/*
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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.annotation.NonNull;
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import android.content.Context;
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import android.net.wifi.ScanResult;
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import android.net.wifi.WifiConfiguration;
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import android.telephony.SubscriptionManager;
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import android.util.LocalLog;
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import com.android.internal.R;
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import com.android.internal.annotations.VisibleForTesting;
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import com.android.server.wifi.util.TelephonyUtil;
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import java.util.List;
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/**
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* This class is the WifiNetworkSelector.NetworkEvaluator implementation for
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* saved networks.
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*/
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public class SavedNetworkEvaluator implements WifiNetworkSelector.NetworkEvaluator {
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private static final String NAME = "SavedNetworkEvaluator";
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private final WifiConfigManager mWifiConfigManager;
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private final Clock mClock;
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private final LocalLog mLocalLog;
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private final WifiConnectivityHelper mConnectivityHelper;
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private final SubscriptionManager mSubscriptionManager;
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private final int mRssiScoreSlope;
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private final int mRssiScoreOffset;
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private final int mSameBssidAward;
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private final int mSameNetworkAward;
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private final int mBand5GHzAward;
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private final int mLastSelectionAward;
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private final int mSecurityAward;
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private final ScoringParams mScoringParams;
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/**
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* Time it takes for the mLastSelectionAward to decay by one point, in milliseconds
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*/
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@VisibleForTesting
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public static final int LAST_SELECTION_AWARD_DECAY_MSEC = 60 * 1000;
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SavedNetworkEvaluator(final Context context, ScoringParams scoringParams,
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WifiConfigManager configManager, Clock clock,
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LocalLog localLog, WifiConnectivityHelper connectivityHelper,
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SubscriptionManager subscriptionManager) {
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mScoringParams = scoringParams;
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mWifiConfigManager = configManager;
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mClock = clock;
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mLocalLog = localLog;
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mConnectivityHelper = connectivityHelper;
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mSubscriptionManager = subscriptionManager;
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mRssiScoreSlope = context.getResources().getInteger(
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R.integer.config_wifi_framework_RSSI_SCORE_SLOPE);
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mRssiScoreOffset = context.getResources().getInteger(
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R.integer.config_wifi_framework_RSSI_SCORE_OFFSET);
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mSameBssidAward = context.getResources().getInteger(
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R.integer.config_wifi_framework_SAME_BSSID_AWARD);
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mSameNetworkAward = context.getResources().getInteger(
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R.integer.config_wifi_framework_current_network_boost);
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mLastSelectionAward = context.getResources().getInteger(
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R.integer.config_wifi_framework_LAST_SELECTION_AWARD);
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mSecurityAward = context.getResources().getInteger(
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R.integer.config_wifi_framework_SECURITY_AWARD);
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mBand5GHzAward = context.getResources().getInteger(
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R.integer.config_wifi_framework_5GHz_preference_boost_factor);
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}
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private void localLog(String log) {
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mLocalLog.log(log);
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}
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/**
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* Get the evaluator type.
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*/
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@Override
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public @EvaluatorId int getId() {
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return EVALUATOR_ID_SAVED;
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}
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/**
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* Get the evaluator name.
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*/
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@Override
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public String getName() {
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return NAME;
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}
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/**
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* Update the evaluator.
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*/
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@Override
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public void update(List<ScanDetail> scanDetails) { }
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private int calculateBssidScore(ScanResult scanResult, WifiConfiguration network,
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WifiConfiguration currentNetwork, String currentBssid,
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StringBuffer sbuf) {
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int score = 0;
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boolean is5GHz = scanResult.is5GHz();
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sbuf.append("[ ").append(scanResult.SSID).append(" ").append(scanResult.BSSID)
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.append(" RSSI:").append(scanResult.level).append(" ] ");
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// Calculate the RSSI score.
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int rssiSaturationThreshold = mScoringParams.getGoodRssi(scanResult.frequency);
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int rssi = Math.min(scanResult.level, rssiSaturationThreshold);
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score += (rssi + mRssiScoreOffset) * mRssiScoreSlope;
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sbuf.append(" RSSI score: ").append(score).append(",");
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// 5GHz band bonus.
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if (is5GHz) {
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score += mBand5GHzAward;
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sbuf.append(" 5GHz bonus: ").append(mBand5GHzAward).append(",");
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}
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// Last user selection award.
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int lastUserSelectedNetworkId = mWifiConfigManager.getLastSelectedNetwork();
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if (lastUserSelectedNetworkId != WifiConfiguration.INVALID_NETWORK_ID
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&& lastUserSelectedNetworkId == network.networkId) {
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long timeDifference = mClock.getElapsedSinceBootMillis()
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- mWifiConfigManager.getLastSelectedTimeStamp();
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if (timeDifference > 0) {
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int decay = (int) (timeDifference / LAST_SELECTION_AWARD_DECAY_MSEC);
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int bonus = Math.max(mLastSelectionAward - decay, 0);
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score += bonus;
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sbuf.append(" User selection ").append(timeDifference)
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.append(" ms ago, bonus: ").append(bonus).append(",");
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}
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}
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// Same network award.
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if (currentNetwork != null && network.networkId == currentNetwork.networkId) {
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score += mSameNetworkAward;
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sbuf.append(" Same network bonus: ").append(mSameNetworkAward).append(",");
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// When firmware roaming is supported, equivalent BSSIDs (the ones under the
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// same network as the currently connected one) get the same BSSID award.
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if (mConnectivityHelper.isFirmwareRoamingSupported()
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&& currentBssid != null && !currentBssid.equals(scanResult.BSSID)) {
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score += mSameBssidAward;
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sbuf.append(" Equivalent BSSID bonus: ").append(mSameBssidAward).append(",");
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}
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}
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// Same BSSID award.
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if (currentBssid != null && currentBssid.equals(scanResult.BSSID)) {
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score += mSameBssidAward;
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sbuf.append(" Same BSSID bonus: ").append(mSameBssidAward).append(",");
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}
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// Security award.
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if (!WifiConfigurationUtil.isConfigForOpenNetwork(network)) {
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score += mSecurityAward;
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sbuf.append(" Secure network bonus: ").append(mSecurityAward).append(",");
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}
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sbuf.append(" ## Total score: ").append(score).append("\n");
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return score;
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}
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/**
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* Evaluate all the networks from the scan results and return
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* the WifiConfiguration of the network chosen for connection.
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*
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* @return configuration of the chosen network;
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* null if no network in this category is available.
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*/
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@Override
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public WifiConfiguration evaluateNetworks(List<ScanDetail> scanDetails,
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WifiConfiguration currentNetwork, String currentBssid, boolean connected,
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boolean untrustedNetworkAllowed,
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@NonNull OnConnectableListener onConnectableListener) {
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int highestScore = Integer.MIN_VALUE;
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ScanResult scanResultCandidate = null;
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WifiConfiguration candidate = null;
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StringBuffer scoreHistory = new StringBuffer();
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for (ScanDetail scanDetail : scanDetails) {
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ScanResult scanResult = scanDetail.getScanResult();
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// One ScanResult can be associated with more than one network, hence we calculate all
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// the scores and use the highest one as the ScanResult's score.
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// TODO(b/112196799): this has side effects, rather not do that in an evaluator
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WifiConfiguration network =
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mWifiConfigManager.getConfiguredNetworkForScanDetailAndCache(scanDetail);
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if (network == null) {
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continue;
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}
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/**
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* Ignore Passpoint and Ephemeral networks. They are configured networks,
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* but without being persisted to the storage. They are evaluated by
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* {@link PasspointNetworkEvaluator} and {@link ScoredNetworkEvaluator}
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* respectively.
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*/
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if (network.isPasspoint() || network.isEphemeral()) {
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continue;
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}
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WifiConfiguration.NetworkSelectionStatus status =
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network.getNetworkSelectionStatus();
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// TODO (b/112196799): another side effect
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status.setSeenInLastQualifiedNetworkSelection(true);
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if (!status.isNetworkEnabled()) {
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continue;
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} else if (network.BSSID != null && !network.BSSID.equals("any")
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&& !network.BSSID.equals(scanResult.BSSID)) {
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// App has specified the only BSSID to connect for this
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// configuration. So only the matching ScanResult can be a candidate.
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localLog("Network " + WifiNetworkSelector.toNetworkString(network)
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+ " has specified BSSID " + network.BSSID + ". Skip "
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+ scanResult.BSSID);
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continue;
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} else if (TelephonyUtil.isSimConfig(network)
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&& !TelephonyUtil.isSimPresent(mSubscriptionManager)) {
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// Don't select if security type is EAP SIM/AKA/AKA' when SIM is not present.
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continue;
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}
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int score = calculateBssidScore(scanResult, network, currentNetwork, currentBssid,
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scoreHistory);
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// Set candidate ScanResult for all saved networks to ensure that users can
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// override network selection. See WifiNetworkSelector#setUserConnectChoice.
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if (score > status.getCandidateScore()
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|| (score == status.getCandidateScore()
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&& status.getCandidate() != null
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&& scanResult.level > status.getCandidate().level)) {
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mWifiConfigManager.setNetworkCandidateScanResult(
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network.networkId, scanResult, score);
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}
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// If the network is marked to use external scores, or is an open network with
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// curate saved open networks enabled, do not consider it for network selection.
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if (network.useExternalScores) {
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localLog("Network " + WifiNetworkSelector.toNetworkString(network)
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+ " has external score.");
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continue;
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}
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onConnectableListener.onConnectable(scanDetail,
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mWifiConfigManager.getConfiguredNetwork(network.networkId), score);
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// TODO(b/112196799) - pull into common code
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if (score > highestScore
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|| (score == highestScore
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&& scanResultCandidate != null
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&& scanResult.level > scanResultCandidate.level)) {
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highestScore = score;
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scanResultCandidate = scanResult;
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mWifiConfigManager.setNetworkCandidateScanResult(
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network.networkId, scanResultCandidate, highestScore);
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// Reload the network config with the updated info.
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candidate = mWifiConfigManager.getConfiguredNetwork(network.networkId);
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}
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}
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if (scoreHistory.length() > 0) {
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localLog("\n" + scoreHistory.toString());
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}
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if (scanResultCandidate == null) {
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localLog("did not see any good candidates.");
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}
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return candidate;
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}
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}
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