NotificationCompatSideChannelService.java revision 41d83b6efd08c558de282223123235e373d7815a 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.support.v4.app;
18
19import android.app.Notification;
20import android.app.Service;
21import android.content.Intent;
22import android.os.Build;
23import android.os.IBinder;
24import android.os.RemoteException;
25
26/**
27 * Abstract service to receive side channel notifications sent from
28 * {@link android.support.v4.app.NotificationManagerCompat}.
29 *
30 * <p>To receive side channel notifications, extend this service and register it in your
31 * android manifest with an intent filter for the BIND_NOTIFICATION_SIDE_CHANNEL action.
32 * Note: you must also have an enabled
33 * {@link android.service.notification.NotificationListenerService} within your package.
34 *
35 * <p>Example AndroidManifest.xml addition:
36 * <pre>
37 * &lt;service android:name="com.example.NotificationSideChannelService"&gt;
38 *     &lt;intent-filter&gt;
39 *         &lt;action android:name="android.support.BIND_NOTIFICATION_SIDE_CHANNEL" /&gt;
40 *     &lt;/intent-filter&gt;
41 * &lt;/service&gt;</pre>
42 *
43 */
44public abstract class NotificationCompatSideChannelService extends Service {
45    // In support lib, we cannot reference version codes >= 4 from android.os.Build.
46    private static final int BUILD_VERSION_CODE_KITKAT_WATCH = 20;
47
48    @Override
49    public IBinder onBind(Intent intent) {
50        if (intent.getAction().equals(NotificationManagerCompat.ACTION_BIND_SIDE_CHANNEL)) {
51            // Group support is the only current reason to use side channel,
52            // so disallow clients to bind for side channel on devices past KITKAT_WATCH for now.
53            if (Build.VERSION.SDK_INT >= BUILD_VERSION_CODE_KITKAT_WATCH) {
54                return null;
55            }
56            return new NotificationSideChannelStub();
57        }
58        return null;
59    }
60
61    /**
62     * Handle a side-channeled notification being posted.
63     */
64    public abstract void notify(String packageName, int id, String tag, Notification notification);
65
66    /**
67     * Handle a side-channelled notification being cancelled.
68     */
69    public abstract void cancel(String packageName, int id, String tag);
70
71    /**
72     * Handle the side-channelled cancelling of all notifications for a package.
73     */
74    public abstract void cancelAll(String packageName);
75
76    private class NotificationSideChannelStub extends INotificationSideChannel.Stub {
77        @Override
78        public void notify(String packageName, int id, String tag, Notification notification)
79                throws RemoteException {
80            checkPermission(getCallingUid(), packageName);
81            long idToken = clearCallingIdentity();
82            try {
83                NotificationCompatSideChannelService.this.notify(packageName, id, tag, notification);
84            } finally {
85                restoreCallingIdentity(idToken);
86            }
87        }
88
89        @Override
90        public void cancel(String packageName, int id, String tag) throws RemoteException {
91            checkPermission(getCallingUid(), packageName);
92            long idToken = clearCallingIdentity();
93            try {
94                NotificationCompatSideChannelService.this.cancel(packageName, id, tag);
95            } finally {
96                restoreCallingIdentity(idToken);
97            }
98        }
99
100        @Override
101        public void cancelAll(String packageName) {
102            checkPermission(getCallingUid(), packageName);
103            long idToken = clearCallingIdentity();
104            try {
105                NotificationCompatSideChannelService.this.cancelAll(packageName);
106            } finally {
107                restoreCallingIdentity(idToken);
108            }
109        }
110    }
111
112    private void checkPermission(int callingUid, String packageName) {
113        for (String validPackage : getPackageManager().getPackagesForUid(callingUid)) {
114            if (validPackage.equals(packageName)) {
115                return;
116            }
117        }
118        throw new SecurityException("NotificationSideChannelService: Uid " + callingUid
119                + " is not authorized for package " + packageName);
120    }
121}
122