/* * Copyright (C) 2018 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 com.android.server.wifi; import static com.android.server.wifi.WifiSettingsConfigStore.WIFI_SCAN_THROTTLE_ENABLED; import android.annotation.NonNull; import android.annotation.Nullable; import android.app.ActivityManager; import android.app.AppOpsManager; import android.content.Context; import android.content.Intent; import android.net.wifi.IScanResultsCallback; import android.net.wifi.ScanResult; import android.net.wifi.WifiManager; import android.net.wifi.WifiScanner; import android.os.Handler; import android.os.HandlerExecutor; import android.os.RemoteCallbackList; import android.os.RemoteException; import android.os.UserHandle; import android.os.WorkSource; import android.util.ArrayMap; import android.util.Log; import android.util.Pair; import com.android.internal.annotations.VisibleForTesting; import com.android.modules.utils.build.SdkLevel; import com.android.server.wifi.util.ScanResultUtil; import com.android.server.wifi.util.WifiPermissionsUtil; import com.android.wifi.resources.R; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import java.util.Map; import javax.annotation.concurrent.NotThreadSafe; /** * This class manages all scan requests originating from external apps using the * {@link WifiManager#startScan()}. * * This class is responsible for: * a) Enable/Disable scanning based on the request from {@link ActiveModeWarden}. * a) Forwarding scan requests from {@link WifiManager#startScan()} to * {@link WifiScanner#startScan(WifiScanner.ScanSettings, WifiScanner.ScanListener)}. * Will essentially proxy scan requests from WifiService to WifiScanningService. * b) Cache the results of these scan requests and return them when * {@link WifiManager#getScanResults()} is invoked. * c) Will send out the {@link WifiManager#SCAN_RESULTS_AVAILABLE_ACTION} broadcast when new * scan results are available. * d) Throttle scan requests from non-setting apps: * a) Each foreground app can request a max of * {@link #SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS} scan every * {@link #SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS}. * b) Background apps combined can request 1 scan every * {@link #SCAN_REQUEST_THROTTLE_INTERVAL_BG_APPS_MS}. * Note: This class is not thread-safe. It needs to be invoked from the main Wifi thread only. */ @NotThreadSafe public class ScanRequestProxy { private static final String TAG = "WifiScanRequestProxy"; @VisibleForTesting public static final int SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS = 120 * 1000; @VisibleForTesting public static final int SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS = 4; @VisibleForTesting public static final int SCAN_REQUEST_THROTTLE_INTERVAL_BG_APPS_MS = 30 * 60 * 1000; private final Context mContext; private final Handler mHandler; private final AppOpsManager mAppOps; private final ActivityManager mActivityManager; private final WifiInjector mWifiInjector; private final WifiConfigManager mWifiConfigManager; private final WifiPermissionsUtil mWifiPermissionsUtil; private final WifiMetrics mWifiMetrics; private final Clock mClock; private final WifiSettingsConfigStore mSettingsConfigStore; private WifiScanner mWifiScanner; // Verbose logging flag. private boolean mVerboseLoggingEnabled = false; private boolean mThrottleEnabled = true; // Flag to decide if we need to scan or not. private boolean mScanningEnabled = false; // Flag to decide if we need to scan for hidden networks or not. private boolean mScanningForHiddenNetworksEnabled = false; // Timestamps for the last scan requested by any background app. private long mLastScanTimestampForBgApps = 0; // Timestamps for the list of last few scan requests by each foreground app. // Keys in the map = Pair of the app. // Values in the map = List of the last few scan request timestamps from the app. private final ArrayMap, LinkedList> mLastScanTimestampsForFgApps = new ArrayMap(); // Scan results cached from the last full single scan request. // Stored as a map of bssid -> ScanResult to allow other clients to perform ScanResult lookup // for bssid more efficiently. private final Map mLastScanResultsMap = new HashMap<>(); // external ScanResultCallback tracker private final RemoteCallbackList mRegisteredScanResultsCallbacks; // Global scan listener for listening to all scan requests. private class GlobalScanListener implements WifiScanner.ScanListener { @Override public void onSuccess() { // Ignore. These will be processed from the scan request listener. } @Override public void onFailure(int reason, String description) { // Ignore. These will be processed from the scan request listener. } @Override public void onResults(WifiScanner.ScanData[] scanDatas) { if (mVerboseLoggingEnabled) { Log.d(TAG, "Scan results received"); } // For single scans, the array size should always be 1. if (scanDatas.length != 1) { Log.wtf(TAG, "Found more than 1 batch of scan results, Failing..."); sendScanResultBroadcast(false); return; } WifiScanner.ScanData scanData = scanDatas[0]; ScanResult[] scanResults = scanData.getResults(); if (mVerboseLoggingEnabled) { Log.d(TAG, "Received " + scanResults.length + " scan results"); } // Only process full band scan results. if (WifiScanner.isFullBandScan(scanData.getScannedBandsInternal(), false)) { // Store the last scan results & send out the scan completion broadcast. mLastScanResultsMap.clear(); Arrays.stream(scanResults).forEach(s -> mLastScanResultsMap.put(s.BSSID, s)); sendScanResultBroadcast(true); sendScanResultsAvailableToCallbacks(); } } @Override public void onFullResult(ScanResult fullScanResult) { // Ignore for single scans. } @Override public void onPeriodChanged(int periodInMs) { // Ignore for single scans. } }; // Common scan listener for scan requests initiated by this class. private class ScanRequestProxyScanListener implements WifiScanner.ScanListener { @Override public void onSuccess() { // Scan request succeeded, wait for results to report to external clients. if (mVerboseLoggingEnabled) { Log.d(TAG, "Scan request succeeded"); } } @Override public void onFailure(int reason, String description) { Log.e(TAG, "Scan failure received. reason: " + reason + ",description: " + description); sendScanResultBroadcast(false); } @Override public void onResults(WifiScanner.ScanData[] scanDatas) { // Ignore. These will be processed from the global listener. } @Override public void onFullResult(ScanResult fullScanResult) { // Ignore for single scans. } @Override public void onPeriodChanged(int periodInMs) { // Ignore for single scans. } }; ScanRequestProxy(Context context, AppOpsManager appOpsManager, ActivityManager activityManager, WifiInjector wifiInjector, WifiConfigManager configManager, WifiPermissionsUtil wifiPermissionUtil, WifiMetrics wifiMetrics, Clock clock, Handler handler, WifiSettingsConfigStore settingsConfigStore) { mContext = context; mHandler = handler; mAppOps = appOpsManager; mActivityManager = activityManager; mWifiInjector = wifiInjector; mWifiConfigManager = configManager; mWifiPermissionsUtil = wifiPermissionUtil; mWifiMetrics = wifiMetrics; mClock = clock; mSettingsConfigStore = settingsConfigStore; mRegisteredScanResultsCallbacks = new RemoteCallbackList<>(); } /** * Enable verbose logging. */ public void enableVerboseLogging(int verbose) { mVerboseLoggingEnabled = (verbose > 0); } /** * Helper method to populate WifiScanner handle. This is done lazily because * WifiScanningService is started after WifiService. */ private boolean retrieveWifiScannerIfNecessary() { if (mWifiScanner == null) { mWifiScanner = mWifiInjector.getWifiScanner(); // Start listening for throttle settings change after we retrieve scanner instance. mThrottleEnabled = mSettingsConfigStore.get(WIFI_SCAN_THROTTLE_ENABLED); if (mVerboseLoggingEnabled) { Log.v(TAG, "Scan throttle enabled " + mThrottleEnabled); } // Register the global scan listener. if (mWifiScanner != null) { mWifiScanner.registerScanListener( new HandlerExecutor(mHandler), new GlobalScanListener()); } } return mWifiScanner != null; } /** * Method that lets public apps know that scans are available. * * @param context Context to use for the notification * @param available boolean indicating if scanning is available */ private void sendScanAvailableBroadcast(Context context, boolean available) { Log.d(TAG, "Sending scan available broadcast: " + available); final Intent intent = new Intent(WifiManager.ACTION_WIFI_SCAN_AVAILABILITY_CHANGED); intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT); intent.putExtra(WifiManager.EXTRA_SCAN_AVAILABLE, available); context.sendStickyBroadcastAsUser(intent, UserHandle.ALL); } private void enableScanningInternal(boolean enable) { if (!retrieveWifiScannerIfNecessary()) { Log.e(TAG, "Failed to retrieve wifiscanner"); return; } mWifiScanner.setScanningEnabled(enable); sendScanAvailableBroadcast(mContext, enable); if (!enable) clearScanResults(); Log.i(TAG, "Scanning is " + (enable ? "enabled" : "disabled")); } /** * Enable/disable scanning. * * @param enable true to enable, false to disable. * @param enableScanningForHiddenNetworks true to enable scanning for hidden networks, * false to disable. */ public void enableScanning(boolean enable, boolean enableScanningForHiddenNetworks) { if (enable) { enableScanningInternal(true); mScanningForHiddenNetworksEnabled = enableScanningForHiddenNetworks; Log.i(TAG, "Scanning for hidden networks is " + (enableScanningForHiddenNetworks ? "enabled" : "disabled")); } else { enableScanningInternal(false); } mScanningEnabled = enable; } /** * Helper method to send the scan request status broadcast. */ private void sendScanResultBroadcast(boolean scanSucceeded) { Intent intent = new Intent(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION); intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT); intent.putExtra(WifiManager.EXTRA_RESULTS_UPDATED, scanSucceeded); mContext.sendBroadcastAsUser(intent, UserHandle.ALL); } /** * Helper method to send the scan request failure broadcast to specified package. */ private void sendScanResultFailureBroadcastToPackage(String packageName) { Intent intent = new Intent(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION); intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT); intent.putExtra(WifiManager.EXTRA_RESULTS_UPDATED, false); intent.setPackage(packageName); mContext.sendBroadcastAsUser(intent, UserHandle.ALL); } private void trimPastScanRequestTimesForForegroundApp( List scanRequestTimestamps, long currentTimeMillis) { Iterator timestampsIter = scanRequestTimestamps.iterator(); while (timestampsIter.hasNext()) { Long scanRequestTimeMillis = timestampsIter.next(); if ((currentTimeMillis - scanRequestTimeMillis) > SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS) { timestampsIter.remove(); } else { // This list is sorted by timestamps, so we can skip any more checks break; } } } private LinkedList getOrCreateScanRequestTimestampsForForegroundApp( int callingUid, String packageName) { Pair uidAndPackageNamePair = Pair.create(callingUid, packageName); LinkedList scanRequestTimestamps = mLastScanTimestampsForFgApps.get(uidAndPackageNamePair); if (scanRequestTimestamps == null) { scanRequestTimestamps = new LinkedList<>(); mLastScanTimestampsForFgApps.put(uidAndPackageNamePair, scanRequestTimestamps); } return scanRequestTimestamps; } /** * Checks if the scan request from the app (specified by packageName) needs * to be throttled. * The throttle limit allows a max of {@link #SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS} * in {@link #SCAN_REQUEST_THROTTLE_TIME_WINDOW_FG_APPS_MS} window. */ private boolean shouldScanRequestBeThrottledForForegroundApp( int callingUid, String packageName) { if (isPackageNameInExceptionList(packageName, true)) { return false; } LinkedList scanRequestTimestamps = getOrCreateScanRequestTimestampsForForegroundApp(callingUid, packageName); long currentTimeMillis = mClock.getElapsedSinceBootMillis(); // First evict old entries from the list. trimPastScanRequestTimesForForegroundApp(scanRequestTimestamps, currentTimeMillis); if (scanRequestTimestamps.size() >= SCAN_REQUEST_THROTTLE_MAX_IN_TIME_WINDOW_FG_APPS) { return true; } // Proceed with the scan request and record the time. scanRequestTimestamps.addLast(currentTimeMillis); return false; } private boolean isPackageNameInExceptionList(String packageName, boolean isForeground) { if (packageName == null) { return false; } String[] exceptionList = mContext.getResources().getStringArray(isForeground ? R.array.config_wifiForegroundScanThrottleExceptionList : R.array.config_wifiBackgroundScanThrottleExceptionList); if (exceptionList == null) { return false; } for (String name : exceptionList) { if (packageName.equals(name)) { return true; } } return false; } /** * Checks if the scan request from a background app needs to be throttled. */ private boolean shouldScanRequestBeThrottledForBackgroundApp(String packageName) { if (isPackageNameInExceptionList(packageName, false)) { return false; } long lastScanMs = mLastScanTimestampForBgApps; long elapsedRealtime = mClock.getElapsedSinceBootMillis(); if (lastScanMs != 0 && (elapsedRealtime - lastScanMs) < SCAN_REQUEST_THROTTLE_INTERVAL_BG_APPS_MS) { return true; } // Proceed with the scan request and record the time. mLastScanTimestampForBgApps = elapsedRealtime; return false; } /** * Safely retrieve package importance. */ private int getPackageImportance(int callingUid, String packageName) { mAppOps.checkPackage(callingUid, packageName); try { return mActivityManager.getPackageImportance(packageName); } catch (SecurityException e) { Log.e(TAG, "Failed to check the app state", e); return ActivityManager.RunningAppProcessInfo.IMPORTANCE_GONE; } } /** * Checks if the scan request from the app (specified by callingUid & packageName) needs * to be throttled. */ private boolean shouldScanRequestBeThrottledForApp(int callingUid, String packageName, int packageImportance) { boolean isThrottled; if (packageImportance > ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND_SERVICE) { isThrottled = shouldScanRequestBeThrottledForBackgroundApp(packageName); if (isThrottled) { if (mVerboseLoggingEnabled) { Log.v(TAG, "Background scan app request [" + callingUid + ", " + packageName + "]"); } mWifiMetrics.incrementExternalBackgroundAppOneshotScanRequestsThrottledCount(); } } else { isThrottled = shouldScanRequestBeThrottledForForegroundApp(callingUid, packageName); if (isThrottled) { if (mVerboseLoggingEnabled) { Log.v(TAG, "Foreground scan app request [" + callingUid + ", " + packageName + "]"); } mWifiMetrics.incrementExternalForegroundAppOneshotScanRequestsThrottledCount(); } } mWifiMetrics.incrementExternalAppOneshotScanRequestsCount(); return isThrottled; } /** * Initiate a wifi scan. * * @param callingUid The uid initiating the wifi scan. Blame will be given to this uid. * @return true if the scan request was placed or a scan is already ongoing, false otherwise. */ public boolean startScan(int callingUid, String packageName) { if (!mScanningEnabled || !retrieveWifiScannerIfNecessary()) { Log.e(TAG, "Failed to retrieve wifiscanner"); sendScanResultFailureBroadcastToPackage(packageName); return false; } boolean fromSettingsOrSetupWizard = mWifiPermissionsUtil.checkNetworkSettingsPermission(callingUid) || mWifiPermissionsUtil.checkNetworkSetupWizardPermission(callingUid); // Check and throttle scan request unless, // a) App has either NETWORK_SETTINGS or NETWORK_SETUP_WIZARD permission. // b) Throttling has been disabled by user. int packageImportance = getPackageImportance(callingUid, packageName); if (!fromSettingsOrSetupWizard && mThrottleEnabled && shouldScanRequestBeThrottledForApp(callingUid, packageName, packageImportance)) { Log.i(TAG, "Scan request from " + packageName + " throttled"); sendScanResultFailureBroadcastToPackage(packageName); return false; } // Create a worksource using the caller's UID. WorkSource workSource = new WorkSource(callingUid, packageName); mWifiMetrics.getScanMetrics().setWorkSource(workSource); mWifiMetrics.getScanMetrics().setImportance(packageImportance); // Create the scan settings. WifiScanner.ScanSettings settings = new WifiScanner.ScanSettings(); // Scan requests from apps with network settings will be of high accuracy type. if (fromSettingsOrSetupWizard) { settings.type = WifiScanner.SCAN_TYPE_HIGH_ACCURACY; } else { if (SdkLevel.isAtLeastS()) { // since the scan request is from a normal app, do not scan all 6Ghz channels. settings.set6GhzPscOnlyEnabled(true); } } settings.band = WifiScanner.WIFI_BAND_ALL; settings.reportEvents = WifiScanner.REPORT_EVENT_AFTER_EACH_SCAN | WifiScanner.REPORT_EVENT_FULL_SCAN_RESULT; if (mScanningForHiddenNetworksEnabled) { settings.hiddenNetworks.clear(); // retrieve the list of hidden network SSIDs from saved network to scan for, if enabled. settings.hiddenNetworks.addAll(mWifiConfigManager.retrieveHiddenNetworkList()); // retrieve the list of hidden network SSIDs from Network suggestion to scan for. settings.hiddenNetworks.addAll( mWifiInjector.getWifiNetworkSuggestionsManager().retrieveHiddenNetworkList()); } mWifiScanner.startScan(settings, new HandlerExecutor(mHandler), new ScanRequestProxyScanListener(), workSource); return true; } /** * Return the results of the most recent access point scan, in the form of * a list of {@link ScanResult} objects. * @return the list of results */ public List getScanResults() { // return a copy to prevent external modification return new ArrayList<>(mLastScanResultsMap.values()); } /** * Return the ScanResult from the most recent access point scan for the provided bssid. * * @param bssid BSSID as string {@link ScanResult#BSSID}. * @return ScanResult for the corresponding bssid if found, null otherwise. */ public @Nullable ScanResult getScanResult(@NonNull String bssid) { ScanResult scanResult = mLastScanResultsMap.get(bssid); if (scanResult == null) return null; // return a copy to prevent external modification return new ScanResult(scanResult); } /** * Clear the stored scan results. */ private void clearScanResults() { mLastScanResultsMap.clear(); mLastScanTimestampForBgApps = 0; mLastScanTimestampsForFgApps.clear(); } /** * Clear any scan timestamps being stored for the app. * * @param uid Uid of the package. * @param packageName Name of the package. */ public void clearScanRequestTimestampsForApp(@NonNull String packageName, int uid) { if (mVerboseLoggingEnabled) { Log.v(TAG, "Clearing scan request timestamps for uid=" + uid + ", packageName=" + packageName); } mLastScanTimestampsForFgApps.remove(Pair.create(uid, packageName)); } private void sendScanResultsAvailableToCallbacks() { int itemCount = mRegisteredScanResultsCallbacks.beginBroadcast(); for (int i = 0; i < itemCount; i++) { try { mRegisteredScanResultsCallbacks.getBroadcastItem(i).onScanResultsAvailable(); } catch (RemoteException e) { Log.e(TAG, "onScanResultsAvailable: remote exception -- " + e); } } mRegisteredScanResultsCallbacks.finishBroadcast(); } /** * Register a callback on scan event * @param callback IScanResultListener instance to add. * @return true if succeed otherwise false. */ public boolean registerScanResultsCallback(IScanResultsCallback callback) { return mRegisteredScanResultsCallbacks.register(callback); } /** * Unregister a callback on scan event * @param callback IScanResultListener instance to add. */ public void unregisterScanResultsCallback(IScanResultsCallback callback) { mRegisteredScanResultsCallbacks.unregister(callback); } /** * Enable/disable wifi scan throttling from 3rd party apps. */ public void setScanThrottleEnabled(boolean enable) { mThrottleEnabled = enable; mSettingsConfigStore.put(WIFI_SCAN_THROTTLE_ENABLED, enable); Log.i(TAG, "Scan throttle enabled " + mThrottleEnabled); } /** * Get the persisted Wi-Fi scan throttle state, set by * {@link #setScanThrottleEnabled(boolean)}. */ public boolean isScanThrottleEnabled() { return mThrottleEnabled; } /** Indicate whether there are WPA2 personal only networks. */ public boolean isWpa2PersonalOnlyNetworkInRange(String ssid) { return mLastScanResultsMap.values().stream().anyMatch(r -> ssid.equals(ScanResultUtil.createQuotedSSID(r.SSID)) && ScanResultUtil.isScanResultForPskNetwork(r) && !ScanResultUtil.isScanResultForSaeNetwork(r)); } /** Indicate whether there are WPA3 only networks. */ public boolean isWpa3PersonalOnlyNetworkInRange(String ssid) { return mLastScanResultsMap.values().stream().anyMatch(r -> ssid.equals(ScanResultUtil.createQuotedSSID(r.SSID)) && ScanResultUtil.isScanResultForSaeNetwork(r) && !ScanResultUtil.isScanResultForPskNetwork(r)); } /** Indicate whether there are OPEN only networks. */ public boolean isOpenOnlyNetworkInRange(String ssid) { return mLastScanResultsMap.values().stream().anyMatch(r -> ssid.equals(ScanResultUtil.createQuotedSSID(r.SSID)) && ScanResultUtil.isScanResultForOpenNetwork(r) && !ScanResultUtil.isScanResultForOweNetwork(r)); } /** Indicate whether there are OWE only networks. */ public boolean isOweOnlyNetworkInRange(String ssid) { return mLastScanResultsMap.values().stream().anyMatch(r -> ssid.equals(ScanResultUtil.createQuotedSSID(r.SSID)) && ScanResultUtil.isScanResultForOweNetwork(r) && !ScanResultUtil.isScanResultForOweTransitionNetwork(r)); } /** Indicate whether there are WPA2 Enterprise only networks. */ public boolean isWpa2EnterpriseOnlyNetworkInRange(String ssid) { return mLastScanResultsMap.values().stream().anyMatch(r -> ssid.equals(ScanResultUtil.createQuotedSSID(r.SSID)) && ScanResultUtil.isScanResultForEapNetwork(r) && !ScanResultUtil.isScanResultForWpa3EnterpriseTransitionNetwork(r) && !ScanResultUtil.isScanResultForWpa3EnterpriseOnlyNetwork(r)); } /** Indicate whether there are WPA3 Enterprise only networks. */ public boolean isWpa3EnterpriseOnlyNetworkInRange(String ssid) { return mLastScanResultsMap.values().stream().anyMatch(r -> ssid.equals(ScanResultUtil.createQuotedSSID(r.SSID)) && ScanResultUtil.isScanResultForWpa3EnterpriseOnlyNetwork(r) && !ScanResultUtil.isScanResultForWpa3EnterpriseTransitionNetwork(r) && !ScanResultUtil.isScanResultForEapNetwork(r)); } }