WifiP2pService工作流程
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WifiP2pService工作流程
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本文為《深入理解Android Wi-Fi、NFC和GPS卷》讀書筆記，Android源碼為Android 5.1
主要特點就是無底線的粘貼源碼
android-5.1/frameworks/opt/net/wifi/service/java/com/android/server/wifi/p2p/WifiP2pService.java
public WifiP2pService(Context context) {super(context);mImpl = new WifiP2pServiceImpl(context);} public WifiP2pServiceImpl(Context context) {mContext = context;//STOPSHIP: get this from native sidemInterface = "p2p0";//P2P使用的虛擬網絡接口設備名為p2p0mNetworkInfo = new NetworkInfo(ConnectivityManager.TYPE_WIFI_P2P, 0, NETWORKTYPE, "");//判斷系統是否支持WiFi-Direct功能mP2pSupported = mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT);//獲取PrimaryDeviceType，默認值是 10-0050F204-5//10是Category ID，代表Telephone//0050F204是WFA的OUI，最后一個5是Sub Category ID，在Telephone大類里邊，它代表支持Dual Mode的Smartphone(規范中定義為Smart phone-Dual mode)mThisDevice.primaryDeviceType = mContext.getResources().getString(com.android.internal.R.string.config_wifi_p2p_device_type);HandlerThread wifiP2pThread = new HandlerThread("WifiP2pService");wifiP2pThread.start();mClientHandler = new ClientHandler(wifiP2pThread.getLooper());//WifiP2pService主要工作也是由狀態機來完成的，即下面的這個P2pStateMachinemP2pStateMachine = new P2pStateMachine(TAG, wifiP2pThread.getLooper(), mP2pSupported);mP2pStateMachine.start();} P2pStateMachine(String name, Looper looper, boolean p2pSupported) {super(name, looper);addState(mDefaultState);//為狀態機添加狀態，一共15個狀態addState(mP2pNotSupportedState, mDefaultState);addState(mP2pDisablingState, mDefaultState);addState(mP2pDisabledState, mDefaultState);addState(mP2pEnablingState, mDefaultState);addState(mP2pEnabledState, mDefaultState);addState(mInactiveState, mP2pEnabledState);addState(mGroupCreatingState, mP2pEnabledState);addState(mUserAuthorizingInviteRequestState, mGroupCreatingState);addState(mUserAuthorizingNegotiationRequestState, mGroupCreatingState);addState(mProvisionDiscoveryState, mGroupCreatingState);addState(mGroupNegotiationState, mGroupCreatingState);addState(mFrequencyConflictState, mGroupCreatingState);addState(mGroupCreatedState, mP2pEnabledState);addState(mUserAuthorizingJoinState, mGroupCreatedState);addState(mOngoingGroupRemovalState, mGroupCreatedState);if (p2pSupported) {setInitialState(mP2pDisabledState);//初始狀態為P2pDisableState} else {setInitialState(mP2pNotSupportedState);}setLogRecSize(50);setLogOnlyTransitions(true);}P2pStateMachine此時處于 P2pDisabledState ，它對 CMD_ENABLE_P2P 消息的處理邏輯如下：
android-5.1/frameworks/opt/net/wifi/service/java/com/android/server/wifi/p2p/WifiP2pServiceImpl.java
class P2pDisabledState extends State {@Overridepublic void enter() {if (DBG) logd(getName());}@Overridepublic boolean processMessage(Message message) {if (DBG) logd(getName() + message.toString());switch (message.what) {case WifiStateMachine.CMD_ENABLE_P2P:try {mNwService.setInterfaceUp(mInterface);} catch (RemoteException re) {loge("Unable to change interface settings: " + re);} catch (IllegalStateException ie) {loge("Unable to change interface settings: " + ie);}//啟動WifiMonitor，它將通過wpa_ctl連接上wpa_supplicantmWifiMonitor.startMonitoring();//轉入P2pEnablingState，其EA未做有益于的事情transitionTo(mP2pEnablingState);break;default:return NOT_HANDLED;}return HANDLED;}}WiFiMonitor連接wpa_supplicant之后，WiFiMonitor會發送一個 SUP_CONNECTION_EVENT 給 P2pStateMachine。該消息將由 P2pEnablingState 處理：
android-5.1/frameworks/opt/net/wifi/service/java/com/android/server/wifi/p2p/WifiP2pServiceImpl.java
class P2pEnablingState extends State {@Overridepublic void enter() {if (DBG) logd(getName());}@Overridepublic boolean processMessage(Message message) {if (DBG) logd(getName() + message.toString());switch (message.what) {case WifiMonitor.SUP_CONNECTION_EVENT:if (DBG) logd("P2p socket connection successful");transitionTo(mInactiveState);//轉入InactiveStatebreak;case WifiMonitor.SUP_DISCONNECTION_EVENT:loge("P2p socket connection failed");transitionTo(mP2pDisabledState);break;case WifiStateMachine.CMD_ENABLE_P2P:case WifiStateMachine.CMD_DISABLE_P2P_REQ:deferMessage(message);break;default:return NOT_HANDLED;}return HANDLED;}}android-5.1/frameworks/opt/net/wifi/service/java/com/android/server/wifi/p2p/WifiP2pServiceImpl.java
class P2pEnabledState extends State {@Overridepublic void enter() {if (DBG) logd(getName());//發送WIFI_P2P_STATE_CHANGED_ACTION廣播并設置 EXTRA_WIFI_STATE 狀態為 WIFI_P2P_STATE_ENABLEDsendP2pStateChangedBroadcast(true);mNetworkInfo.setIsAvailable(true);//發送WIFI_P2P_CONNECTION_CHANGED_ACTION廣播,它將攜帶WifiP2pInfo和NetworkInfo消息。//注意，下面這個函數還會向WiFiStateMachine發送P2P_CONNECTION_CHANGED消息。sendP2pConnectionChangedBroadcast();initializeP2pSettings();//初始化P2P的一些設置}@Overridepublic boolean processMessage(Message message) {if (DBG) logd(getName() + message.toString());switch (message.what) {case WifiMonitor.SUP_DISCONNECTION_EVENT:loge("Unexpected loss of p2p socket connection");transitionTo(mP2pDisabledState);break;case WifiStateMachine.CMD_ENABLE_P2P://Nothing to dobreak;case WifiStateMachine.CMD_DISABLE_P2P_REQ:if (mPeers.clear()) {sendPeersChangedBroadcast();}if (mGroups.clear()) sendP2pPersistentGroupsChangedBroadcast();mWifiMonitor.stopMonitoring();transitionTo(mP2pDisablingState);break;case WifiP2pManager.SET_DEVICE_NAME:{WifiP2pDevice d = (WifiP2pDevice) message.obj;if (d != null && setAndPersistDeviceName(d.deviceName)) {if (DBG) logd("set device name " + d.deviceName);replyToMessage(message, WifiP2pManager.SET_DEVICE_NAME_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.SET_DEVICE_NAME_FAILED,WifiP2pManager.ERROR);}break;}case WifiP2pManager.SET_WFD_INFO:{WifiP2pWfdInfo d = (WifiP2pWfdInfo) message.obj;if (d != null && setWfdInfo(d)) {replyToMessage(message, WifiP2pManager.SET_WFD_INFO_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.SET_WFD_INFO_FAILED,WifiP2pManager.ERROR);}break;}case BLOCK_DISCOVERY:boolean blocked = (message.arg1 == ENABLED ? true : false);if (mDiscoveryBlocked == blocked) break;mDiscoveryBlocked = blocked;if (blocked && mDiscoveryStarted) {mWifiNative.p2pStopFind();mDiscoveryPostponed = true;}if (!blocked && mDiscoveryPostponed) {mDiscoveryPostponed = false;mWifiNative.p2pFind(DISCOVER_TIMEOUT_S);}if (blocked) {try {StateMachine m = (StateMachine)message.obj;m.sendMessage(message.arg2);} catch (Exception e) {loge("unable to send BLOCK_DISCOVERY response: " + e);}}break;case WifiP2pManager.DISCOVER_PEERS:if (mDiscoveryBlocked) {replyToMessage(message, WifiP2pManager.DISCOVER_PEERS_FAILED,WifiP2pManager.BUSY);break;}// do not send service discovery request while normal find operation.clearSupplicantServiceRequest();//先取消Service Discovery請求//發送P2P_FIND 超時時間給WPAS， DISCOVER_TIMEOUT_S 值為120秒if (mWifiNative.p2pFind(DISCOVER_TIMEOUT_S)) {replyToMessage(message, WifiP2pManager.DISCOVER_PEERS_SUCCEEDED);發送 WIFI_P2P_DISCOVERY_CHANGED_ACTION廣播以通知P2P Device Discovery已啟動sendP2pDiscoveryChangedBroadcast(true);} else {replyToMessage(message, WifiP2pManager.DISCOVER_PEERS_FAILED,WifiP2pManager.ERROR);}break;case WifiMonitor.P2P_FIND_STOPPED_EVENT:sendP2pDiscoveryChangedBroadcast(false);break;case WifiP2pManager.STOP_DISCOVERY:if (mWifiNative.p2pStopFind()) {replyToMessage(message, WifiP2pManager.STOP_DISCOVERY_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.STOP_DISCOVERY_FAILED,WifiP2pManager.ERROR);}break;case WifiP2pManager.DISCOVER_SERVICES:if (mDiscoveryBlocked) {replyToMessage(message, WifiP2pManager.DISCOVER_SERVICES_FAILED,WifiP2pManager.BUSY);break;}if (DBG) logd(getName() + " discover services");if (!updateSupplicantServiceRequest()) {replyToMessage(message, WifiP2pManager.DISCOVER_SERVICES_FAILED,WifiP2pManager.NO_SERVICE_REQUESTS);break;}if (mWifiNative.p2pFind(DISCOVER_TIMEOUT_S)) {replyToMessage(message, WifiP2pManager.DISCOVER_SERVICES_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.DISCOVER_SERVICES_FAILED,WifiP2pManager.ERROR);}break;case WifiMonitor.P2P_DEVICE_FOUND_EVENT://WifiMonitor根據WPAS反饋的信息構建一個WifiP2pDevice對象WifiP2pDevice device = (WifiP2pDevice) message.obj;//如果搜索到的這個P2P Device是自己(根據Device Address來判斷)，則不處理它if (mThisDevice.deviceAddress.equals(device.deviceAddress)) break;//mPeers執行一個WifiP2pDeviceList對象。如果之前已存儲了此Device的信息，更新這些信息，否則將添加一個新的WifiP2pDevice對象mPeers.updateSupplicantDetails(device);sendPeersChangedBroadcast();//發送 WIFI_P2P_PEERS_CHANGED_ACTION 廣播break;case WifiMonitor.P2P_DEVICE_LOST_EVENT:device = (WifiP2pDevice) message.obj;// Gets current details for the one removeddevice = mPeers.remove(device.deviceAddress);if (device != null) {sendPeersChangedBroadcast();}break;case WifiP2pManager.ADD_LOCAL_SERVICE:if (DBG) logd(getName() + " add service");WifiP2pServiceInfo servInfo = (WifiP2pServiceInfo)message.obj;if (addLocalService(message.replyTo, servInfo)) {replyToMessage(message, WifiP2pManager.ADD_LOCAL_SERVICE_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.ADD_LOCAL_SERVICE_FAILED);}break;case WifiP2pManager.REMOVE_LOCAL_SERVICE:if (DBG) logd(getName() + " remove service");servInfo = (WifiP2pServiceInfo)message.obj;removeLocalService(message.replyTo, servInfo);replyToMessage(message, WifiP2pManager.REMOVE_LOCAL_SERVICE_SUCCEEDED);break;case WifiP2pManager.CLEAR_LOCAL_SERVICES:if (DBG) logd(getName() + " clear service");clearLocalServices(message.replyTo);replyToMessage(message, WifiP2pManager.CLEAR_LOCAL_SERVICES_SUCCEEDED);break;case WifiP2pManager.ADD_SERVICE_REQUEST:if (DBG) logd(getName() + " add service request");if (!addServiceRequest(message.replyTo, (WifiP2pServiceRequest)message.obj)) {replyToMessage(message, WifiP2pManager.ADD_SERVICE_REQUEST_FAILED);break;}replyToMessage(message, WifiP2pManager.ADD_SERVICE_REQUEST_SUCCEEDED);break;case WifiP2pManager.REMOVE_SERVICE_REQUEST:if (DBG) logd(getName() + " remove service request");removeServiceRequest(message.replyTo, (WifiP2pServiceRequest)message.obj);replyToMessage(message, WifiP2pManager.REMOVE_SERVICE_REQUEST_SUCCEEDED);break;case WifiP2pManager.CLEAR_SERVICE_REQUESTS:if (DBG) logd(getName() + " clear service request");clearServiceRequests(message.replyTo);replyToMessage(message, WifiP2pManager.CLEAR_SERVICE_REQUESTS_SUCCEEDED);break;case WifiMonitor.P2P_SERV_DISC_RESP_EVENT:if (DBG) logd(getName() + " receive service response");List<WifiP2pServiceResponse> sdRespList =(List<WifiP2pServiceResponse>) message.obj;for (WifiP2pServiceResponse resp : sdRespList) {WifiP2pDevice dev =mPeers.get(resp.getSrcDevice().deviceAddress);resp.setSrcDevice(dev);sendServiceResponse(resp);}break;case WifiP2pManager.DELETE_PERSISTENT_GROUP:if (DBG) logd(getName() + " delete persistent group");mGroups.remove(message.arg1);replyToMessage(message, WifiP2pManager.DELETE_PERSISTENT_GROUP_SUCCEEDED);break;case SET_MIRACAST_MODE:mWifiNative.setMiracastMode(message.arg1);break;case WifiP2pManager.START_LISTEN:if (DBG) logd(getName() + " start listen mode");mWifiNative.p2pFlush();if (mWifiNative.p2pExtListen(true, 500, 500)) {replyToMessage(message, WifiP2pManager.START_LISTEN_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.START_LISTEN_FAILED);}break;case WifiP2pManager.STOP_LISTEN:if (DBG) logd(getName() + " stop listen mode");if (mWifiNative.p2pExtListen(false, 0, 0)) {replyToMessage(message, WifiP2pManager.STOP_LISTEN_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.STOP_LISTEN_FAILED);}mWifiNative.p2pFlush();break;case WifiP2pManager.SET_CHANNEL:Bundle p2pChannels = (Bundle) message.obj;int lc = p2pChannels.getInt("lc", 0);int oc = p2pChannels.getInt("oc", 0);if (DBG) logd(getName() + " set listen and operating channel");if (mWifiNative.p2pSetChannel(lc, oc)) {replyToMessage(message, WifiP2pManager.SET_CHANNEL_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.SET_CHANNEL_FAILED);}break;case SET_COUNTRY_CODE:String countryCode = (String) message.obj;countryCode = countryCode.toUpperCase(Locale.ROOT);if (mLastSetCountryCode == null ||countryCode.equals(mLastSetCountryCode) == false) {if (mWifiNative.setCountryCode(countryCode)) {mLastSetCountryCode = countryCode;}}break;case WifiP2pManager.GET_HANDOVER_REQUEST:Bundle requestBundle = new Bundle();requestBundle.putString(WifiP2pManager.EXTRA_HANDOVER_MESSAGE,mWifiNative.getNfcHandoverRequest());replyToMessage(message, WifiP2pManager.RESPONSE_GET_HANDOVER_MESSAGE,requestBundle);break;case WifiP2pManager.GET_HANDOVER_SELECT:Bundle selectBundle = new Bundle();selectBundle.putString(WifiP2pManager.EXTRA_HANDOVER_MESSAGE,mWifiNative.getNfcHandoverSelect());replyToMessage(message, WifiP2pManager.RESPONSE_GET_HANDOVER_MESSAGE,selectBundle);break;default:return NOT_HANDLED;}return HANDLED;}@Overridepublic void exit() {sendP2pDiscoveryChangedBroadcast(false);sendP2pStateChangedBroadcast(false);mNetworkInfo.setIsAvailable(false);mLastSetCountryCode = null;}} private void initializeP2pSettings() {//發送SET persistent_reconnect 1給WPAS，該命令對應如下一種應用場景//當發現一個Persistent Group時，如果 persistent_reconnect 為1，則可利用之前保存的配置信息自動重連，重新連接時無需用戶參與。如果 persistent_reconnect 為0，則需要提醒用戶，讓用戶來決定是否加入此persistent group。mWifiNative.setPersistentReconnect(true);//獲取P2P設備名稱，先從數據庫中查詢 wifi_p2p_device_name 字段的值，如果數據庫中沒有設置該字段，則取數據庫中 android_id 字段值的前4個字符并在其前面加上 Android_ 字符串以組成P2P設備名。以Galaxy Note 2為例，數據庫文件是 /data/data/com.android.providers.settings/database/settings.db，所查詢的表名為secure， wifi_p2p_device_name字段取值為 Android_4aa9， android_id 字段取值為 4aa9213016889423mThisDevice.deviceName = getPersistedDeviceName();//mThisDevice指向一個WifiP2pDevice對象//將P2P設備名保存到WPAS中mWifiNative.setDeviceName(mThisDevice.deviceName);//設置P2P網絡SSID的后綴。如果本設備能扮演GO，則它創建的Group對應的SSID后綴就是此處設置的后綴名mWifiNative.setP2pSsidPostfix("-" + mThisDevice.deviceName);//設置Primary DeviceTypemWifiNative.setDeviceType(mThisDevice.primaryDeviceType);// Supplicant defaults to using virtual display with display// which refers to a remote display. Use physical_display//設置支持的WSC設置方法mWifiNative.setConfigMethods("virtual_push_button physical_display keypad");// STA has higher priority over P2P//設置STA連接的優先級高于P2P連接mWifiNative.setConcurrencyPriority("sta");//從WPAS獲取P2P Device AddressmThisDevice.deviceAddress = mWifiNative.p2pGetDeviceAddress();//更新自己的狀態，并發送 WIFI_P2P_THIS_DEVICE_CHANGED_ACTION 消息updateThisDevice(WifiP2pDevice.AVAILABLE);if (DBG) logd("DeviceAddress: " + mThisDevice.deviceAddress);mClientInfoList.clear();//清空WPAS中保存peer P2P Device和Service信息mWifiNative.p2pFlush();mWifiNative.p2pServiceFlush();mServiceTransactionId = 0;mServiceDiscReqId = null;String countryCode = Settings.Global.getString(mContext.getContentResolver(),Settings.Global.WIFI_COUNTRY_CODE);if (countryCode != null && !countryCode.isEmpty()) {mP2pStateMachine.sendMessage(SET_COUNTRY_CODE, countryCode);}//WPAS會保存 persistent Group 消息，而 P2pStateMachine 也會保存一些信息，下面這個函數將根據WPAS中的信息來更新P2pStateMachine 中保存的 Group 信息。 P2pStateMachine 通過一個名為 mGroups的成員變量(類型為WifiP2PGroupList)來保存所有的Group信息updatePersistentNetworks(RELOAD);}首先來看WifiP2pSettings中WifiP2pManager的discoveryPeers函數，它將發送DISCOVERY_PEERS消息給P2pStateMachine。
P2pStateMachine當前處于InactiveState，不過 DISCOVER_PEERS 消息確實由其父狀態P2pEnabledState來處理的，相關代碼見上面"case WifiP2pManager.DISCOVER_PEERS:"
當WPAS搜索到周圍的P2P Device后，將發送消息給WiFiMonitor，WiFiMonitor將根據這些信息構建一個WifiP2pDevice對象，然后發送 P2P_DEVICE_FOUND_EVENT 給 P2pStateMachine,P2P_DEVICE_FOUND_EVENT 也由InactiveState的父狀態 P2pEnabledState來處理，相關代碼見"case WifiMonitor.P2P_DEVICE_FOUND_EVENT:"
WifiP2pSettings收到 WIFI_P2P_PEERS_CHANGED_ACTION 廣播后，將通過WifiP2pManager的requestPeers來獲得當前搜索到的P2P Device信息(即mPeers的內容)。
現在用戶將選擇一個P2P Device然后通過 WifiP2pManager的connect函數向其發起連接，見下面的"case WifiP2pManager.CONNECT:"：
class InactiveState extends State {@Overridepublic void enter() {if (DBG) logd(getName());mSavedPeerConfig.invalidate();}@Overridepublic boolean processMessage(Message message) {if (DBG) logd(getName() + message.toString());switch (message.what) {case WifiP2pManager.CONNECT:if (DBG) logd(getName() + " sending connect");//WifiP2pSettings將設置一個WifiP2pConfig對象以告訴 P2pStateMachine該連接哪一個 P2P DeviceWifiP2pConfig config = (WifiP2pConfig) message.obj;if (isConfigInvalid(config)) {loge("Dropping connect requeset " + config);replyToMessage(message, WifiP2pManager.CONNECT_FAILED);break;}mAutonomousGroup = false;mWifiNative.p2pStopFind();if (reinvokePersistentGroup(config)) {transitionTo(mGroupNegotiationState);} else {transitionTo(mProvisionDiscoveryState);}mSavedPeerConfig = config;mPeers.updateStatus(mSavedPeerConfig.deviceAddress, WifiP2pDevice.INVITED);sendPeersChangedBroadcast();replyToMessage(message, WifiP2pManager.CONNECT_SUCCEEDED);break;case WifiP2pManager.STOP_DISCOVERY:if (mWifiNative.p2pStopFind()) {// When discovery stops in inactive state, flush to clear// state peer datamWifiNative.p2pFlush();mServiceDiscReqId = null;replyToMessage(message, WifiP2pManager.STOP_DISCOVERY_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.STOP_DISCOVERY_FAILED,WifiP2pManager.ERROR);}break;case WifiMonitor.P2P_GO_NEGOTIATION_REQUEST_EVENT:config = (WifiP2pConfig) message.obj;if (isConfigInvalid(config)) {loge("Dropping GO neg request " + config);break;}mSavedPeerConfig = config;mAutonomousGroup = false;mJoinExistingGroup = false;transitionTo(mUserAuthorizingNegotiationRequestState);break;case WifiMonitor.P2P_INVITATION_RECEIVED_EVENT:WifiP2pGroup group = (WifiP2pGroup) message.obj;WifiP2pDevice owner = group.getOwner();if (owner == null) {loge("Ignored invitation from null owner");break;}config = new WifiP2pConfig();config.deviceAddress = group.getOwner().deviceAddress;if (isConfigInvalid(config)) {loge("Dropping invitation request " + config);break;}mSavedPeerConfig = config;//Check if we have the owner in peer list and use appropriate//wps method. Default is to use PBC.if ((owner = mPeers.get(owner.deviceAddress)) != null) {if (owner.wpsPbcSupported()) {mSavedPeerConfig.wps.setup = WpsInfo.PBC;} else if (owner.wpsKeypadSupported()) {mSavedPeerConfig.wps.setup = WpsInfo.KEYPAD;} else if (owner.wpsDisplaySupported()) {mSavedPeerConfig.wps.setup = WpsInfo.DISPLAY;}}mAutonomousGroup = false;mJoinExistingGroup = true;transitionTo(mUserAuthorizingInviteRequestState);break;case WifiMonitor.P2P_PROV_DISC_PBC_REQ_EVENT:case WifiMonitor.P2P_PROV_DISC_ENTER_PIN_EVENT:case WifiMonitor.P2P_PROV_DISC_SHOW_PIN_EVENT://We let the supplicant handle the provision discovery response//and wait instead for the GO_NEGOTIATION_REQUEST_EVENT.//Handling provision discovery and issuing a p2p_connect before//group negotiation comes through causes issuesbreak;case WifiP2pManager.CREATE_GROUP:mAutonomousGroup = true;int netId = message.arg1;boolean ret = false;if (netId == WifiP2pGroup.PERSISTENT_NET_ID) {// check if the go persistent group is present.netId = mGroups.getNetworkId(mThisDevice.deviceAddress);if (netId != -1) {ret = mWifiNative.p2pGroupAdd(netId);} else {ret = mWifiNative.p2pGroupAdd(true);}} else {ret = mWifiNative.p2pGroupAdd(false);}if (ret) {replyToMessage(message, WifiP2pManager.CREATE_GROUP_SUCCEEDED);transitionTo(mGroupNegotiationState);} else {replyToMessage(message, WifiP2pManager.CREATE_GROUP_FAILED,WifiP2pManager.ERROR);// remain at this state.}break;case WifiMonitor.P2P_GROUP_STARTED_EVENT:mGroup = (WifiP2pGroup) message.obj;if (DBG) logd(getName() + " group started");// We hit this scenario when a persistent group is reinvokedif (mGroup.getNetworkId() == WifiP2pGroup.PERSISTENT_NET_ID) {mAutonomousGroup = false;deferMessage(message);transitionTo(mGroupNegotiationState);//轉入GroupCreatedState} else {loge("Unexpected group creation, remove " + mGroup);mWifiNative.p2pGroupRemove(mGroup.getInterface());}break;case WifiP2pManager.START_LISTEN:if (DBG) logd(getName() + " start listen mode");mWifiNative.p2pFlush();if (mWifiNative.p2pExtListen(true, 500, 500)) {replyToMessage(message, WifiP2pManager.START_LISTEN_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.START_LISTEN_FAILED);}break;case WifiP2pManager.STOP_LISTEN:if (DBG) logd(getName() + " stop listen mode");if (mWifiNative.p2pExtListen(false, 0, 0)) {replyToMessage(message, WifiP2pManager.STOP_LISTEN_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.STOP_LISTEN_FAILED);}mWifiNative.p2pFlush();break;case WifiP2pManager.SET_CHANNEL:Bundle p2pChannels = (Bundle) message.obj;int lc = p2pChannels.getInt("lc", 0);int oc = p2pChannels.getInt("oc", 0);if (DBG) logd(getName() + " set listen and operating channel");if (mWifiNative.p2pSetChannel(lc, oc)) {replyToMessage(message, WifiP2pManager.SET_CHANNEL_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.SET_CHANNEL_FAILED);}break;case WifiP2pManager.INITIATOR_REPORT_NFC_HANDOVER:String handoverSelect = null;if (message.obj != null) {handoverSelect = ((Bundle) message.obj).getString(WifiP2pManager.EXTRA_HANDOVER_MESSAGE);}if (handoverSelect != null&& mWifiNative.initiatorReportNfcHandover(handoverSelect)) {replyToMessage(message, WifiP2pManager.REPORT_NFC_HANDOVER_SUCCEEDED);transitionTo(mGroupCreatingState);} else {replyToMessage(message, WifiP2pManager.REPORT_NFC_HANDOVER_FAILED);}break;case WifiP2pManager.RESPONDER_REPORT_NFC_HANDOVER:String handoverRequest = null;if (message.obj != null) {handoverRequest = ((Bundle) message.obj).getString(WifiP2pManager.EXTRA_HANDOVER_MESSAGE);}if (handoverRequest != null&& mWifiNative.responderReportNfcHandover(handoverRequest)) {replyToMessage(message, WifiP2pManager.REPORT_NFC_HANDOVER_SUCCEEDED);transitionTo(mGroupCreatingState);} else {replyToMessage(message, WifiP2pManager.REPORT_NFC_HANDOVER_FAILED);}break;default:return NOT_HANDLED;}return HANDLED;}} class ProvisionDiscoveryState extends State {@Overridepublic void enter() {if (DBG) logd(getName());//觸發本機設備向對端設備發送 Provision Discovery Request幀mWifiNative.p2pProvisionDiscovery(mSavedPeerConfig);}@Overridepublic boolean processMessage(Message message) {if (DBG) logd(getName() + message.toString());WifiP2pProvDiscEvent provDisc;WifiP2pDevice device;switch (message.what) {case WifiMonitor.P2P_PROV_DISC_PBC_RSP_EVENT:provDisc = (WifiP2pProvDiscEvent) message.obj;device = provDisc.device;if (!device.deviceAddress.equals(mSavedPeerConfig.deviceAddress)) break;if (mSavedPeerConfig.wps.setup == WpsInfo.PBC) {if (DBG) logd("Found a match " + mSavedPeerConfig);//下面這個函數將調用WifiNative的P2pConnect函數，此函數將觸發WPAS發送GON Request幀。接收端設備收到該幀后，將彈出提示框以提醒用戶p2pConnectWithPinDisplay(mSavedPeerConfig);//轉入GroupNegotiationStatetransitionTo(mGroupNegotiationState);}break;case WifiMonitor.P2P_PROV_DISC_ENTER_PIN_EVENT:provDisc = (WifiP2pProvDiscEvent) message.obj;device = provDisc.device;if (!device.deviceAddress.equals(mSavedPeerConfig.deviceAddress)) break;if (mSavedPeerConfig.wps.setup == WpsInfo.KEYPAD) {if (DBG) logd("Found a match " + mSavedPeerConfig);/* we already have the pin */if (!TextUtils.isEmpty(mSavedPeerConfig.wps.pin)) {p2pConnectWithPinDisplay(mSavedPeerConfig);transitionTo(mGroupNegotiationState);} else {mJoinExistingGroup = false;transitionTo(mUserAuthorizingNegotiationRequestState);}}break;case WifiMonitor.P2P_PROV_DISC_SHOW_PIN_EVENT:provDisc = (WifiP2pProvDiscEvent) message.obj;device = provDisc.device;if (!device.deviceAddress.equals(mSavedPeerConfig.deviceAddress)) break;if (mSavedPeerConfig.wps.setup == WpsInfo.DISPLAY) {if (DBG) logd("Found a match " + mSavedPeerConfig);mSavedPeerConfig.wps.pin = provDisc.pin;p2pConnectWithPinDisplay(mSavedPeerConfig);notifyInvitationSent(provDisc.pin, device.deviceAddress);transitionTo(mGroupNegotiationState);}break;case WifiMonitor.P2P_PROV_DISC_FAILURE_EVENT:loge("provision discovery failed");handleGroupCreationFailure();transitionTo(mInactiveState);break;default:return NOT_HANDLED;}return HANDLED;}}P2pStateMachine通過 p2pConnectWithPinDisplay 向對端發起 Group Negotiation Request請求。接下來的工作就由WPAS來處理。當Group Formation結束后， P2pStateMachine將收到一個 P2P_GROUP_STARTED_EVENT 消息以通知 Group 建立完畢，詳細代碼見"case WifiMonitor.P2P_GROUP_STARTED_EVENT:"
P2pStateMachine將轉入GroupCreatedState：
class GroupCreatedState extends State {@Overridepublic void enter() {if (DBG) logd(getName());// Once connected, peer config details are invalidmSavedPeerConfig.invalidate();mNetworkInfo.setDetailedState(NetworkInfo.DetailedState.CONNECTED, null, null);updateThisDevice(WifiP2pDevice.CONNECTED);//連接成功//DHCP server has already been started if I am a group ownerif (mGroup.isGroupOwner()) {//SERVER_ADDRESS為192.168.49.1，該地址也被設置到Dhcp Server中//另外，P2pStateMachine由一個名為mWifiP2pInfo的成員變量，其類型為 WifiP2pInfo,//下面這個函數也將GO的IP地址保存到mWifiP2pInfo中setWifiP2pInfoOnGroupFormation(NetworkUtils.numericToInetAddress(SERVER_ADDRESS));}// In case of a negotiation group, connection changed is sent// after a client joins. For autonomous, send nowif (mAutonomousGroup) {sendP2pConnectionChangedBroadcast();}}@Overridepublic boolean processMessage(Message message) {if (DBG) logd(getName() + message.toString());switch (message.what) {case WifiMonitor.AP_STA_CONNECTED_EVENT://該消息表示一個P2P Client關聯上本機GOWifiP2pDevice device = (WifiP2pDevice) message.obj;String deviceAddress = device.deviceAddress;// Clear timeout that was set when group was started.mWifiNative.setP2pGroupIdle(mGroup.getInterface(), 0);if (deviceAddress != null) {if (mPeers.get(deviceAddress) != null) {mGroup.addClient(mPeers.get(deviceAddress));//添加一個P2P Client} else {mGroup.addClient(deviceAddress);}mPeers.updateStatus(deviceAddress, WifiP2pDevice.CONNECTED);if (DBG) logd(getName() + " ap sta connected");sendPeersChangedBroadcast();} else {loge("Connect on null device address, ignore");}sendP2pConnectionChangedBroadcast();break;case WifiMonitor.AP_STA_DISCONNECTED_EVENT:device = (WifiP2pDevice) message.obj;deviceAddress = device.deviceAddress;if (deviceAddress != null) {mPeers.updateStatus(deviceAddress, WifiP2pDevice.AVAILABLE);if (mGroup.removeClient(deviceAddress)) {if (DBG) logd("Removed client " + deviceAddress);if (!mAutonomousGroup && mGroup.isClientListEmpty()) {logd("Client list empty, remove non-persistent p2p group");mWifiNative.p2pGroupRemove(mGroup.getInterface());// We end up sending connection changed broadcast// when this happens at exit()} else {// Notify when a client disconnects from groupsendP2pConnectionChangedBroadcast();}} else {if (DBG) logd("Failed to remove client " + deviceAddress);for (WifiP2pDevice c : mGroup.getClientList()) {if (DBG) logd("client " + c.deviceAddress);}}sendPeersChangedBroadcast();if (DBG) logd(getName() + " ap sta disconnected");} else {loge("Disconnect on unknown device: " + device);}break;case DhcpStateMachine.CMD_POST_DHCP_ACTION:DhcpResults dhcpResults = (DhcpResults) message.obj;if (message.arg1 == DhcpStateMachine.DHCP_SUCCESS &&dhcpResults != null) {if (DBG) logd("DhcpResults: " + dhcpResults);setWifiP2pInfoOnGroupFormation(dhcpResults.serverAddress);sendP2pConnectionChangedBroadcast();//Turn on power save on clientmWifiNative.setP2pPowerSave(mGroup.getInterface(), true);try {String iface = mGroup.getInterface();mNwService.addInterfaceToLocalNetwork(iface,dhcpResults.getRoutes(iface));} catch (RemoteException e) {loge("Failed to add iface to local network " + e);}} else {loge("DHCP failed");mWifiNative.p2pGroupRemove(mGroup.getInterface());}break;case WifiP2pManager.REMOVE_GROUP:if (DBG) logd(getName() + " remove group");if (mWifiNative.p2pGroupRemove(mGroup.getInterface())) {transitionTo(mOngoingGroupRemovalState);replyToMessage(message, WifiP2pManager.REMOVE_GROUP_SUCCEEDED);} else {handleGroupRemoved();transitionTo(mInactiveState);replyToMessage(message, WifiP2pManager.REMOVE_GROUP_FAILED,WifiP2pManager.ERROR);}break;/* We do not listen to NETWORK_DISCONNECTION_EVENT for group removal* handling since supplicant actually tries to reconnect after a temporary* disconnect until group idle time out. Eventually, a group removal event* will come when group has been removed.** When there are connectivity issues during temporary disconnect, the application* will also just remove the group.** Treating network disconnection as group removal causes race conditions since* supplicant would still maintain the group at that stage.*/case WifiMonitor.P2P_GROUP_REMOVED_EVENT:if (DBG) logd(getName() + " group removed");handleGroupRemoved();transitionTo(mInactiveState);break;case WifiMonitor.P2P_DEVICE_LOST_EVENT:device = (WifiP2pDevice) message.obj;//Device loss for a connected device indicates it is not in discovery any moreif (mGroup.contains(device)) {if (DBG) logd("Add device to lost list " + device);mPeersLostDuringConnection.updateSupplicantDetails(device);return HANDLED;}// Do the regular device lost handlingreturn NOT_HANDLED;case WifiStateMachine.CMD_DISABLE_P2P_REQ:sendMessage(WifiP2pManager.REMOVE_GROUP);deferMessage(message);break;// This allows any client to join the GO during the// WPS windowcase WifiP2pManager.START_WPS:WpsInfo wps = (WpsInfo) message.obj;if (wps == null) {replyToMessage(message, WifiP2pManager.START_WPS_FAILED);break;}boolean ret = true;if (wps.setup == WpsInfo.PBC) {ret = mWifiNative.startWpsPbc(mGroup.getInterface(), null);} else {if (wps.pin == null) {String pin = mWifiNative.startWpsPinDisplay(mGroup.getInterface());try {Integer.parseInt(pin);notifyInvitationSent(pin, "any");} catch (NumberFormatException ignore) {ret = false;}} else {ret = mWifiNative.startWpsPinKeypad(mGroup.getInterface(),wps.pin);}}replyToMessage(message, ret ? WifiP2pManager.START_WPS_SUCCEEDED :WifiP2pManager.START_WPS_FAILED);break;case WifiP2pManager.CONNECT:WifiP2pConfig config = (WifiP2pConfig) message.obj;if (isConfigInvalid(config)) {loge("Dropping connect requeset " + config);replyToMessage(message, WifiP2pManager.CONNECT_FAILED);break;}logd("Inviting device : " + config.deviceAddress);mSavedPeerConfig = config;if (mWifiNative.p2pInvite(mGroup, config.deviceAddress)) {mPeers.updateStatus(config.deviceAddress, WifiP2pDevice.INVITED);sendPeersChangedBroadcast();replyToMessage(message, WifiP2pManager.CONNECT_SUCCEEDED);} else {replyToMessage(message, WifiP2pManager.CONNECT_FAILED,WifiP2pManager.ERROR);}// TODO: figure out updating the status to declined when invitation is rejectedbreak;case WifiMonitor.P2P_INVITATION_RESULT_EVENT:P2pStatus status = (P2pStatus)message.obj;if (status == P2pStatus.SUCCESS) {// invocation was succeeded.break;}loge("Invitation result " + status);if (status == P2pStatus.UNKNOWN_P2P_GROUP) {// target device has already removed the credential.// So, remove this credential accordingly.int netId = mGroup.getNetworkId();if (netId >= 0) {if (DBG) logd("Remove unknown client from the list");if (!removeClientFromList(netId,mSavedPeerConfig.deviceAddress, false)) {// not found the client on the listloge("Already removed the client, ignore");break;}// try invitation.sendMessage(WifiP2pManager.CONNECT, mSavedPeerConfig);}}break;case WifiMonitor.P2P_PROV_DISC_PBC_REQ_EVENT:case WifiMonitor.P2P_PROV_DISC_ENTER_PIN_EVENT:case WifiMonitor.P2P_PROV_DISC_SHOW_PIN_EVENT:WifiP2pProvDiscEvent provDisc = (WifiP2pProvDiscEvent) message.obj;mSavedPeerConfig = new WifiP2pConfig();mSavedPeerConfig.deviceAddress = provDisc.device.deviceAddress;if (message.what == WifiMonitor.P2P_PROV_DISC_ENTER_PIN_EVENT) {mSavedPeerConfig.wps.setup = WpsInfo.KEYPAD;} else if (message.what == WifiMonitor.P2P_PROV_DISC_SHOW_PIN_EVENT) {mSavedPeerConfig.wps.setup = WpsInfo.DISPLAY;mSavedPeerConfig.wps.pin = provDisc.pin;} else {mSavedPeerConfig.wps.setup = WpsInfo.PBC;}transitionTo(mUserAuthorizingJoinState);break;case WifiMonitor.P2P_GROUP_STARTED_EVENT:loge("Duplicate group creation event notice, ignore");break;default:return NOT_HANDLED;}return HANDLED;}public void exit() {updateThisDevice(WifiP2pDevice.AVAILABLE);resetWifiP2pInfo();mNetworkInfo.setDetailedState(NetworkInfo.DetailedState.DISCONNECTED, null, null);sendP2pConnectionChangedBroadcast();}}至此，一個P2P Device(扮演Client)就成功關聯上本機的P2P Device(扮演GO)
總結
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