Android(安卓)O WiFi启动流程

版权声明：本文为博主原创文章，未经博主允许不得转载。https://blog.csdn.net/huangweiqing80/article/details/82384518
一. Android O wifi 架构：

由于Android O的Treble化，Android O上Wifi架构变动也比较大，尤其是JNI层、Hal层、HIDL层。

下图是Android O Treble HIDL大致结构：

下图是Android O wifi架构：

二.WiFi启动流程梳理
2.1 设置启动WiFi

设置这边说到底其实就是监控WiFi开关的变化，然后根据开关走对应的逻辑处理。

两个比较重要的类：

1）WifiSettings:设置中wifi主界面所对应的代码

2）WifiEnabler:设置中负责wifi开关打开和关闭事件处理的类

在wifisettings activity的onStart函数中，创建一个WifiEnabler对象，用于实现wifi开关功能。
packages/apps/Settings/src/com/android/settings/wifi/WifiSettings.java

    public void onStart() {        super.onStart();        // On/off switch is hidden for Setup Wizard (returns null)        mWifiEnabler = createWifiEnabler();        mWifiTracker.startTracking();        if (mIsRestricted) {            restrictUi();            return;        }        onWifiStateChanged(mWifiManager.getWifiState());    }

onStart函数调用createWifiEnabler：

    /**     * @return new WifiEnabler or null (as overridden by WifiSettingsForSetupWizard)     */    private WifiEnabler createWifiEnabler() {        final SettingsActivity activity = (SettingsActivity) getActivity();        return new WifiEnabler(activity, new SwitchBarController(activity.getSwitchBar()),            mMetricsFeatureProvider);    }

下面进入
/aosp/packages/apps/Settings/src/com/android/settings/widget/SwitchBarController.java
看看SwitchBarController这个类

public class SwitchBarController extends SwitchWidgetController implements    SwitchBar.OnSwitchChangeListener {    private final SwitchBar mSwitchBar;    public SwitchBarController(SwitchBar switchBar) {        mSwitchBar = switchBar;    }     .     .     .    @Override    public void startListening() {        mSwitchBar.addOnSwitchChangeListener(this);    }     .     .     .     @Override    public void onSwitchChanged(Switch switchView, boolean isChecked) {        if (mListener != null) {            mListener.onSwitchToggled(isChecked);        }    }    .    .    .}

上面的两个函数startListening和onSwitchChanged是重点，一个是启动SwitchBar的监听，一个监听到有变化之后的调用

然后我们再回到刚才的createWifiEnabler函数调用的WifiEnabler类
/aosp/packages/apps/Settings/src/com/android/settings/wifi/WifiEnabler.java

@VisibleForTesting    WifiEnabler(Context context, SwitchWidgetController switchWidget,            MetricsFeatureProvider metricsFeatureProvider,            ConnectivityManagerWrapper connectivityManagerWrapper) {        mContext = context;        mSwitchWidget = switchWidget;        mSwitchWidget.setListener(this);        mMetricsFeatureProvider = metricsFeatureProvider;        mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);        mConnectivityManager = connectivityManagerWrapper;        mIntentFilter = new IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION);        // The order matters! We really should not depend on this. :(        mIntentFilter.addAction(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION);        mIntentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);        setupSwitchController();    }

WifiEnabler类我们重点看setupSwitchController这个函数

    public void setupSwitchController() {        final int state = mWifiManager.getWifiState();        handleWifiStateChanged(state);        if (!mListeningToOnSwitchChange) {            mSwitchWidget.startListening();            mListeningToOnSwitchChange = true;        }        mSwitchWidget.setupView();    }

在setupSwitchController函数中，我们看到有
if (!mListeningToOnSwitchChange) {
mSwitchWidget.startListening();
mListeningToOnSwitchChange = true;
}
这里是调用前面的启动监听将mListeningToOnSwitchChange设为true，这样当我们点击wifi开关按钮的时候就会调用前面的onSwitchChanged随即调用mListener.onSwitchToggled(isChecked);
下面再来看看onSwitchToggled这个函数

public boolean onSwitchToggled(boolean isChecked) {        //Do nothing if called as a result of a state machine event        if (mStateMachineEvent) {            return true;        }        // Show toast message if Wi-Fi is not allowed in airplane mode        if (isChecked && !WirelessUtils.isRadioAllowed(mContext, Settings.Global.RADIO_WIFI)) {            Toast.makeText(mContext, R.string.wifi_in_airplane_mode, Toast.LENGTH_SHORT).show();            // Reset switch to off. No infinite check/listenenr loop.            mSwitchWidget.setChecked(false);            return false;        }        // Disable tethering if enabling Wifi        if (mayDisableTethering(isChecked)) {            mConnectivityManager.stopTethering(ConnectivityManager.TETHERING_WIFI);        }        if (isChecked) {            mMetricsFeatureProvider.action(mContext, MetricsEvent.ACTION_WIFI_ON);        } else {            // Log if user was connected at the time of switching off.            mMetricsFeatureProvider.action(mContext, MetricsEvent.ACTION_WIFI_OFF,                    mConnected.get());        }        if (!mWifiManager.setWifiEnabled(isChecked)) {            // Error            mSwitchWidget.setEnabled(true);            Toast.makeText(mContext, R.string.wifi_error, Toast.LENGTH_SHORT).show();        }        return true;    }

我们可以看到WifiEnabler开关SwitchToggled中会调用WifiManager.setWifiEnabled方法。
看到这里其实发现应用层打开和关闭WiFi就是调用了WifiManager的setWifiEabled(boolean)接口。

2.2 WiFi framework

看下WifiManager的setWifiEabled(boolean)接口

framework/base/wifi/java/android/net/wifi/WifiManager.javapublic boolean setWifiEnabled(boolean enabled) {        try {            return mService.setWifiEnabled(mContext.getOpPackageName(), enabled);        } catch (RemoteException e) {            throw e.rethrowFromSystemServer();        }    }

应用层的WifiManager都是怎么来的呢

mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);

2.2.1 mService是什么

而WifiManager.setWifiEnabled函数中的mService是啥呢

IWifiManager mService;

 public WifiManager(Context context, IWifiManager service, Looper looper) {        mContext = context;        mService = service;        mLooper = looper;        mTargetSdkVersion = context.getApplicationInfo().targetSdkVersion;    }

其实WiFiManager使用aidl方式和WifiService进行通信。

frameworks/base/wifi/java/android/net/wifi/IWifiManager.aidl

     boolean setWifiEnabled(String packageName, boolean enable);

2.3.最终调用的的是WifiServiceImpl中的setWifiEnabled方法：
WifiServiceImpl中实现WifiService的方法，像WifiController发消息：CMD_WIFI_TOGGLED.

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

public synchronized boolean setWifiEnabled(String packageName, boolean enable)    mWifiController.sendMessage(CMD_WIFI_TOGGLED);

2.4. WifiController状态机处理消息：CMD_WIFI_TOGGLED

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

WifiController状态机的状态变化，这里我们只说softap关闭状态下打开sta的情况；有时间的话，可以跟一下softap打开状态下打开sta的流程。这里只需关注“Turn ON STA” .

2.4.1 ApStaDisabledState 状态下，不对CMD_WIFI_TOGGLED消息处理

2.4.2 转向StaEnabledState状态，在该状态的enter()函数中启动supplicant， processMessage中会根据扫描、sta/ap共存等条件做相应的状态处理。

class StaEnabledState extends State {        @Override        public void enter() {            mWifiStateMachine.setSupplicantRunning(true);        }        @Override        public boolean processMessage(Message msg) {            switch (msg.what) {                case CMD_WIFI_TOGGLED:                    if (! mSettingsStore.isWifiToggleEnabled()) {                        if (mSettingsStore.isScanAlwaysAvailable()) {                            transitionTo(mStaDisabledWithScanState);                        } else {                            transitionTo(mApStaDisabledState);                        }                    }                    break;

可以看到WifiController再让mWifiStateMachine状态机去启动Supplicant
下面看看mWifiStateMachine.setSupplicantRunning(true);

2.5. frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachine.java

  public void setSupplicantRunning(boolean enable) {        if (enable) {            sendMessage(CMD_START_SUPPLICANT);        } else {            sendMessage(CMD_STOP_SUPPLICANT);        }    }

从上面可以看到setSupplicantRunning发送了一个消息CMD_START_SUPPLICANT，那么我们就到WifiStateMachine的InitialState状态里面去看看processMessage函数
2.6. frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachine.java

这里先简单给出wifi状态机WifiStateMachine的各状态及结构。

WifiStateMachine state:    |- DefaultState        |-- InitialState        |-- SupplicantStartingState        |-- SupplicantStartedState            |--- ScanModeState            |--- ConnectModeState                |---- L2ConnectedState                    |----- ObtainingIpState                    |----- ConnectedState                    |----- RoamingState                |---- DisconnectingState                |---- DisconnectedState                |---- WpsRunningState                |---- FilsState            |--- WaitForP2pDisableState        |-- SupplicantStoppingState        |-- SoftApstate

InitialState状态中处理消息：CMD_START_SUPPLICANT, 做加载驱动、启动supplicant操作，mWifiMonitor.startMonitoring然后转向SupplicantStartingState状态。

    class InitialState extends State {        @Override        public boolean processMessage(Message message) {            logStateAndMessage(message, this);        switch (message.what) {        case CMD_START_SUPPLICANT:           ...            mClientInterface = mWifiNative.setupForClientMode();                              // loadDriver           ...                               if (!mWifiNative.enableSupplicant()) {                         // start supplicant                        loge("Failed to start supplicant!");                        setWifiState(WifiManager.WIFI_STATE_UNKNOWN);                        cleanup();                        break;                    }                    if (mVerboseLoggingEnabled) log("Supplicant start successful");                    mWifiMonitor.startMonitoring(mInterfaceName, true);                      //startMonitoring                    mWifiInjector.getWifiLastResortWatchdog().clearAllFailureCounts();                    setSupplicantLogLevel();                    transitionTo(mSupplicantStartingState);                    break;

2.7. frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java

    public Pair<Integer, IClientInterface> setupForClientMode() {        if (!startHalIfNecessary(true)) {                                                              // start Hal            Log.e(mTAG, "Failed to start HAL for client mode");            return Pair.create(SETUP_FAILURE_HAL, null);        }        IClientInterface iClientInterface = mWificondControl.setupDriverForClientMode();        if (iClientInterface == null) {            return Pair.create(SETUP_FAILURE_WIFICOND, null);        }        return Pair.create(SETUP_SUCCESS, iClientInterface);    }

//启动Hal层。如果支持STA/AP共存，startConcurrentVendorHal；如果不支持共存：isStaMode=true启动sta模式，isStaMode=false启动ap模式。

    private boolean startHalIfNecessary(boolean isStaMode)        if (mStaAndAPConcurrency)              // start ap & sta Concurrent Hal               return mWifiVendorHal.startConcurrentVendorHal(isStaMode);        return mWifiVendorHal.startVendorHal(isStaMode); // start Hal. Here

2.8. 不同于android N，wifinative会调用JNI层com_android_server_wifi_WifiNative.cpp. Android O在framework增加了调用Hal层的相关接口及hal设备管理接口。

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

    public boolean startVendorHal(boolean isStaMode)        mHalDeviceManager.start()  //start wifi vendor hal        mIWifiStaIface = mHalDeviceManager.createStaIface(null, null); //loadDriver

2.9. 继续跟mIWifiStaIface = mHalDeviceManager.createStaIface(null, null);

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

    public IWifiStaIface createStaIface(InterfaceDestroyedListener destroyedListener,            Looper looper) {        return (IWifiStaIface) createIface(IfaceType.STA, destroyedListener, looper);    }

    private IWifiIface createIface(int ifaceType, InterfaceDestroyedListener destroyedListener, Looper looper)         IWifiIface iface = createIfaceIfPossible(chipInfos, ifaceType, destroyedListener, looper);

  private IWifiIface createIfaceIfPossible(WifiChipInfo[] chipInfos, int ifaceType, InterfaceDestroyedListener destroyedListener, Looper looper)         IWifiIface iface = executeChipReconfiguration(bestIfaceCreationProposal, ifaceType);

   private IWifiIface executeChipReconfiguration(IfaceCreationData ifaceCreationData, int ifaceType)         WifiStatus status = ifaceCreationData.chipInfo.chip.configureChip(ifaceCreationData.chipModeId);

2.10. Android O不在使用之前版本的JNI com_android_server_wifi_WifiNative.cpp。而是用HIDL，其实现在/hardware/interfaces/.

hardware/interfaces/wifi/1.1/default/wifi_chip.cpp

    Return<void> WifiChip::configureChip(ChipModeId mode_id, configureChip_cb hidl_status_cb)         return validateAndCall(this, WifiStatusCode::ERROR_WIFI_CHIP_INVALID, &WifiChip::configureChipInternal, hidl_status_cb, mode_id);

 WifiStatus WifiChip::configureChipInternal(ChipModeId mode_id)          WifiStatus status = handleChipConfiguration(mode_id);

    WifiStatus WifiChip::handleChipConfiguration(ChipModeId mode_id)        if (mode_id == kStaChipModeId) {            success = mode_controller_.lock()->changeFirmwareMode(IfaceType::STA);        } else {            success = mode_controller_.lock()->changeFirmwareMode(IfaceType::AP);        }

2.11. hardware/interfaces/wifi/1.0/default/wifi_mode_controller.cpp

 bool WifiModeController::changeFirmwareMode(IfaceType type)         driver_tool_->LoadDriver()        driver_tool_->ChangeFirmwareMode(convertIfaceTypeToFirmwareMode(type))

2.12. 最后调到hal层，android O的hal层也进行了重写。位置也从之前的版本中的hardware/libhardware_legacy/wifi/移到了frameworks/opt/net/wifi/libwifi_hal/

frameworks/opt/net/wifi/libwifi_hal/driver_tool.cpp

    bool DriverTool::LoadDriver()         return ::wifi_load_driver() == 0;

2.13 frameworks/opt/net/wifi/libwifi_hal/wifi_hal_common.cpp

int wifi_load_driver() if (is_wifi_driver_loaded())  return 0;        insmod(DRIVER_MODULE_PATH, DRIVER_MODULE_ARG)

除了一些打开wifi时的消息通知、广播、状态变化，这里没有详细描述；至此，wifi打开的相关工作已经完成。

有些平台把加载wifi驱动的动作放在了开机时，在init.$(target).rc文件中：

insmod /vendor/lib/modules/wlan.ko

根据实际情况，可能需要将开机加载驱动改为原来的动态加载。只需要做两处改动：

A. init脚本中删除加载wlan driver的行

B. 确认如下几个宏是打开和正确定义，在产品平台对应的makefile文件中加入即可：

   WIFI_DRIVER_MODULE_PATH := "/vendor/lib/modules/wlan.ko"    WIFI_DRIVER_MODULE_NAME := "wlan"    WIFI_DRIVER_MODULE_ARG := ""

参考https://blog.csdn.net/h784707460/article/details/79572861

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