/*
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* Copyright (C) 2016 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.wifi;
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import android.os.Binder;
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import android.os.IBinder;
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import android.os.RemoteException;
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import android.util.Slog;
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import android.util.StatsLog;
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import com.android.internal.app.IBatteryStats;
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import java.io.PrintWriter;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* WifiMulticastLockManager tracks holders of multicast locks and
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* triggers enabling and disabling of filtering.
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*
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* @hide
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*/
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public class WifiMulticastLockManager {
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private static final String TAG = "WifiMulticastLockManager";
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private final List<Multicaster> mMulticasters = new ArrayList<>();
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private int mMulticastEnabled = 0;
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private int mMulticastDisabled = 0;
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private boolean mVerboseLoggingEnabled = false;
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private final IBatteryStats mBatteryStats;
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private final FilterController mFilterController;
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/** Delegate for handling state change events for multicast filtering. */
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public interface FilterController {
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/** Called when multicast filtering should be enabled */
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void startFilteringMulticastPackets();
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/** Called when multicast filtering should be disabled */
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void stopFilteringMulticastPackets();
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}
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public WifiMulticastLockManager(FilterController filterController, IBatteryStats batteryStats) {
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mBatteryStats = batteryStats;
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mFilterController = filterController;
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}
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private class Multicaster implements IBinder.DeathRecipient {
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String mTag;
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int mUid;
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IBinder mBinder;
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Multicaster(String tag, IBinder binder) {
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mTag = tag;
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mUid = Binder.getCallingUid();
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mBinder = binder;
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try {
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mBinder.linkToDeath(this, 0);
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} catch (RemoteException e) {
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binderDied();
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}
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}
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@Override
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public void binderDied() {
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Slog.e(TAG, "Multicaster binderDied");
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synchronized (mMulticasters) {
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int i = mMulticasters.indexOf(this);
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if (i != -1) {
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removeMulticasterLocked(i, mUid, mTag);
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}
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}
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}
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void unlinkDeathRecipient() {
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mBinder.unlinkToDeath(this, 0);
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}
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public int getUid() {
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return mUid;
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}
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public String getTag() {
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return mTag;
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}
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public String toString() {
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return "Multicaster{" + mTag + " uid=" + mUid + "}";
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}
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}
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protected void dump(PrintWriter pw) {
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pw.println("mMulticastEnabled " + mMulticastEnabled);
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pw.println("mMulticastDisabled " + mMulticastDisabled);
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pw.println("Multicast Locks held:");
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for (Multicaster l : mMulticasters) {
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pw.print(" ");
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pw.println(l);
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}
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}
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protected void enableVerboseLogging(int verbose) {
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if (verbose > 0) {
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mVerboseLoggingEnabled = true;
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} else {
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mVerboseLoggingEnabled = false;
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}
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}
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/** Start filtering if no multicasters exist. */
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public void initializeFiltering() {
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synchronized (mMulticasters) {
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// if anybody had requested filters be off, leave off
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if (mMulticasters.size() != 0) {
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return;
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} else {
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mFilterController.startFilteringMulticastPackets();
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}
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}
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}
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/**
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* Acquire a multicast lock.
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* @param binder a binder used to ensure caller is still alive
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* @param tag string name of the caller.
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*/
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public void acquireLock(IBinder binder, String tag) {
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synchronized (mMulticasters) {
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mMulticastEnabled++;
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mMulticasters.add(new Multicaster(tag, binder));
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// Note that we could call stopFilteringMulticastPackets only when
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// our new size == 1 (first call), but this function won't
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// be called often and by making the stopPacket call each
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// time we're less fragile and self-healing.
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mFilterController.stopFilteringMulticastPackets();
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}
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int uid = Binder.getCallingUid();
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final long ident = Binder.clearCallingIdentity();
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try {
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mBatteryStats.noteWifiMulticastEnabled(uid);
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StatsLog.write_non_chained(
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StatsLog.WIFI_MULTICAST_LOCK_STATE_CHANGED, uid, null,
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StatsLog.WIFI_MULTICAST_LOCK_STATE_CHANGED__STATE__ON, tag);
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} catch (RemoteException e) {
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} finally {
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Binder.restoreCallingIdentity(ident);
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}
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}
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/** Releases a multicast lock */
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public void releaseLock(String tag) {
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int uid = Binder.getCallingUid();
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synchronized (mMulticasters) {
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mMulticastDisabled++;
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int size = mMulticasters.size();
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for (int i = size - 1; i >= 0; i--) {
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Multicaster m = mMulticasters.get(i);
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if ((m != null) && (m.getUid() == uid) && (m.getTag().equals(tag))) {
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removeMulticasterLocked(i, uid, tag);
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break;
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}
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}
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}
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}
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private void removeMulticasterLocked(int i, int uid, String tag) {
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Multicaster removed = mMulticasters.remove(i);
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if (removed != null) {
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removed.unlinkDeathRecipient();
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}
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if (mMulticasters.size() == 0) {
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mFilterController.startFilteringMulticastPackets();
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}
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final long ident = Binder.clearCallingIdentity();
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try {
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mBatteryStats.noteWifiMulticastDisabled(uid);
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StatsLog.write_non_chained(
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StatsLog.WIFI_MULTICAST_LOCK_STATE_CHANGED, uid, null,
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StatsLog.WIFI_MULTICAST_LOCK_STATE_CHANGED__STATE__OFF, tag);
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} catch (RemoteException e) {
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} finally {
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Binder.restoreCallingIdentity(ident);
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}
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}
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/** Returns whether multicast should be allowed (filterning disabled). */
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public boolean isMulticastEnabled() {
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synchronized (mMulticasters) {
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return (mMulticasters.size() > 0);
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}
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}
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}
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