Android -- Wifi的save()操作

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

   /**     * Save the given network in the supplicant config. If the network already     * exists, the configuration is updated. A new network is enabled     * by default.     *     * For a new network, this function is used instead of a     * sequence of addNetwork(), enableNetwork() and saveConfiguration().     *     * For an existing network, it accomplishes the task of updateNetwork()     * and saveConfiguration()     *     * @param config the set of variables that describe the configuration,     *            contained in a {@link WifiConfiguration} object.     * @param listener for callbacks on success or failure. Can be null.     * @throws IllegalStateException if the WifiManager instance needs to be     * initialized again     * @hide     */    public void save(WifiConfiguration config, ActionListener listener) {        if (config == null) throw new IllegalArgumentException("config cannot be null");        validateChannel();        sAsyncChannel.sendMessage(SAVE_NETWORK, 0, putListener(listener), config);    }

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：

/* Client commands are forwarded to state machine */                case WifiManager.CONNECT_NETWORK:                case WifiManager.SAVE_NETWORK: {                    WifiConfiguration config = (WifiConfiguration) msg.obj;                    int networkId = msg.arg1;                    if (msg.what == WifiManager.SAVE_NETWORK) {                        Slog.e("WiFiServiceImpl ", "SAVE"                                + " nid=" + Integer.toString(networkId)                                + " uid=" + msg.sendingUid                                + " name="                                + mContext.getPackageManager().getNameForUid(msg.sendingUid));                    }                    if (msg.what == WifiManager.CONNECT_NETWORK) {                        Slog.e("WiFiServiceImpl ", "CONNECT "                                + " nid=" + Integer.toString(networkId)                                + " uid=" + msg.sendingUid                                + " name="                                + mContext.getPackageManager().getNameForUid(msg.sendingUid));                    }                    if (config != null && isValid(config)) {                        if (DBG) Slog.d(TAG, "Connect with config" + config);                        mWifiStateMachine.sendMessage(Message.obtain(msg));                    } else if (config == null                            && networkId != WifiConfiguration.INVALID_NETWORK_ID) {                        if (DBG) Slog.d(TAG, "Connect with networkId" + networkId);                        mWifiStateMachine.sendMessage(Message.obtain(msg));                    } else {                        Slog.e(TAG, "ClientHandler.handleMessage ignoring invalid msg=" + msg);                        if (msg.what == WifiManager.CONNECT_NETWORK) {                            replyFailed(msg, WifiManager.CONNECT_NETWORK_FAILED,                                    WifiManager.INVALID_ARGS);                        } else {                            replyFailed(msg, WifiManager.SAVE_NETWORK_FAILED,                                    WifiManager.INVALID_ARGS);                        }                    }                    break;                }

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：

case WifiManager.SAVE_NETWORK:                    mWifiConnectionStatistics.numWifiManagerJoinAttempt++;                    // Fall thru                case WifiStateMachine.CMD_AUTO_SAVE_NETWORK:                    lastSavedConfigurationAttempt = null; // Used for debug                    config = (WifiConfiguration) message.obj;                    if (config == null) {                        loge("ERROR: SAVE_NETWORK with null configuration"                                + mSupplicantStateTracker.getSupplicantStateName()                                + " my state " + getCurrentState().getName());                        messageHandlingStatus = MESSAGE_HANDLING_STATUS_FAIL;                        replyToMessage(message, WifiManager.SAVE_NETWORK_FAILED,                                WifiManager.ERROR);                        break;                    }                    lastSavedConfigurationAttempt = new WifiConfiguration(config);                    int nid = config.networkId;                    logd("SAVE_NETWORK id=" + Integer.toString(nid)                                + " config=" + config.SSID                                + " nid=" + config.networkId                                + " supstate=" + mSupplicantStateTracker.getSupplicantStateName()                                + " my state " + getCurrentState().getName());                    // Only record the uid if this is user initiated                    boolean checkUid = (message.what == WifiManager.SAVE_NETWORK);                    if (checkUid && !recordUidIfAuthorized(config, message.sendingUid,                            /* onlyAnnotate */ false)) {                        logw("Not authorized to update network "                             + " config=" + config.SSID                             + " cnid=" + config.networkId                             + " uid=" + message.sendingUid);                        replyToMessage(message, WifiManager.SAVE_NETWORK_FAILED,                                       WifiManager.NOT_AUTHORIZED);                        break;                    }                    result = mWifiConfigStore.saveNetwork(config, WifiConfiguration.UNKNOWN_UID);                    if (result.getNetworkId() != WifiConfiguration.INVALID_NETWORK_ID) {                        if (mWifiInfo.getNetworkId() == result.getNetworkId()) {                            if (result.hasIpChanged()) {                                // The currently connection configuration was changed                                // We switched from DHCP to static or from static to DHCP, or the                                // static IP address has changed.                                log("Reconfiguring IP on connection");                                // TODO: clear addresses and disable IPv6                                // to simplify obtainingIpState.                                transitionTo(mObtainingIpState);                            }                            if (result.hasProxyChanged()) {                                log("Reconfiguring proxy on connection");                                updateLinkProperties(CMD_UPDATE_LINKPROPERTIES);                            }                        }                        replyToMessage(message, WifiManager.SAVE_NETWORK_SUCCEEDED);                        broadcastWifiCredentialChanged(WifiManager.WIFI_CREDENTIAL_SAVED, config);                        if (VDBG) {                           logd("Success save network nid="                                    + Integer.toString(result.getNetworkId()));                        }                        synchronized(mScanResultCache) {                            /**                             * If the command comes from WifiManager, then                             * tell autojoin the user did try to modify and save that network,                             * and interpret the SAVE_NETWORK as a request to connect                             */                            boolean user = message.what == WifiManager.SAVE_NETWORK;                            // Did this connect come from settings                            boolean persistConnect =                                mWifiConfigStore.checkConfigOverridePermission(message.sendingUid);                            if (user) {                                mWifiConfigStore.updateLastConnectUid(config, message.sendingUid);                                mWifiConfigStore.writeKnownNetworkHistory(false);                            }                            mWifiAutoJoinController.updateConfigurationHistory(result.getNetworkId()                                    , user, persistConnect);                            mWifiAutoJoinController.attemptAutoJoin();                        }                    } else {                        loge("Failed to save network");                        messageHandlingStatus = MESSAGE_HANDLING_STATUS_FAIL;                        replyToMessage(message, WifiManager.SAVE_NETWORK_FAILED,                                WifiManager.ERROR);                    }                    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：

if (!mWifiConfigStore.isUsingStaticIp(mLastNetworkId)) {                if (isRoaming()) {                    renewDhcp();                } else {                    // Remove any IP address on the interface in case we're switching from static                    // IP configuration to DHCP. This is safe because if we get here when not                    // roaming, we don't have a usable address.                    clearIPv4Address(mInterfaceName);                    startDhcp();                }                obtainingIpWatchdogCount++;                logd("Start Dhcp Watchdog " + obtainingIpWatchdogCount);                // Get Link layer stats so as we get fresh tx packet counters                getWifiLinkLayerStats(true);                sendMessageDelayed(obtainMessage(CMD_OBTAINING_IP_ADDRESS_WATCHDOG_TIMER,                        obtainingIpWatchdogCount, 0), OBTAINING_IP_ADDRESS_GUARD_TIMER_MSEC);            } else {                // stop any running dhcp before assigning static IP                stopDhcp();                StaticIpConfiguration config = mWifiConfigStore.getStaticIpConfiguration(                        mLastNetworkId);                if (config.ipAddress == null) {                    logd("Static IP lacks address");                    sendMessage(CMD_STATIC_IP_FAILURE);                } else {                    InterfaceConfiguration ifcg = new InterfaceConfiguration();                    ifcg.setLinkAddress(config.ipAddress);                    ifcg.setInterfaceUp();                    try {                        mNwService.setInterfaceConfig(mInterfaceName, ifcg);                        if (DBG) log("Static IP configuration succeeded");                        DhcpResults dhcpResults = new DhcpResults(config);                        sendMessage(CMD_STATIC_IP_SUCCESS, dhcpResults);                    } catch (RemoteException re) {                        loge("Static IP configuration failed: " + re);                        sendMessage(CMD_STATIC_IP_FAILURE);                    } catch (IllegalStateException e) {                        loge("Static IP configuration failed: " + e);                        sendMessage(CMD_STATIC_IP_FAILURE);                    }                }            }

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：

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

    private void handleIPv4Success(DhcpResults dhcpResults, int reason) {        if (PDBG) {            logd("handleIPv4Success <" + dhcpResults.toString() + ">");            logd("link address " + dhcpResults.ipAddress);        }        Inet4Address addr;        synchronized (mDhcpResultsLock) {            mDhcpResults = dhcpResults;            addr = (Inet4Address) dhcpResults.ipAddress.getAddress();        }        if (isRoaming()) {            int previousAddress = mWifiInfo.getIpAddress();            int newAddress = NetworkUtils.inetAddressToInt(addr);            if (previousAddress != newAddress) {                logd("handleIPv4Success, roaming and address changed" +                        mWifiInfo + " got: " + addr);            }        }        mWifiInfo.setInetAddress(addr);        mWifiInfo.setMeteredHint(dhcpResults.hasMeteredHint());        updateLinkProperties(reason);    }

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：

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

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

                case CMD_IP_CONFIGURATION_SUCCESSFUL:                    handleSuccessfulIpConfiguration();                    sendConnectedState();                    transitionTo(mConnectedState);                    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。