Android WiFi

1. WiFi Enabled
   1.1 WiFi enable 3 ways.
   1.1.1 Enable WiFi in SetupWizard.

OnCreate()
if (isFirstEnterWifiSetupWizard == FIRST_ENTER && mSetupWizardCheck == 0) {
if (“ON”.equals(SecProductFeature_WLAN.SEC_PRODUCT_FEATURE_WLAN_CONFIG_DEF_STATUS) && !WIFI_OFF) {
mWifiManager.setWifiEnabled(true);
} else {
mWifiManager.setWifiEnabled(false);
}
private void updateLayoutMargin(Configuration newConfig)
mWifiEnabler = new WifiEnabler(this, mSwitchBar);

1.1.2 Enable Wifi in Notification

WifiTile.java
protected void handleClick()
//MultiState.OFF ==2
if (mWifiManager != null
&& mWifiManager.setWifiEnabled(mState.value == MultiState.OFF)) {
Log.d(TW_TAG, “onClick setWifiEnabled”);

        if(Feature.mQsAnimationIcon) {
            if (mState.value == MultiState.OFF)
                mIconOn.setAllowAnimation(true);
            else {
                mIconOff.get(0).setAllowAnimation(true);
            }
        }   
        if (SecProductFeature_KNOX.SEC_PRODUCT_FEATURE_KNOX_SUPPORT_MDM) {
         AuditLog.log(AuditLog.NOTICE, AuditLog.AUDIT_LOG_GROUP_APPLICATION, true,
                    android.os.Process.myPid(), this.getClass().getSimpleName(),
                    AuditEvents.WIFI_ENABLING );
       }
    } else {
        refreshState(mState.value);
        Slog.d(TW_TAG, "!setWifiEnabled");
        if (SecProductFeature_KNOX.SEC_PRODUCT_FEATURE_KNOX_SUPPORT_MDM) {
             AuditLog.log(AuditLog.NOTICE, AuditLog.AUDIT_LOG_GROUP_APPLICATION, true,
                       android.os.Process.myPid(), this.getClass().getSimpleName(),
                       AuditEvents.WIFI_DISABLING );
        }
    }

    if (mState.value == MultiState.OFF) {
        WifiStatusReceiver.enableToShowWifiPickerDialog(true);
    }

Log
12-29 15:31:05.907 D 3529 STATUSBAR-WifiTile handleClick : 2, 1
12-29 15:31:05.947 D 3529 STATUSBAR-WifiTile onClick setWifiEnabled
12-29 15:31:05.947 D 3529 WifiStatusReceiver Want to show AP LIST:true
12-29 15:31:06.017 D 3529 STATUSBAR-WifiTile onReceive : android.net.wifi.WIFI_STATE_CHANGED

1.1.3 Enable WiFi in Settings

WifiSettings
public void onStart() {
// On/off switch is hidden for Setup Wizard (returns null)
if (!mSecSetupWizardMode && !mInPickerDialog && !mInOffloadDialog && mWifiEnabler == null && !mInSetupWizardWifiScreen) {
mWifiEnabler = createWifiEnabler();
}
}

/**
 * @return new WifiEnabler or null (as overridden by WifiSettingsForSetupWizard)
 */
/* package */ WifiEnabler createWifiEnabler() {
    if ((getActivity() instanceof SettingsActivity)) {
        final SettingsActivity activity = (SettingsActivity) getActivity();
        mSwitchBar = activity.getSwitchBar();
        return new WifiEnabler(activity, mSwitchBar);
    } else {
        return null;
    }

}

public void onResume() {
if (mWifiEnabler != null) {
mWifiEnabler.resume(activity);
}
}
WifiEnabler
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
setWifiEnable(isChecked);
}

private void setWifiEnable(boolean enable) {
    if (mWifiManager.isWifiEnabled() == enable)
        return;
    mSwitch.setEnabled(false);
    if (!mWifiManager.setWifiEnabled(enable)) {
        // Error
        mSwitch.setEnabled(true);
        if (mSwitchBar != null) {
            mSwitchBar.setChecked(false);
        }
        if (mSwitchHandler != null) {
            mSwitchHandler.sendEmptyMessage(SWITCH_DISABLED);
        }
        //Toast.makeText(mContext, R.string.wifi_error, Toast.LENGTH_SHORT).show();
    }
}

1.1.4
1.2
2. Initialization for Wifi Module
2.1 Wifi Structure

2.2 WiFi Server Start
SystemServer
public static void main(String[] args) {
new SystemServer().run();
}

private void run() {
try {
startBootstrapServices();
startCoreServices();
startOtherServices();
//startThemeService();
} catch (Throwable ex) {
Slog.e(“System”, “********************************”);
Slog.e(“System”, “** Failure starting system services”, ex);
throw ex;
}
}

private void startOtherServices() {
mSystemServiceManager.startService(WIFI_P2P_SERVICE_CLASS);
mSystemServiceManager.startService(WIFI_SERVICE_CLASS);
if (SecProductFeature_WLAN.SEC_PRODUCT_FEATURE_WLAN_SUPPORT_HOTSPOT_20) {
mSystemServiceManager.startService(WIFI_HS20_SERVICE_CLASS);
}

            mSystemServiceManager.startService(
                        "com.android.server.wifi.WifiScanningService");

            mSystemServiceManager.startService("com.android.server.wifi.RttService");

//< RNTFIX:: Ethernet
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_ETHERNET) ||
SecProductFeature_COMMON.SEC_PRODUCT_FEATURE_COMMON_SUPPORT_ETHERNET) {
mSystemServiceManager.startService(ETHERNET_SERVICE_CLASS);
try {
Slog.i(TAG, “Connectivity Service”);
connectivity = new ConnectivityService(
context, networkManagement, networkStats, networkPolicy);
ServiceManager.addService(Context.CONNECTIVITY_SERVICE, connectivity);
networkStats.bindConnectivityManager(connectivity);
networkPolicy.bindConnectivityManager(connectivity);
} catch (Throwable e) {
reportWtf(“starting Connectivity Service”, e);
}
}

(1) ConnectivityService
ConnectivityService ‘s core role is to provide data connection management services. It can get information from NetworkStateTracker.
NetworkInfo():Describe a given type of network interface information, including the network connection, network type whether such information. (getTypeName() can return “WIFI” or “MOBILE”)
LinkProperties():Describe a network connection attribute information. Including the network address, gateway, DNS, such as set/get HTTP proxy attribute information.
NetworkCapabilities(): Describe the network interface state information, including bandwidth, delay, etc.
NetworkStateTracker(): It is an interface. BaseNetworkStateTracker() is base class. It is control and observe state of a specific network.

(2) WifiService
public WifiService(Context context) {
super(context);
mImpl = new WifiServiceImpl(context);
}

public final class WifiServiceImpl extends IWifiManager.Stub {
private class ClientHandler extends Handler{}
private class WifiStateMachineHandler extends Handler {}
public WifiServiceImpl(Context context) {
mTrafficPoller = new WifiTrafficPoller(mContext, this, mInterfaceName);
mWifiStateMachine = new WifiStateMachine(mContext, mInterfaceName, mTrafficPoller);

mNotificationController = new WifiNotificationController(mContext, mWifiStateMachine);
mSettingsStore = new WifiSettingsStore(mContext);

HandlerThread wifiThread = new HandlerThread("WifiService");
wifiThread.start();
mClientHandler = new ClientHandler(wifiThread.getLooper());
mWifiStateMachineHandler = new WifiStateMachineHandler(wifiThread.getLooper());
mWifiController = new WifiController(mContext, this, wifiThread.getLooper());

}

/**
* Check if Wi-Fi needs to be enabled and start
* if needed
*
* This function is used only at boot time
*/
public void checkAndStartWifi() {
/* Check if wi-fi needs to be enabled */
boolean wifiEnabled = mSettingsStore.isWifiToggleEnabled();
mWifiController.start();
}
}
WifiServer Start Flow

Enabled WiFi flow

1. Disabled Wifi

Explain for Chart:
(1) WifiService will sent message CMD_WIFI_TOGGLED.and WifiController ApStaDisableState deal with this message.
(2) WifiStateMachine will deal with CMD_STOP_SUPPLICANT. In WaitForP2pDisableState will sent CMD_DISABLE_P2P_REQ and deal with CMD_DISABLE_P2P_RSP. State change to SupplicantStoppingState.
(3) In SupplicantStoppingState, it will call handleNetworkDisconnect() to stop DHCP and clear some message. It will call WifiNative.stopSupplicant() to deal with “TERMINATE” order in wpa_supplicant.
(4) In WifiP2PService deal with WifiMonitor.stopMonitoring, WifiStateMachine receive SUP_DISCONNECTION_EVENT, process this message.
Usefully log:
3041 D WifiController: handleMessage: E msg.what=CMD_WIFI_TOGGLED
3041 D WifiController: processMsg: ApStaDisabledState
3025 D WifiStateMachine: handleMessage: E msg.what=CMD_STOP_SUPPLICANT
3025 D WifiStateMachine: processMsg: DisconnectedState
3025 D WifiStateMachine: processMsg: ConnectModeState
3025 D WifiStateMachine: processMsg: DriverStartedState
3025 D WifiStateMachine: processMsg: SupplicantStartedState
3025 D WifiStateMachine: transitionTo: destState=WaitForP2pDisableState
3025 D WifiStateMachine: handleMessage: E msg.what=CMD_DISABLE_P2P_RSP
3025 D WifiStateMachine: processMsg: WaitForP2pDisableState
3025 D WifiStateMachine: transitionTo: destState=SupplicantStoppingState
3025 D WifiStateMachine: setWifiState: disabled
3025 D WifiStateMachine: transitionTo: destState=InitialState

1. Scan and connect AP
   4.1 WiFi Scan Flow

c
Explain for Chart:
(1) In WifiStateMachine process CMD_START_SCAN.
(2) WifiNative.scan deal with scan in wap_supplicant.
(3) WifiMonitor receive the message from wap_supplicant.
(4) WifiStateMachine process the those message, sendbroadcast, notify the interface to update AP list.
Usefully log:
3025 D WifiStateMachine: handleMessage: E msg.what=131143—- CMD_START_SCAN
3025 D WifiStateMachine: processMsg: DriverStartedState
3025 D WifiNative-wlan0: doBoolean: SCAN
8290 D WifiService: startScan by pid=3598, uid=1000
13617 D WifiMonitor: Event [IFNAME=wlan0 WPS-AP-AVAILABLE ]
3025 D WifiStateMachine: handleMessage: E msg.what=147461—- SCAN_RESULTS_EVENT
3025 D WifiStateMachine: processMsg: SupplicantStartedState
3025 D WifiNative-wlan0: doString: BSS RANGE=0- MASK=0x21987
3598 D WifiSettings: [updateAccessPoints] wifiState : 3

4.2 Connect AP

Explain for Chart:
(1) Mainly work is WifiManager.connect().WifiConfigStore.saveNetwok(config) is used for save AP to wpa_supplicant.conf. WifiConfigStore.selectNetwork(netId) is used for enable connecting AP. WifiNative.reconnect() sent the reconnect request to wpa_supplicant. You can refer the Figure1.
(2) wpa_supplicant continuous delivery CTRL-EVENT-STATE-CHANGE、ASSOCIATING、ASSOCIATED event, and WifiMonitor will parse event.
(3) After connection is successful between WLAN and AP, wpa_supplicant will sent CTRL-EVENT-CONNECTED event. After processed this event, enter get IP address part.
(4) Two ways to get IP address. One is static, the other is dynamic. This need interact with DhcpStateMachine.
(5) VerifyingLinkState verify the connection state. This function come true by WifiWatchdogStateMachine.
(6) Captive Portal is the authentication method. After captive check complete, the upper translation to ConnectedState.Connection ok.

Usefully log:
3025 D WifiStateMachine: handleMessage: E msg.what=151553—- CONNECT_NETWORK
21315 I wpa_supplicant: CTRL-EVENT-CONNECTED - Connection to 00:24:01:66:31:6d completed (auth) [id=0 id_str=]
21321 D WifiMonitor: Event [IFNAME=wlan0 CTRL-EVENT-CONNECTED - Connection to 00:24:01:66:31:6d completed (auth) [id=0 id_str=]]
3025 D WifiStateMachine: handleMessage: E msg.what=147459—- NETWORK_CONNECTION_EVENT
21387 D DhcpStateMachine: DHCP succeeded on wlan0
3025 D WifiStateMachine: DHCP successful
3042 D ConnectivityService: Captive portal check NetworkInfo: type: WIFI[], state: CONNECTING/CAPTIVE_PORTAL_CHECK, reason: (unspecified), extra: “dlink”, roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false
3042 D ConnectivityService: handleCaptivePortalTrackerCheck: call captivePortalCheckComplete ni=NetworkInfo: type: WIFI[], state: CONNECTING/CAPTIVE_PORTAL_CHECK, reason: (unspecified), extra: “dlink”, roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false
3025 D WifiStateMachine: transitionTo: destState=ConnectedState

1. WifiStateMachine
   Learn about relationship about HSM.

(1) addState
(2) transitionTo
(3) obtainMessage
(4) sendMessage
(5) deferMessage
(6) enter()
(7) exit()
HSM is complex, you can treat it as tree. Two point: (1) About change the state, for example, ConnectModeState change to ScanModeState. The flow as blew: ConnectModeState.exit()->ScanModeState.enter. (2) If the current state can’t deal with this message, its father will handle it.

1. IPC
   WifiManager and WifiServer.