Define VcnStatusCallback register/unregister.

This CL defines VcnStatusCallbacks, which are callbacks used to register
for status updates to a specific subscription group. These Callbacks may
be registered with VcnManager at any time, but will only be invoked for
the specifies subscription group and only if the registering app has
carrier privileges for that subscription.

Bug: 163433613
Test: atest FrameworksVcnTests
Change-Id: Iefd284ae2d09676d195e2a12bf660be3596da59b

3 files changed, 145 insertions, 1 deletions

diff --git a/core/java/android/net/vcn/IVcnManagementService.aidl b/core/java/android/net/vcn/IVcnManagementService.aidl
index 4f293eeb3c3b..6a3cb42ed75d 100644
--- a/core/java/android/net/vcn/IVcnManagementService.aidl
+++ b/core/java/android/net/vcn/IVcnManagementService.aidl
@@ -18,6 +18,7 @@ package android.net.vcn;
 
 import android.net.LinkProperties;
 import android.net.NetworkCapabilities;
+import android.net.vcn.IVcnStatusCallback;
 import android.net.vcn.IVcnUnderlyingNetworkPolicyListener;
 import android.net.vcn.VcnConfig;
 import android.net.vcn.VcnUnderlyingNetworkPolicy;
@@ -33,4 +34,7 @@ interface IVcnManagementService {
     void addVcnUnderlyingNetworkPolicyListener(in IVcnUnderlyingNetworkPolicyListener listener);
     void removeVcnUnderlyingNetworkPolicyListener(in IVcnUnderlyingNetworkPolicyListener listener);
     VcnUnderlyingNetworkPolicy getUnderlyingNetworkPolicy(in NetworkCapabilities nc, in LinkProperties lp);
+
+    void registerVcnStatusCallback(in ParcelUuid subscriptionGroup, in IVcnStatusCallback callback, in String opPkgName);
+    void unregisterVcnStatusCallback(in IVcnStatusCallback callback);
 }
diff --git a/core/java/android/net/vcn/IVcnStatusCallback.aidl b/core/java/android/net/vcn/IVcnStatusCallback.aidl
new file mode 100644
index 000000000000..a7386718d5ae
--- /dev/null
+++ b/core/java/android/net/vcn/IVcnStatusCallback.aidl
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2021, 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.vcn;
+
+/** @hide */
+interface IVcnStatusCallback {
+    void onEnteredSafeMode();
+}
\ No newline at end of file
diff --git a/core/java/android/net/vcn/VcnManager.java b/core/java/android/net/vcn/VcnManager.java
index 1a38338c26aa..4d110d0fbf7e 100644
--- a/core/java/android/net/vcn/VcnManager.java
+++ b/core/java/android/net/vcn/VcnManager.java
@@ -23,6 +23,7 @@ import android.annotation.SystemService;
 import android.content.Context;
 import android.net.LinkProperties;
 import android.net.NetworkCapabilities;
+import android.os.Binder;
 import android.os.ParcelUuid;
 import android.os.RemoteException;
 import android.os.ServiceSpecificException;
@@ -267,6 +268,100 @@ public class VcnManager {
         }
     }
 
+    // TODO: make VcnStatusCallback @SystemApi
+    /**
+     * VcnStatusCallback is the interface for Carrier apps to receive updates for their VCNs.
+     *
+     * <p>VcnStatusCallbacks may be registered before {@link VcnConfig}s are provided for a
+     * subscription group.
+     *
+     * @hide
+     */
+    public abstract static class VcnStatusCallback {
+        private VcnStatusCallbackBinder mCbBinder;
+
+        /**
+         * Invoked when the VCN for this Callback's subscription group enters safe mode.
+         *
+         * <p>A VCN will be put into safe mode if any of the gateway connections were unable to
+         * establish a connection within a system-determined timeout (while underlying networks were
+         * available).
+         *
+         * <p>A VCN-configuring app may opt to exit safe mode by (re)setting the VCN configuration
+         * via {@link #setVcnConfig(ParcelUuid, VcnConfig)}.
+         */
+        public abstract void onEnteredSafeMode();
+    }
+
+    /**
+     * Registers the given callback to receive status updates for the specified subscription.
+     *
+     * <p>Callbacks can be registered for a subscription before {@link VcnConfig}s are set for it.
+     *
+     * <p>A {@link VcnStatusCallback} may only be registered for one subscription at a time. {@link
+     * VcnStatusCallback}s may be reused once unregistered.
+     *
+     * <p>A {@link VcnStatusCallback} will only be invoked if the registering package has carrier
+     * privileges for the specified subscription at the time of invocation.
+     *
+     * @param subscriptionGroup The subscription group to match for callbacks
+     * @param executor The {@link Executor} to be used for invoking callbacks
+     * @param callback The VcnStatusCallback to be registered
+     * @throws IllegalStateException if callback is currently registered with VcnManager
+     * @hide
+     */
+    public void registerVcnStatusCallback(
+            @NonNull ParcelUuid subscriptionGroup,
+            @NonNull Executor executor,
+            @NonNull VcnStatusCallback callback) {
+        requireNonNull(subscriptionGroup, "subscriptionGroup must not be null");
+        requireNonNull(executor, "executor must not be null");
+        requireNonNull(callback, "callback must not be null");
+
+        synchronized (callback) {
+            if (callback.mCbBinder != null) {
+                throw new IllegalStateException("callback is already registered with VcnManager");
+            }
+            callback.mCbBinder = new VcnStatusCallbackBinder(executor, callback);
+
+            try {
+                mService.registerVcnStatusCallback(
+                        subscriptionGroup, callback.mCbBinder, mContext.getOpPackageName());
+            } catch (RemoteException e) {
+                callback.mCbBinder = null;
+                throw e.rethrowFromSystemServer();
+            }
+        }
+    }
+
+    /**
+     * Unregisters the given callback.
+     *
+     * <p>Once unregistered, the callback will stop receiving status updates for the subscription it
+     * was registered with.
+     *
+     * @param callback The callback to be unregistered
+     * @hide
+     */
+    public void unregisterVcnStatusCallback(@NonNull VcnStatusCallback callback) {
+        requireNonNull(callback, "callback must not be null");
+
+        synchronized (callback) {
+            if (callback.mCbBinder == null) {
+                // no Binder attached to this callback, so it's not currently registered
+                return;
+            }
+
+            try {
+                mService.unregisterVcnStatusCallback(callback.mCbBinder);
+            } catch (RemoteException e) {
+                throw e.rethrowFromSystemServer();
+            } finally {
+                callback.mCbBinder = null;
+            }
+        }
+    }
+
     /**
      * Binder wrapper for added VcnUnderlyingNetworkPolicyListeners to receive signals from System
      * Server.
@@ -286,7 +381,30 @@ public class VcnManager {
 
         @Override
         public void onPolicyChanged() {
-            mExecutor.execute(() -> mListener.onPolicyChanged());
+            Binder.withCleanCallingIdentity(
+                    () -> mExecutor.execute(() -> mListener.onPolicyChanged()));
+        }
+    }
+
+    /**
+     * Binder wrapper for VcnStatusCallbacks to receive signals from VcnManagementService.
+     *
+     * @hide
+     */
+    private class VcnStatusCallbackBinder extends IVcnStatusCallback.Stub {
+        @NonNull private final Executor mExecutor;
+        @NonNull private final VcnStatusCallback mCallback;
+
+        private VcnStatusCallbackBinder(
+                @NonNull Executor executor, @NonNull VcnStatusCallback callback) {
+            mExecutor = executor;
+            mCallback = callback;
+        }
+
+        @Override
+        public void onEnteredSafeMode() {
+            Binder.withCleanCallingIdentity(
+                    () -> mExecutor.execute(() -> mCallback.onEnteredSafeMode()));
         }
     }
 }