Android 8.09.0 wifi 自动连接评分机制

概述前言AndroidNwifiautoconnect流程分析AndroidNselectQualifiedNetwork分析Wifi自动连接时的评分机制今天了解了一下Wifi自动连接时的评分机制，总结如下：WifiConnectivityManager的初始化：/frameworks/optet/wifi/service/java/com/android/server/wifi/WifiStateMachin 前言

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Android N selectQualifiedNetwork分析

Wifi自动连接时的评分机制

今天了解了一下Wifi自动连接时的评分机制，总结如下：
WifiConnectivityManager的初始化：
/frameworks/opt/net/wifi/service/java/com/androID/server/wifi/WifiStateMachine.java

    class SupplicantStartedState extends State {            if (mWifiScanner == null) {                mWifiScanner = mWifiInjector.getWifiScanner();                synchronized (mWifiReqCountLock) {                    mWifiConnectivityManager =                            mWifiInjector.makeWifiConnectivityManager(mWifiInfo,                                                                      hasConnectionRequests());                    mWifiConnectivityManager.setUntrustedConnectionAllowed(mUntrustedReqCount > 0);                    mWifiConnectivityManager.handleScreenStateChanged(mScreenOn);                }            }

/frameworks/opt/net/wifi/service/java/com/androID/server/wifi/WifiInjector.java

    public WifiConnectivityManager makeWifiConnectivityManager(WifiInfo wifiInfo,                                                               boolean hasConnectionRequests) {        return new WifiConnectivityManager(mContext, mWifiStateMachine, getWifiScanner(),                mWifiConfigManager, wifiInfo, mWifiNetworkSelector, mWifiConnectivityHelper,               mWifiLastResortWatchdog, mOpenNetworkNotifIEr, mWifiMetrics,                mWifiStateMachineHandlerThread.getLooper(), mClock, mConnectivityLocalLog,                hasConnectionRequests, mFrameworkFacade, mSavednetworkEvaluator,                mscoredNetworkEvaluator, mPasspointNetworkEvaluator);    }

WifiConnectivityManager中会注册三个Evaluator。
/frameworks/opt/net/wifi/service/java/com/androID/server/wifi/WifiConnectivityManager.java

        mNetworkSelector.registerNetworkEvaluator(savednetworkEvaluator,                SAVED_NETWORK_EVALUATOR_PRIORITY);        if (hs2Enabled) {            mNetworkSelector.registerNetworkEvaluator(passpointNetworkEvaluator,                    PAsspOINT_NETWORK_EVALUATOR_PRIORITY);        }        mNetworkSelector.registerNetworkEvaluator(scoredNetworkEvaluator,                scoreD_NETWORK_EVALUATOR_PRIORITY);

继续看下注册方法，其实就是初始化一个NetworkEvaluator数组，大小为6，即优先级从高到低0-5。
/frameworks/opt/net/wifi/service/java/com/androID/server/wifi/WifiNetworkSelector.java

    public static final int EVALUATOR_MIN_PRIORITY = 6;    private final NetworkEvaluator[] mEvaluators = new NetworkEvaluator[MAX_NUM_EVALUATORS];    public boolean registerNetworkEvaluator(NetworkEvaluator evaluator, int priority) {        if (priority < 0 || priority >= EVALUATOR_MIN_PRIORITY) {            localLog("InvalID network evaluator priority: " + priority);            return false;        }        if (mEvaluators[priority] != null) {            localLog("Priority " + priority + " is already registered by "                    + mEvaluators[priority].getname());            return false;        }        mEvaluators[priority] = evaluator;        return true;    }

WifiConnectivityManager的网络评估

    private boolean handleScanResults(@R_502_6818@<ScanDetail> scanDetails, String @R_502_6818@enername) {        if (mSupportCMCC && mWifiManagerEx.isautoConnect() == false) {            Log.i(TAG, "WifiManagerEx isautoConnect false,  " + mWifiManagerEx.isautoConnect());            return false;        }                if (!mP2pWifiCoexistSupported && wifip2pServiceImpl.mP2pConnectingOrConnected) {            Log.i(TAG, "Do not auto connect when wifi and p2p should not coexsit");            return false;        }            refreshBssIDBlack@R_502_6818@();        if (mStateMachine.islinkDebouncing() || mStateMachine.isSupplicantTransIEntState()) {            localLog(@R_502_6818@enername + " onResults: No network selection because linkDebouncing is "                    + mStateMachine.islinkDebouncing() + " and supplicantTransIEnt is "                    + mStateMachine.isSupplicantTransIEntState());            return false;        }        localLog(@R_502_6818@enername + " onResults: start network selection");        WifiConfiguration candIDate =                mNetworkSelector.selectNetwork(scanDetails, buildBssIDBlack@R_502_6818@(), mWifiInfo,                mStateMachine.isConnected(), mStateMachine.isdisconnected(),                mUntrustedConnectionAllowed);        mWifiLastResortWatchdog.updateAvailableNetworks(                mNetworkSelector.getConnectableScanDetails());        mWifiMetrics.countScanResults(scanDetails);        if (candIDate != null) {            localLog(@R_502_6818@enername + ":  WNS candIDate-" + candIDate.SSID);            connectToNetwork(candIDate);            return true;        } else {            if (mWifiState == WIFI_STATE_disCONNECTED) {                mOpenNetworkNotifIEr.handleScanResults(                        mNetworkSelector.getFilteredScanDetailsForOpenUnsavednetworks());            }            return false;        }    }

如API注释所述，对周期性、单次和pno扫描的结果进行潜在网络候选者的选择，如果有合适的网络，则进行连接

看下candiate是如何产生的：

    public WifiConfiguration selectNetwork(@R_502_6818@<ScanDetail> scanDetails,            HashSet<String> bssIDBlack@R_502_6818@, WifiInfo wifiInfo,        boolean connected, boolean disconnected, boolean untrustednetworkAllowed)         mFilterednetworks.clear();       mConnectableNetworks.clear();        if (scanDetails.size() == 0) {           localLog("Empty connectivity scan result");            return null;        WifiConfiguration currentNetwork =                mWifiConfigManager.getConfigurednetwork(wifiInfo.getNetworkID());        String currentBssID = wifiInfo.getBSSID();        if (!isNetworkSelectionNeeded(scanDetails, wifiInfo, connected, disconnected)) {            return null;        }        for (NetworkEvaluator registeredEvaluator : mEvaluators) {            if (registeredEvaluator != null) {                registeredEvaluator.update(scanDetails);            }        }        mFilterednetworks = filterScanResults(scanDetails, bssIDBlack@R_502_6818@,                connected, currentBssID);        if (mFilterednetworks.size() == 0) {            return null;        }        WifiConfiguration selectednetwork = null;        for (NetworkEvaluator registeredEvaluator : mEvaluators) {            if (registeredEvaluator != null) {                localLog("About to run " + registeredEvaluator.getname() + " :");                selectednetwork = registeredEvaluator.evaluateNetworks(                        new Array@R_502_6818@<>(mFilterednetworks), currentNetwork, currentBssID, connected,                        untrustednetworkAllowed, mConnectableNetworks);                if (selectednetwork != null) {                    localLog(registeredEvaluator.getname() + " selects "                            + WifiNetworkSelector.toNetworkString(selectednetwork) + " : "                            + selectednetwork.getNetworkSelectionStatus().getCandIDate().BSSID);                    break;                }        if (selectednetwork != null) {         selectednetwork = overrIDeCandIDateWithUserConnectChoice(selectednetwork);            mLastNetworkSelectionTimeStamp = mClock.getElapsedSinceBootMillis();       }        return selectednetwork;    }

看下是否可以进行网络选择：
1、 当前网络无效时
2、 当前没有连接网络时

    private boolean isNetworkSelectionNeeded(@R_502_6818@<ScanDetail> scanDetails, WifiInfo wifiInfo,                        boolean connected, boolean disconnected) {        if (scanDetails.size() == 0) {            localLog("Empty connectivity scan results. Skip network selection.");            return false;        }        if (connected) {            if (isCurrentNetworkSufficIEnt(wifiInfo, scanDetails)) {                localLog("Current connected network already sufficIEnt. Skip network selection.");                return false;            } else {                localLog("Current connected network is not sufficIEnt.");                return true;            }        } else if (disconnected) {            return true;        } else {

判断网络是否有效，主要是看以下几点要素：

RSSi(区分2.4G还是5G)packet rateephemeral(短暂的)open network5G优先级>2.4G

    private boolean isCurrentNetworkSufficIEnt(WifiInfo wifiInfo, @R_502_6818@<ScanDetail> scanDetails) {        WifiConfiguration network =                   mWifiConfigManager.getConfigurednetwork(wifiInfo.getNetworkID());        int currentRSSi = wifiInfo.getRSSi();        boolean hasQualifIEdRSSi =                (wifiInfo.is24GHz() && (currentRSSi > mThresholdQualifIEdRSSi24))                        || (wifiInfo.is5GHz() && (currentRSSi > mThresholdQualifIEdRSSi5));        boolean hasActiveStream = (wifiInfo.getTxSuccessRatePps() > mStayOnNetworkMinimumTxRate)                || (wifiInfo.getRxSuccessRatePps() > mStayOnNetworkMinimumRxRate);        if (hasQualifIEdRSSi && hasActiveStream) {            localLog("Stay on current network because of good RSSI and ongoing traffic");            return true;        }        if (network.ephemeral) {            localLog("Current network is an ephemeral one.");            return false;        }        if (WifiConfigurationUtil.isConfigForOpenNetwork(network)) {            localLog("Current network is a open one.");            return false;        }        if (wifiInfo.is24GHz()) {            if (is5GHzNetworkAvailable(scanDetails)) {                localLog("Current network is 2.4GHz. 5GHz networks available.");                return false;            }        }        if (!hasQualifIEdRSSi) {            localLog("Current network RSSI[" + currentRSSi + "]-acceptable but not qualifIEd.");            return false;        }        return true;    }

SavednetworkEvaluator的筛选
首先遍历扫描结果：

  for (ScanDetail scanDetail : scanDetails) {            ScanResult scanResult = scanDetail.getScanResult();            int highestscoreOfScanResult = Integer.MIN_VALUE;            int candIDateIDOfScanResult = WifiConfiguration.INVALID_NETWORK_ID;            //过滤passpoint和ephemeral，如API所述这类网络交由PasspointNetworkEvaluator            //和scoredNetworkEvaluator进行评估                if (network.isPasspoint() || network.isEphemeral()) {                    continue;                }

接着过滤没有enabled的，scan bssID和config对不上的和eap-sim之类的网络但是没插卡的。

                if (!status.isNetworkEnabled()) {                    continue;                } else if (network.BSSID != null &&  !network.BSSID.equals("any")                        && !network.BSSID.equals(scanResult.BSSID)) {                    localLog("Network " + WifiNetworkSelector.toNetworkString(network)+ " has specifIEd BSSID " +                     network.BSSID + ". Skip " + scanResult.BSSID);                    continue;                } else if (TelephonyUtil.isSimConfig(network)                        && !mWifiConfigManager.isSimPresent()) {                    localLog("isSimPresent");                    continue;                }

网络评分的关键：计算BSSID的分数，评分几大要素如下：

RSSI5GlastUserSelectednetworkIDcurrentNetworkisFirmwareRoamingSupportedisConfigForOpenNetwork

    private int calculateBssIDscore(ScanResult scanResult, WifiConfiguration network,                        WifiConfiguration currentNetwork, String currentBssID,                        StringBuffer sbuf) {        int score = 0;        boolean is5GHz = scanResult.is5GHz();        sbuf.append("[ ").append(scanResult.SSID).append(" ").append(scanResult.BSSID)                .append(" RSSI:").append(scanResult.level).append(" ] ");        int RSSiSaturationThreshold = is5GHz ? mThresholdSaturatedRSSi5 : mThresholdSaturatedRSSi24;        int RSSi = scanResult.level < RSSiSaturationThreshold ? scanResult.level                : RSSiSaturationThreshold;        score += (RSSi + mRSSiscoreOffset) * mRSSiscoreSlope;        sbuf.append(" RSSI score: ").append(score).append(",");        //如果是5G频段，会有奖励。        if (is5GHz) {            score += mBand5GHzAward;            sbuf.append(" 5GHz bonus: ").append(mBand5GHzAward).append(",");        }       //之前连接过也有奖励       int lastUserSelectednetworkID = mWifiConfigManager.getLastSelectednetwork();        if (lastUserSelectednetworkID != WifiConfiguration.INVALID_NETWORK_ID                && lastUserSelectednetworkID == network.networkID) {            long timeDifference = mClock.getElapsedSinceBootMillis()                    - mWifiConfigManager.getLastSelectedTimeStamp();            if (timeDifference > 0) {                int bonus = mLastSelectionAward - (int) (timeDifference / 1000 / 60);                score += bonus > 0 ? bonus : 0;                sbuf.append(" User selection ").append(timeDifference / 1000 / 60)                        .append(" minutes ago, bonus: ").append(bonus).append(",");            }        }        //如果是当前正在连接的网络，也会加分        if (currentNetwork != null                && (network.networkID == currentNetwork.networkID                  /* || network.islinked(currentNetwork) */)) {            score += mSameNetworkAward;            sbuf.append(" Same network bonus: ").append(mSameNetworkAward).append(",");            //支持漫游也会有奖励            if (mConnectivityHelper.isFirmwareRoamingSupported()                    && currentBssID != null && !currentBssID.equals(scanResult.BSSID)) {                score += mSameBssIDAward;                sbuf.append(" Equivalent BSSID bonus: ").append(mSameBssIDAward).append(",");            }        }        //BSSID相同也会有奖励        if (currentBssID != null && currentBssID.equals(scanResult.BSSID)) {            score += mSameBssIDAward;            sbuf.append(" Same BSSID bonus: ").append(mSameBssIDAward).append(",");        }        //不是开放的网络，也会有奖励        if (!WifiConfigurationUtil.isConfigForOpenNetwork(network)) {            score += mSecurityAward;            sbuf.append(" Secure network bonus: ").append(mSecurityAward).append(",");        sbuf.append(" ## Total score: ").append(score).append("\n");        return score;    }

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