Android(安卓)P Wifi Enable 之后扫描流程
16lz
2021-12-18
文章目录
- 流程框架图
- 代码流程
- 1. ClientModeManager.ClientModeStateMachine
- 2. WifiTracker.BroadcastReceiver --> wifiManager.StartScan
- 3. wifiManager.StartScan --> WifiServiceImpl --> ScanRequestProxy.StartScan
- 4. WifiScanner.startScan --> WifiScaningServiceImpl.ClientHandler.handleMessage
- 5. WifiScanner.startScan --> WifiScaningServiceImpl.ClientHandler.handleMessage
- 6. WifiScaningServiceImpl.tryToStartNewScan -- WifiNative.scan
- 7. WifiNative.scan --> WificondControl
- 8. 扫描结果回传
流程框架图
通常，我们在设备开启Wifi之后，等会儿自动扫描出周围的热点，注意此时我们并没有点击扫描键，只是点击了一下wifi 开关就可以完成两件事情（1. 开启wifi，2. 扫描周围热点），问题，第二点是如何实现的呢？请详看本文 ~~ - 这里先参考Android P Wifi Enable 流程
- 有上一步，本文就容易理解
- 先上一张流程图
代码流程
以下的代码流程，在Android P WiFi Enable 流程基础上往下继续
1. ClientModeManager.ClientModeStateMachine
- ClientModeStateMachine 由CMD_START 转换到StartedState
- StartedState 状态机，在更新wifiState时，发送广播 WifiManager.WIFI_STATE_CHANGED_ACTION ， 通知WifiTracker 开始进行Scan
frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeManager.javapublic boolean processMessage(Message message) { .... mClientInterfaceName = mWifiNative.setupInterfaceForClientMode .... transitionTo(mStartedState); //跳转到 StartedState}private class StartedState extends State { ... private void onUpChanged(boolean isUp) { .... sendScanAvailableBroadcast(true); mWifiStateMachine.setOperationalMode(WifiStateMachine.CONNECT_MODE, // 发 WifiManager.WIFI_STATE_CHANGED_ACTION 广播通知 wifiTracker 启动startScan updateWifiState(WifiManager.WIFI_STATE_ENABLED,WifiManager.WIFI_STATE_ENABLING); }}2. WifiTracker.BroadcastReceiver --> wifiManager.StartScan
- WifiTracker 广播监听到WifiManager.WIFI_STATE_CHANGED_ACTION ，开启wifiManager.StartScan
frameworks/base/packages/SettingsLib/src/com/android/settingslib/wifi/WifiTracker.javapublic void onReceive(Context context, Intent intent) {if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)){updateWifiState(intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE,WifiManager.WIFI_STATE_UNKNOWN));}}private void updateWifiState(int state) {1. WifiManager.WIFI_STATE_ENABLEDmScanner.resume();2.wifi 非enabled 则 mScanner.pause();}public void handleMessage(Message message) { .. mWifiManager.startScan(); // 开启Wifi Scan }3. wifiManager.StartScan --> WifiServiceImpl --> ScanRequestProxy.StartScan
- 获取mWifiScanner 实例
- 检查 调用者UID ， apk package 是否有权限进行Scan，如无则直接放回
- Create a worksource using the caller’s UID.
- Create the scan settings.
- 初始化Scan 的band 为DFS，是否Scan 隐藏的AP
- mWifiScanner 发起StartScan
frameworks/opt/net/wifi/service/java/com/android/server/wifi/ScanRequestProxy.javapublic boolean startScan(int callingUid, String packageName){retrieveWifiScannerIfNecessary();...// Create a worksource using the caller's UID. WorkSource workSource = new WorkSource(callingUid); // Create the scan settings. WifiScanner.ScanSettings settings = new WifiScanner.ScanSettings(); // always do full scans settings.band = WifiScanner.WIFI_BAND_BOTH_WITH_DFS; settings.reportEvents = WifiScanner.REPORT_EVENT_AFTER_EACH_SCAN | WifiScanner.REPORT_EVENT_FULL_SCAN_RESULT;mWifiScanner.startScan(settings, new ScanRequestProxyScanListener(), workSource);}4. WifiScanner.startScan --> WifiScaningServiceImpl.ClientHandler.handleMessage
- 发送scan 请求[CMD_START_SINGLE_SCAN ] to WifiScaningServiceImpl 处理
frameworks/base/wifi/java/android/net/wifi/WifiScanner.javapublic void startScan(ScanSettings settings, ScanListener listener, WorkSource workSource) {scanParams.putParcelable(SCAN_PARAMS_SCAN_SETTINGS_KEY, settings);scanParams.putParcelable(SCAN_PARAMS_WORK_SOURCE_KEY, workSource);mAsyncChannel.sendMessage(CMD_START_SINGLE_SCAN, 0, key, scanParams);}5. WifiScanner.startScan --> WifiScaningServiceImpl.ClientHandler.handleMessage
- 先进行有效Scan检查
- 当前正在Scanning，如为有效的(活)scaning，标志为ActiveScans，否则标志为PendingScans
- 当前非Scanning，标志为PendingScans，开启一次新的Scan – tryToStartNewScan()
- 非有效Scan，上报错误Failed
frameworks/opt/net/wifi/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.java class DriverStartedState extends State { case WifiScanner.CMD_START_SINGLE_SCAN: .... 一大堆code （其实就干了几件事情，见上面描述） .... tryToStartNewScan(); }6. WifiScaningServiceImpl.tryToStartNewScan – WifiNative.scan
- WifiScaningServiceImpl 到WifiScannerImpl
- WifiScannerImpl 再到WificondScannerImpl
- WificondScannerImpl最终到WifiNative ， 可见与Android N 相比，O、P 的Scan变化太大，但是其套路还是不变，就是上面的环节无论是如何地进行封装，最后还是给到WifiNative 来处理
frameworks/opt/net/wifi/service/java/com/android/server/wifi/scanner/WifiScanningServiceImpl.javavoid tryToStartNewScan() {....mScannerImpl.startSingleScan(settings, this);}frameworks/opt/net/wifi/service/java/com/android/server/wifi/scanner/WifiScannerImpl.javapublic abstract boolean startSingleScan(WifiNative.ScanSettings settings,WifiNative.ScanEventHandler eventHandler);frameworks/opt/net/wifi/service/java/com/android/server/wifi/scanner/WificondScannerImpl.java public boolean startSingleScan(WifiNative.ScanSettings settings, WifiNative.ScanEventHandler eventHandler) { .... freqs = allFreqs.getScanFreqs(); success = mWifiNative.scan(mIfaceName, settings.scanType, freqs, hiddenNetworkSSIDSet); }7. WifiNative.scan --> WificondControl
- WifiNative 转到 WificondControl
- WificondControl 通过binder 到wificond
- wificond 开始初步的scan 任务 （scannerImpl.scan）
- scannerImpl 传到scan_utils
- scan_utils 通过netlink 将 NL80211_CMD_TRIGGER_SCAN传递wpa_supplicant(driver_nl80211_event.c)
- driver_nl80211_event 将cmd下到wlan drv 里，开始了真正的干活 – scanning
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.javapublic boolean scan( @NonNull String ifaceName, int scanType, Set freqs, Set hiddenNetworkSSIDs) {mWificondControl.scan(ifaceName, scanType, freqs, hiddenNetworkSSIDs);}frameworks/opt/net/wifi/service/java/com/android/server/wifi/WificondControl.java public boolean scan(@NonNull String ifaceName, int scanType, Set freqs,Set hiddenNetworkSSIDs){ .. scannerImpl.scan(settings); }system/connectivity/wificond/scanning/scanner_impl.cppStatus ScannerImpl::scan(const SingleScanSettings& scan_settings, bool* out_success) {scan_utils_->Scan(interface_index_, request_random_mac, scan_type,ssids, freqs, &error_code)； // }system/connectivity/wificond/scanning/scan_utils.cppbool ScanUtils::Scan(uint32_t interface_index, bool request_random_mac, int scan_type, const vector>& ssids, const vector& freqs, int* error_code) { NL80211Packet trigger_scan( netlink_manager_->GetFamilyId(), NL80211_CMD_TRIGGER_SCAN, netlink_manager_->GetSequenceNumber(), getpid()); if (scan_flags) { trigger_scan.AddAttribute( NL80211Attr(NL80211_ATTR_SCAN_FLAGS, scan_flags)); } // We are receiving an ERROR/ACK message instead of the actual // scan results here, so it is OK to expect a timely response because // kernel is supposed to send the ERROR/ACK back before the scan starts. vector> response; if (!netlink_manager_->SendMessageAndGetAckOrError(trigger_scan, error_code)) { // Logging is done inside |SendMessageAndGetAckOrError|. return false; }} 8. 扫描结果回传
- 具体与scan 执行流恰为逆向，可参见上面的整体框架图
- 这里简单说明下，当wlan drv 完成scan 之后
- 由 wificond 直接给到WificondControl，
- WificondControl.OnScanResultReady 上报 WifiMonitor
- WifiMonitor -> WificondScannerImpl -> WifiScaningServiceImpl->
- WifiScaningServiceImpl ->WifiService --> WifiTraker --> WifiSettings 刷新扫描结果
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