R.string.version_kernel_summary, version);
+                else
+                    versionSummary = getContext().getString(R.string.version_kernel_unknown_summary);
+                notifyChanged();
+            });
+        }
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        return versionSummary;
+    }
+
+    @Override
+    public CharSequence getTitle() {
+        return getContext().getString(R.string.version_title, BuildConfig.VERSION_NAME);
+    }
+
+    @Override
+    protected void onClick() {
+        final Intent intent = new Intent(Intent.ACTION_VIEW);
+        intent.setData(Uri.parse("https://www.wireguard.com/"));
+        getContext().startActivity(intent);
+    }
+
+}

app/src/main/java/com/wireguard/android/util/ToolsInstaller.java

@@ -10,6 +10,7 @@ import android.content.Context;
 import android.system.OsConstants;
 import android.util.Log;
 
+import com.wireguard.android.Application;
 import com.wireguard.android.Application.ApplicationContext;
 import com.wireguard.android.Application.ApplicationScope;
 import com.wireguard.android.util.RootShell.NoRootException;
@@ -17,11 +18,14 @@ import com.wireguard.android.util.RootShell.NoRootException;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
 import javax.inject.Inject;
 
+import java9.util.concurrent.CompletionStage;
+
 /**
  * Helper to install WireGuard tools to the system partition.
  */
@@ -52,6 +56,15 @@ public final class ToolsInstaller {
         this.rootShell = rootShell;
     }
 
+    public CompletionStage<String> getVersion() {
+        return Application.getComponent().getAsyncWorker().supplyAsync(() -> {
+            final ArrayList<String> output = new ArrayList<>();
+            if (rootShell.run(output, "cat /sys/module/wireguard/version") != 0 || output.isEmpty())
+                throw new RuntimeException("Unable to determine kernel module version");
+            return output.get(0);
+        });
+    }
+
     private static File getInstallDir() {
         final String path = System.getenv("PATH");
         if (path == null)