Android 11 WiFi开启流程

从刚接触WiFi时跟过wifi的开启流程，当时还是android9。到了Android11代码架构有了不小的改动，在这里重新梳理一遍，便于在工作中更快速的跟踪代码。

一、Settings里改动不大，还是从WifiEnabler开始，调用WiFiManager的setWifiEnabled。
packages/apps/Settings/src/com/android/settings/wifi/WifiEnabler.java

if (!mWifiManager.setWifiEnabled(isChecked)) {// ErrormSwitchWidget.setEnabled(true);Toast.makeText(mContext, R.string.wifi_error, Toast.LENGTH_SHORT).show();}

二、这里要注意了，Android11默认加入了支持双WiFi的代码。这里打开WiFi就提供了俩个接口
frameworks/base/wifi/java/android/net/wifi/WifiManager.java
正常打开WiFi是调用这个单参的函数。

public boolean setWifiEnabled(boolean enabled) {try {return mService.setWifiEnabled(mContext.getOpPackageName(), enabled);} catch (RemoteException e) {throw e.rethrowFromSystemServer();}
}

如果是指定打开哪个STA，就要调用双参的函数。

public boolean setWifiEnabled(int staId, boolean enabled) {try {return mService.setWifiEnabled2(mContext.getOpPackageName(), staId, enabled);} catch (RemoteException e) {throw e.rethrowFromSystemServer();}
}

三、可以看到Wifimanager中正常打开WiFi和指定打开哪个STA的区别就是在WifiServiceImpl中setWifiEnabled2的参数不同。如果是打开第一个WiFi，则参数2为STA_PRIMARY，如果是打开其他WiFi，则参数2为传入的staId。
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiServiceImpl.java

public synchronized boolean setWifiEnabled(String packageName, boolean enable) {return setWifiEnabled2(packageName, STA_PRIMARY, enable);
}

public synchronized boolean setWifiEnabled2(String packageName, int staId,boolean enable) {if (enforceChangePermission(packageName) != MODE_ALLOWED) {return false;}boolean isPrivileged = isPrivileged(Binder.getCallingPid(), Binder.getCallingUid());if (!isPrivileged && !isDeviceOrProfileOwner(Binder.getCallingUid(), packageName)&& !mWifiPermissionsUtil.isTargetSdkLessThan(packageName, Build.VERSION_CODES.Q,Binder.getCallingUid())&& !isSystem(packageName, Binder.getCallingUid())) {mLog.info("setWifiEnabled not allowed for uid=%").c(Binder.getCallingUid()).flush();return false;}// If Airplane mode is enabled, only privileged apps are allowed to toggle Wifiif (mSettingsStore.isAirplaneModeOn() && !isPrivileged) {mLog.err("setWifiEnabled in Airplane mode: only Settings can toggle wifi").flush();return false;}// If SoftAp is enabled, only privileged apps are allowed to toggle wifiif (!isPrivileged && mTetheredSoftApTracker.getState() == WIFI_AP_STATE_ENABLED) {mLog.err("setWifiEnabled with SoftAp enabled: only Settings can toggle wifi").flush();return false;}mLog.info("setWifiEnabled package=% uid=% enable=%").c(packageName).c(Binder.getCallingUid()).c(enable).flush();long ident = Binder.clearCallingIdentity();try {if (staId == STA_PRIMARY && !mSettingsStore.handleWifiToggled(enable)) {// Nothing to do if wifi cannot be toggledreturn true;}} finally {Binder.restoreCallingIdentity(ident);}if (mWifiPermissionsUtil.checkNetworkSettingsPermission(Binder.getCallingUid())) {mWifiMetrics.logUserActionEvent(enable ? UserActionEvent.EVENT_TOGGLE_WIFI_ON: UserActionEvent.EVENT_TOGGLE_WIFI_OFF);}if (!mIsControllerStarted) {Log.e(TAG,"WifiController is not yet started, abort setWifiEnabled");return false;}mWifiMetrics.incrementNumWifiToggles(isPrivileged, enable);
if(staId == STA_PRIMARY)mActiveModeWarden.wifiToggled();
else if(staId == STA_SECONDARY && (getNumConcurrentStaSupported() > 1) && (getWifiEnabledState() == WifiManager.WIFI_STATE_ENABLED))
mActiveModeWarden.qtiWifiToggled(staId, enable);elseLog.e(TAG,"setWifiEnabled not allowed for Id: " + staId);return true;
}

四、可以看到wifiservice调用了ActiveModeWarden的wifiToggled，发送了CMD_WIFI_TOGGLED的消息，通知WiFi切换了。
frameworks/opt/net/wifi/service/java/com/android/server/wifi/ActiveModeWarden.java

public void wifiToggled() {mWifiController.sendMessage(WifiController.CMD_WIFI_TOGGLED);
}

五、我们看WifiController是怎么处理这个消息的。WifiController是ActiveModeWarden中的一个状态机，用来管理WiFi的操作，包括热点啊飞行模式什么的。
打开WiFi之前，状态机应该是在Disabled状态，我们看Disable状态里的处理。

class DisabledState extends BaseState {public boolean processMessageFiltered(Message msg) {switch (msg.what) {case CMD_WIFI_TOGGLED:case CMD_SCAN_ALWAYS_MODE_CHANGED:if (shouldEnableSta()) {startClientModeManager();transitionTo(mEnabledState);}break;

启动一个新的客户端管理。

private boolean startClientModeManager() {Log.d(TAG, "Starting ClientModeManager");ClientListener listener = new ClientListener();ClientModeManager manager = mWifiInjector.makeClientModeManager(listener);listener.setActiveModeManager(manager);manager.start();if (!switchClientModeManagerRole(manager)) {return false;}mActiveModeManagers.add(manager);return true;
}

六、start了ClientModeManager
frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeManager.java

public void start() {Log.d(TAG, "Starting with role ROLE_CLIENT_SCAN_ONLY");mRole = ROLE_CLIENT_SCAN_ONLY;mTargetRole = ROLE_CLIENT_SCAN_ONLY;mStateMachine.sendMessage(ClientModeStateMachine.CMD_START);
}

看一下是谁处理了这个START消息呢

private class IdleState extends State {@Overridepublic boolean processMessage(Message message) {switch (message.what) {case CMD_START:// Always start in scan mode first.mClientInterfaceName =mWifiNative.setupInterfaceForClientInScanMode(mWifiNativeInterfaceCallback);if (TextUtils.isEmpty(mClientInterfaceName)) {Log.e(TAG, "Failed to create ClientInterface. Sit in Idle");mModeListener.onStartFailure();break;}transitionTo(mScanOnlyModeState);break;}
}

七、这里可以看出，WifiNative先去启动HAL
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java

public String setupInterfaceForClientInScanMode(@NonNull InterfaceCallback interfaceCallback) {synchronized (mLock) {if (!startHal()) {mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToHal();return null;}Iface iface = mIfaceMgr.allocateIface(Iface.IFACE_TYPE_STA_FOR_SCAN);iface.externalListener = interfaceCallback;iface.name = createStaIface(iface);if (!mWifiCondManager.setupInterfaceForClientMode(iface.name, Runnable::run,new NormalScanEventCallback(iface.name),new PnoScanEventCallback(iface.name))) {Log.e(TAG, "Failed to setup iface in wificond=" + iface.name);teardownInterface(iface.name);mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToWificond();return null;}iface.networkObserver = new NetworkObserverInternal(iface.id);if (!registerNetworkObserver(iface.networkObserver)) {teardownInterface(iface.name);return null;}mWifiMonitor.startMonitoring(iface.name);onInterfaceStateChanged(iface, isInterfaceUp(iface.name));iface.featureSet = getSupportedFeatureSetInternal(iface.name);return iface.name;}
}

八、启动HAL

WifiVendorHal.java-->startVendorHal --> HalDeviceManager.java --> startWifi --> IWifi.start

mWifi.start()方法是启动实际加载WiFi动作的调用，这里涉及HIDL机制调用。通过获取IWifi接口对象，调用其方法。这里IWifi接口对象是IWifi.hal文件中实现。

android/hardware/interfaces/wifi/1.0/IWifi.hal

在编译时，编译器会将IWifi.hal解析为IWifi.java文件,直接看该文件中的start方法实现即可。

android/out/soong//.intermediates/hardware/interfaces/wifi/1.0/android.hardware.wifi-V1.0-java_gen_java/gen/srcs/android/hardware/wifi/V1_0/IWifi.javapublic android.hardware.wifi.V1_0.WifiStatus start() throws android.os.RemoteException {try {... ... ... ...mRemote.transact(3 /* start */, _hidl_request, _hidl_reply, 0 /* flags */);_hidl_reply.verifySuccess();_hidl_request.releaseTemporaryStorage();return _hidl_out_status;} finally {_hidl_reply.release();}}

通过binder调用，将调用到wifi.cpp中的start()方法.

android/hardware/interfaces/wifi/1.4/default/wifi.cppReturn<void> Wifi::start(start_cb hidl_status_cb) {return validateAndCall(this, WifiStatusCode::ERROR_UNKNOWN,&Wifi::startInternal, hidl_status_cb);}wifi.cpp->start() ==> wifi.cpp->startInternal() ==> wifi.cpp->initializeModeControllerAndLegacyHal()==> WifiModeController->initialize() ==> DriverTool->LoadDriver()

通过调用DriverTool->LoadDriver将返回到Android framework中。下面是LoadDriver()的实现。

android/frameworks/opt/net/wifi/libwifi_hal/include/wifi_hal/driver_tool.cppbool DriverTool::LoadDriver() {return ::wifi_load_driver() == 0;}

在wifi_load_driver()方法中，将调用系统接口加载WiFi驱动ko。关于系统insmod接口的调用，本文不做分析。到这里，已梳理完在WifiNative类中调用的startHal()方法。

android/frameworks/opt/net/wifi/libwifi_hal/wifi_hal_common.cppint wifi_load_driver() {... ... ... ...insmod(file,args);... ... ... ...}

调用WifiNl80211Manager类的setupInterfaceForClientMode()方法。

该类的主要对WiFi 80211nl管理接口的封装，接口在WiFicond守护进程中呈现给WiFi框架。该类提供的接口仅使用与WiFi框架，访问权限受selinux权限保护。

setupInterfaceForClientMode()方法主要为Station模式设置接口。

android/frameworks/base/wifi/java/android/net/wifi/nl80211/WifiNl80211Manager.javapublic boolean setupInterfaceForClientMode(@NonNull String ifaceName,@NonNull @CallbackExecutor Executor executor,@NonNull ScanEventCallback scanCallback, @NonNull ScanEventCallback pnoScanCallback) {... ... ... ...// Refresh HandlersmClientInterfaces.put(ifaceName, clientInterface);try {IWifiScannerImpl wificondScanner = clientInterface.getWifiScannerImpl();mWificondScanners.put(ifaceName, wificondScanner);Binder.allowBlocking(wificondScanner.asBinder());ScanEventHandler scanEventHandler = new ScanEventHandler(executor, scanCallback);mScanEventHandlers.put(ifaceName, scanEventHandler);wificondScanner.subscribeScanEvents(scanEventHandler);PnoScanEventHandler pnoScanEventHandler = new PnoScanEventHandler(executor,pnoScanCallback);mPnoScanEventHandlers.put(ifaceName, pnoScanEventHandler);wificondScanner.subscribePnoScanEvents(pnoScanEventHandler);... ... ... ...}

到这里，ClientModeStateMachine状态机在IdleState状态成功处理完了CMD_START消息。状态机将转到“mScanOnlyModeState”状态，将会执行以下调用流程(具体原因可查看状态机机制)。

IdleState.exit()->StartedState.enter()->StartedState.exit()->ScanOnlyModeState.enter()。

九、启动HAL以后，就要启动supplicant了。
在第五步的时候我们调用了ActiveModeWarden.java的startClientModeManagerh函数。start以后会执行switchClientModeManagerRole

 private boolean switchClientModeManagerRole(@NonNull ClientModeManager modeManager) {if (mSettingsStore.isWifiToggleEnabled()) {modeManager.setRole(ActiveModeManager.ROLE_CLIENT_PRIMARY);} else if (checkScanOnlyModeAvailable()) {modeManager.setRole(ActiveModeManager.ROLE_CLIENT_SCAN_ONLY);} else {Log.e(TAG, "Something is wrong, no client mode toggles enabled");return false;}return true;
n true;}

十、从上一步可以看出setRole的参数为ROLE_CLIENT_SCAN_ONLY，所以这里发送的是CMD_SWITCH_TO_CONNECT_MODE广播
frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeManager.java

public void setRole(@Role int role) {Preconditions.checkState(CLIENT_ROLES.contains(role));if (role == ROLE_CLIENT_SCAN_ONLY) {mTargetRole = role;// Switch client mode manager to scan only mode.mStateMachine.sendMessage(ClientModeStateMachine.CMD_SWITCH_TO_SCAN_ONLY_MODE);} else if (CLIENT_CONNECTIVITY_ROLES.contains(role)) {mTargetRole = role;// Switch client mode manager to connect mode.mStateMachine.sendMessage(ClientModeStateMachine.CMD_SWITCH_TO_CONNECT_MODE, role);}
}

十一、看一下CMD_SWITCH_TO_CONNECT_MODE的处理，这里先执行了switchClientInterfaceToConnectivityMode

private class StartedState extends State {public boolean processMessage(Message message) {switch(message.what) {case CMD_SWITCH_TO_CONNECT_MODE:mRole = message.arg1; // could be any one of possible connect mode roles.updateConnectModeState(WifiManager.WIFI_STATE_ENABLING,WifiManager.WIFI_STATE_DISABLED);if (!mWifiNative.switchClientInterfaceToConnectivityMode(mClientInterfaceName)) {updateConnectModeState(WifiManager.WIFI_STATE_UNKNOWN,WifiManager.WIFI_STATE_ENABLING);updateConnectModeState(WifiManager.WIFI_STATE_DISABLED,WifiManager.WIFI_STATE_UNKNOWN);mModeListener.onStartFailure();break;}transitionTo(mConnectModeState);break;

十二、可以看到这里启动了supplicant
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java

public boolean switchClientInterfaceToConnectivityMode(@NonNull String ifaceName) {synchronized (mLock) {final Iface iface = mIfaceMgr.getIface(ifaceName);if (!startSupplicant()) {Log.e(TAG, "Failed to start supplicant");teardownInterface(iface.name);mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();return false;}if (!mSupplicantStaIfaceHal.setupIface(iface.name)) {Log.e(TAG, "Failed to setup iface in supplicant on " + iface);teardownInterface(iface.name);mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();return false;}iface.type = Iface.IFACE_TYPE_STA_FOR_CONNECTIVITY;iface.featureSet = getSupportedFeatureSetInternal(iface.name);Log.i(TAG, "Successfully switched to connectivity mode on iface=" + iface);return true;}}

private boolean startSupplicant() {synchronized (mLock) {if (!mIfaceMgr.hasAnyStaIfaceForConnectivity()) {if (!startAndWaitForSupplicantConnection()) {Log.e(TAG, "Failed to connect to supplicant");return false;}if (!mSupplicantStaIfaceHal.registerDeathHandler(new SupplicantDeathHandlerInternal())) {Log.e(TAG, "Failed to register supplicant death handler");return false;}}return true;}
}

在这里等待与supplicant建立连接

private boolean startAndWaitForSupplicantConnection() {// Start initialization if not already started.if (!mSupplicantStaIfaceHal.isInitializationStarted()&& !mSupplicantStaIfaceHal.initialize()) {return false;}if (!mSupplicantStaIfaceHal.startDaemon()) {Log.e(TAG, "Failed to startup supplicant");return false;}boolean connected = false;int connectTries = 0;while (!connected && connectTries++ < CONNECT_TO_SUPPLICANT_RETRY_TIMES) {// Check if the initialization is complete.connected = mSupplicantStaIfaceHal.isInitializationComplete();if (connected) {break;}try {Thread.sleep(CONNECT_TO_SUPPLICANT_RETRY_INTERVAL_MS);} catch (InterruptedException ignore) {}}return connected;
}

十三、这里是通过HIDL来打开supplicant的
frameworks/opt/net/wifi/service/java/com/android/server/wifi/SupplicantStaIfaceHal.java

startDaemon -> startDaemon_V1_1 -> getSupplicantMockableV1_1 -> getSupplicantMockable

protected ISupplicant getSupplicantMockable() throws RemoteException, NoSuchElementException {synchronized (mLock) {ISupplicant iSupplicant = ISupplicant.getService();if (iSupplicant == null) {throw new NoSuchElementException("Cannot get root service.");}return iSupplicant;}
}

android/out/soong/intermediates/hardware/interfaces/wifi/supplicant/1.0/android.hardware.wifi.supplicant-V1.0-java_gen_java/gen/srcs/android/hardware/wifi/supplicant/V1_0/ISupplicant.java

public static ISupplicant getService(String serviceName) throws android.os.RemoteException {return ISupplicant.asInterface(android.os.HwBinder.getService("android.hardware.wifi.supplicant@1.0::ISupplicant", serviceName));
}

十四、在这个方法中将触发启动wpa_supplicant进程，这里需要注意，在manifest.xml中对其需要进行配置，运行时会将服务名称注册到hwservicemanager中。

wpa_supplicant目录下文件调用：

main.c ==> wpa_supplicant.c->wpa_supplicant_init() ==> notify.c->wpas_notify_supplicant_initialized() ==> hidl.cpp->wpas_hidl_init() ==> Hidl_manager.cpp->registerHidlService()

int HidlManager::registerHidlService(struct wpa_global *global){// Create the main hidl service object and register it.supplicant_object_ = new Supplicant(global);if (supplicant_object_->registerAsService("wpa_supplicant") != android::NO_ERROR) {return 1;}return 0;}

十五、将wpa_supplicant添加注册到hwservicemanager，SupplicantStaIfaceHal.getSupplicantMockable()执行完成返回。

这里再深入看下“supplicant_object_->registerAsService(“wpa_supplicant”)”是如何通过调用注册的呢？

android/out/soong/.intermediates/hardware/interfaces/wifi/supplicant/1.3/android.hardware.wifi.supplicant@1.3_genc++/gen/android/hardware/wifi/supplicant/1.3/SupplicantAll.cppandroid/system/libhidl/transport/ServiceManagement.cppandroid/system/hwservicemanager/ServiceManager.cpp

supplicant_object_->registerAsService("wpa_supplicant") ==> ISupplicant.hal
==> ISupplicantAll.cpp->registerAsService()
==> ::android::hardware::details::registerAsServiceInternal(this, serviceName)
==> ServiceManagement.cpp->registerAsServiceInternal()
==> ServiceManager->addWithChain()==> ServiceManager->addImpl()

十六、wpa_supplicant注册完成后，SupplicantStaIfaceHal类中将收到回调通知信息，

private final IServiceNotification mServiceNotificationCallback =
new IServiceNotification.Stub() {public void onRegistration(String fqName, String name, boolean preexisting) {synchronized (mLock) {if (!initSupplicantService()) {supplicantServiceDiedHandler(mDeathRecipientCookie);
}

返回通知的调用逻辑。

SupplicantStaIfaceHal.initSupplicantService() -> SupplicantStaIfaceHal.getSupplicantMockable()

十七、到此位置supplicant已经启动。
switchClientInterfaceToConnectivityMode会继续调用SupplicantStaIfaceHal.setupIface()方法设置接口。设置成功后，就会打印成功的日志。

Log.i(TAG, "Successfully switched to connectivity mode on iface=" + iface);

十八、CMD_SWITCH_TO_CONNECT_MODE消息处理完以后状态机就会切换到ConnectModeState。
这里会调用setOperationalMode

transitionTo(mConnectModeState);

private class ConnectModeState extends State {@Overridepublic void enter() {Log.d(TAG, "entering ConnectModeState");mClientModeImpl.registerModeListener(mClientModeImplListener);mClientModeImpl.setOperationalMode(ClientModeImpl.CONNECT_MODE,mClientInterfaceName);}

十九、这里会进入到mDisconnectedState
frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeImpl.java

public void setOperationalMode(int mode, String ifaceName) {if (mVerboseLoggingEnabled) {log("setting operational mode to " + String.valueOf(mode) + " for iface: " + ifaceName);}mModeChange = true;if (mode != CONNECT_MODE) {// we are disabling client mode...   need to exit connect mode nowtransitionTo(mDefaultState);} else {// do a quick sanity check on the iface name, make sure it isn't nullif (ifaceName != null) {mInterfaceName = ifaceName;updateInterfaceCapabilities(ifaceName);transitionTo(mDisconnectedState);mWifiScoreReport.setInterfaceName(ifaceName);} else {Log.e(TAG, "supposed to enter connect mode, but iface is null -> DefaultState");transitionTo(mDefaultState);}}// use the CMD_SET_OPERATIONAL_MODE to force the transitions before other messages are// handled.sendMessageAtFrontOfQueue(CMD_SET_OPERATIONAL_MODE);
}

二十、ActiveModeWarden类中设置的ClientLister将被触发回调。 wifiScaner.setScanningEnabled()发送消息CMD_ENABLE，给到WiFiscanningSerivceimpl类中。
到这里，WiFi已处于打开状态，并将进行扫描网络，待连接。WiFi打开流程分析完成。

ActiveModeWarden.ClientListener -> ScanRequestProxy.enableScanning() ->
ScanRequestProxy.enableScanningInternal() -> wifiScaner.setScanningEnabled()

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