Add onSupportedTetheringType callback

This new callback could tell caller Tethering is supported for what tethering
types.

Bug: 184996041
Test: atest TetheringTests
      atest EthernetTetheringTest
CTS-Coverage-Bug: 223340235

Change-Id: Ib80ed8d7f73f4a098b8965db186d24d8cf1884d3

Tethering/common/TetheringLib/src/android/net/ITetheringEventCallback.aidl

@@ -36,4 +36,5 @@ oneway interface ITetheringEventCallback
     void onTetherStatesChanged(in TetherStatesParcel states);
     void onTetherClientsChanged(in List<TetheredClient> clients);
     void onOffloadStatusChanged(int status);
+    void onSupportedTetheringTypes(long supportedBitmap);
 }

Tethering/common/TetheringLib/src/android/net/TetheringCallbackStartedParcel.aidl

@@ -26,7 +26,7 @@ import android.net.TetherStatesParcel;
  * @hide
  */
 parcelable TetheringCallbackStartedParcel {
-    boolean tetheringSupported;
+    long supportedTypes;
     Network upstreamNetwork;
     TetheringConfigurationParcel config;
     TetherStatesParcel states;

Tethering/common/TetheringLib/src/android/net/TetheringManager.java

@@ -183,6 +183,12 @@ public class TetheringManager {
      */
     public static final int TETHERING_WIGIG = 6;
 
+    /**
+     * The int value of last tethering type.
+     * @hide
+     */
+    public static final int MAX_TETHERING_TYPE = TETHERING_WIGIG;
+
     /** @hide */
     @Retention(RetentionPolicy.SOURCE)
     @IntDef(value = {
@@ -519,6 +525,9 @@ public class TetheringManager {
             }
         }
 
+        @Override
+        public void onSupportedTetheringTypes(long supportedBitmap) { }
+
         @Override
         public void onUpstreamChanged(Network network) { }
 
@@ -1030,6 +1039,19 @@ public class TetheringManager {
      * upstream status.
      */
     public interface TetheringEventCallback {
+        /**
+         * Called when tethering supported status changed.
+         *
+         * <p>This callback will be called immediately after the callback is
+         * registered, and never be called if there is changes afterward.
+         *
+         * <p>Tethering may be disabled via system properties, device configuration, or device
+         * policy restrictions.
+         *
+         * @param supported whether any tethering type is supported.
+         */
+        default void onTetheringSupported(boolean supported) {}
+
         /**
          * Called when tethering supported status changed.
          *
@@ -1039,9 +1061,10 @@ public class TetheringManager {
          * <p>Tethering may be disabled via system properties, device configuration, or device
          * policy restrictions.
          *
-         * @param supported The new supported status
+         * @param supportedTypes a set of @TetheringType which is supported.
+         * @hide
          */
-        default void onTetheringSupported(boolean supported) {}
+        default void onSupportedTetheringTypes(@NonNull Set<Integer> supportedTypes) {}
 
         /**
          * Called when tethering upstream changed.
@@ -1339,7 +1362,8 @@ public class TetheringManager {
                 @Override
                 public void onCallbackStarted(TetheringCallbackStartedParcel parcel) {
                     executor.execute(() -> {
-                        callback.onTetheringSupported(parcel.tetheringSupported);
+                        callback.onSupportedTetheringTypes(unpackBits(parcel.supportedTypes));
+                        callback.onTetheringSupported(parcel.supportedTypes != 0);
                         callback.onUpstreamChanged(parcel.upstreamNetwork);
                         sendErrorCallbacks(parcel.states);
                         sendRegexpsChanged(parcel.config);
@@ -1358,6 +1382,13 @@ public class TetheringManager {
                     });
                 }
 
+                @Override
+                public void onSupportedTetheringTypes(long supportedBitmap) {
+                    executor.execute(() -> {
+                        callback.onSupportedTetheringTypes(unpackBits(supportedBitmap));
+                    });
+                }
+
                 private void sendRegexpsChanged(TetheringConfigurationParcel parcel) {
                     callback.onTetherableInterfaceRegexpsChanged(new TetheringInterfaceRegexps(
                             parcel.tetherableBluetoothRegexs,
@@ -1395,6 +1426,23 @@ public class TetheringManager {
         }
     }
 
+    /**
+     * Unpack bitmap to a set of bit position intergers.
+     * @hide
+     */
+    public static ArraySet<Integer> unpackBits(long val) {
+        final ArraySet<Integer> result = new ArraySet<>(Long.bitCount(val));
+        int bitPos = 0;
+        while (val != 0) {
+            if ((val & 1) == 1) result.add(bitPos);
+
+            val = val >>> 1;
+            bitPos++;
+        }
+
+        return result;
+    }
+
     /**
      * Remove tethering event callback previously registered with
      * {@link #registerTetheringEventCallback}.