/*
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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.util;
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import android.net.wifi.WifiConfiguration;
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import android.net.wifi.WifiScanner;
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import android.util.Log;
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import com.android.server.wifi.WifiNative;
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import java.util.ArrayList;
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import java.util.Random;
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/**
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* Provide utility functions for updating soft AP related configuration.
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*/
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public class ApConfigUtil {
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private static final String TAG = "ApConfigUtil";
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public static final int DEFAULT_AP_BAND = WifiConfiguration.AP_BAND_2GHZ;
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public static final int DEFAULT_AP_CHANNEL = 6;
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/* Return code for updateConfiguration. */
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public static final int SUCCESS = 0;
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public static final int ERROR_NO_CHANNEL = 1;
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public static final int ERROR_GENERIC = 2;
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/* Random number generator used for AP channel selection. */
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private static final Random sRandom = new Random();
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/**
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* Convert frequency to channel.
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* @param frequency frequency to convert
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* @return channel number associated with given frequency, -1 if no match
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*/
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public static int convertFrequencyToChannel(int frequency) {
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if (frequency >= 2412 && frequency <= 2472) {
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return (frequency - 2412) / 5 + 1;
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} else if (frequency == 2484) {
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return 14;
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} else if (frequency >= 5170 && frequency <= 5825) {
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/* DFS is included. */
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return (frequency - 5170) / 5 + 34;
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}
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return -1;
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}
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/**
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* Return a channel number for AP setup based on the frequency band.
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* @param apBand one of the value of WifiConfiguration.AP_BAND_*.
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* @param allowed2GChannels list of allowed 2GHz channels
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* @param allowed5GFreqList list of allowed 5GHz frequencies
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* @return a valid channel number on success, -1 on failure.
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*/
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public static int chooseApChannel(int apBand,
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ArrayList<Integer> allowed2GChannels,
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int[] allowed5GFreqList) {
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if (apBand != WifiConfiguration.AP_BAND_2GHZ
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&& apBand != WifiConfiguration.AP_BAND_5GHZ
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&& apBand != WifiConfiguration.AP_BAND_ANY) {
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Log.e(TAG, "Invalid band: " + apBand);
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return -1;
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}
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// TODO(b/72120668): Create channel selection logic for AP_BAND_ANY.
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if (apBand == WifiConfiguration.AP_BAND_2GHZ
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|| apBand == WifiConfiguration.AP_BAND_ANY) {
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/* Select a channel from 2GHz band. */
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if (allowed2GChannels == null || allowed2GChannels.size() == 0) {
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Log.d(TAG, "2GHz allowed channel list not specified");
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/* Use default channel. */
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return DEFAULT_AP_CHANNEL;
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}
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/* Pick a random channel. */
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int index = sRandom.nextInt(allowed2GChannels.size());
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return allowed2GChannels.get(index).intValue();
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}
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/* 5G without DFS. */
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if (allowed5GFreqList != null && allowed5GFreqList.length > 0) {
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/* Pick a random channel from the list of supported channels. */
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return convertFrequencyToChannel(
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allowed5GFreqList[sRandom.nextInt(allowed5GFreqList.length)]);
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}
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Log.e(TAG, "No available channels on 5GHz band");
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return -1;
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}
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/**
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* Update AP band and channel based on the provided country code and band.
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* This will also set
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* @param wifiNative reference to WifiNative
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* @param countryCode country code
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* @param allowed2GChannels list of allowed 2GHz channels
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* @param config configuration to update
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* @return an integer result code
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*/
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public static int updateApChannelConfig(WifiNative wifiNative,
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String countryCode,
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ArrayList<Integer> allowed2GChannels,
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WifiConfiguration config) {
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/* Use default band and channel for device without HAL. */
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if (!wifiNative.isHalStarted()) {
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config.apBand = DEFAULT_AP_BAND;
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config.apChannel = DEFAULT_AP_CHANNEL;
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return SUCCESS;
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}
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/* Country code is mandatory for 5GHz band. */
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if (config.apBand == WifiConfiguration.AP_BAND_5GHZ
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&& countryCode == null) {
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Log.e(TAG, "5GHz band is not allowed without country code");
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return ERROR_GENERIC;
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}
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/* Select a channel if it is not specified. */
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if (config.apChannel == 0) {
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config.apChannel = chooseApChannel(
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config.apBand, allowed2GChannels,
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wifiNative.getChannelsForBand(WifiScanner.WIFI_BAND_5_GHZ));
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if (config.apChannel == -1) {
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/* We're not able to get channel from wificond. */
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Log.e(TAG, "Failed to get available channel.");
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return ERROR_NO_CHANNEL;
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}
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}
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return SUCCESS;
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}
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}
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