Move the VPN code out of packages/Connectivity.

Bug: 173331190
Test: atest FrameworksNetTests HostsideVpnTests CtsNetTestCases
Change-Id: Idc6ed1a544e744f8661d1e387da278736d407489

2 files changed, 1308 insertions, 0 deletions

diff --git a/core/java/android/net/VpnManager.java b/core/java/android/net/VpnManager.java
new file mode 100644
index 000000000000..f472ed4381d1
--- /dev/null
+++ b/core/java/android/net/VpnManager.java
@@ -0,0 +1,406 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import static com.android.internal.util.Preconditions.checkNotNull;
+
+import android.annotation.IntDef;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.RequiresPermission;
+import android.annotation.UserIdInt;
+import android.app.Activity;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.res.Resources;
+import android.os.RemoteException;
+
+import com.android.internal.net.LegacyVpnInfo;
+import com.android.internal.net.VpnConfig;
+import com.android.internal.net.VpnProfile;
+
+import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.security.GeneralSecurityException;
+import java.util.List;
+
+/**
+ * This class provides an interface for apps to manage platform VPN profiles
+ *
+ * <p>Apps can use this API to provide profiles with which the platform can set up a VPN without
+ * further app intermediation. When a VPN profile is present and the app is selected as an always-on
+ * VPN, the platform will directly trigger the negotiation of the VPN without starting or waking the
+ * app (unlike VpnService).
+ *
+ * <p>VPN apps using supported protocols should preferentially use this API over the {@link
+ * VpnService} API for ease-of-development and reduced maintainance burden. This also give the user
+ * the guarantee that VPN network traffic is not subjected to on-device packet interception.
+ *
+ * @see Ikev2VpnProfile
+ */
+public class VpnManager {
+    /** Type representing a lack of VPN @hide */
+    public static final int TYPE_VPN_NONE = -1;
+
+    /**
+     * A VPN created by an app using the {@link VpnService} API.
+     * @hide
+     */
+    public static final int TYPE_VPN_SERVICE = 1;
+
+    /**
+     * A VPN created using a {@link VpnManager} API such as {@link #startProvisionedVpnProfile}.
+     * @hide
+     */
+    public static final int TYPE_VPN_PLATFORM = 2;
+
+    /**
+     * An IPsec VPN created by the built-in LegacyVpnRunner.
+     * @deprecated new Android devices should use VPN_TYPE_PLATFORM instead.
+     * @hide
+     */
+    @Deprecated
+    public static final int TYPE_VPN_LEGACY = 3;
+
+    /**
+     * Channel for VPN notifications.
+     * @hide
+     */
+    public static final String NOTIFICATION_CHANNEL_VPN = "VPN";
+
+    /** @hide */
+    @IntDef(value = {TYPE_VPN_NONE, TYPE_VPN_SERVICE, TYPE_VPN_PLATFORM, TYPE_VPN_LEGACY})
+    @Retention(RetentionPolicy.SOURCE)
+    public @interface VpnType {}
+
+    @NonNull private final Context mContext;
+    @NonNull private final IVpnManager mService;
+
+    private static Intent getIntentForConfirmation() {
+        final Intent intent = new Intent();
+        final ComponentName componentName = ComponentName.unflattenFromString(
+                Resources.getSystem().getString(
+                        com.android.internal.R.string.config_platformVpnConfirmDialogComponent));
+        intent.setComponent(componentName);
+        return intent;
+    }
+
+    /**
+     * Create an instance of the VpnManager with the given context.
+     *
+     * <p>Internal only. Applications are expected to obtain an instance of the VpnManager via the
+     * {@link Context.getSystemService()} method call.
+     *
+     * @hide
+     */
+    public VpnManager(@NonNull Context ctx, @NonNull IVpnManager service) {
+        mContext = checkNotNull(ctx, "missing Context");
+        mService = checkNotNull(service, "missing IVpnManager");
+    }
+
+    /**
+     * Install a VpnProfile configuration keyed on the calling app's package name.
+     *
+     * <p>This method returns {@code null} if user consent has already been granted, or an {@link
+     * Intent} to a system activity. If an intent is returned, the application should launch the
+     * activity using {@link Activity#startActivityForResult} to request user consent. The activity
+     * may pop up a dialog to require user action, and the result will come back via its {@link
+     * Activity#onActivityResult}. If the result is {@link Activity#RESULT_OK}, the user has
+     * consented, and the VPN profile can be started.
+     *
+     * @param profile the VpnProfile provided by this package. Will override any previous VpnProfile
+     *     stored for this package.
+     * @return an Intent requesting user consent to start the VPN, or null if consent is not
+     *     required based on privileges or previous user consent.
+     */
+    @Nullable
+    public Intent provisionVpnProfile(@NonNull PlatformVpnProfile profile) {
+        final VpnProfile internalProfile;
+
+        try {
+            internalProfile = profile.toVpnProfile();
+        } catch (GeneralSecurityException | IOException e) {
+            // Conversion to VpnProfile failed; this is an invalid profile. Both of these exceptions
+            // indicate a failure to convert a PrivateKey or X509Certificate to a Base64 encoded
+            // string as required by the VpnProfile.
+            throw new IllegalArgumentException("Failed to serialize PlatformVpnProfile", e);
+        }
+
+        try {
+            // Profile can never be null; it either gets set, or an exception is thrown.
+            if (mService.provisionVpnProfile(internalProfile, mContext.getOpPackageName())) {
+                return null;
+            }
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+        return getIntentForConfirmation();
+    }
+
+    /**
+     * Delete the VPN profile configuration that was provisioned by the calling app
+     *
+     * @throws SecurityException if this would violate user settings
+     */
+    public void deleteProvisionedVpnProfile() {
+        try {
+            mService.deleteVpnProfile(mContext.getOpPackageName());
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Request the startup of a previously provisioned VPN.
+     *
+     * @throws SecurityException exception if user or device settings prevent this VPN from being
+     *     setup, or if user consent has not been granted
+     */
+    public void startProvisionedVpnProfile() {
+        try {
+            mService.startVpnProfile(mContext.getOpPackageName());
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /** Tear down the VPN provided by the calling app (if any) */
+    public void stopProvisionedVpnProfile() {
+        try {
+            mService.stopVpnProfile(mContext.getOpPackageName());
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Return the VPN configuration for the given user ID.
+     * @hide
+     */
+    @Nullable
+    public VpnConfig getVpnConfig(@UserIdInt int userId) {
+        try {
+            return mService.getVpnConfig(userId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Resets all VPN settings back to factory defaults.
+     * @hide
+     */
+    @RequiresPermission(android.Manifest.permission.NETWORK_SETTINGS)
+    public void factoryReset() {
+        try {
+            mService.factoryReset();
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Prepare for a VPN application.
+     * VPN permissions are checked in the {@link Vpn} class. If the caller is not {@code userId},
+     * {@link android.Manifest.permission.INTERACT_ACROSS_USERS_FULL} permission is required.
+     *
+     * @param oldPackage Package name of the application which currently controls VPN, which will
+     *                   be replaced. If there is no such application, this should should either be
+     *                   {@code null} or {@link VpnConfig.LEGACY_VPN}.
+     * @param newPackage Package name of the application which should gain control of VPN, or
+     *                   {@code null} to disable.
+     * @param userId User for whom to prepare the new VPN.
+     *
+     * @hide
+     */
+    public boolean prepareVpn(@Nullable String oldPackage, @Nullable String newPackage,
+            int userId) {
+        try {
+            return mService.prepareVpn(oldPackage, newPackage, userId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Set whether the VPN package has the ability to launch VPNs without user intervention. This
+     * method is used by system-privileged apps. VPN permissions are checked in the {@link Vpn}
+     * class. If the caller is not {@code userId}, {@link
+     * android.Manifest.permission.INTERACT_ACROSS_USERS_FULL} permission is required.
+     *
+     * @param packageName The package for which authorization state should change.
+     * @param userId User for whom {@code packageName} is installed.
+     * @param vpnType The {@link VpnManager.VpnType} constant representing what class of VPN
+     *     permissions should be granted. When unauthorizing an app, {@link
+     *     VpnManager.TYPE_VPN_NONE} should be used.
+     * @hide
+     */
+    public void setVpnPackageAuthorization(
+            String packageName, int userId, @VpnManager.VpnType int vpnType) {
+        try {
+            mService.setVpnPackageAuthorization(packageName, userId, vpnType);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Checks if a VPN app supports always-on mode.
+     *
+     * In order to support the always-on feature, an app has to
+     * <ul>
+     *     <li>target {@link VERSION_CODES#N API 24} or above, and
+     *     <li>not opt out through the {@link VpnService#SERVICE_META_DATA_SUPPORTS_ALWAYS_ON}
+     *         meta-data field.
+     * </ul>
+     *
+     * @param userId The identifier of the user for whom the VPN app is installed.
+     * @param vpnPackage The canonical package name of the VPN app.
+     * @return {@code true} if and only if the VPN app exists and supports always-on mode.
+     * @hide
+     */
+    public boolean isAlwaysOnVpnPackageSupportedForUser(int userId, @Nullable String vpnPackage) {
+        try {
+            return mService.isAlwaysOnVpnPackageSupported(userId, vpnPackage);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Configures an always-on VPN connection through a specific application.
+     * This connection is automatically granted and persisted after a reboot.
+     *
+     * <p>The designated package should declare a {@link VpnService} in its
+     *    manifest guarded by {@link android.Manifest.permission.BIND_VPN_SERVICE},
+     *    otherwise the call will fail.
+     *
+     * @param userId The identifier of the user to set an always-on VPN for.
+     * @param vpnPackage The package name for an installed VPN app on the device, or {@code null}
+     *                   to remove an existing always-on VPN configuration.
+     * @param lockdownEnabled {@code true} to disallow networking when the VPN is not connected or
+     *        {@code false} otherwise.
+     * @param lockdownAllowlist The list of packages that are allowed to access network directly
+     *         when VPN is in lockdown mode but is not running. Non-existent packages are ignored so
+     *         this method must be called when a package that should be allowed is installed or
+     *         uninstalled.
+     * @return {@code true} if the package is set as always-on VPN controller;
+     *         {@code false} otherwise.
+     * @hide
+     */
+    @RequiresPermission(android.Manifest.permission.CONTROL_ALWAYS_ON_VPN)
+    public boolean setAlwaysOnVpnPackageForUser(int userId, @Nullable String vpnPackage,
+            boolean lockdownEnabled, @Nullable List<String> lockdownAllowlist) {
+        try {
+            return mService.setAlwaysOnVpnPackage(
+                    userId, vpnPackage, lockdownEnabled, lockdownAllowlist);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Returns the package name of the currently set always-on VPN application.
+     * If there is no always-on VPN set, or the VPN is provided by the system instead
+     * of by an app, {@code null} will be returned.
+     *
+     * @return Package name of VPN controller responsible for always-on VPN,
+     *         or {@code null} if none is set.
+     * @hide
+     */
+    @RequiresPermission(android.Manifest.permission.CONTROL_ALWAYS_ON_VPN)
+    public String getAlwaysOnVpnPackageForUser(int userId) {
+        try {
+            return mService.getAlwaysOnVpnPackage(userId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * @return whether always-on VPN is in lockdown mode.
+     *
+     * @hide
+     **/
+    @RequiresPermission(android.Manifest.permission.CONTROL_ALWAYS_ON_VPN)
+    public boolean isVpnLockdownEnabled(int userId) {
+        try {
+            return mService.isVpnLockdownEnabled(userId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * @return the list of packages that are allowed to access network when always-on VPN is in
+     * lockdown mode but not connected. Returns {@code null} when VPN lockdown is not active.
+     *
+     * @hide
+     **/
+    @RequiresPermission(android.Manifest.permission.CONTROL_ALWAYS_ON_VPN)
+    public List<String> getVpnLockdownAllowlist(int userId) {
+        try {
+            return mService.getVpnLockdownAllowlist(userId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Return the legacy VPN information for the specified user ID.
+     * @hide
+     */
+    public LegacyVpnInfo getLegacyVpnInfo(@UserIdInt int userId) {
+        try {
+            return mService.getLegacyVpnInfo(userId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Starts a legacy VPN.
+     * @hide
+     */
+    public void startLegacyVpn(VpnProfile profile) {
+        try {
+            mService.startLegacyVpn(profile);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Informs the service that legacy lockdown VPN state should be updated (e.g., if its keystore
+     * entry has been updated). If the LockdownVpn mechanism is enabled, updates the vpn
+     * with a reload of its profile.
+     *
+     * <p>This method can only be called by the system UID
+     * @return a boolean indicating success
+     *
+     * @hide
+     */
+    public boolean updateLockdownVpn() {
+        try {
+            return mService.updateLockdownVpn();
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+}
\ No newline at end of file
diff --git a/core/java/android/net/VpnService.java b/core/java/android/net/VpnService.java
new file mode 100644
index 000000000000..e43b0b6fa635
--- /dev/null
+++ b/core/java/android/net/VpnService.java
@@ -0,0 +1,902 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import static android.system.OsConstants.AF_INET;
+import static android.system.OsConstants.AF_INET6;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.RequiresPermission;
+import android.annotation.SystemApi;
+import android.app.Activity;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.app.admin.DevicePolicyManager;
+import android.compat.annotation.UnsupportedAppUsage;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.IPackageManager;
+import android.content.pm.PackageManager;
+import android.os.Binder;
+import android.os.IBinder;
+import android.os.Parcel;
+import android.os.ParcelFileDescriptor;
+import android.os.RemoteException;
+import android.os.ServiceManager;
+import android.os.UserHandle;
+
+import com.android.internal.net.VpnConfig;
+
+import java.net.DatagramSocket;
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.Socket;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * VpnService is a base class for applications to extend and build their
+ * own VPN solutions. In general, it creates a virtual network interface,
+ * configures addresses and routing rules, and returns a file descriptor
+ * to the application. Each read from the descriptor retrieves an outgoing
+ * packet which was routed to the interface. Each write to the descriptor
+ * injects an incoming packet just like it was received from the interface.
+ * The interface is running on Internet Protocol (IP), so packets are
+ * always started with IP headers. The application then completes a VPN
+ * connection by processing and exchanging packets with the remote server
+ * over a tunnel.
+ *
+ * <p>Letting applications intercept packets raises huge security concerns.
+ * A VPN application can easily break the network. Besides, two of them may
+ * conflict with each other. The system takes several actions to address
+ * these issues. Here are some key points:
+ * <ul>
+ *   <li>User action is required the first time an application creates a VPN
+ *       connection.</li>
+ *   <li>There can be only one VPN connection running at the same time. The
+ *       existing interface is deactivated when a new one is created.</li>
+ *   <li>A system-managed notification is shown during the lifetime of a
+ *       VPN connection.</li>
+ *   <li>A system-managed dialog gives the information of the current VPN
+ *       connection. It also provides a button to disconnect.</li>
+ *   <li>The network is restored automatically when the file descriptor is
+ *       closed. It also covers the cases when a VPN application is crashed
+ *       or killed by the system.</li>
+ * </ul>
+ *
+ * <p>There are two primary methods in this class: {@link #prepare} and
+ * {@link Builder#establish}. The former deals with user action and stops
+ * the VPN connection created by another application. The latter creates
+ * a VPN interface using the parameters supplied to the {@link Builder}.
+ * An application must call {@link #prepare} to grant the right to use
+ * other methods in this class, and the right can be revoked at any time.
+ * Here are the general steps to create a VPN connection:
+ * <ol>
+ *   <li>When the user presses the button to connect, call {@link #prepare}
+ *       and launch the returned intent, if non-null.</li>
+ *   <li>When the application becomes prepared, start the service.</li>
+ *   <li>Create a tunnel to the remote server and negotiate the network
+ *       parameters for the VPN connection.</li>
+ *   <li>Supply those parameters to a {@link Builder} and create a VPN
+ *       interface by calling {@link Builder#establish}.</li>
+ *   <li>Process and exchange packets between the tunnel and the returned
+ *       file descriptor.</li>
+ *   <li>When {@link #onRevoke} is invoked, close the file descriptor and
+ *       shut down the tunnel gracefully.</li>
+ * </ol>
+ *
+ * <p>Services extending this class need to be declared with an appropriate
+ * permission and intent filter. Their access must be secured by
+ * {@link android.Manifest.permission#BIND_VPN_SERVICE} permission, and
+ * their intent filter must match {@link #SERVICE_INTERFACE} action. Here
+ * is an example of declaring a VPN service in {@code AndroidManifest.xml}:
+ * <pre>
+ * &lt;service android:name=".ExampleVpnService"
+ *         android:permission="android.permission.BIND_VPN_SERVICE"&gt;
+ *     &lt;intent-filter&gt;
+ *         &lt;action android:name="android.net.VpnService"/&gt;
+ *     &lt;/intent-filter&gt;
+ * &lt;/service&gt;</pre>
+ *
+ * <p> The Android system starts a VPN in the background by calling
+ * {@link android.content.Context#startService startService()}. In Android 8.0
+ * (API level 26) and higher, the system places VPN apps on the temporary
+ * allowlist for a short period so the app can start in the background. The VPN
+ * app must promote itself to the foreground after it's launched or the system
+ * will shut down the app.
+ *
+ * <h3>Developer's guide</h3>
+ *
+ * <p>To learn more about developing VPN apps, read the
+ * <a href="{@docRoot}guide/topics/connectivity/vpn">VPN developer's guide</a>.
+ *
+ * @see Builder
+ */
+public class VpnService extends Service {
+
+    /**
+     * The action must be matched by the intent filter of this service. It also
+     * needs to require {@link android.Manifest.permission#BIND_VPN_SERVICE}
+     * permission so that other applications cannot abuse it.
+     */
+    public static final String SERVICE_INTERFACE = VpnConfig.SERVICE_INTERFACE;
+
+    /**
+     * Key for boolean meta-data field indicating whether this VpnService supports always-on mode.
+     *
+     * <p>For a VPN app targeting {@link android.os.Build.VERSION_CODES#N API 24} or above, Android
+     * provides users with the ability to set it as always-on, so that VPN connection is
+     * persisted after device reboot and app upgrade. Always-on VPN can also be enabled by device
+     * owner and profile owner apps through
+     * {@link DevicePolicyManager#setAlwaysOnVpnPackage}.
+     *
+     * <p>VPN apps not supporting this feature should opt out by adding this meta-data field to the
+     * {@code VpnService} component of {@code AndroidManifest.xml}. In case there is more than one
+     * {@code VpnService} component defined in {@code AndroidManifest.xml}, opting out any one of
+     * them will opt out the entire app. For example,
+     * <pre> {@code
+     * <service android:name=".ExampleVpnService"
+     *         android:permission="android.permission.BIND_VPN_SERVICE">
+     *     <intent-filter>
+     *         <action android:name="android.net.VpnService"/>
+     *     </intent-filter>
+     *     <meta-data android:name="android.net.VpnService.SUPPORTS_ALWAYS_ON"
+     *             android:value=false/>
+     * </service>
+     * } </pre>
+     *
+     * <p>This meta-data field defaults to {@code true} if absent. It will only have effect on
+     * {@link android.os.Build.VERSION_CODES#O_MR1} or higher.
+     */
+    public static final String SERVICE_META_DATA_SUPPORTS_ALWAYS_ON =
+            "android.net.VpnService.SUPPORTS_ALWAYS_ON";
+
+    /**
+     * Use IVpnManager since those methods are hidden and not available in VpnManager.
+     */
+    private static IVpnManager getService() {
+        return IVpnManager.Stub.asInterface(
+                ServiceManager.getService(Context.VPN_MANAGEMENT_SERVICE));
+    }
+
+    /**
+     * Prepare to establish a VPN connection. This method returns {@code null}
+     * if the VPN application is already prepared or if the user has previously
+     * consented to the VPN application. Otherwise, it returns an
+     * {@link Intent} to a system activity. The application should launch the
+     * activity using {@link Activity#startActivityForResult} to get itself
+     * prepared. The activity may pop up a dialog to require user action, and
+     * the result will come back via its {@link Activity#onActivityResult}.
+     * If the result is {@link Activity#RESULT_OK}, the application becomes
+     * prepared and is granted to use other methods in this class.
+     *
+     * <p>Only one application can be granted at the same time. The right
+     * is revoked when another application is granted. The application
+     * losing the right will be notified via its {@link #onRevoke}. Unless
+     * it becomes prepared again, subsequent calls to other methods in this
+     * class will fail.
+     *
+     * <p>The user may disable the VPN at any time while it is activated, in
+     * which case this method will return an intent the next time it is
+     * executed to obtain the user's consent again.
+     *
+     * @see #onRevoke
+     */
+    public static Intent prepare(Context context) {
+        try {
+            if (getService().prepareVpn(context.getPackageName(), null, context.getUserId())) {
+                return null;
+            }
+        } catch (RemoteException e) {
+            // ignore
+        }
+        return VpnConfig.getIntentForConfirmation();
+    }
+
+    /**
+     * Version of {@link #prepare(Context)} which does not require user consent.
+     *
+     * <p>Requires {@link android.Manifest.permission#CONTROL_VPN} and should generally not be
+     * used. Only acceptable in situations where user consent has been obtained through other means.
+     *
+     * <p>Once this is run, future preparations may be done with the standard prepare method as this
+     * will authorize the package to prepare the VPN without consent in the future.
+     *
+     * @hide
+     */
+    @SystemApi
+    @RequiresPermission(android.Manifest.permission.CONTROL_VPN)
+    public static void prepareAndAuthorize(Context context) {
+        IVpnManager vm = getService();
+        String packageName = context.getPackageName();
+        try {
+            // Only prepare if we're not already prepared.
+            int userId = context.getUserId();
+            if (!vm.prepareVpn(packageName, null, userId)) {
+                vm.prepareVpn(null, packageName, userId);
+            }
+            vm.setVpnPackageAuthorization(packageName, userId, VpnManager.TYPE_VPN_SERVICE);
+        } catch (RemoteException e) {
+            // ignore
+        }
+    }
+
+    /**
+     * Protect a socket from VPN connections. After protecting, data sent
+     * through this socket will go directly to the underlying network,
+     * so its traffic will not be forwarded through the VPN.
+     * This method is useful if some connections need to be kept
+     * outside of VPN. For example, a VPN tunnel should protect itself if its
+     * destination is covered by VPN routes. Otherwise its outgoing packets
+     * will be sent back to the VPN interface and cause an infinite loop. This
+     * method will fail if the application is not prepared or is revoked.
+     *
+     * <p class="note">The socket is NOT closed by this method.
+     *
+     * @return {@code true} on success.
+     */
+    public boolean protect(int socket) {
+        return NetworkUtils.protectFromVpn(socket);
+    }
+
+    /**
+     * Convenience method to protect a {@link Socket} from VPN connections.
+     *
+     * @return {@code true} on success.
+     * @see #protect(int)
+     */
+    public boolean protect(Socket socket) {
+        return protect(socket.getFileDescriptor$().getInt$());
+    }
+
+    /**
+     * Convenience method to protect a {@link DatagramSocket} from VPN
+     * connections.
+     *
+     * @return {@code true} on success.
+     * @see #protect(int)
+     */
+    public boolean protect(DatagramSocket socket) {
+        return protect(socket.getFileDescriptor$().getInt$());
+    }
+
+    /**
+     * Adds a network address to the VPN interface.
+     *
+     * Both IPv4 and IPv6 addresses are supported. The VPN must already be established. Fails if the
+     * address is already in use or cannot be assigned to the interface for any other reason.
+     *
+     * Adding an address implicitly allows traffic from that address family (i.e., IPv4 or IPv6) to
+     * be routed over the VPN. @see Builder#allowFamily
+     *
+     * @throws IllegalArgumentException if the address is invalid.
+     *
+     * @param address The IP address (IPv4 or IPv6) to assign to the VPN interface.
+     * @param prefixLength The prefix length of the address.
+     *
+     * @return {@code true} on success.
+     * @see Builder#addAddress
+     *
+     * @hide
+     */
+    public boolean addAddress(InetAddress address, int prefixLength) {
+        check(address, prefixLength);
+        try {
+            return getService().addVpnAddress(address.getHostAddress(), prefixLength);
+        } catch (RemoteException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    /**
+     * Removes a network address from the VPN interface.
+     *
+     * Both IPv4 and IPv6 addresses are supported. The VPN must already be established. Fails if the
+     * address is not assigned to the VPN interface, or if it is the only address assigned (thus
+     * cannot be removed), or if the address cannot be removed for any other reason.
+     *
+     * After removing an address, if there are no addresses, routes or DNS servers of a particular
+     * address family (i.e., IPv4 or IPv6) configured on the VPN, that <b>DOES NOT</b> block that
+     * family from being routed. In other words, once an address family has been allowed, it stays
+     * allowed for the rest of the VPN's session. @see Builder#allowFamily
+     *
+     * @throws IllegalArgumentException if the address is invalid.
+     *
+     * @param address The IP address (IPv4 or IPv6) to assign to the VPN interface.
+     * @param prefixLength The prefix length of the address.
+     *
+     * @return {@code true} on success.
+     *
+     * @hide
+     */
+    public boolean removeAddress(InetAddress address, int prefixLength) {
+        check(address, prefixLength);
+        try {
+            return getService().removeVpnAddress(address.getHostAddress(), prefixLength);
+        } catch (RemoteException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    /**
+     * Sets the underlying networks used by the VPN for its upstream connections.
+     *
+     * <p>Used by the system to know the actual networks that carry traffic for apps affected by
+     * this VPN in order to present this information to the user (e.g., via status bar icons).
+     *
+     * <p>This method only needs to be called if the VPN has explicitly bound its underlying
+     * communications channels &mdash; such as the socket(s) passed to {@link #protect(int)} &mdash;
+     * to a {@code Network} using APIs such as {@link Network#bindSocket(Socket)} or
+     * {@link Network#bindSocket(DatagramSocket)}. The VPN should call this method every time
+     * the set of {@code Network}s it is using changes.
+     *
+     * <p>{@code networks} is one of the following:
+     * <ul>
+     * <li><strong>a non-empty array</strong>: an array of one or more {@link Network}s, in
+     * decreasing preference order. For example, if this VPN uses both wifi and mobile (cellular)
+     * networks to carry app traffic, but prefers or uses wifi more than mobile, wifi should appear
+     * first in the array.</li>
+     * <li><strong>an empty array</strong>: a zero-element array, meaning that the VPN has no
+     * underlying network connection, and thus, app traffic will not be sent or received.</li>
+     * <li><strong>null</strong>: (default) signifies that the VPN uses whatever is the system's
+     * default network. I.e., it doesn't use the {@code bindSocket} or {@code bindDatagramSocket}
+     * APIs mentioned above to send traffic over specific channels.</li>
+     * </ul>
+     *
+     * <p>This call will succeed only if the VPN is currently established. For setting this value
+     * when the VPN has not yet been established, see {@link Builder#setUnderlyingNetworks}.
+     *
+     * @param networks An array of networks the VPN uses to tunnel traffic to/from its servers.
+     *
+     * @return {@code true} on success.
+     */
+    public boolean setUnderlyingNetworks(Network[] networks) {
+        try {
+            return getService().setUnderlyingNetworksForVpn(networks);
+        } catch (RemoteException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    /**
+     * Returns whether the service is running in always-on VPN mode. In this mode the system ensures
+     * that the service is always running by restarting it when necessary, e.g. after reboot.
+     *
+     * @see DevicePolicyManager#setAlwaysOnVpnPackage(ComponentName, String, boolean, Set)
+     */
+    public final boolean isAlwaysOn() {
+        try {
+            return getService().isCallerCurrentAlwaysOnVpnApp();
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Returns whether the service is running in always-on VPN lockdown mode. In this mode the
+     * system ensures that the service is always running and that the apps aren't allowed to bypass
+     * the VPN.
+     *
+     * @see DevicePolicyManager#setAlwaysOnVpnPackage(ComponentName, String, boolean, Set)
+     */
+    public final boolean isLockdownEnabled() {
+        try {
+            return getService().isCallerCurrentAlwaysOnVpnLockdownApp();
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Return the communication interface to the service. This method returns
+     * {@code null} on {@link Intent}s other than {@link #SERVICE_INTERFACE}
+     * action. Applications overriding this method must identify the intent
+     * and return the corresponding interface accordingly.
+     *
+     * @see Service#onBind
+     */
+    @Override
+    public IBinder onBind(Intent intent) {
+        if (intent != null && SERVICE_INTERFACE.equals(intent.getAction())) {
+            return new Callback();
+        }
+        return null;
+    }
+
+    /**
+     * Invoked when the application is revoked. At this moment, the VPN
+     * interface is already deactivated by the system. The application should
+     * close the file descriptor and shut down gracefully. The default
+     * implementation of this method is calling {@link Service#stopSelf()}.
+     *
+     * <p class="note">Calls to this method may not happen on the main thread
+     * of the process.
+     *
+     * @see #prepare
+     */
+    public void onRevoke() {
+        stopSelf();
+    }
+
+    /**
+     * Use raw Binder instead of AIDL since now there is only one usage.
+     */
+    private class Callback extends Binder {
+        @Override
+        protected boolean onTransact(int code, Parcel data, Parcel reply, int flags) {
+            if (code == IBinder.LAST_CALL_TRANSACTION) {
+                onRevoke();
+                return true;
+            }
+            return false;
+        }
+    }
+
+    /**
+     * Private method to validate address and prefixLength.
+     */
+    private static void check(InetAddress address, int prefixLength) {
+        if (address.isLoopbackAddress()) {
+            throw new IllegalArgumentException("Bad address");
+        }
+        if (address instanceof Inet4Address) {
+            if (prefixLength < 0 || prefixLength > 32) {
+                throw new IllegalArgumentException("Bad prefixLength");
+            }
+        } else if (address instanceof Inet6Address) {
+            if (prefixLength < 0 || prefixLength > 128) {
+                throw new IllegalArgumentException("Bad prefixLength");
+            }
+        } else {
+            throw new IllegalArgumentException("Unsupported family");
+        }
+    }
+
+    /**
+     * Helper class to create a VPN interface. This class should be always
+     * used within the scope of the outer {@link VpnService}.
+     *
+     * @see VpnService
+     */
+    public class Builder {
+
+        private final VpnConfig mConfig = new VpnConfig();
+        @UnsupportedAppUsage
+        private final List<LinkAddress> mAddresses = new ArrayList<LinkAddress>();
+        @UnsupportedAppUsage
+        private final List<RouteInfo> mRoutes = new ArrayList<RouteInfo>();
+
+        public Builder() {
+            mConfig.user = VpnService.this.getClass().getName();
+        }
+
+        /**
+         * Set the name of this session. It will be displayed in
+         * system-managed dialogs and notifications. This is recommended
+         * not required.
+         */
+        @NonNull
+        public Builder setSession(@NonNull String session) {
+            mConfig.session = session;
+            return this;
+        }
+
+        /**
+         * Set the {@link PendingIntent} to an activity for users to
+         * configure the VPN connection. If it is not set, the button
+         * to configure will not be shown in system-managed dialogs.
+         */
+        @NonNull
+        public Builder setConfigureIntent(@NonNull PendingIntent intent) {
+            mConfig.configureIntent = intent;
+            return this;
+        }
+
+        /**
+         * Set the maximum transmission unit (MTU) of the VPN interface. If
+         * it is not set, the default value in the operating system will be
+         * used.
+         *
+         * @throws IllegalArgumentException if the value is not positive.
+         */
+        @NonNull
+        public Builder setMtu(int mtu) {
+            if (mtu <= 0) {
+                throw new IllegalArgumentException("Bad mtu");
+            }
+            mConfig.mtu = mtu;
+            return this;
+        }
+
+        /**
+         * Sets an HTTP proxy for the VPN network. This proxy is only a recommendation
+         * and it is possible that some apps will ignore it.
+         */
+        @NonNull
+        public Builder setHttpProxy(@NonNull ProxyInfo proxyInfo) {
+            mConfig.proxyInfo = proxyInfo;
+            return this;
+        }
+
+        /**
+         * Add a network address to the VPN interface. Both IPv4 and IPv6
+         * addresses are supported. At least one address must be set before
+         * calling {@link #establish}.
+         *
+         * Adding an address implicitly allows traffic from that address family
+         * (i.e., IPv4 or IPv6) to be routed over the VPN. @see #allowFamily
+         *
+         * @throws IllegalArgumentException if the address is invalid.
+         */
+        @NonNull
+        public Builder addAddress(@NonNull InetAddress address, int prefixLength) {
+            check(address, prefixLength);
+
+            if (address.isAnyLocalAddress()) {
+                throw new IllegalArgumentException("Bad address");
+            }
+            mAddresses.add(new LinkAddress(address, prefixLength));
+            mConfig.updateAllowedFamilies(address);
+            return this;
+        }
+
+        /**
+         * Convenience method to add a network address to the VPN interface
+         * using a numeric address string. See {@link InetAddress} for the
+         * definitions of numeric address formats.
+         *
+         * Adding an address implicitly allows traffic from that address family
+         * (i.e., IPv4 or IPv6) to be routed over the VPN. @see #allowFamily
+         *
+         * @throws IllegalArgumentException if the address is invalid.
+         * @see #addAddress(InetAddress, int)
+         */
+        @NonNull
+        public Builder addAddress(@NonNull String address, int prefixLength) {
+            return addAddress(InetAddress.parseNumericAddress(address), prefixLength);
+        }
+
+        /**
+         * Add a network route to the VPN interface. Both IPv4 and IPv6
+         * routes are supported.
+         *
+         * Adding a route implicitly allows traffic from that address family
+         * (i.e., IPv4 or IPv6) to be routed over the VPN. @see #allowFamily
+         *
+         * @throws IllegalArgumentException if the route is invalid.
+         */
+        @NonNull
+        public Builder addRoute(@NonNull InetAddress address, int prefixLength) {
+            check(address, prefixLength);
+
+            int offset = prefixLength / 8;
+            byte[] bytes = address.getAddress();
+            if (offset < bytes.length) {
+                for (bytes[offset] <<= prefixLength % 8; offset < bytes.length; ++offset) {
+                    if (bytes[offset] != 0) {
+                        throw new IllegalArgumentException("Bad address");
+                    }
+                }
+            }
+            mRoutes.add(new RouteInfo(new IpPrefix(address, prefixLength), null));
+            mConfig.updateAllowedFamilies(address);
+            return this;
+        }
+
+        /**
+         * Convenience method to add a network route to the VPN interface
+         * using a numeric address string. See {@link InetAddress} for the
+         * definitions of numeric address formats.
+         *
+         * Adding a route implicitly allows traffic from that address family
+         * (i.e., IPv4 or IPv6) to be routed over the VPN. @see #allowFamily
+         *
+         * @throws IllegalArgumentException if the route is invalid.
+         * @see #addRoute(InetAddress, int)
+         */
+        @NonNull
+        public Builder addRoute(@NonNull String address, int prefixLength) {
+            return addRoute(InetAddress.parseNumericAddress(address), prefixLength);
+        }
+
+        /**
+         * Add a DNS server to the VPN connection. Both IPv4 and IPv6
+         * addresses are supported. If none is set, the DNS servers of
+         * the default network will be used.
+         *
+         * Adding a server implicitly allows traffic from that address family
+         * (i.e., IPv4 or IPv6) to be routed over the VPN. @see #allowFamily
+         *
+         * @throws IllegalArgumentException if the address is invalid.
+         */
+        @NonNull
+        public Builder addDnsServer(@NonNull InetAddress address) {
+            if (address.isLoopbackAddress() || address.isAnyLocalAddress()) {
+                throw new IllegalArgumentException("Bad address");
+            }
+            if (mConfig.dnsServers == null) {
+                mConfig.dnsServers = new ArrayList<String>();
+            }
+            mConfig.dnsServers.add(address.getHostAddress());
+            return this;
+        }
+
+        /**
+         * Convenience method to add a DNS server to the VPN connection
+         * using a numeric address string. See {@link InetAddress} for the
+         * definitions of numeric address formats.
+         *
+         * Adding a server implicitly allows traffic from that address family
+         * (i.e., IPv4 or IPv6) to be routed over the VPN. @see #allowFamily
+         *
+         * @throws IllegalArgumentException if the address is invalid.
+         * @see #addDnsServer(InetAddress)
+         */
+        @NonNull
+        public Builder addDnsServer(@NonNull String address) {
+            return addDnsServer(InetAddress.parseNumericAddress(address));
+        }
+
+        /**
+         * Add a search domain to the DNS resolver.
+         */
+        @NonNull
+        public Builder addSearchDomain(@NonNull String domain) {
+            if (mConfig.searchDomains == null) {
+                mConfig.searchDomains = new ArrayList<String>();
+            }
+            mConfig.searchDomains.add(domain);
+            return this;
+        }
+
+        /**
+         * Allows traffic from the specified address family.
+         *
+         * By default, if no address, route or DNS server of a specific family (IPv4 or IPv6) is
+         * added to this VPN, then all outgoing traffic of that family is blocked. If any address,
+         * route or DNS server is added, that family is allowed.
+         *
+         * This method allows an address family to be unblocked even without adding an address,
+         * route or DNS server of that family. Traffic of that family will then typically
+         * fall-through to the underlying network if it's supported.
+         *
+         * {@code family} must be either {@code AF_INET} (for IPv4) or {@code AF_INET6} (for IPv6).
+         * {@link IllegalArgumentException} is thrown if it's neither.
+         *
+         * @param family The address family ({@code AF_INET} or {@code AF_INET6}) to allow.
+         *
+         * @return this {@link Builder} object to facilitate chaining of method calls.
+         */
+        @NonNull
+        public Builder allowFamily(int family) {
+            if (family == AF_INET) {
+                mConfig.allowIPv4 = true;
+            } else if (family == AF_INET6) {
+                mConfig.allowIPv6 = true;
+            } else {
+                throw new IllegalArgumentException(family + " is neither " + AF_INET + " nor " +
+                        AF_INET6);
+            }
+            return this;
+        }
+
+        private void verifyApp(String packageName) throws PackageManager.NameNotFoundException {
+            IPackageManager pm = IPackageManager.Stub.asInterface(
+                    ServiceManager.getService("package"));
+            try {
+                pm.getApplicationInfo(packageName, 0, UserHandle.getCallingUserId());
+            } catch (RemoteException e) {
+                throw new IllegalStateException(e);
+            }
+        }
+
+        /**
+         * Adds an application that's allowed to access the VPN connection.
+         *
+         * If this method is called at least once, only applications added through this method (and
+         * no others) are allowed access. Else (if this method is never called), all applications
+         * are allowed by default.  If some applications are added, other, un-added applications
+         * will use networking as if the VPN wasn't running.
+         *
+         * A {@link Builder} may have only a set of allowed applications OR a set of disallowed
+         * ones, but not both. Calling this method after {@link #addDisallowedApplication} has
+         * already been called, or vice versa, will throw an {@link UnsupportedOperationException}.
+         *
+         * {@code packageName} must be the canonical name of a currently installed application.
+         * {@link PackageManager.NameNotFoundException} is thrown if there's no such application.
+         *
+         * @throws PackageManager.NameNotFoundException If the application isn't installed.
+         *
+         * @param packageName The full name (e.g.: "com.google.apps.contacts") of an application.
+         *
+         * @return this {@link Builder} object to facilitate chaining method calls.
+         */
+        @NonNull
+        public Builder addAllowedApplication(@NonNull String packageName)
+                throws PackageManager.NameNotFoundException {
+            if (mConfig.disallowedApplications != null) {
+                throw new UnsupportedOperationException("addDisallowedApplication already called");
+            }
+            verifyApp(packageName);
+            if (mConfig.allowedApplications == null) {
+                mConfig.allowedApplications = new ArrayList<String>();
+            }
+            mConfig.allowedApplications.add(packageName);
+            return this;
+        }
+
+        /**
+         * Adds an application that's denied access to the VPN connection.
+         *
+         * By default, all applications are allowed access, except for those denied through this
+         * method.  Denied applications will use networking as if the VPN wasn't running.
+         *
+         * A {@link Builder} may have only a set of allowed applications OR a set of disallowed
+         * ones, but not both. Calling this method after {@link #addAllowedApplication} has already
+         * been called, or vice versa, will throw an {@link UnsupportedOperationException}.
+         *
+         * {@code packageName} must be the canonical name of a currently installed application.
+         * {@link PackageManager.NameNotFoundException} is thrown if there's no such application.
+         *
+         * @throws PackageManager.NameNotFoundException If the application isn't installed.
+         *
+         * @param packageName The full name (e.g.: "com.google.apps.contacts") of an application.
+         *
+         * @return this {@link Builder} object to facilitate chaining method calls.
+         */
+        @NonNull
+        public Builder addDisallowedApplication(@NonNull String packageName)
+                throws PackageManager.NameNotFoundException {
+            if (mConfig.allowedApplications != null) {
+                throw new UnsupportedOperationException("addAllowedApplication already called");
+            }
+            verifyApp(packageName);
+            if (mConfig.disallowedApplications == null) {
+                mConfig.disallowedApplications = new ArrayList<String>();
+            }
+            mConfig.disallowedApplications.add(packageName);
+            return this;
+        }
+
+        /**
+         * Allows all apps to bypass this VPN connection.
+         *
+         * By default, all traffic from apps is forwarded through the VPN interface and it is not
+         * possible for apps to side-step the VPN. If this method is called, apps may use methods
+         * such as {@link ConnectivityManager#bindProcessToNetwork} to instead send/receive
+         * directly over the underlying network or any other network they have permissions for.
+         *
+         * @return this {@link Builder} object to facilitate chaining of method calls.
+         */
+        @NonNull
+        public Builder allowBypass() {
+            mConfig.allowBypass = true;
+            return this;
+        }
+
+        /**
+         * Sets the VPN interface's file descriptor to be in blocking/non-blocking mode.
+         *
+         * By default, the file descriptor returned by {@link #establish} is non-blocking.
+         *
+         * @param blocking True to put the descriptor into blocking mode; false for non-blocking.
+         *
+         * @return this {@link Builder} object to facilitate chaining method calls.
+         */
+        @NonNull
+        public Builder setBlocking(boolean blocking) {
+            mConfig.blocking = blocking;
+            return this;
+        }
+
+        /**
+         * Sets the underlying networks used by the VPN for its upstream connections.
+         *
+         * @see VpnService#setUnderlyingNetworks
+         *
+         * @param networks An array of networks the VPN uses to tunnel traffic to/from its servers.
+         *
+         * @return this {@link Builder} object to facilitate chaining method calls.
+         */
+        @NonNull
+        public Builder setUnderlyingNetworks(@Nullable Network[] networks) {
+            mConfig.underlyingNetworks = networks != null ? networks.clone() : null;
+            return this;
+        }
+
+        /**
+         * Marks the VPN network as metered. A VPN network is classified as metered when the user is
+         * sensitive to heavy data usage due to monetary costs and/or data limitations. In such
+         * cases, you should set this to {@code true} so that apps on the system can avoid doing
+         * large data transfers. Otherwise, set this to {@code false}. Doing so would cause VPN
+         * network to inherit its meteredness from its underlying networks.
+         *
+         * <p>VPN apps targeting {@link android.os.Build.VERSION_CODES#Q} or above will be
+         * considered metered by default.
+         *
+         * @param isMetered {@code true} if VPN network should be treated as metered regardless of
+         *     underlying network meteredness
+         * @return this {@link Builder} object to facilitate chaining method calls
+         * @see #setUnderlyingNetworks(Network[])
+         * @see ConnectivityManager#isActiveNetworkMetered()
+         */
+        @NonNull
+        public Builder setMetered(boolean isMetered) {
+            mConfig.isMetered = isMetered;
+            return this;
+        }
+
+        /**
+         * Create a VPN interface using the parameters supplied to this
+         * builder. The interface works on IP packets, and a file descriptor
+         * is returned for the application to access them. Each read
+         * retrieves an outgoing packet which was routed to the interface.
+         * Each write injects an incoming packet just like it was received
+         * from the interface. The file descriptor is put into non-blocking
+         * mode by default to avoid blocking Java threads. To use the file
+         * descriptor completely in native space, see
+         * {@link ParcelFileDescriptor#detachFd()}. The application MUST
+         * close the file descriptor when the VPN connection is terminated.
+         * The VPN interface will be removed and the network will be
+         * restored by the system automatically.
+         *
+         * <p>To avoid conflicts, there can be only one active VPN interface
+         * at the same time. Usually network parameters are never changed
+         * during the lifetime of a VPN connection. It is also common for an
+         * application to create a new file descriptor after closing the
+         * previous one. However, it is rare but not impossible to have two
+         * interfaces while performing a seamless handover. In this case, the
+         * old interface will be deactivated when the new one is created
+         * successfully. Both file descriptors are valid but now outgoing
+         * packets will be routed to the new interface. Therefore, after
+         * draining the old file descriptor, the application MUST close it
+         * and start using the new file descriptor. If the new interface
+         * cannot be created, the existing interface and its file descriptor
+         * remain untouched.
+         *
+         * <p>An exception will be thrown if the interface cannot be created
+         * for any reason. However, this method returns {@code null} if the
+         * application is not prepared or is revoked. This helps solve
+         * possible race conditions between other VPN applications.
+         *
+         * @return {@link ParcelFileDescriptor} of the VPN interface, or
+         *         {@code null} if the application is not prepared.
+         * @throws IllegalArgumentException if a parameter is not accepted
+         *         by the operating system.
+         * @throws IllegalStateException if a parameter cannot be applied
+         *         by the operating system.
+         * @throws SecurityException if the service is not properly declared
+         *         in {@code AndroidManifest.xml}.
+         * @see VpnService
+         */
+        @Nullable
+        public ParcelFileDescriptor establish() {
+            mConfig.addresses = mAddresses;
+            mConfig.routes = mRoutes;
+
+            try {
+                return getService().establishVpn(mConfig);
+            } catch (RemoteException e) {
+                throw new IllegalStateException(e);
+            }
+        }
+    }
+}