Android -- Wifi的save()操作

代码主要来自android 6.0

当我们在Settings中设置静态IP连接时，会调用到WifiManager::save()函数：

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1. /** 
2.   * Save the given network in the supplicant config. If the network already 
3.   * exists, the configuration is updated. A new network is enabled 
4.   * by default. 
5.   * 
6.   * For a new network, this function is used instead of a 
7.   * sequence of addNetwork(), enableNetwork() and saveConfiguration(). 
8.   * 
9.   * For an existing network, it accomplishes the task of updateNetwork() 
10.   * and saveConfiguration() 
11.   * 
12.   * @param config the set of variables that describe the configuration, 
13.   *            contained in a {@link WifiConfiguration} object. 
14.   * @param listener for callbacks on success or failure. Can be null. 
15.   * @throws IllegalStateException if the WifiManager instance needs to be 
16.   * initialized again 
17.   * @hide 
18.   */  
19.  public void save(WifiConfiguration config, ActionListener listener) {  
20.      if (config == null) throw new IllegalArgumentException("config cannot be null");  
21.      validateChannel();  
22.      sAsyncChannel.sendMessage(SAVE_NETWORK, 0, putListener(listener), config);  
23.  }  

有注释可知，save函数会把传入WifiConfiguration信息代表的网络保存进wpa_supplicant.conf文件中；如果网络是已经存在的，则会更新信息；如果是新添加的，则会重新添加到配置文件中。

WifiServiceImpl::ClientHandler处理该消息：

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1. /* Client commands are forwarded to state machine */  
2.                 case WifiManager.CONNECT_NETWORK:  
3.                 case WifiManager.SAVE_NETWORK: {  
4.                     WifiConfiguration config = (WifiConfiguration) msg.obj;  
5.                     int networkId = msg.arg1;  
6.                     if (msg.what == WifiManager.SAVE_NETWORK) {  
7.                         Slog.e("WiFiServiceImpl ", "SAVE"  
8.                                 + " nid=" + Integer.toString(networkId)  
9.                                 + " uid=" + msg.sendingUid  
10.                                 + " name="  
11.                                 + mContext.getPackageManager().getNameForUid(msg.sendingUid));  
12.                     }  
13.                     if (msg.what == WifiManager.CONNECT_NETWORK) {  
14.                         Slog.e("WiFiServiceImpl ", "CONNECT "  
15.                                 + " nid=" + Integer.toString(networkId)  
16.                                 + " uid=" + msg.sendingUid  
17.                                 + " name="  
18.                                 + mContext.getPackageManager().getNameForUid(msg.sendingUid));  
19.                     }  
20.   
21.                     if (config != null && isValid(config)) {  
22.                         if (DBG) Slog.d(TAG, "Connect with config" + config);  
23.                         mWifiStateMachine.sendMessage(Message.obtain(msg));  
24.                     } else if (config == null  
25.                             && networkId != WifiConfiguration.INVALID_NETWORK_ID) {  
26.                         if (DBG) Slog.d(TAG, "Connect with networkId" + networkId);  
27.                         mWifiStateMachine.sendMessage(Message.obtain(msg));  
28.                     } else {  
29.                         Slog.e(TAG, "ClientHandler.handleMessage ignoring invalid msg=" + msg);  
30.                         if (msg.what == WifiManager.CONNECT_NETWORK) {  
31.                             replyFailed(msg, WifiManager.CONNECT_NETWORK_FAILED,  
32.                                     WifiManager.INVALID_ARGS);  
33.                         } else {  
34.                             replyFailed(msg, WifiManager.SAVE_NETWORK_FAILED,  
35.                                     WifiManager.INVALID_ARGS);  
36.                         }  
37.                     }  
38.                     break;  
39.                 }  

主要做消息转发处理，看WifiStateMachine中的处理流程。ConnectModeState状态处理该消息：

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1. case WifiManager.SAVE_NETWORK:  
2.                     mWifiConnectionStatistics.numWifiManagerJoinAttempt++;  
3.                     // Fall thru  
4.                 case WifiStateMachine.CMD_AUTO_SAVE_NETWORK:  
5.                     lastSavedConfigurationAttempt = null; // Used for debug  
6.                     config = (WifiConfiguration) message.obj;  
7.                     if (config == null) {  
8.                         loge("ERROR: SAVE_NETWORK with null configuration"  
9.                                 + mSupplicantStateTracker.getSupplicantStateName()  
10.                                 + " my state " + getCurrentState().getName());  
11.                         messageHandlingStatus = MESSAGE_HANDLING_STATUS_FAIL;  
12.                         replyToMessage(message, WifiManager.SAVE_NETWORK_FAILED,  
13.                                 WifiManager.ERROR);  
14.                         break;  
15.                     }  
16.                     lastSavedConfigurationAttempt = new WifiConfiguration(config);  
17.                     int nid = config.networkId;  
18.                     logd("SAVE_NETWORK id=" + Integer.toString(nid)  
19.                                 + " config=" + config.SSID  
20.                                 + " nid=" + config.networkId  
21.                                 + " supstate=" + mSupplicantStateTracker.getSupplicantStateName()  
22.                                 + " my state " + getCurrentState().getName());  
23.   
24.                     // Only record the uid if this is user initiated  
25.                     boolean checkUid = (message.what == WifiManager.SAVE_NETWORK);  
26.                     if (checkUid && !recordUidIfAuthorized(config, message.sendingUid,  
27.                             /* onlyAnnotate */ false)) {  
28.                         logw("Not authorized to update network "  
29.                              + " config=" + config.SSID  
30.                              + " cnid=" + config.networkId  
31.                              + " uid=" + message.sendingUid);  
32.                         replyToMessage(message, WifiManager.SAVE_NETWORK_FAILED,  
33.                                        WifiManager.NOT_AUTHORIZED);  
34.                         break;  
35.                     }  
36.   
37.                     result = mWifiConfigStore.saveNetwork(config, WifiConfiguration.UNKNOWN_UID);  
38.                     if (result.getNetworkId() != WifiConfiguration.INVALID_NETWORK_ID) {  
39.                         if (mWifiInfo.getNetworkId() == result.getNetworkId()) {  
40.                             if (result.hasIpChanged()) {  
41.                                 // The currently connection configuration was changed  
42.                                 // We switched from DHCP to static or from static to DHCP, or the  
43.                                 // static IP address has changed.  
44.                                 log("Reconfiguring IP on connection");  
45.                                 // TODO: clear addresses and disable IPv6  
46.                                 // to simplify obtainingIpState.  
47.                                 transitionTo(mObtainingIpState);  
48.                             }  
49.                             if (result.hasProxyChanged()) {  
50.                                 log("Reconfiguring proxy on connection");  
51.                                 updateLinkProperties(CMD_UPDATE_LINKPROPERTIES);  
52.                             }  
53.                         }  
54.                         replyToMessage(message, WifiManager.SAVE_NETWORK_SUCCEEDED);  
55.                         broadcastWifiCredentialChanged(WifiManager.WIFI_CREDENTIAL_SAVED, config);  
56.   
57.                         if (VDBG) {  
58.                            logd("Success save network nid="  
59.                                     + Integer.toString(result.getNetworkId()));  
60.                         }  
61.   
62.                         synchronized(mScanResultCache) {  
63.                             /** 
64.                              * If the command comes from WifiManager, then 
65.                              * tell autojoin the user did try to modify and save that network, 
66.                              * and interpret the SAVE_NETWORK as a request to connect 
67.                              */  
68.                             boolean user = message.what == WifiManager.SAVE_NETWORK;  
69.   
70.                             // Did this connect come from settings  
71.                             boolean persistConnect =  
72.                                 mWifiConfigStore.checkConfigOverridePermission(message.sendingUid);  
73.   
74.                             if (user) {  
75.                                 mWifiConfigStore.updateLastConnectUid(config, message.sendingUid);  
76.                                 mWifiConfigStore.writeKnownNetworkHistory(false);  
77.                             }  
78.   
79.                             mWifiAutoJoinController.updateConfigurationHistory(result.getNetworkId()  
80.                                     , user, persistConnect);  
81.                             mWifiAutoJoinController.attemptAutoJoin();  
82.                         }  
83.                     } else {  
84.                         loge("Failed to save network");  
85.                         messageHandlingStatus = MESSAGE_HANDLING_STATUS_FAIL;  
86.                         replyToMessage(message, WifiManager.SAVE_NETWORK_FAILED,  
87.                                 WifiManager.ERROR);  
88.                     }  
89.                     break;  

如果检测出IP配置信息有变化，则会切换到ObtainingIpState状态，并触发autojoin流程。如果用户使用的是静态IP，看ObtainingIpState的enter()函数：

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1. if (!mWifiConfigStore.isUsingStaticIp(mLastNetworkId)) {  
2.                 if (isRoaming()) {  
3.                     renewDhcp();  
4.                 } else {  
5.                     // Remove any IP address on the interface in case we're switching from static  
6.                     // IP configuration to DHCP. This is safe because if we get here when not  
7.                     // roaming, we don't have a usable address.  
8.                     clearIPv4Address(mInterfaceName);  
9.                     startDhcp();  
10.                 }  
11.                 obtainingIpWatchdogCount++;  
12.                 logd("Start Dhcp Watchdog " + obtainingIpWatchdogCount);  
13.                 // Get Link layer stats so as we get fresh tx packet counters  
14.                 getWifiLinkLayerStats(true);  
15.                 sendMessageDelayed(obtainMessage(CMD_OBTAINING_IP_ADDRESS_WATCHDOG_TIMER,  
16.                         obtainingIpWatchdogCount, 0), OBTAINING_IP_ADDRESS_GUARD_TIMER_MSEC);  
17.             } else {  
18.                 // stop any running dhcp before assigning static IP  
19.                 stopDhcp();  
20.                 StaticIpConfiguration config = mWifiConfigStore.getStaticIpConfiguration(  
21.                         mLastNetworkId);  
22.                 if (config.ipAddress == null) {  
23.                     logd("Static IP lacks address");  
24.                     sendMessage(CMD_STATIC_IP_FAILURE);  
25.                 } else {  
26.                     InterfaceConfiguration ifcg = new InterfaceConfiguration();  
27.                     ifcg.setLinkAddress(config.ipAddress);  
28.                     ifcg.setInterfaceUp();  
29.                     try {  
30.                         mNwService.setInterfaceConfig(mInterfaceName, ifcg);  
31.                         if (DBG) log("Static IP configuration succeeded");  
32.                         DhcpResults dhcpResults = new DhcpResults(config);  
33.                         sendMessage(CMD_STATIC_IP_SUCCESS, dhcpResults);  
34.                     } catch (RemoteException re) {  
35.                         loge("Static IP configuration failed: " + re);  
36.                         sendMessage(CMD_STATIC_IP_FAILURE);  
37.                     } catch (IllegalStateException e) {  
38.                         loge("Static IP configuration failed: " + e);  
39.                         sendMessage(CMD_STATIC_IP_FAILURE);  
40.                     }  
41.                 }  
42.             }  

看else分支，在设置静态IP之前，调用stopDhcp()停掉当前的dhcp流程，获取到上层传入的静态IP配置信息：

1. 如果config为null，则认为静态配置失败
2. 调用mNwService.setInterfaceConfig()，设置配置的IP地址信息
   
3. 组装DhcpResults对象，并发送CMD_STATIC_IP_SUCCESS消息，更新网络状态

CMD_STATIC_IP_SUCCESS在ObtainingIpState被处理：

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1. case CMD_STATIC_IP_SUCCESS:  
2.     handleIPv4Success((DhcpResults) message.obj, CMD_STATIC_IP_SUCCESS);  
3.     break;  

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1. private void handleIPv4Success(DhcpResults dhcpResults, int reason) {  
2.   
3.     if (PDBG) {  
4.         logd("handleIPv4Success <" + dhcpResults.toString() + ">");  
5.         logd("link address " + dhcpResults.ipAddress);  
6.     }  
7.   
8.     Inet4Address addr;  
9.     synchronized (mDhcpResultsLock) {  
10.         mDhcpResults = dhcpResults;  
11.         addr = (Inet4Address) dhcpResults.ipAddress.getAddress();  
12.     }  
13.   
14.     if (isRoaming()) {  
15.         int previousAddress = mWifiInfo.getIpAddress();  
16.         int newAddress = NetworkUtils.inetAddressToInt(addr);  
17.         if (previousAddress != newAddress) {  
18.             logd("handleIPv4Success, roaming and address changed" +  
19.                     mWifiInfo + " got: " + addr);  
20.         }  
21.     }  
22.     mWifiInfo.setInetAddress(addr);  
23.     mWifiInfo.setMeteredHint(dhcpResults.hasMeteredHint());  
24.     updateLinkProperties(reason);  
25. }  

将当前静态IP设置的DhcpResults赋给状态机的成员变量mDchpResults，最后调用updateLinkProperties()更新连接配置信息：

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1. // If we just configured or lost IP configuration, do the needful.  
2.         // We don't just call handleSuccessfulIpConfiguration() or handleIpConfigurationLost()  
3.         // here because those should only be called if we're attempting to connect or already  
4.         // connected, whereas updateLinkProperties can be called at any time.  
5.         switch (reason) {  
6.             case DhcpStateMachine.DHCP_SUCCESS:  
7.             case CMD_STATIC_IP_SUCCESS:  
8.                 // IPv4 provisioning succeded. Advance to connected state.  
9.                 sendMessage(CMD_IP_CONFIGURATION_SUCCESSFUL);  
10.                 if (!isProvisioned) {  
11.                     // Can never happen unless DHCP reports success but isProvisioned thinks the  
12.                     // resulting configuration is invalid (e.g., no IPv4 address, or the state in  
13.                     // mLinkProperties is out of sync with reality, or there's a bug in this code).  
14.                     // TODO: disconnect here instead. If our configuration is not usable, there's no  
15.                     // point in staying connected, and if mLinkProperties is out of sync with  
16.                     // reality, that will cause problems in the future.  
17.                     logd("IPv4 config succeeded, but not provisioned");  
18.                 }  
19.                 break;  

跟踪CMD_IP_CONFIGURATION_SUCCESSFUL消息。ObtainingIpState不处理该消息，其父状态L2ConnectedState处理：

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1. case CMD_IP_CONFIGURATION_SUCCESSFUL:  
2.     handleSuccessfulIpConfiguration();  
3.     sendConnectedState();  
4.     transitionTo(mConnectedState);  
5.     break;  

静态IP配置成功后，调用handleSuccessfulIpConfiguration()做之后的一些准备工作；调用sendConnectedState()，发送WifiManager.NETWORK_STATE_CHANGED_ACTION广播，通知其他组件网络连接状态的变化（此处是CONNECTED）。最后将Wifi状态机切换到ConnectedSate，代表网络已经连接完成。