一、先上流程
wifi1.png
二、代码流程
2.1 应用层
2.1.1 入口
//packages/apps/settings/WifiSettings.java
@Override
public void onStart() {
super.onStart();
// On/off switch is hidden for Setup Wizard (returns null)
mWifiEnabler = createWifiEnabler();
if (mIsRestricted) {
restrictUi();
return;
}
onWifiStateChanged(mWifiManager.getWifiState());
}
private WifiEnabler createWifiEnabler() {
final SettingsActivity activity = (SettingsActivity) getActivity();
return new WifiEnabler(activity, new SwitchBarController(activity.getSwitchBar()),
mMetricsFeatureProvider);
}
2.1.2 监听动作：开启Wifi开关变会有下面的操作。
@Override
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/listener loop.
mSwitchWidget.setChecked(false);
return false;
}
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;
}
2.2 java 框架层
2.2.1 入口 WifiManager.java
//frameworks/base/wifi/java/android/net/wifi/WifiManager.java
public boolean setWifiEnabled(boolean enabled) {
try {
return mService.setWifiEnabled(mContext.getOpPackageName(), enabled);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}
//调用service的接口aidl
//frameworks/base/wifi/java/android/net/wifi/IWifiManager.aidl
boolean setWifiEnabled(String packageName, boolean enable);
2.2.2 实现 WifiSeviceImpl.java
//frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiSeviceImpl.java
@Override
public synchronized boolean setWifiEnabled(String packageName, boolean enable)throws RemoteException {
if (enforceChangePermission(packageName) != MODE_ALLOWED) { return false;
}
Slog.d(TAG, "setWifiEnabled: " + enable + " pid=" + Binder.getCallingPid()
+ ", uid=" + Binder.getCallingUid() + ", package=" + packageName);
mLog.info("setWifiEnabled package=% uid=% enable=%").c(packageName).c(Binder.getCallingUid()).c(enable).flush();
boolean isFromSettings = checkNetworkSettingsPermission(
Binder.getCallingPid(), Binder.getCallingUid());
// If Airplane mode is enabled, only Settings is allowed to toggle Wifi
if (mSettingsStore.isAirplaneModeOn() && !isFromSettings) {
mLog.info("setWifiEnabled in Airplane mode: only Settings can enable wifi").flush();
return false;
}
// If SoftAp is enabled, only Settings is allowed to toggle wifi
boolean apEnabled = mWifiApState == WifiManager.WIFI_AP_STATE_ENABLED;
if (apEnabled && !isFromSettings) {
mLog.info("setWifiEnabled SoftAp not disabled: only Settings can enable wifi").flush();
return false;
}
/*
* Caller might not have WRITE_SECURE_SETTINGS,
* only CHANGE_WIFI_STATE is enforced
*/
long ident = Binder.clearCallingIdentity();
try {
if (! mSettingsStore.handleWifiToggled(enable)) {
// Nothing to do if wifi cannot be toggled
return true;
}
} finally {
Binder.restoreCallingIdentity(ident);
}
if (mPermissionReviewRequired) {
final int wiFiEnabledState = getWifiEnabledState();
if (enable) {
if (wiFiEnabledState == WifiManager.WIFI_STATE_DISABLING
|| wiFiEnabledState == WifiManager.WIFI_STATE_DISABL){
if (startConsentUi(packageName, Binder.getCallingUid(),
WifiManager.ACTION_REQUEST_ENABLE)) {
return true;
}
}
} else if (wiFiEnabledState == WifiManager.WIFI_STATE_ENABLING
|| wiFiEnabledState == WifiManager.WIFI_STATE_ENABLED) {
if (startConsentUi(packageName, Binder.getCallingUid(),
WifiManager.ACTION_REQUEST_DISABLE)) {
return true;
}
}
}
mWifiController.sendMessage(CMD_WIFI_TOGGLED);
return true;
}
解释：
WifiManager.setWifiEnabled通过aidl跨进程调用到了WifiServiceImpl.setWifiEnabled,
其中WifiServiceImpl是WifiService的实现类。
在WifiServiceImpl的setWifiEnabled方法里做的一些事情：
- enforceChangePermission 判断调用的进程是否有权限。想要开关wifi需要CHANGE_WIFI_STATE 权限。
- isAirplaneModeOn 判断飞行模式。
- handleWifiToggled 保存wifi 操作的状态。
- 向【WifiController】发送CMD_WIFI_TOGGLED消息。
2.2.3 WifiController处理
WifiController，是一个状态机，可能Android每个版本的状态机不完全一样，比如Android P 和Android O比起来状态机减少了一些分支。 WifiController在WIfiServiceImpl的构造函数中初始化、并开始运行。
WifiController 和WifiStateMachine 不同，WifiStateMachine是一个复杂的状态机，它维护了Wifi的启动、扫描、连接、断开等多个状态。WifiController 是高级别的wifi状态机，因为它管理的状态是wifi开关，wifi热点开关等状态，只有在wifi开关等具体状态下，判断wifi处于启动扫描附近热点状态等才是有意义的。
//frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiController.java
WifiController(Context context, WifiStateMachine wsm, Looper
wifiStateMachineLooper, WifiSettingsStore wss, Looper
wifiServiceLooper, FrameworkFacade f,WifiStateMachinePrime wsmp) {
super(TAG, wifiServiceLooper);
...
// CHECKSTYLE:OFF IndentationCheck
addState(mDefaultState);
addState(mStaDisabledState, mDefaultState);
addState(mStaEnabledState, mDefaultState);
addState(mDeviceActiveState, mStaEnabledState);
addState(mStaDisabledWithScanState, mDefaultState);
addState(mEcmState, mDefaultState);
// CHECKSTYLE:ON IndentationCheck
...
if (checkScanOnlyModeAvailable()) {
setInitialState(mStaDisabledWithScanState);
}else {
setInitialState(mStaDisabledState);
}
//...
}
WifiController状态机各状态关系：
状态机关系图
状态机初始状态为StaDisabledState，在该状态下对CMD_WIFI_TOGGLED消息的处理：
在DeviceActiveState状态下主要做了两个操作：
- mWifiStateMachinePrime.enterClientMode()
- mWifiStateMachine.setHighPerfModeEnabled(false)
接下来，我们主要看mWifiStateMachinePrime.enterClientMode()。
2.2.4 ClientMode模式
//frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiStateMachinePrime.java
/**
* Method to switch wifi into client mode where connections to configured networks will be
* attempted.
*/
public void enterClientMode() {
changeMode(ModeStateMachine.CMD_START_CLIENT_MODE);
}
private void changeMode(int newMode) {
mModeStateMachine.sendMessage(newMode);
}
ModeStateMachine又是一个状态机，不过这个状态机比较简单只有三个状态，初始状态为WifiDisabledState。
2.2.5 ModeStateMachine状态机处理
private class ModeStateMachine extends StateMachine {
// Commands for the state machine - these will be removed,
// along with the StateMachine itself
public static final int CMD_START_CLIENT_MODE = 0;
public static final int CMD_START_SCAN_ONLY_MODE = 1;
public static final int CMD_DISABLE_WIFI = 3;
private final State mWifiDisabledState = new WifiDisabledState();
private final State mClientModeActiveState = new ClientModeActiveState();
private final State mScanOnlyModeActiveState = new ScanOnlyModeActiveState();
ModeStateMachine() {
super(TAG, mLooper);
addState(mClientModeActiveState);
addState(mScanOnlyModeActiveState);
addState(mWifiDisabledState);
Log.d(TAG, "Starting Wifi in WifiDisabledState");
setInitialState(mWifiDisabledState);
start();
...
}
}
状态机从WifiDisabledState状态转向ClientModeActiveState状态，所以再继续看ClientModeActiveState。
ClientModeActiveState将进入ActiveModeManager
2.2.6 ActiveModeManager
//frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeManager.java
/**
* Start client mode.
*/
public void start() {
mStateMachine.sendMessage(ClientModeStateMachine.CMD_START);
}
private class ClientModeStateMachine extends StateMachine {
// Commands for the state machine.
public static final int CMD_START = 0;
public static final int CMD_INTERFACE_STATUS_CHANGED = 3;
public static final int CMD_INTERFACE_DESTROYED = 4;
public static final int CMD_INTERFACE_DOWN = 5;
private final State mIdleState = new IdleState();
private final State mStartedState = new StartedState();
...
ClientModeStateMachine(Looper looper) {
super(TAG, looper);
addState(mIdleState);
addState(mStartedState);
setInitialState(mIdleState);
start();
}
...
}
2.2.7 Idlesate状态
此状态机将让wifi进入到Native层，
请关注：mWifiNative.setupInterfaceForClientMode的操作。
private class IdleState extends State {
@Override
public void enter() {
Log.d(TAG, "entering IdleState");
mClientInterfaceName = null;
mIfaceIsUp = false;
}
@Override
public boolean processMessage(Message message) {
switch (message.what) {
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);
mScanRequestProxy.enableScanningForHiddenNetworks(false);
mScanRequestProxy.clearScanResults();
transitionTo(mStartedState);
break;
default:
Log.d(TAG, "received an invalid message: " + message);
return NOT_HANDLED;
}
return HANDLED;
}
}
3 Native层
3.1 入口及调用
- 启动Hal：startHal()
- 启动supplicant：startSupplicant()
- 加载驱动（loadDriver）：setupInterfaceForClientMode()
- 启动WifiMonitor：WifiMonitor.startMonitoring()
//frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java
/**
* Setup an interface for Client mode operations.
*
* * This method configures an interface in STA mode in all the native daemons
* (wificond, wpa_supplicant & vendor HAL).
*
* @param lowPrioritySta The requested STA has a low request priority (lower probability of
* getting created, higher probability of getting destroyed).
* @param interfaceCallback Associated callback for notifying status changes for the iface.
* @return Returns the name of the allocated interface, will be null on failure.
*/
public String setupInterfaceForClientMode(boolean lowPrioritySta,
@NonNull InterfaceCallback interfaceCallback) {
synchronized (mLock) {
if (!startHal()) {
Log.e(TAG, "Failed to start Hal");
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToHal();
return null;
}
if (!startSupplicant()) {
Log.e(TAG, "Failed to start supplicant");
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();
return null;
}
Iface iface = mIfaceMgr.allocateIface(Iface.IFACE_TYPE_STA);
if (iface == null) {
Log.e(TAG, "Failed to allocate new STA iface");
return null;
}
iface.externalListener = interfaceCallback;
iface.name = createStaIface(iface, lowPrioritySta);
if (TextUtils.isEmpty(iface.name)) {
Log.e(TAG, "Failed to create STA iface in vendor HAL");
mIfaceMgr.removeIface(iface.id);
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToHal();
return null;
}
if (mWificondControl.setupInterfaceForClientMode(iface.name) == null) {
Log.e(TAG, "Failed to setup iface in wificond on " + iface);
teardownInterface(iface.name);
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToWificond();
return null;
}
if (!mSupplicantStaIfaceHal.setupIface(iface.name)) {
Log.e(TAG, "Failed to setup iface in supplicant on " + iface);
teardownInterface(iface.name);
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();
return null;
}
iface.networkObserver = new NetworkObserverInternal(iface.id);
if (!registerNetworkObserver(iface.networkObserver)) {
Log.e(TAG, "Failed to register network observer on " + iface);
teardownInterface(iface.name);
return null;
}
mWifiMonitor.startMonitoring(iface.name);
// Just to avoid any race conditions with interface state change callbacks,
// update the interface state before we exit.
onInterfaceStateChanged(iface, isInterfaceUp(iface.name));
initializeNwParamsForClientInterface(iface.name);
Log.i(TAG, "Successfully setup " + iface);
return iface.name;
}
}
总结：
WifiMonitor.startMonitoring()：这一步主要是在WifiMonitor中建立与wpa_supplicant通信的socket通道、创建一个线程接收底层事件并分发处理。这里会创建两个socket通道与wpa_s通信，一个用于下发指令，另一个用于接收事件。成功后WifiMonitor会向WifiStateMachine发送一个代表socket通信建立成功的消息：SUP_CONNECTION_EVENT；收到这个消息就表示Wifi已经启动成功了。
Android P和Android O相比还是有不少变化的，主要是关键性的操作不再走WifiStateMachine这个线了，而是通过另外两个比较简单的状态机ModeStateMachine和ClientModeStateMachine。
接下来将详解Wifi的Native的流程。
完~~
文 | 力卉编程
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