1/*
2 * Copyright (C) 2013 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 com.android.server.media;
18
19import android.Manifest;
20import android.content.BroadcastReceiver;
21import android.content.ComponentName;
22import android.content.Context;
23import android.content.Intent;
24import android.content.IntentFilter;
25import android.content.pm.PackageManager;
26import android.content.pm.ResolveInfo;
27import android.content.pm.ServiceInfo;
28import android.media.RemoteDisplayState;
29import android.os.Handler;
30import android.os.UserHandle;
31import android.util.Log;
32import android.util.Slog;
33
34import java.io.PrintWriter;
35import java.util.ArrayList;
36import java.util.Collections;
37
38/**
39 * Watches for remote display provider services to be installed.
40 * Adds a provider to the media router for each registered service.
41 *
42 * @see RemoteDisplayProviderProxy
43 */
44public final class RemoteDisplayProviderWatcher {
45    private static final String TAG = "RemoteDisplayProvider";  // max. 23 chars
46    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
47
48    private final Context mContext;
49    private final Callback mCallback;
50    private final Handler mHandler;
51    private final int mUserId;
52    private final PackageManager mPackageManager;
53
54    private final ArrayList<RemoteDisplayProviderProxy> mProviders =
55            new ArrayList<RemoteDisplayProviderProxy>();
56    private boolean mRunning;
57
58    public RemoteDisplayProviderWatcher(Context context,
59            Callback callback, Handler handler, int userId) {
60        mContext = context;
61        mCallback = callback;
62        mHandler = handler;
63        mUserId = userId;
64        mPackageManager = context.getPackageManager();
65    }
66
67    public void dump(PrintWriter pw, String prefix) {
68        pw.println(prefix + "Watcher");
69        pw.println(prefix + "  mUserId=" + mUserId);
70        pw.println(prefix + "  mRunning=" + mRunning);
71        pw.println(prefix + "  mProviders.size()=" + mProviders.size());
72    }
73
74    public void start() {
75        if (!mRunning) {
76            mRunning = true;
77
78            IntentFilter filter = new IntentFilter();
79            filter.addAction(Intent.ACTION_PACKAGE_ADDED);
80            filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
81            filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
82            filter.addAction(Intent.ACTION_PACKAGE_REPLACED);
83            filter.addAction(Intent.ACTION_PACKAGE_RESTARTED);
84            filter.addDataScheme("package");
85            mContext.registerReceiverAsUser(mScanPackagesReceiver,
86                    new UserHandle(mUserId), filter, null, mHandler);
87
88            // Scan packages.
89            // Also has the side-effect of restarting providers if needed.
90            mHandler.post(mScanPackagesRunnable);
91        }
92    }
93
94    public void stop() {
95        if (mRunning) {
96            mRunning = false;
97
98            mContext.unregisterReceiver(mScanPackagesReceiver);
99            mHandler.removeCallbacks(mScanPackagesRunnable);
100
101            // Stop all providers.
102            for (int i = mProviders.size() - 1; i >= 0; i--) {
103                mProviders.get(i).stop();
104            }
105        }
106    }
107
108    private void scanPackages() {
109        if (!mRunning) {
110            return;
111        }
112
113        // Add providers for all new services.
114        // Reorder the list so that providers left at the end will be the ones to remove.
115        int targetIndex = 0;
116        Intent intent = new Intent(RemoteDisplayState.SERVICE_INTERFACE);
117        for (ResolveInfo resolveInfo : mPackageManager.queryIntentServicesAsUser(
118                intent, 0, mUserId)) {
119            ServiceInfo serviceInfo = resolveInfo.serviceInfo;
120            if (serviceInfo != null && verifyServiceTrusted(serviceInfo)) {
121                int sourceIndex = findProvider(serviceInfo.packageName, serviceInfo.name);
122                if (sourceIndex < 0) {
123                    RemoteDisplayProviderProxy provider =
124                            new RemoteDisplayProviderProxy(mContext,
125                            new ComponentName(serviceInfo.packageName, serviceInfo.name),
126                            mUserId);
127                    provider.start();
128                    mProviders.add(targetIndex++, provider);
129                    mCallback.addProvider(provider);
130                } else if (sourceIndex >= targetIndex) {
131                    RemoteDisplayProviderProxy provider = mProviders.get(sourceIndex);
132                    provider.start(); // restart the provider if needed
133                    provider.rebindIfDisconnected();
134                    Collections.swap(mProviders, sourceIndex, targetIndex++);
135                }
136            }
137        }
138
139        // Remove providers for missing services.
140        if (targetIndex < mProviders.size()) {
141            for (int i = mProviders.size() - 1; i >= targetIndex; i--) {
142                RemoteDisplayProviderProxy provider = mProviders.get(i);
143                mCallback.removeProvider(provider);
144                mProviders.remove(provider);
145                provider.stop();
146            }
147        }
148    }
149
150    private boolean verifyServiceTrusted(ServiceInfo serviceInfo) {
151        if (serviceInfo.permission == null || !serviceInfo.permission.equals(
152                Manifest.permission.BIND_REMOTE_DISPLAY)) {
153            // If the service does not require this permission then any app could
154            // potentially bind to it and cause the remote display service to
155            // misbehave.  So we only want to trust providers that require the
156            // correct permissions.
157            Slog.w(TAG, "Ignoring remote display provider service because it did not "
158                    + "require the BIND_REMOTE_DISPLAY permission in its manifest: "
159                    + serviceInfo.packageName + "/" + serviceInfo.name);
160            return false;
161        }
162        if (!hasCaptureVideoPermission(serviceInfo.packageName)) {
163            // If the service does not have permission to capture video then it
164            // isn't going to be terribly useful as a remote display, is it?
165            // Kind of makes you wonder what it's doing there in the first place.
166            Slog.w(TAG, "Ignoring remote display provider service because it does not "
167                    + "have the CAPTURE_VIDEO_OUTPUT or CAPTURE_SECURE_VIDEO_OUTPUT "
168                    + "permission: " + serviceInfo.packageName + "/" + serviceInfo.name);
169            return false;
170        }
171        // Looks good.
172        return true;
173    }
174
175    private boolean hasCaptureVideoPermission(String packageName) {
176        if (mPackageManager.checkPermission(Manifest.permission.CAPTURE_VIDEO_OUTPUT,
177                packageName) == PackageManager.PERMISSION_GRANTED) {
178            return true;
179        }
180        if (mPackageManager.checkPermission(Manifest.permission.CAPTURE_SECURE_VIDEO_OUTPUT,
181                packageName) == PackageManager.PERMISSION_GRANTED) {
182            return true;
183        }
184        return false;
185    }
186
187    private int findProvider(String packageName, String className) {
188        int count = mProviders.size();
189        for (int i = 0; i < count; i++) {
190            RemoteDisplayProviderProxy provider = mProviders.get(i);
191            if (provider.hasComponentName(packageName, className)) {
192                return i;
193            }
194        }
195        return -1;
196    }
197
198    private final BroadcastReceiver mScanPackagesReceiver = new BroadcastReceiver() {
199        @Override
200        public void onReceive(Context context, Intent intent) {
201            if (DEBUG) {
202                Slog.d(TAG, "Received package manager broadcast: " + intent);
203            }
204            scanPackages();
205        }
206    };
207
208    private final Runnable mScanPackagesRunnable = new Runnable() {
209        @Override
210        public void run() {
211            scanPackages();
212        }
213    };
214
215    public interface Callback {
216        void addProvider(RemoteDisplayProviderProxy provider);
217        void removeProvider(RemoteDisplayProviderProxy provider);
218    }
219}
220