Add onBlockedStatusChanged(Network, int) to NetworkCallback.

This is similar to onBlockedStatusChanged(Network, boolean) but
it allows the callback holder to know the exact reason why
networking was blocked. It is useful to privileged system
components such as JobScheduler that are able to ignore some
blocked reasons but not others.

Also add a new BLOCKED_REASON_LOCKDOWN_VPN that is used when
networking is blocked because an always-on VPN is in
lockdown mode.

Also move BLOCKED_METERED_REASON_MASK to ConnectivityManager.
This is necessary because ConnectivityService must ensure that
the blocked status callbacks are correctly sent when meteredness
changes (e.g., a UID that is blocked on metered networks will
become unblocked on a network that becomes unmetered). In order
to do this it needs to know which reasons apply only on metered
networks.

Bug: 165835257
Test: unit tests in subsequent CLs in the stack
Change-Id: I647db4f5a01280be220288e73ffa85c15bec9370

framework/src/android/net/ConnectivityManager.java

@@ -38,7 +38,9 @@ import android.annotation.SuppressLint;
 import android.annotation.SystemApi;
 import android.annotation.SystemService;
 import android.app.PendingIntent;
+import android.app.admin.DevicePolicyManager;
 import android.compat.annotation.UnsupportedAppUsage;
+import android.content.ComponentName;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
@@ -871,6 +873,17 @@ public class ConnectivityManager {
     @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
     public static final int BLOCKED_REASON_RESTRICTED_MODE = 1 << 3;
 
+    /**
+     * Flag to indicate that an app is blocked because it is subject to an always-on VPN but the VPN
+     * is not currently connected.
+     *
+     * @see DevicePolicyManager#setAlwaysOnVpnPackage(ComponentName, String, boolean)
+     *
+     * @hide
+     */
+    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+    public static final int BLOCKED_REASON_LOCKDOWN_VPN = 1 << 4;
+
     /**
      * Flag to indicate that an app is subject to Data saver restrictions that would
      * result in its metered network access being blocked.
@@ -914,6 +927,14 @@ public class ConnectivityManager {
     })
     public @interface BlockedReason {}
 
+    /**
+     * Set of blocked reasons that are only applicable on metered networks.
+     *
+     * @hide
+     */
+    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+    public static final int BLOCKED_METERED_REASON_MASK = 0xffff0000;
+
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 130143562)
     private final IConnectivityManager mService;
 
@@ -3442,12 +3463,30 @@ public class ConnectivityManager {
          * @param blocked Whether access to the {@link Network} is blocked due to system policy.
          * @hide
          */
-        public void onAvailable(@NonNull Network network,
+        public final void onAvailable(@NonNull Network network,
                 @NonNull NetworkCapabilities networkCapabilities,
-                @NonNull LinkProperties linkProperties, boolean blocked) {
+                @NonNull LinkProperties linkProperties, @BlockedReason int blocked) {
             // Internally only this method is called when a new network is available, and
             // it calls the callback in the same way and order that older versions used
             // to call so as not to change the behavior.
+            onAvailable(network, networkCapabilities, linkProperties, blocked != 0);
+            onBlockedStatusChanged(network, blocked);
+        }
+
+        /**
+         * Legacy variant of onAvailable that takes a boolean blocked reason.
+         *
+         * This method has never been public API, but it's not final, so there may be apps that
+         * implemented it and rely on it being called. Do our best not to break them.
+         * Note: such apps will also get a second call to onBlockedStatusChanged immediately after
+         * this method is called. There does not seem to be a way to avoid this.
+         * TODO: add a compat check to move apps off this method, and eventually stop calling it.
+         *
+         * @hide
+         */
+        public void onAvailable(@NonNull Network network,
+                @NonNull NetworkCapabilities networkCapabilities,
+                @NonNull LinkProperties linkProperties, boolean blocked) {
             onAvailable(network);
             if (!networkCapabilities.hasCapability(
                     NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED)) {
@@ -3455,7 +3494,7 @@ public class ConnectivityManager {
             }
             onCapabilitiesChanged(network, networkCapabilities);
             onLinkPropertiesChanged(network, linkProperties);
-            onBlockedStatusChanged(network, blocked);
+            // No call to onBlockedStatusChanged here. That is done by the caller.
         }
 
         /**
@@ -3619,6 +3658,26 @@ public class ConnectivityManager {
          */
         public void onBlockedStatusChanged(@NonNull Network network, boolean blocked) {}
 
+        /**
+         * Called when access to the specified network is blocked or unblocked.
+         *
+         * If a NetworkCallback object implements this method,
+         * {@link #onBlockedStatusChanged(Network, boolean)} will not be called.
+         *
+         * <p>Do NOT call {@link #getNetworkCapabilities(Network)} or
+         * {@link #getLinkProperties(Network)} or other synchronous ConnectivityManager methods in
+         * this callback as this is prone to race conditions : calling these methods while in a
+         * callback may return an outdated or even a null object.
+         *
+         * @param network The {@link Network} whose blocked status has changed.
+         * @param blocked The blocked status of this {@link Network}.
+         * @hide
+         */
+        @SystemApi(client = MODULE_LIBRARIES)
+        public void onBlockedStatusChanged(@NonNull Network network, @BlockedReason int blocked) {
+            onBlockedStatusChanged(network, blocked != 0);
+        }
+
         private NetworkRequest networkRequest;
         private final int mFlags;
     }
@@ -3733,7 +3792,7 @@ public class ConnectivityManager {
                 case CALLBACK_AVAILABLE: {
                     NetworkCapabilities cap = getObject(message, NetworkCapabilities.class);
                     LinkProperties lp = getObject(message, LinkProperties.class);
-                    callback.onAvailable(network, cap, lp, message.arg1 != 0);
+                    callback.onAvailable(network, cap, lp, message.arg1);
                     break;
                 }
                 case CALLBACK_LOSING: {
@@ -3767,8 +3826,7 @@ public class ConnectivityManager {
                     break;
                 }
                 case CALLBACK_BLK_CHANGED: {
-                    boolean blocked = message.arg1 != 0;
-                    callback.onBlockedStatusChanged(network, blocked);
+                    callback.onBlockedStatusChanged(network, message.arg1);
                 }
             }
         }