NetworkScorerAppManager.java revision 161977998feebf0a855ea56558464470877040cf 
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.net;
18
19import android.Manifest;
20import android.Manifest.permission;
21import android.annotation.Nullable;
22import android.app.AppOpsManager;
23import android.content.Context;
24import android.content.Intent;
25import android.content.pm.ActivityInfo;
26import android.content.pm.PackageManager;
27import android.content.pm.ResolveInfo;
28import android.os.UserHandle;
29import android.provider.Settings;
30import android.text.TextUtils;
31import android.util.Log;
32
33import java.util.ArrayList;
34import java.util.Collection;
35import java.util.List;
36
37/**
38 * Internal class for managing the primary network scorer application.
39 *
40 * TODO: Rename this to something more generic.
41 *
42 * @hide
43 */
44public final class NetworkScorerAppManager {
45    private static final String TAG = "NetworkScorerAppManager";
46
47    private static final Intent SCORE_INTENT =
48            new Intent(NetworkScoreManager.ACTION_SCORE_NETWORKS);
49
50    /** This class cannot be instantiated. */
51    private NetworkScorerAppManager() {}
52
53    public static class NetworkScorerAppData {
54        /** Package name of this scorer app. */
55        public final String mPackageName;
56
57        /** Name of this scorer app for display. */
58        public final CharSequence mScorerName;
59
60        /**
61         * Optional class name of a configuration activity. Null if none is set.
62         *
63         * @see NetworkScoreManager#ACTION_CUSTOM_ENABLE
64         */
65        public final String mConfigurationActivityClassName;
66
67        public NetworkScorerAppData(String packageName, CharSequence scorerName,
68                @Nullable String configurationActivityClassName) {
69            mScorerName = scorerName;
70            mPackageName = packageName;
71            mConfigurationActivityClassName = configurationActivityClassName;
72        }
73    }
74
75    /**
76     * Returns the list of available scorer apps.
77     *
78     * <p>A network scorer is any application which:
79     * <ul>
80     * <li>Declares the {@link android.Manifest.permission#SCORE_NETWORKS} permission.
81     * <li>Includes a receiver for {@link NetworkScoreManager#ACTION_SCORE_NETWORKS} guarded by the
82     *     {@link android.Manifest.permission#BROADCAST_NETWORK_PRIVILEGED} permission.
83     * </ul>
84     *
85     * @return the list of scorers, or the empty list if there are no valid scorers.
86     */
87    public static Collection<NetworkScorerAppData> getAllValidScorers(Context context) {
88        List<NetworkScorerAppData> scorers = new ArrayList<>();
89
90        PackageManager pm = context.getPackageManager();
91        // Only apps installed under the primary user of the device can be scorers.
92        List<ResolveInfo> receivers =
93                pm.queryBroadcastReceivers(SCORE_INTENT, 0 /* flags */, UserHandle.USER_OWNER);
94        for (ResolveInfo receiver : receivers) {
95            // This field is a misnomer, see android.content.pm.ResolveInfo#activityInfo
96            final ActivityInfo receiverInfo = receiver.activityInfo;
97            if (receiverInfo == null) {
98                // Should never happen with queryBroadcastReceivers, but invalid nonetheless.
99                continue;
100            }
101            if (!permission.BROADCAST_NETWORK_PRIVILEGED.equals(receiverInfo.permission)) {
102                // Receiver doesn't require the BROADCAST_NETWORK_PRIVILEGED permission, which means
103                // anyone could trigger network scoring and flood the framework with score requests.
104                continue;
105            }
106            if (pm.checkPermission(permission.SCORE_NETWORKS, receiverInfo.packageName) !=
107                    PackageManager.PERMISSION_GRANTED) {
108                // Application doesn't hold the SCORE_NETWORKS permission, so the user never
109                // approved it as a network scorer.
110                continue;
111            }
112
113            // Optionally, this package may specify a configuration activity.
114            String configurationActivityClassName = null;
115            Intent intent = new Intent(NetworkScoreManager.ACTION_CUSTOM_ENABLE);
116            intent.setPackage(receiverInfo.packageName);
117            List<ResolveInfo> configActivities = pm.queryIntentActivities(intent, 0 /* flags */);
118            if (!configActivities.isEmpty()) {
119                ActivityInfo activityInfo = configActivities.get(0).activityInfo;
120                if (activityInfo != null) {
121                    configurationActivityClassName = activityInfo.name;
122                }
123            }
124
125            // NOTE: loadLabel will attempt to load the receiver's label and fall back to the app
126            // label if none is present.
127            scorers.add(new NetworkScorerAppData(receiverInfo.packageName,
128                    receiverInfo.loadLabel(pm), configurationActivityClassName));
129        }
130
131        return scorers;
132    }
133
134    /**
135     * Get the application to use for scoring networks.
136     *
137     * @return the scorer app info or null if scoring is disabled (including if no scorer was ever
138     *     selected) or if the previously-set scorer is no longer a valid scorer app (e.g. because
139     *     it was disabled or uninstalled).
140     */
141    public static NetworkScorerAppData getActiveScorer(Context context) {
142        String scorerPackage = Settings.Global.getString(context.getContentResolver(),
143                Settings.Global.NETWORK_SCORER_APP);
144        return getScorer(context, scorerPackage);
145    }
146
147    /**
148     * Set the specified package as the default scorer application.
149     *
150     * <p>The caller must have permission to write to {@link android.provider.Settings.Global}.
151     *
152     * @param context the context of the calling application
153     * @param packageName the packageName of the new scorer to use. If null, scoring will be
154     *     disabled. Otherwise, the scorer will only be set if it is a valid scorer application.
155     * @return true if the scorer was changed, or false if the package is not a valid scorer.
156     */
157    public static boolean setActiveScorer(Context context, String packageName) {
158        String oldPackageName = Settings.Global.getString(context.getContentResolver(),
159                Settings.Global.NETWORK_SCORER_APP);
160        if (TextUtils.equals(oldPackageName, packageName)) {
161            // No change.
162            return true;
163        }
164
165        Log.i(TAG, "Changing network scorer from " + oldPackageName + " to " + packageName);
166
167        if (packageName == null) {
168            Settings.Global.putString(context.getContentResolver(),
169                    Settings.Global.NETWORK_SCORER_APP, null);
170            return true;
171        } else {
172            // We only make the change if the new package is valid.
173            if (getScorer(context, packageName) != null) {
174                Settings.Global.putString(context.getContentResolver(),
175                        Settings.Global.NETWORK_SCORER_APP, packageName);
176                return true;
177            } else {
178                Log.w(TAG, "Requested network scorer is not valid: " + packageName);
179                return false;
180            }
181        }
182    }
183
184    /** Determine whether the application with the given UID is the enabled scorer. */
185    public static boolean isCallerActiveScorer(Context context, int callingUid) {
186        NetworkScorerAppData defaultApp = getActiveScorer(context);
187        if (defaultApp == null) {
188            return false;
189        }
190        AppOpsManager appOpsMgr = (AppOpsManager) context.getSystemService(Context.APP_OPS_SERVICE);
191        try {
192            appOpsMgr.checkPackage(callingUid, defaultApp.mPackageName);
193        } catch (SecurityException e) {
194            return false;
195        }
196
197        // To be extra safe, ensure the caller holds the SCORE_NETWORKS permission. It always
198        // should, since it couldn't become the active scorer otherwise, but this can't hurt.
199        return context.checkCallingPermission(Manifest.permission.SCORE_NETWORKS) ==
200                PackageManager.PERMISSION_GRANTED;
201    }
202
203    /** Returns the {@link NetworkScorerAppData} for the given app, or null if it's not a scorer. */
204    public static NetworkScorerAppData getScorer(Context context, String packageName) {
205        if (TextUtils.isEmpty(packageName)) {
206            return null;
207        }
208        Collection<NetworkScorerAppData> applications = getAllValidScorers(context);
209        for (NetworkScorerAppData app : applications) {
210            if (packageName.equals(app.mPackageName)) {
211                return app;
212            }
213        }
214        return null;
215    }
216}
217