GoBackend: integrate into app

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

15 files changed, 347 insertions, 59 deletions

diff --git a/.gitmodules b/.gitmodules
index 32ab0d51..5d767f4f 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "app/tools/wireguard"]
 	path = app/tools/wireguard
 	url = https://git.zx2c4.com/WireGuard
+[submodule "app/tools/wireguard-go"]
+	path = app/tools/wireguard-go
+	url = https://git.zx2c4.com/wireguard-go
diff --git a/README.md b/README.md
index ad216bf2..3f221c9c 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,8 @@
 # Android GUI for [WireGuard](https://www.wireguard.com/)
 
-##### [Test this app on the Play Store](https://play.google.com/apps/testing/com.wireguard.android).
-
-This is a work in progress Android GUI for [WireGuard](https://www.wireguard.com/). The ultimate goal is to [opportunistically use the kernel implementation](https://git.zx2c4.com/android_kernel_wireguard/about/), and fallback to using the non-root userspace implementation. At the time of writing, this only supports using the kernel module, but this should change in the near future.
+### [Test this app on the Play Store](https://play.google.com/apps/testing/com.wireguard.android).
 
+This is an Android GUI for [WireGuard](https://www.wireguard.com/). It [opportunistically uses the kernel implementation](https://git.zx2c4.com/android_kernel_wireguard/about/), and falls back to using the non-root [userspace implementation](https://git.zx2c4.com/wireguard-go/about/).
 
 ## License
 
diff --git a/app/src/main/java/com/wireguard/android/Application.java b/app/src/main/java/com/wireguard/android/Application.java
index 4676e0bc..c1b21373 100644
--- a/app/src/main/java/com/wireguard/android/Application.java
+++ b/app/src/main/java/com/wireguard/android/Application.java
@@ -8,6 +8,7 @@ import android.os.Looper;
 import android.preference.PreferenceManager;
 
 import com.wireguard.android.backend.Backend;
+import com.wireguard.android.backend.GoBackend;
 import com.wireguard.android.backend.WgQuickBackend;
 import com.wireguard.android.configStore.ConfigStore;
 import com.wireguard.android.configStore.FileConfigStore;
@@ -16,6 +17,7 @@ import com.wireguard.android.util.AsyncWorker;
 import com.wireguard.android.util.RootShell;
 import com.wireguard.android.util.ToolsInstaller;
 
+import java.io.File;
 import java.util.concurrent.Executor;
 
 import javax.inject.Qualifier;
@@ -56,6 +58,8 @@ public class Application extends android.app.Application {
         ToolsInstaller getToolsInstaller();
 
         TunnelManager getTunnelManager();
+
+        Class getBackendType();
     }
 
     @Qualifier
@@ -83,7 +87,16 @@ public class Application extends android.app.Application {
         public static Backend getBackend(@ApplicationContext final Context context,
                                          final RootShell rootShell,
                                          final ToolsInstaller toolsInstaller) {
-            return new WgQuickBackend(context, rootShell, toolsInstaller);
+            if (new File("/sys/module/wireguard").exists())
+                return new WgQuickBackend(context, rootShell, toolsInstaller);
+            else
+                return new GoBackend(context);
+        }
+
+        @ApplicationScope
+        @Provides
+        public static Class getBackendType(final Backend backend) {
+            return backend.getClass();
         }
 
         @ApplicationScope
diff --git a/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java b/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java
index 3eb633ff..e3cd46b1 100644
--- a/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java
+++ b/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java
@@ -2,9 +2,12 @@ package com.wireguard.android.activity;
 
 import android.app.Activity;
 import android.os.Bundle;
+import android.preference.Preference;
 import android.preference.PreferenceFragment;
 
+import com.wireguard.android.Application;
 import com.wireguard.android.R;
+import com.wireguard.android.backend.WgQuickBackend;
 
 /**
  * Interface for changing application-global persistent settings.
@@ -26,6 +29,11 @@ public class SettingsActivity extends Activity {
         public void onCreate(final Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);
             addPreferencesFromResource(R.xml.preferences);
+            if (Application.getComponent().getBackendType() != WgQuickBackend.class) {
+                final Preference toolsInstaller =
+                        getPreferenceManager().findPreference("tools_installer");
+                getPreferenceScreen().removePreference(toolsInstaller);
+            }
         }
     }
 }
diff --git a/app/src/main/java/com/wireguard/android/backend/GoBackend.java b/app/src/main/java/com/wireguard/android/backend/GoBackend.java
new file mode 100644
index 00000000..db059e22
--- /dev/null
+++ b/app/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -0,0 +1,125 @@
+package com.wireguard.android.backend;
+
+import android.content.Context;
+import android.support.v4.util.ArraySet;
+import android.util.Log;
+
+import com.wireguard.android.model.Tunnel;
+import com.wireguard.android.model.Tunnel.State;
+import com.wireguard.android.model.Tunnel.Statistics;
+import com.wireguard.config.Config;
+import com.wireguard.config.Interface;
+import com.wireguard.config.Peer;
+import com.wireguard.crypto.KeyEncoding;
+
+import java.util.Collections;
+import java.util.Formatter;
+import java.util.Set;
+
+public final class GoBackend implements Backend {
+    private static final String TAG = "WireGuard/" + GoBackend.class.getSimpleName();
+
+    static {
+        System.loadLibrary("wg-go");
+    }
+
+    private final Context context;
+    private Tunnel currentTunnel;
+
+    public GoBackend(final Context context) {
+        this.context = context;
+    }
+
+    private static native int wgGetSocketV4(int handle);
+
+    private static native int wgGetSocketV6(int handle);
+
+    private static native void wgTurnOff(int handle);
+
+    private static native int wgTurnOn(String ifName, int tunFd, String settings);
+
+    @Override
+    public Config applyConfig(final Tunnel tunnel, final Config config) throws Exception {
+        if (tunnel.getState() == State.UP) {
+            // Restart the tunnel to apply the new config.
+            setStateInternal(tunnel, tunnel.getConfig(), State.DOWN);
+            try {
+                setStateInternal(tunnel, config, State.UP);
+            } catch (final Exception e) {
+                // The new configuration didn't work, so try to go back to the old one.
+                setStateInternal(tunnel, tunnel.getConfig(), State.UP);
+                throw e;
+            }
+        }
+        return config;
+    }
+
+    @Override
+    public Set<String> enumerate() {
+        if (currentTunnel != null) {
+            final Set<String> runningTunnels = new ArraySet<>();
+            runningTunnels.add(currentTunnel.getName());
+            return runningTunnels;
+        }
+        return Collections.emptySet();
+    }
+
+    @Override
+    public State getState(final Tunnel tunnel) {
+        return currentTunnel == tunnel ? State.UP : State.DOWN;
+    }
+
+    @Override
+    public Statistics getStatistics(final Tunnel tunnel) {
+        return new Statistics();
+    }
+
+    @Override
+    public State setState(final Tunnel tunnel, State state) throws Exception {
+        final State originalState = getState(tunnel);
+        if (state == State.TOGGLE)
+            state = originalState == State.UP ? State.DOWN : State.UP;
+        if (state == originalState)
+            return originalState;
+        if (state == State.UP && currentTunnel != null)
+            throw new IllegalStateException("Only one userspace tunnel can run at a time");
+        Log.d(TAG, "Changing tunnel " + tunnel.getName() + " to state " + state);
+        setStateInternal(tunnel, tunnel.getConfig(), state);
+        return getState(tunnel);
+    }
+
+    private void setStateInternal(final Tunnel tunnel, final Config config, final State state)
+            throws Exception {
+        if (state == State.UP) {
+            // Do something (context.startService()...).
+            currentTunnel = tunnel;
+
+            Formatter fmt = new Formatter(new StringBuilder());
+            final Interface iface = config.getInterface();
+            fmt.format("replace_peers=true\n");
+            if (iface.getPrivateKey() != null)
+                fmt.format("private_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(iface.getPrivateKey())));
+            if (iface.getListenPort() != null)
+                fmt.format("listen_port=%d\n", Integer.parseInt(config.getInterface().getListenPort()));
+            for (final Peer peer : config.getPeers()) {
+                if (peer.getPublicKey() != null)
+                    fmt.format("public_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(peer.getPublicKey())));
+                if (peer.getPreSharedKey() != null)
+                    fmt.format("preshared_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(peer.getPreSharedKey())));
+                if (peer.getEndpoint() != null)
+                    fmt.format("endpoint=%s\n", peer.getEndpoint());
+                if (peer.getPersistentKeepalive() != null)
+                    fmt.format("persistent_keepalive_interval=%d\n", Integer.parseInt(peer.getPersistentKeepalive()));
+                if (peer.getAllowedIPs() != null) {
+                    for (final String allowedIp : peer.getAllowedIPs().split(" *, *")) {
+                        fmt.format("allowed_ip=%s\n", allowedIp);
+                    }
+                }
+            }
+            wgTurnOn(tunnel.getName(), -1, fmt.toString());
+        } else {
+            // Do something else.
+            currentTunnel = null;
+        }
+    }
+}
diff --git a/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java b/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
index 907f5d6d..760aac85 100644
--- a/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
+++ b/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
@@ -88,8 +88,6 @@ public final class WgQuickBackend implements Backend {
             state = originalState == State.UP ? State.DOWN : State.UP;
         if (state == originalState)
             return originalState;
-        if (state == State.UP && !new File("/sys/module/wireguard").exists())
-            throw new ModuleNotLoadedException("WireGuard module not loaded");
         Log.d(TAG, "Changing tunnel " + tunnel.getName() + " to state " + state);
         toolsInstaller.ensureToolsAvailable();
         setStateInternal(tunnel, tunnel.getConfig(), state);
@@ -113,14 +111,4 @@ public final class WgQuickBackend implements Backend {
         if (result != 0)
             throw new Exception("Unable to configure tunnel (wg-quick returned " + result + ')');
     }
-
-    public static class ModuleNotLoadedException extends Exception {
-        public ModuleNotLoadedException(final String message, final Throwable cause) {
-            super(message, cause);
-        }
-
-        public ModuleNotLoadedException(final String message) {
-            super(message);
-        }
-    }
 }
diff --git a/app/src/main/java/com/wireguard/android/fragment/TunnelController.java b/app/src/main/java/com/wireguard/android/fragment/TunnelController.java
index ca40654e..990509e0 100644
--- a/app/src/main/java/com/wireguard/android/fragment/TunnelController.java
+++ b/app/src/main/java/com/wireguard/android/fragment/TunnelController.java
@@ -1,18 +1,13 @@
 package com.wireguard.android.fragment;
 
-import android.app.AlertDialog;
 import android.content.Context;
 import android.databinding.DataBindingUtil;
 import android.databinding.ViewDataBinding;
-import android.text.Html;
-import android.text.method.LinkMovementMethod;
 import android.util.Log;
 import android.view.View;
-import android.widget.TextView;
 
 import com.commonsware.cwac.crossport.design.widget.Snackbar;
 import com.wireguard.android.R;
-import com.wireguard.android.backend.WgQuickBackend;
 import com.wireguard.android.databinding.TunnelDetailFragmentBinding;
 import com.wireguard.android.databinding.TunnelListItemBinding;
 import com.wireguard.android.model.Tunnel;
@@ -47,26 +42,11 @@ public final class TunnelController {
             if (throwable == null)
                 return;
             final Context context = view.getContext();
-            if (ExceptionLoggers.unwrap(throwable)
-                    instanceof WgQuickBackend.ModuleNotLoadedException) {
-                final String message = context.getString(R.string.not_supported_message);
-                final String title = context.getString(R.string.not_supported_title);
-                final AlertDialog dialog = new AlertDialog.Builder(context)
-                        .setMessage(Html.fromHtml(message))
-                        .setPositiveButton(R.string.ok, null)
-                        .setTitle(title)
-                        .show();
-                // Make links work.
-                ((TextView) dialog.findViewById(android.R.id.message))
-                        .setMovementMethod(LinkMovementMethod.getInstance());
-                Log.e(TAG, title, throwable);
-            } else {
-                final String error = ExceptionLoggers.unwrap(throwable).getMessage();
-                final int messageResId = checked ? R.string.error_up : R.string.error_down;
-                final String message = context.getString(messageResId, error);
-                Snackbar.make(view, message, Snackbar.LENGTH_LONG).show();
-                Log.e(TAG, message, throwable);
-            }
+            final String error = ExceptionLoggers.unwrap(throwable).getMessage();
+            final int messageResId = checked ? R.string.error_up : R.string.error_down;
+            final String message = context.getString(messageResId, error);
+            Snackbar.make(view, message, Snackbar.LENGTH_LONG).show();
+            Log.e(TAG, message, throwable);
         });
     }
 }
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 7140bb7b..7de33f15 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -39,23 +39,6 @@
     <string name="listen_port">Listen port</string>
     <string name="mtu">MTU</string>
     <string name="name">Name</string>
-    <string name="not_supported_message" tools:ignore="TypographyQuotes"><![CDATA[
-        <p>Your Android device does not <em>currently</em> have the WireGuard kernel module. Please
-        talk to the manufacturer of your Android device or the author of your device&rsquo;s ROM
-        about including the WireGuard kernel module.</p>
-
-        <p>Fortunately, we are in the process of implementing support for WireGuard in a way that
-        will work on all devices, without any need for the kernel module. This means that while you
-        may not be able to use WireGuard today, you will very likely be able to use WireGuard in
-        several weeks. Things are looking up!</p>
-
-        <p>Sorry for the wait. In the mean time, you may stay up to date on the latest project news
-        by <a href="https://lists.zx2c4.com/mailman/listinfo/wireguard">subscribing to our mailing
-        list</a>. General information about the project is available at
-        <a href="https://www.wireguard.com/">WireGuard.com</a>.</p>
-    ]]></string>
-    <string name="not_supported_title">WireGuard not installed</string>
-    <string name="ok">OK</string>
     <string name="peer">Peer</string>
     <string name="persistent_keepalive">Persistent keepalive</string>
     <string name="pre_shared_key">Pre-shared key</string>
diff --git a/app/src/main/res/xml/preferences.xml b/app/src/main/res/xml/preferences.xml
index 17fd4fc8..b032bea7 100644
--- a/app/src/main/res/xml/preferences.xml
+++ b/app/src/main/res/xml/preferences.xml
@@ -5,5 +5,5 @@
         android:key="restore_on_boot"
         android:summary="@string/restore_on_boot_summary"
         android:title="@string/restore_on_boot_title" />
-    <com.wireguard.android.preference.ToolsInstallerPreference />
+    <com.wireguard.android.preference.ToolsInstallerPreference android:key="tools_installer" />
 </PreferenceScreen>
diff --git a/app/tools/CMakeLists.txt b/app/tools/CMakeLists.txt
index 22ddbcc1..4cf030bf 100644
--- a/app/tools/CMakeLists.txt
+++ b/app/tools/CMakeLists.txt
@@ -10,3 +10,16 @@ target_compile_options(libwg-quick.so PUBLIC -O3 -std=gnu11 -Wall -pedantic -Wno
 file(GLOB WG_SOURCES wireguard/src/tools/*.c libmnl/src/*.c)
 add_executable(libwg.so ${WG_SOURCES})
 target_compile_options(libwg.so PUBLIC "-I${CMAKE_CURRENT_SOURCE_DIR}libmnl/src/" "-I${CMAKE_CURRENT_SOURCE_DIR}/libmnl/include/" "-I${CMAKE_CURRENT_SOURCE_DIR}/wireguard/src/tools/" -O3 -std=gnu11 -D_GNU_SOURCE -DHAVE_VISIBILITY_HIDDEN -DRUNSTATEDIR=\"\\\"/data/data/com.wireguard.android/cache\\\"\" -Wno-pointer-arith -Wno-unused-parameter)
+
+add_custom_target(libwg-go.so WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/libwg-go" COMMENT "Building wireguard-go" VERBATIM COMMAND make
+    ANDROID_ARCH_NAME=${ANDROID_ARCH_NAME}
+    ANDROID_C_COMPILER=${ANDROID_C_COMPILER}
+    ANDROID_TOOLCHAIN_ROOT=${ANDROID_TOOLCHAIN_ROOT}
+    ANDROID_LLVM_TRIPLE=${ANDROID_LLVM_TRIPLE}
+    ANDROID_SYSROOT=${ANDROID_SYSROOT}
+    CFLAGS=${CMAKE_C_FLAGS}\ -Wno-unused-command-line-argument
+    LDFLAGS=${CMAKE_SHARED_LINKER_FLAGS}\ -fuse-ld=gold
+    DESTDIR=${CMAKE_LIBRARY_OUTPUT_DIRECTORY}
+)
+# Hack to make it actually build as part of the default target
+add_dependencies(libwg.so libwg-go.so)
diff --git a/app/tools/libwg-go/.gitignore b/app/tools/libwg-go/.gitignore
new file mode 100644
index 00000000..c039ddfb
--- /dev/null
+++ b/app/tools/libwg-go/.gitignore
@@ -0,0 +1,4 @@
+go/
+*.go
+libwg-go.h
+jni.o
diff --git a/app/tools/libwg-go/Makefile b/app/tools/libwg-go/Makefile
new file mode 100644
index 00000000..300b3841
--- /dev/null
+++ b/app/tools/libwg-go/Makefile
@@ -0,0 +1,21 @@
+containing = $(foreach v,$2,$(if $(findstring $1,$v),$v))
+FILES := $(wildcard ../wireguard-go/*/*.go) $(wildcard ../wireguard-go/*.go)
+FILES := $(filter-out %/main.go $(filter-out %_linux.go,$(call containing,_,$(FILES))),$(FILES))
+
+export GOPATH := $(CURDIR)/go
+CLANG_FLAGS := --target=$(ANDROID_LLVM_TRIPLE) --gcc-toolchain=$(ANDROID_TOOLCHAIN_ROOT) --sysroot=$(ANDROID_SYSROOT)
+export CGO_CFLAGS := $(CLANG_FLAGS) $(CFLAGS)
+export CGO_LDFLAGS := $(CLANG_FLAGS) $(LDFLAGS)
+export CC := $(ANDROID_C_COMPILER)
+GO_ARCH_FILTER := case "$(ANDROID_ARCH_NAME)" in x86) echo 386 ;; x86_64) echo amd64 ;; *) echo $(ANDROID_ARCH_NAME) ;; esac
+export GOARCH := $(shell $(GO_ARCH_FILTER))
+export GOOS := android
+export CGO_ENABLED := 1
+
+$(DESTDIR)/libwg-go.so: $(FILES) api-android.go jni.c
+	find . -name '*.go' -type l -delete
+	find . -type d -empty -delete
+	mkdir -p $(subst ../wireguard-go/,./,$(dir $(FILES)))
+	$(foreach FILE,$(FILES),ln -sfrt $(subst ../wireguard-go/,./,$(dir $(FILE))) $(FILE);)
+	go get -v -d
+	go build -v -o $(DESTDIR)/libwg-go.so -buildmode c-shared
diff --git a/app/tools/libwg-go/api-android.go b/app/tools/libwg-go/api-android.go
new file mode 100644
index 00000000..b2e3da17
--- /dev/null
+++ b/app/tools/libwg-go/api-android.go
@@ -0,0 +1,111 @@
+package main
+
+// #cgo LDFLAGS: -llog
+// #include <android/log.h>
+import "C"
+
+import (
+	"bufio"
+	"io/ioutil"
+	"log"
+	"math"
+	"os"
+	"strings"
+)
+
+type AndroidLogger struct {
+	level         C.int
+	interfaceName string
+}
+
+func (l AndroidLogger) Write(p []byte) (int, error) {
+	C.__android_log_write(l.level, C.CString("WireGuard/GoBackend/"+l.interfaceName), C.CString(string(p)))
+	return len(p), nil
+}
+
+var tunnelHandles map[int32]*Device
+
+func init() {
+	tunnelHandles = make(map[int32]*Device)
+}
+
+//export wgTurnOn
+func wgTurnOn(ifnameRef string, tun_fd int32, settings string) int32 {
+	interfaceName := string([]byte(ifnameRef))
+
+	logger := &Logger{
+		Debug: log.New(&AndroidLogger{level: C.ANDROID_LOG_DEBUG, interfaceName: interfaceName}, "", 0),
+		Info:  log.New(&AndroidLogger{level: C.ANDROID_LOG_INFO, interfaceName: interfaceName}, "", 0),
+		Error: log.New(&AndroidLogger{level: C.ANDROID_LOG_ERROR, interfaceName: interfaceName}, "", 0),
+	}
+
+	logger.Debug.Println("Debug log enabled")
+
+	tun := &NativeTun{
+		fd:     os.NewFile(uintptr(tun_fd), ""),
+		events: make(chan TUNEvent, 5),
+		errors: make(chan error, 5),
+	}
+	device := NewDevice(tun, logger)
+	device.tun.mtu = DefaultMTU //TODO: make dynamic
+
+	bufferedSettings := bufio.NewReadWriter(bufio.NewReader(strings.NewReader(settings)), bufio.NewWriter(ioutil.Discard))
+	setError := ipcSetOperation(device, bufferedSettings)
+	if setError != nil {
+		logger.Debug.Println(setError)
+		return -1
+	}
+
+	device.Up()
+	logger.Info.Println("Device started")
+
+	var i int32
+	for i = 0; i < math.MaxInt32; i++ {
+		if _, exists := tunnelHandles[i]; !exists {
+			break
+		}
+	}
+	if i == math.MaxInt32 {
+		return -1
+	}
+	tunnelHandles[i] = device
+	return i
+}
+
+//export wgTurnOff
+func wgTurnOff(tunnelHandle int32) {
+	device, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return
+	}
+	delete(tunnelHandles, tunnelHandle)
+	device.Close()
+}
+
+//export wgGetSocketV4
+func wgGetSocketV4(tunnelHandle int32) int32 {
+	device, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return -1
+	}
+	native, ok := device.net.bind.(NativeBind)
+	if !ok {
+		return -1
+	}
+	return int32(native.sock4)
+}
+
+//export wgGetSocketV6
+func wgGetSocketV6(tunnelHandle int32) int32 {
+	device, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return -1
+	}
+	native, ok := device.net.bind.(NativeBind)
+	if !ok {
+		return -1
+	}
+	return int32(native.sock6)
+}
+
+func main() {}
diff --git a/app/tools/libwg-go/jni.c b/app/tools/libwg-go/jni.c
new file mode 100644
index 00000000..1476dab7
--- /dev/null
+++ b/app/tools/libwg-go/jni.c
@@ -0,0 +1,40 @@
+#include <jni.h>
+
+struct go_string { const char *str; long n; };
+extern int wgTurnOn(struct go_string ifname, int tun_fd, struct go_string settings);
+extern void wgTurnOff(int handle);
+extern int wgGetSocketV4(int handle);
+extern int wgGetSocketV6(int handle);
+
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings)
+{
+	const char *ifname_str = (*env)->GetStringUTFChars(env, ifname, 0);
+	size_t ifname_len = (*env)->GetStringUTFLength(env, ifname);
+	const char *settings_str = (*env)->GetStringUTFChars(env, settings, 0);
+	size_t settings_len = (*env)->GetStringUTFLength(env, settings);
+	int ret = wgTurnOn((struct go_string){
+		.str = ifname_str,
+		.n = ifname_len
+	}, tun_fd, (struct go_string){
+		.str = settings_str,
+		.n = settings_len
+	});
+	(*env)->ReleaseStringUTFChars(env, ifname, ifname_str);
+	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
+	return ret;
+}
+
+JNIEXPORT void JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOff(JNIEnv *env, jclass c, jint handle)
+{
+	wgTurnOff(handle);
+}
+
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetSocketV4(JNIEnv *env, jclass c, jint handle)
+{
+	return wgGetSocketV4(handle);
+}
+
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetSocketV6(JNIEnv *env, jclass c, jint handle)
+{
+	return wgGetSocketV6(handle);
+}
diff --git a/app/tools/wireguard-go b/app/tools/wireguard-go
new file mode 160000
+Subproject 8f1d1b8c54d747309d9fdf06b157823af2a823b