【Android 11 framework学习之wifi 断开连接】

wifi断开连接时序图如下，直接从framework api开始分析：

WifiManager最终调用到WifiServiceImpl中的disconnect

/*** android.net.wifi.WifiManager.disconnect ***/

public boolean disconnect() {
    try { 
        return mService.disconnect(mContext.getOpPackageName());
    } catch (RemoteException e) {
        throw e.rethrowSystemServer();
    }
}

disconnect是disconnect2的一个封装，实际调用到disconnect2

/*** com.android.server.wifi.WifiServiceImpl.disconnect2 ***/

public boolean disconnect2(int staId, String packageName) {
    ...
    if (staId == STA_PRIMARY) {
        mClientModeImpl.disconnectCommand();
    } ...
}

ClientModeImpl状态机中发送了CMD_DISCONNECT的消息

/*** com.android.server.wifi.ClientModeImpl.disconnectCommand ***/

public void disconnectCommand() {
    sendMessage(CMD_DISCONNECT);
}

连接之后状态机为ConnectedState，接下来处理此消息，由于ConnectedState对消息CMD_DISCONNECT没有处理，将交给其父状态L2ConnectedState处理此消息

在L2ConnectedState中，直接调用了WifiNative.disconnect方法断开当前连接的热点，然后将状态机切换到DisconnectingState状态

/*** com.android.server.wifi.ClientModeImpl.L2ConnectedState.processMessage ***/

public boolean processMessage(Message message) {
    ...
    switch (message.what) {
        case CDM_DISCONNECT:
            ...
            mWifiNative.disconnect(mInterfaceName);
            transitionTo(mDisconnectingState);
            break;
        ...
    }
}

可以看到WifiNative中直接调用了 SupplicantStaIfaceHal.disconnect

/*** com.android.server.wifi.WifiNative.disconnect ***/

public boolean disconnect(@NonNull String ifaceName) {
    return mSupplicantStaIfaceHal.disconnect(ifaceName);
}

通过HIDL调用了HAL层中的disconnect方法

/*** com.android.server.wifi.SupplicantStaIfaceHal.disconnect ***/

public boolean disconnect(@NonNull String ifaceName) {
    ...
    ISupplicantStaIface iface = checkSupplicantStaIfaceAndLogFailure(ifaceName, methodStr);
    ...
    SupplicantStatus status = iface.disconnect();
    ...
}

上报断开状态
由于在开启wifi时，向ISupplicantStaIface注册了回调类SupplicantStaIfaceHalCallback其父类为SupplicantStaIfaceCallbackImpl，再看SupplicantStaIfaceCallbackImpl的回调方法onDisconnect

/*** com.android.server.wifi.SupplicantStaIfaceCallbackImpl.onDisconnected ***/

public void onDisconnected(byte[/* 6 */] bssid, boolean locallyGenerated, int reasonCode) {
   synchronized (mLock) {
        ...
        mWifiMonitor.broadcastNetworkDisconnectionEvent(
                mIfaceName, locallyGenerated ? 1 : 0, reasonCode,
                NativeUtil.macAddressFromByteArray(bssid));
   }
}

这里其实是给ClientModeImpl发送消息(Handler机制)，由于回调是跨进程的，所以会排在当前消息后面。

/*** com.android.server.wifi.WifiMonitor.broadcastNetworkDisconnectionEvent ***/

public void broadcastNetworkDisconnectionEvent(String iface, int local, int reason,
                                              String bssid) {
   sendMessage(iface, NETWORK_DISCONNECTION_EVENT, local, reason, bssid);
}

上面step4状态机切换到了DisconnectingState，那么 broadcastNetworkDisconnectionEvent 方法发送的NETWORK_DISCONNECTION_EVENT是交给DisconnectingState状态处理了。由于DisconnectingState状态没有处理，会交由其父状态ConnectModeState处理
调用handleNetworkDisconnect之后，状态机切换到DisconnectedState状态

/*** com.android.server.wifi.ClientModeImpl.ConnectModeState.processMessage ***/

public boolean processMessage(Message message) {
    ...
    switch (message.what) {
        ...
        case WifiMonitor.NETWORK_DISCONNECTION_EVENT:
            if (mVerboseLoggingEnabled) log("ConnectModeState: Network connection lost ");
            clearNetworkCachedDataIfNeeded(getTargetWifiConfiguration(), message.arg2);
            handleNetworkDisconnect();
            transitionTo(mDisconnectedState);
            break;
        ...
    }
...
}

这里对外发送了wifi状态变化的广播，并且状态为DetailedState.DISCONNECTED，这个广播发送出去后表示wifi完全断开热点成功

/*** com.android.server.wifi.ClientModeImpl.sendNetworkChangeBroadcast ***/

private void handleNetworkDisconnect() {
    ...
    sendNetworkChangeBroadcast(DetailedState.DISCONNECTED);
    ...
}

参考：
https://blog.youkuaiyun.com/qq_39036223/article/details/125166836