/*
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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.scanner;
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import android.net.wifi.WifiScanner;
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import android.util.ArraySet;
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import com.android.server.wifi.WifiNative;
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import java.util.Set;
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/**
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* ChannelHelper offers an abstraction for channel manipulation utilities allowing operation to be
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* adjusted based on the amount of information known about the available channels.
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*/
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public abstract class ChannelHelper {
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// TODO: Currently this is simply an estimate and is used for both active and passive channels
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// scans. Eventually it should be split between passive and active and perhaps retrieved
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// from the driver.
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/**
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* The estimated period spent scanning each channel. This is used for estimating scan duration.
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*/
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public static final int SCAN_PERIOD_PER_CHANNEL_MS = 200;
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protected static final WifiScanner.ChannelSpec[] NO_CHANNELS = new WifiScanner.ChannelSpec[0];
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/**
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* Create a new collection that can be used to store channels
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*/
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public abstract ChannelCollection createChannelCollection();
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/**
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* Return true if the specified channel is expected for a scan with the given settings
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*/
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public abstract boolean settingsContainChannel(WifiScanner.ScanSettings settings, int channel);
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/**
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* Get the channels that are available for scanning on the supplied band.
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* This method may return empty if the information is not available.
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*/
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public abstract WifiScanner.ChannelSpec[] getAvailableScanChannels(int band);
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/**
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* Estimates the duration that the chip will spend scanning with the given settings
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*/
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public abstract int estimateScanDuration(WifiScanner.ScanSettings settings);
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/**
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* Update the channel information that this object has. The source of the update is
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* implementation dependent and may result in no change. Warning the behavior of a
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* ChannelCollection created using {@link #createChannelCollection createChannelCollection} is
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* undefined after calling this method until the {@link ChannelColleciton#clear() clear} method
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* is called on it.
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*/
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public void updateChannels() {
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// default implementation does nothing
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}
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/**
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* Object that supports accumulation of channels and bands
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*/
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public abstract class ChannelCollection {
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/**
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* Add a channel to the collection
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*/
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public abstract void addChannel(int channel);
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/**
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* Add all channels in the band to the collection
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*/
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public abstract void addBand(int band);
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/**
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* @return true if the collection contains the supplied channel
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*/
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public abstract boolean containsChannel(int channel);
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/**
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* @return true if the collection contains all the channels of the supplied band
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*/
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public abstract boolean containsBand(int band);
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/**
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* @return true if the collection contains some of the channels of the supplied band
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*/
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public abstract boolean partiallyContainsBand(int band);
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/**
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* @return true if the collection contains no channels
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*/
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public abstract boolean isEmpty();
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/**
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* @return true if the collection contains all available channels
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*/
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public abstract boolean isAllChannels();
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/**
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* Remove all channels from the collection
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*/
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public abstract void clear();
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/**
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* Retrieves a list of channels from the band which are missing in the channel collection.
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*/
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public abstract Set<Integer> getMissingChannelsFromBand(int band);
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/**
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* Retrieves a list of channels from the band which are contained in the channel collection.
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*/
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public abstract Set<Integer> getContainingChannelsFromBand(int band);
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/**
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* Gets a list of channels specified in the current channel collection. This will return
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* an empty set if an entire Band if specified or if the list is empty.
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*/
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public abstract Set<Integer> getChannelSet();
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/**
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* Add all channels in the ScanSetting to the collection
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*/
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public void addChannels(WifiScanner.ScanSettings scanSettings) {
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if (scanSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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for (int j = 0; j < scanSettings.channels.length; ++j) {
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addChannel(scanSettings.channels[j].frequency);
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}
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} else {
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addBand(scanSettings.band);
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}
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}
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/**
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* Add all channels in the BucketSettings to the collection
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*/
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public void addChannels(WifiNative.BucketSettings bucketSettings) {
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if (bucketSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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for (int j = 0; j < bucketSettings.channels.length; ++j) {
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addChannel(bucketSettings.channels[j].frequency);
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}
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} else {
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addBand(bucketSettings.band);
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}
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}
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/**
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* Checks if all channels in ScanSetting is in the collection
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*/
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public boolean containsSettings(WifiScanner.ScanSettings scanSettings) {
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if (scanSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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for (int j = 0; j < scanSettings.channels.length; ++j) {
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if (!containsChannel(scanSettings.channels[j].frequency)) {
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return false;
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}
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}
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return true;
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} else {
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return containsBand(scanSettings.band);
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}
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}
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/**
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* Checks if at least some of the channels in ScanSetting is in the collection
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*/
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public boolean partiallyContainsSettings(WifiScanner.ScanSettings scanSettings) {
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if (scanSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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for (int j = 0; j < scanSettings.channels.length; ++j) {
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if (containsChannel(scanSettings.channels[j].frequency)) {
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return true;
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}
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}
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return false;
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} else {
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return partiallyContainsBand(scanSettings.band);
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}
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}
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/**
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* Retrieves a list of missing channels in the collection from the provided settings.
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*/
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public Set<Integer> getMissingChannelsFromSettings(WifiScanner.ScanSettings scanSettings) {
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if (scanSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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ArraySet<Integer> missingChannels = new ArraySet<>();
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for (int j = 0; j < scanSettings.channels.length; ++j) {
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if (!containsChannel(scanSettings.channels[j].frequency)) {
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missingChannels.add(scanSettings.channels[j].frequency);
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}
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}
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return missingChannels;
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} else {
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return getMissingChannelsFromBand(scanSettings.band);
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}
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}
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/**
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* Retrieves a list of containing channels in the collection from the provided settings.
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*/
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public Set<Integer> getContainingChannelsFromSettings(
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WifiScanner.ScanSettings scanSettings) {
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if (scanSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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ArraySet<Integer> containingChannels = new ArraySet<>();
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for (int j = 0; j < scanSettings.channels.length; ++j) {
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if (containsChannel(scanSettings.channels[j].frequency)) {
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containingChannels.add(scanSettings.channels[j].frequency);
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}
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}
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return containingChannels;
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} else {
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return getContainingChannelsFromBand(scanSettings.band);
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}
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}
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/**
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* Store the channels in this collection in the supplied BucketSettings. If maxChannels is
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* exceeded or a band better describes the channels then a band is specified instead of a
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* channel list.
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*/
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public abstract void fillBucketSettings(WifiNative.BucketSettings bucket, int maxChannels);
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/**
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* Gets the list of channels scan. Will either be a collection of all channels or null
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* if all channels should be scanned.
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*/
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public abstract Set<Integer> getScanFreqs();
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}
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/*
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* Utility methods for converting band/channels to strings
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*/
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/**
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* Create a string representation of the channels in the ScanSettings.
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* If it contains a list of channels then the channels are returned, otherwise a string name of
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* the band is returned.
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*/
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public static String toString(WifiScanner.ScanSettings scanSettings) {
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if (scanSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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return toString(scanSettings.channels);
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} else {
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return bandToString(scanSettings.band);
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}
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}
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/**
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* Create a string representation of the channels in the BucketSettings.
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* If it contains a list of channels then the channels are returned, otherwise a string name of
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* the band is returned.
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*/
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public static String toString(WifiNative.BucketSettings bucketSettings) {
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if (bucketSettings.band == WifiScanner.WIFI_BAND_UNSPECIFIED) {
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return toString(bucketSettings.channels, bucketSettings.num_channels);
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} else {
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return bandToString(bucketSettings.band);
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}
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}
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private static String toString(WifiScanner.ChannelSpec[] channels) {
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if (channels == null) {
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return "null";
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}
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StringBuilder sb = new StringBuilder();
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sb.append("[");
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for (int c = 0; c < channels.length; c++) {
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sb.append(channels[c].frequency);
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if (c != channels.length - 1) {
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sb.append(",");
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}
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}
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sb.append("]");
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return sb.toString();
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}
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private static String toString(WifiNative.ChannelSettings[] channels, int numChannels) {
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if (channels == null) {
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return "null";
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}
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StringBuilder sb = new StringBuilder();
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sb.append("[");
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for (int c = 0; c < numChannels; c++) {
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sb.append(channels[c].frequency);
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if (c != numChannels - 1) {
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sb.append(",");
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}
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}
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sb.append("]");
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return sb.toString();
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}
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/**
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* Converts a WifiScanner.WIFI_BAND_* constant to a meaningful String
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*/
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public static String bandToString(int band) {
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switch (band) {
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case WifiScanner.WIFI_BAND_UNSPECIFIED:
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return "unspecified";
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case WifiScanner.WIFI_BAND_24_GHZ:
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return "24Ghz";
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case WifiScanner.WIFI_BAND_5_GHZ:
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return "5Ghz (no DFS)";
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case WifiScanner.WIFI_BAND_5_GHZ_DFS_ONLY:
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return "5Ghz (DFS only)";
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case WifiScanner.WIFI_BAND_5_GHZ_WITH_DFS:
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return "5Ghz (DFS incl)";
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case WifiScanner.WIFI_BAND_BOTH:
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return "24Ghz & 5Ghz (no DFS)";
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case WifiScanner.WIFI_BAND_BOTH_WITH_DFS:
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return "24Ghz & 5Ghz (DFS incl)";
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}
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return "invalid band";
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}
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}
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