tunnel: add isAlwaysOn and isLockdownEnabled

Signed-off-by: Brandon T <JustBrandonT@gmail.com>
[Harsh: fix build and Javadoc errors]
Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

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

@@ -52,6 +52,28 @@ public interface Backend {
      */
     String getVersion() throws Exception;
 
+    /**
+     * Determines 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.
+     *
+     * @return A boolean indicating whether the service is running in always-on VPN mode.
+     * @throws Exception Exception raised while retrieving the always-on status.
+     */
+
+    boolean isAlwaysOn() throws Exception;
+
+    /**
+     * Determines 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.
+     *
+     * @return A boolean indicating whether the service is running in always-on VPN lockdown mode.
+     * @throws Exception Exception raised while retrieving the lockdown status.
+     */
+
+    boolean isLockdownEnabled() throws Exception;
+
     /**
      * Set the state of a tunnel, updating it's configuration. If the tunnel is already up, config
      * may update the running configuration; config may be null when setting the tunnel down.

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

@@ -188,6 +188,24 @@ public final class GoBackend implements Backend {
         return wgVersion();
     }
 
+    /**
+     * Determines if the service is running in always-on VPN mode.
+     * @return {@link boolean} whether the service is running in always-on VPN mode.
+     */
+    @Override
+    public boolean isAlwaysOn() throws ExecutionException, InterruptedException, TimeoutException {
+        return vpnService.get(0, TimeUnit.NANOSECONDS).isAlwaysOn();
+    }
+
+    /**
+     * Determines if the service is running in always-on VPN lockdown mode.
+     * @return {@link boolean} whether the service is running in always-on VPN lockdown mode.
+     */
+    @Override
+    public boolean isLockdownEnabled() throws ExecutionException, InterruptedException, TimeoutException {
+        return vpnService.get(0, TimeUnit.NANOSECONDS).isLockdownEnabled();
+    }
+
     /**
      * Change the state of a given {@link Tunnel}, optionally applying a given {@link Config}.
      *

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

@@ -109,6 +109,16 @@ public final class WgQuickBackend implements Backend {
         return output.get(0);
     }
 
+    @Override
+    public boolean isAlwaysOn() {
+        return false;
+    }
+
+    @Override
+    public boolean isLockdownEnabled() {
+        return false;
+    }
+
     public void setMultipleTunnels(final boolean on) {
         multipleTunnels = on;
     }