android wifi scan and auto re-connect

Target platform: android Q10 platform

android 会将已连接的wifi AP保存到这个文件： data/misc/wifi/WifiConfigStore.xml

然后当wifi 再次打开的时候 scan results后会将scan results和保存的已连接的wifi AP 中对比, 如果有已保存的wifi网络，则自动重连。

以下是一个已保存的网络节点

ID: 0 SSID: "Pixel_8287" PROVIDER-NAME: null BSSID: null FQDN: null PRIO: 0 HIDDEN: false PMF: false
NetworkSelectionStatus NETWORK_SELECTION_ENABLED
hasEverConnected: true
numAssociation 3
update time=04-13 15:58:20.958
creation time=04-13 15:56:48.640
validatedInternetAccess trusted
macRandomizationSetting: 0
mRandomizedMacAddress: 4e:c2:34:a4:04:79
KeyMgmt: WPA_PSK Protocols: WPA RSN
AuthAlgorithms: OPEN
PairwiseCiphers: TKIP CCMP
GroupCiphers: WEP40 WEP104 TKIP CCMP
GroupMgmtCiphers:
SuiteBCiphers:
PSK/SAE: *
Enterprise config:
IP config:
IP assignment: DHCP
Proxy settings: NONE
cuid=1000 cname=android.uid.system:1000 luid=1000 lname=android.uid.system:1000 lcuid=1000 userApproved=USER_UNSPECIFIED noInternetAccessExpected=true
lastConnected: 04-13 18:04:49.865
recentFailure: Association Rejection code: 0

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiConnectivityManager.java

handleScanResults

WifiConfiguration candidate = mNetworkSelector.selectNetwork(scanDetails, buildBssidBlacklist(), mWifiInfo, mStateMachine.isConnected(), mStateMachine.isDisconnected(), mUntrustedConnectionAllowed);

685    /**686     * Select the best network from the ones in range.687     *688     * @param scanDetails    List of ScanDetail for all the APs in range689     * @param bssidBlacklist Blacklisted BSSIDs690     * @param wifiInfo       Currently connected network691     * @param connected      True if the device is connected692     * @param disconnected   True if the device is disconnected693     * @param untrustedNetworkAllowed True if untrusted networks are allowed for connection694     * @return Configuration of the selected network, or Null if nothing695     */696    @Nullable697    public WifiConfiguration selectNetwork(List scanDetails,698            HashSet bssidBlacklist, WifiInfo wifiInfo,699            boolean connected, boolean disconnected, boolean untrustedNetworkAllowed) {700        mFilteredNetworks.clear();701        mConnectableNetworks.clear();702        if (scanDetails.size() == 0) {703            localLog("Empty connectivity scan result");704            return null;705        }706707        WifiConfiguration currentNetwork =708                mWifiConfigManager.getConfiguredNetwork(wifiInfo.getNetworkId());709710        // Always get the current BSSID from WifiInfo in case that firmware initiated711        // roaming happened.712        String currentBssid = wifiInfo.getBSSID();713714        // Shall we start network selection at all?715        if (!isNetworkSelectionNeeded(scanDetails, wifiInfo, connected, disconnected)) {716            return null;717        }718719        // Update all configured networks before initiating network selection.720        updateConfiguredNetworks();721722        // Update the registered network evaluators.723        for (NetworkEvaluator registeredEvaluator : mEvaluators) {724            registeredEvaluator.update(scanDetails);725        }726727        // Filter out unwanted networks.728        mFilteredNetworks = filterScanResults(scanDetails, bssidBlacklist,729                connected && wifiInfo.score >= WIFI_POOR_SCORE, currentBssid);730        if (mFilteredNetworks.size() == 0) {731            return null;732        }733734        // Determine the weight for the last user selection735        final int lastUserSelectedNetworkId = mWifiConfigManager.getLastSelectedNetwork();736        final double lastSelectionWeight = calculateLastSelectionWeight();737        final ArraySet mNetworkIds = new ArraySet<>();738739        // Go through the registered network evaluators in order740        WifiConfiguration selectedNetwork = null;741        WifiCandidates wifiCandidates = new WifiCandidates(mWifiScoreCard);742        if (currentNetwork != null) {743            wifiCandidates.setCurrent(currentNetwork.networkId, currentBssid);744        }745        for (NetworkEvaluator registeredEvaluator : mEvaluators) {746            localLog("About to run " + registeredEvaluator.getName() + " :");747            WifiConfiguration choice = registeredEvaluator.evaluateNetworks(748                    new ArrayList<>(mFilteredNetworks), currentNetwork, currentBssid, connected,749                    untrustedNetworkAllowed,750                    (scanDetail, config, score) -> {751                        if (config != null) {752                            mConnectableNetworks.add(Pair.create(scanDetail, config));753                            mNetworkIds.add(config.networkId);754                            if (config.networkId == lastUserSelectedNetworkId) {755                                wifiCandidates.add(scanDetail, config,756                                        registeredEvaluator.getId(), score, lastSelectionWeight);757                            } else {758                                wifiCandidates.add(scanDetail, config,759                                        registeredEvaluator.getId(), score);760                            }761                            mWifiMetrics.setNominatorForNetwork(config.networkId,762                                    evaluatorIdToNominatorId(registeredEvaluator.getId()));763                        }764                    });765            if (choice != null && !mNetworkIds.contains(choice.networkId)) {766                Log.wtf(TAG, registeredEvaluator.getName()767                        + " failed to report choice with noConnectibleListener");768            }769            if (selectedNetwork == null && choice != null) {770                selectedNetwork = choice; // First one wins771                localLog(registeredEvaluator.getName() + " selects "772                        + WifiNetworkSelector.toNetworkString(selectedNetwork));773            }774        }775776        if (mConnectableNetworks.size() != wifiCandidates.size()) {777            localLog("Connectable: " + mConnectableNetworks.size()778                    + " Candidates: " + wifiCandidates.size());779        }780781        // Update the NetworkSelectionStatus in the configs for the current candidates782        // This is needed for the legacy user connect choice, at least783        Collection> groupedCandidates =784                wifiCandidates.getGroupedCandidates();785        for (Collection group: groupedCandidates) {786            WifiCandidates.Candidate best = null;787            for (WifiCandidates.Candidate candidate: group) {788                // Of all the candidates with the same networkId, choose the789                // one with the smallest evaluatorId, and break ties by790                // picking the one with the highest score.791                if (best == null792                        || candidate.getEvaluatorId() < best.getEvaluatorId()793                        || (candidate.getEvaluatorId() == best.getEvaluatorId()794                            && candidate.getEvaluatorScore() > best.getEvaluatorScore())) {795                    best = candidate;796                }797            }798            if (best != null) {799                ScanDetail scanDetail = best.getScanDetail();800                if (scanDetail != null) {801                    mWifiConfigManager.setNetworkCandidateScanResult(best.getNetworkConfigId(),802                            scanDetail.getScanResult(), best.getEvaluatorScore());803                }804            }805        }806807        ArrayMap experimentNetworkSelections = new ArrayMap<>(); // for metrics808809        final int legacySelectedNetworkId = selectedNetwork == null810                ? WifiConfiguration.INVALID_NETWORK_ID811                : selectedNetwork.networkId;812813        int selectedNetworkId = legacySelectedNetworkId;814815        // Run all the CandidateScorers816        boolean legacyOverrideWanted = true;817        final WifiCandidates.CandidateScorer activeScorer = getActiveCandidateScorer();818        for (WifiCandidates.CandidateScorer candidateScorer : mCandidateScorers.values()) {819            WifiCandidates.ScoredCandidate choice;820            try {821                choice = wifiCandidates.choose(candidateScorer);822            } catch (RuntimeException e) {823                Log.wtf(TAG, "Exception running a CandidateScorer", e);824                continue;825            }826            int networkId = choice.candidateKey == null827                    ? WifiConfiguration.INVALID_NETWORK_ID828                    : choice.candidateKey.networkId;829            String chooses = " would choose ";830            if (candidateScorer == activeScorer) {831                chooses = " chooses ";832                legacyOverrideWanted = candidateScorer.userConnectChoiceOverrideWanted();833                selectedNetworkId = networkId;834            }835            String id = candidateScorer.getIdentifier();836            int expid = experimentIdFromIdentifier(id);837            localLog(id + chooses + networkId838                    + " score " + choice.value + "+/-" + choice.err839                    + " expid " + expid);840            experimentNetworkSelections.put(expid, networkId);841        }842843        // Update metrics about differences in the selections made by various methods844        final int activeExperimentId = activeScorer == null ? LEGACY_CANDIDATE_SCORER_EXP_ID845                : experimentIdFromIdentifier(activeScorer.getIdentifier());846        experimentNetworkSelections.put(LEGACY_CANDIDATE_SCORER_EXP_ID, legacySelectedNetworkId);847        for (Map.Entry entry :848                experimentNetworkSelections.entrySet()) {849            int experimentId = entry.getKey();850            if (experimentId == activeExperimentId) continue;851            int thisSelectedNetworkId = entry.getValue();852            mWifiMetrics.logNetworkSelectionDecision(experimentId, activeExperimentId,853                    selectedNetworkId == thisSelectedNetworkId,854                    groupedCandidates.size());855        }856857        // Get a fresh copy of WifiConfiguration reflecting any scan result updates858        selectedNetwork = mWifiConfigManager.getConfiguredNetwork(selectedNetworkId);859        if (selectedNetwork != null && legacyOverrideWanted) {860            selectedNetwork = overrideCandidateWithUserConnectChoice(selectedNetwork);861            mLastNetworkSelectionTimeStamp = mClock.getElapsedSinceBootMillis();862        }863        return selectedNetwork;864    }

303    private boolean isNetworkSelectionNeeded(List scanDetails, WifiInfo wifiInfo,304                        boolean connected, boolean disconnected) {305        if (scanDetails.size() == 0) {306            localLog("Empty connectivity scan results. Skip network selection.");307            return false;308        }309310        if (connected) {311            // Is roaming allowed?312            if (!mEnableAutoJoinWhenAssociated) {313                localLog("Switching networks in connected state is not allowed."314                        + " Skip network selection.");315                return false;316            }317318            // Has it been at least the minimum interval since last network selection?319            if (mLastNetworkSelectionTimeStamp != INVALID_TIME_STAMP) {320                long gap = mClock.getElapsedSinceBootMillis()321                            - mLastNetworkSelectionTimeStamp;322                if (gap < MINIMUM_NETWORK_SELECTION_INTERVAL_MS) {323                    localLog("Too short since last network selection: " + gap + " ms."324                            + " Skip network selection.");325                    return false;326                }327            }328329            if (isCurrentNetworkSufficient(wifiInfo, scanDetails)) {330                localLog("Current connected network already sufficient. Skip network selection.");331                return false;332            } else {333                localLog("Current connected network is not sufficient.");334                return true;335            }336        } else if (disconnected) {337            return true;338        } else {339            // No network selection if ClientModeImpl is in a state other than340            // CONNECTED or DISCONNECTED.341            localLog("ClientModeImpl is in neither CONNECTED nor DISCONNECTED state."342                    + " Skip network selection.");343            return false;344        }345    }

221    private boolean isCurrentNetworkSufficient(WifiInfo wifiInfo, List scanDetails) {222        // Currently connected?223        if (wifiInfo.getSupplicantState() != SupplicantState.COMPLETED) {224            localLog("No current connected network.");225            return false;226        } else {227            localLog("Current connected network: " + wifiInfo.getSSID()228                    + " , ID: " + wifiInfo.getNetworkId());229        }230231        int currentRssi = wifiInfo.getRssi();232        boolean hasQualifiedRssi = currentRssi233                > mScoringParams.getSufficientRssi(wifiInfo.getFrequency());234        boolean hasActiveStream = (wifiInfo.txSuccessRate > mStayOnNetworkMinimumTxRate)235                || (wifiInfo.rxSuccessRate > mStayOnNetworkMinimumRxRate);236        if (hasQualifiedRssi && hasActiveStream) {237            localLog("Stay on current network because of good RSSI and ongoing traffic");238            return true;239        }240        WifiConfiguration network =241                mWifiConfigManager.getConfiguredNetwork(wifiInfo.getNetworkId());242243        if (network == null) {244            localLog("Current network was removed.");245            return false;246        }247248        if (mWifiConfigManager.getLastSelectedNetwork() == network.networkId249                && (mClock.getElapsedSinceBootMillis()250                    - mWifiConfigManager.getLastSelectedTimeStamp())251                <= LAST_USER_SELECTION_SUFFICIENT_MS) {252            localLog("Current network is recently user-selected.");253            return true;254        }255256        // OSU (Online Sign Up) network for Passpoint Release 2 is sufficient network.257        if (network.osu) {258            return true;259        }260261        // Ephemeral network is not qualified.262        if (wifiInfo.isEphemeral()) {263            localLog("Current network is an ephemeral one.");264            return false;265        }266267        if (wifiInfo.is24GHz()) {268            // 2.4GHz networks is not qualified whenever 5GHz is available269            if (is5GHzNetworkAvailable(scanDetails)) {270                localLog("Current network is 2.4GHz. 5GHz networks available.");271                return false;272            }273        }274        if (!hasQualifiedRssi) {275            localLog("Current network RSSI[" + currentRssi + "]-acceptable but not qualified.");276            return false;277        }278279        // Open network is not qualified.280        if (WifiConfigurationUtil.isConfigForOpenNetwork(network)) {281            localLog("Current network is a open one.");282            return false;283        }284285        // Network with no internet access reports is not qualified.286        if (network.numNoInternetAccessReports > 0 && !network.noInternetAccessExpected) {287            localLog("Current network has [" + network.numNoInternetAccessReports288                    + "] no-internet access reports.");289            return false;290        }291        return true;292    }

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