/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server.media;
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import android.Manifest;
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import android.content.BroadcastReceiver;
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import android.content.ComponentName;
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import android.content.Context;
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import android.content.Intent;
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import android.content.IntentFilter;
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import android.content.pm.PackageManager;
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import android.content.pm.ResolveInfo;
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import android.content.pm.ServiceInfo;
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import android.media.RemoteDisplayState;
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import android.os.Handler;
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import android.os.UserHandle;
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import android.util.Log;
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import android.util.Slog;
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import java.io.PrintWriter;
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import java.util.ArrayList;
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import java.util.Collections;
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/**
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* Watches for remote display provider services to be installed.
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* Adds a provider to the media router for each registered service.
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*
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* @see RemoteDisplayProviderProxy
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*/
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public final class RemoteDisplayProviderWatcher {
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private static final String TAG = "RemoteDisplayProvider"; // max. 23 chars
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private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
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private final Context mContext;
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private final Callback mCallback;
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private final Handler mHandler;
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private final int mUserId;
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private final PackageManager mPackageManager;
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private final ArrayList<RemoteDisplayProviderProxy> mProviders =
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new ArrayList<RemoteDisplayProviderProxy>();
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private boolean mRunning;
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public RemoteDisplayProviderWatcher(Context context,
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Callback callback, Handler handler, int userId) {
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mContext = context;
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mCallback = callback;
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mHandler = handler;
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mUserId = userId;
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mPackageManager = context.getPackageManager();
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}
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public void dump(PrintWriter pw, String prefix) {
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pw.println(prefix + "Watcher");
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pw.println(prefix + " mUserId=" + mUserId);
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pw.println(prefix + " mRunning=" + mRunning);
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pw.println(prefix + " mProviders.size()=" + mProviders.size());
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}
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public void start() {
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if (!mRunning) {
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mRunning = true;
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IntentFilter filter = new IntentFilter();
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filter.addAction(Intent.ACTION_PACKAGE_ADDED);
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filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
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filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
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filter.addAction(Intent.ACTION_PACKAGE_REPLACED);
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filter.addAction(Intent.ACTION_PACKAGE_RESTARTED);
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filter.addDataScheme("package");
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mContext.registerReceiverAsUser(mScanPackagesReceiver,
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new UserHandle(mUserId), filter, null, mHandler);
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// Scan packages.
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// Also has the side-effect of restarting providers if needed.
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mHandler.post(mScanPackagesRunnable);
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}
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}
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public void stop() {
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if (mRunning) {
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mRunning = false;
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mContext.unregisterReceiver(mScanPackagesReceiver);
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mHandler.removeCallbacks(mScanPackagesRunnable);
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// Stop all providers.
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for (int i = mProviders.size() - 1; i >= 0; i--) {
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mProviders.get(i).stop();
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}
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}
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}
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private void scanPackages() {
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if (!mRunning) {
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return;
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}
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// Add providers for all new services.
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// Reorder the list so that providers left at the end will be the ones to remove.
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int targetIndex = 0;
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Intent intent = new Intent(RemoteDisplayState.SERVICE_INTERFACE);
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for (ResolveInfo resolveInfo : mPackageManager.queryIntentServicesAsUser(
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intent, 0, mUserId)) {
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ServiceInfo serviceInfo = resolveInfo.serviceInfo;
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if (serviceInfo != null && verifyServiceTrusted(serviceInfo)) {
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int sourceIndex = findProvider(serviceInfo.packageName, serviceInfo.name);
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if (sourceIndex < 0) {
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RemoteDisplayProviderProxy provider =
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new RemoteDisplayProviderProxy(mContext,
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new ComponentName(serviceInfo.packageName, serviceInfo.name),
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mUserId);
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provider.start();
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mProviders.add(targetIndex++, provider);
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mCallback.addProvider(provider);
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} else if (sourceIndex >= targetIndex) {
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RemoteDisplayProviderProxy provider = mProviders.get(sourceIndex);
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provider.start(); // restart the provider if needed
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provider.rebindIfDisconnected();
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Collections.swap(mProviders, sourceIndex, targetIndex++);
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}
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}
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}
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// Remove providers for missing services.
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if (targetIndex < mProviders.size()) {
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for (int i = mProviders.size() - 1; i >= targetIndex; i--) {
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RemoteDisplayProviderProxy provider = mProviders.get(i);
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mCallback.removeProvider(provider);
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mProviders.remove(provider);
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provider.stop();
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}
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}
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}
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private boolean verifyServiceTrusted(ServiceInfo serviceInfo) {
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if (serviceInfo.permission == null || !serviceInfo.permission.equals(
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Manifest.permission.BIND_REMOTE_DISPLAY)) {
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// If the service does not require this permission then any app could
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// potentially bind to it and cause the remote display service to
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// misbehave. So we only want to trust providers that require the
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// correct permissions.
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Slog.w(TAG, "Ignoring remote display provider service because it did not "
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+ "require the BIND_REMOTE_DISPLAY permission in its manifest: "
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+ serviceInfo.packageName + "/" + serviceInfo.name);
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return false;
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}
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if (mPackageManager.checkPermission(Manifest.permission.REMOTE_DISPLAY_PROVIDER,
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serviceInfo.packageName) != PackageManager.PERMISSION_GRANTED) {
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// If the service does not have this permission then the system will not bind to it.
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// This is to prevent non privileged apps declaring themselves as remote display
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// providers just to be bound to by the system and keep their process alive.
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Slog.w(TAG, "Ignoring remote display provider service because it does not "
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+ "have the REMOTE_DISPLAY_PROVIDER "
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+ "permission: " + serviceInfo.packageName + "/" + serviceInfo.name);
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return false;
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}
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// Looks good.
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return true;
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}
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private int findProvider(String packageName, String className) {
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int count = mProviders.size();
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for (int i = 0; i < count; i++) {
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RemoteDisplayProviderProxy provider = mProviders.get(i);
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if (provider.hasComponentName(packageName, className)) {
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return i;
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}
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}
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return -1;
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}
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private final BroadcastReceiver mScanPackagesReceiver = new BroadcastReceiver() {
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@Override
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public void onReceive(Context context, Intent intent) {
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if (DEBUG) {
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Slog.d(TAG, "Received package manager broadcast: " + intent);
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}
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scanPackages();
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}
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};
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private final Runnable mScanPackagesRunnable = new Runnable() {
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@Override
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public void run() {
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scanPackages();
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}
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};
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public interface Callback {
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void addProvider(RemoteDisplayProviderProxy provider);
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void removeProvider(RemoteDisplayProviderProxy provider);
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}
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}
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