Android wifi 框架以及Enable流程

Android P相比于Android O的变化

• 多了WifiStateMachinePrime（状态机的前处理机制），wifiService的相关cmd 不再是直接send 给WifiStateMachine，而是被送到WifiStateMachinePrime先进行处理后，再送往WifiStateMachine
• 也多了一层ClientModeManager处理（将之前初始化wpa_supplicant专门抽出一层类在这里面来做），详细看后面的代码

Wifi 整体流程框架图

• 基本与Android O Wifi 主体框架一致
• 三板斧的套路还是被传承下来（1. Application <–> 2. WiFiService(WifiStateMachine) <–> 3. WifiNative（wpa_supplicant – wlan drv））

代码流程

1. WifiSettings --> WifiManager

点击 wifi button 开启wifi 触发的代码流程如下，

• wifiSettings 响应onPreferenceTreeClick 送往WifiEnable
• WifiEnabler 根据传入的状态，call WifiManager 设置wifi状态 （开启跳转到WifiServiceImpl）

packages/apps/Settings/src/com/android/settings/wifi/WifiSettings.java
 public boolean onPreferenceTreeClick(Preference preference){
  ..... 
  return super.onPreferenceTreeClick(preference);
 }

packages/apps/Settings/src/com/android/settings/wifi/WifiEnabler.java
public boolean onSwitchToggled(boolean isChecked){
.... 
mWifiManager.setWifiEnabled(isChecked); // wifiManager 设置wifi 状态
}

2. WifiManager --> WifiService --> WifiServiceImpl -->WifiController

• 还是老套路，逐级进入WifiService，WifiServiceImpl ，WifiController，WifiStateMachinePrime，WifiNative 等完成CMD_WIFI_TOGGLED的火炬传递
• 注意随着Android 版本升级后，接递火炬CMD_WIFI_TOGGLED的顺序也发生了变化
• Android P 版本WifiServiceImpl 将CMD_WIFI_TOGGLED 先送到了WifiController处理，这里稍微有点儿复杂的状态机（都会涉及到处理此cmd），具体根据设备所处状态来跟就可以。（这里以设备从开机状态第一次打开wifi为场景进行说明，此case 直接会进入）

frameworks/base/wifi/java/android/net/wifi/WifiManager.java
public boolean setWifiEnabled(boolean enabled){
 return mService.setWifiEnabled(mContext.getOpPackageName(), enabled); // jump to WifiServiceImpl
}

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);
}

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiController.java
 class StaDisabledState extends State {
....
   public boolean processMessage(Message msg) {
		switch (msg.what) {
		 case CMD_WIFI_TOGGLED:
		 .....
		 transitionTo(mDeviceActiveState); // jump to DeviceActiveState 
}
}
  class DeviceActiveState extends State {
       public void enter() {
          mWifiStateMachinePrime.enterClientMode(); // jump to WifiStateMachinePrime
           mWifiStateMachine.setHighPerfModeEnabled(false);
       }
  }

3. WifiController --> WifiStateMachinePrime

• WifiStateMachinePrime 传递CMD_START_CLIENT_MODE，先在内部状态机完成一轮转动
• ModeStateMachine --> ClientModeActiveState
• 送往ClientModeManager 创建WifiClientModeManager 实例

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachinePrime.java
public void enterClientMode() {
changeMode(ModeStateMachine.CMD_START_CLIENT_MODE);
}

private class ModeStateMachine extends StateMachine {
...
 private boolean checkForAndHandleModeChange(Message message) {
	 case ModeStateMachine.CMD_START_CLIENT_MODE:
	 mModeStateMachine.transitionTo(mClientModeActiveState); //跳转到ClientModeActiveState
 }
 }

class ClientModeActiveState extends ModeActiveState {
	public void enter() {
	mManager = mWifiInjector.makeClientModeManager(mListener); //创建ClientModeManager实例
	mManager.start(); //
	mActiveModeManagers.add(mManager);
	updateBatteryStatsWifiState(true);
	}
}

4. WifiStateMachinePrime --> ClientModeManager

• ClientModeManager 传递ClientModeStateMachine.CMD_START 开始wpa_supplicant初始化信号
• 更新 wifiState updateWifiState
• 通过WifiNative初始化Client Mode

frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeManager.java
public void start() {
mStateMachine.sendMessage(ClientModeStateMachine.CMD_START);
}

private class IdleState extends State {
public boolean processMessage(Message message) {
	 case CMD_START:
	  updateWifiState(WifiManager.WIFI_STATE_ENABLING,
               WifiManager.WIFI_STATE_DISABLED);

		mClientInterfaceName = mWifiNative.setupInterfaceForClientMode(
	       false /* not low priority */, mWifiNativeInterfaceCallback);
	if (TextUtils.isEmpty(mClientInterfaceName)) {
	   Log.e(TAG, "Failed to create ClientInterface. Sit in Idle");
	   updateWifiState(WifiManager.WIFI_STATE_UNKNOWN,
	                   WifiManager.WIFI_STATE_ENABLING);
	   updateWifiState(WifiManager.WIFI_STATE_DISABLED,
	                   WifiManager.WIFI_STATE_UNKNOWN);
	   break;
	}
	sendScanAvailableBroadcast(false); //send wifi  Scan Available  Broadcast
	mScanRequestProxy.enableScanningForHiddenNetworks(false);
	mScanRequestProxy.clearScanResults();
	transitionTo(mStartedState);
 }
}

5. ClientModeManager --> WifiNative

• ClientModeManager 通过CMD_START 将启动传递给WifiNative
• WifiNative 启动wpa_supplicant service
• wifiNative 通过SupplicantStaHal 建立与 wpa_supplicant/hidl/1.1 的sta_iface.cpp 关联（ifaceName）
• wifiNative 向NetworkManagementService 注册NetworkObserverInternal 实例，用于监视 设备iface一举一动
• wifiNative 开启wifiMonitor ， 其开始接手所有的事项（消息以及事件），一有变化就上报framework(wifiStateMachine、wifiServiceImpl、SupplicantStaIfaceHal等等），就像是东厂的小兵，监视着下面的一举一动，一有变化马上上报头头

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java
public String setupInterfaceForClientMode(boolean lowPrioritySta, @NonNull InterfaceCallback interfaceCallback) {
	... 
    	startSupplicant(); // 启动 wpa_supplicant 
    	.. 
    	mWificondControl.setupInterfaceForClientMode(iface.name); // 初始化与wificondcontrol 关联(用于后续wificond 作为framework与 wpa_supplicant 之间的通信信使
    	..
    	mSupplicantStaIfaceHal.setupIface(iface.name); // 
    	mWifiMonitor.startMonitoring(iface.name); // 启动WifiMonitor 上报所有的wpa_supplicant msg&event 
    	initializeNwParamsForClientInterface(iface.name);
}

6. WifiNative–> WificondControl

• WificondControl 通过 binder 连接到wificond （server.cpp），创建ClientInterface
• WificondControl 通过binder 连接到 client_interface_binder.cpp 获取 wificondScaner ，用于wifi scan（上报scan results）
• WificondControl 创建 pnoScan + Scan Event Handler ， 且将之与设备 ifaceName 关联

frameworks/opt/net/wifi/service/java/com/android/server/wifi/WificondControl.java
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WificondControl.java
 public IClientInterface setupInterfaceForClientMode(@NonNull String ifaceName){
   ... 
    clientInterface = mWificond.createClientInterface(ifaceName); //创建ClientInterface
    ..
    mClientInterfaces.put(ifaceName, clientInterface); 
     IWifiScannerImpl wificondScanner = clientInterface.getWifiScannerImpl(); // 获取WifiScannerImpl
     PnoScanEventHandler pnoScanEventHandler = new PnoScanEventHandler(ifaceName);
     mPnoScanEventHandlers.put(ifaceName,  pnoScanEventHandler);
     wificondScanner.subscribePnoScanEvents(pnoScanEventHandler);
}