（一百四十九）Android P WificondControl的setupInterfaceForClientMode

本文主要是介绍（一百四十九）Android P WificondControl的setupInterfaceForClientMode，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

1.回顾

之前在（一百四十八）Android P wifi启动过程中的sta interface创建中梳理了sta interface的创建流程，之后还有

           if (mWificondControl.setupInterfaceForClientMode(iface.name) == null) {Log.e(TAG, "Failed to setup iface in wificond on " + iface);teardownInterface(iface.name);mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToWificond();return null;}if (!mSupplicantStaIfaceHal.setupIface(iface.name)) {Log.e(TAG, "Failed to setup iface in supplicant on " + iface);teardownInterface(iface.name);mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();return null;}

先梳理下WificondControl的setupInterfaceForClientMode

2.流程梳理

WificondControl

    /*** Setup interface for client mode via wificond.* @return An IClientInterface as wificond client interface binder handler.* Returns null on failure.*/public IClientInterface setupInterfaceForClientMode(@NonNull String ifaceName) {Log.d(TAG, "Setting up interface for client mode");if (!retrieveWificondAndRegisterForDeath()) {return null;}IClientInterface clientInterface = null;try {clientInterface = mWificond.createClientInterface(ifaceName);} catch (RemoteException e1) {Log.e(TAG, "Failed to get IClientInterface due to remote exception");return null;}if (clientInterface == null) {Log.e(TAG, "Could not get IClientInterface instance from wificond");return null;}Binder.allowBlocking(clientInterface.asBinder());// Refresh HandlersmClientInterfaces.put(ifaceName, clientInterface);try {IWifiScannerImpl wificondScanner = clientInterface.getWifiScannerImpl();if (wificondScanner == null) {Log.e(TAG, "Failed to get WificondScannerImpl");return null;}mWificondScanners.put(ifaceName, wificondScanner);Binder.allowBlocking(wificondScanner.asBinder());ScanEventHandler scanEventHandler = new ScanEventHandler(ifaceName);mScanEventHandlers.put(ifaceName,  scanEventHandler);wificondScanner.subscribeScanEvents(scanEventHandler);PnoScanEventHandler pnoScanEventHandler = new PnoScanEventHandler(ifaceName);mPnoScanEventHandlers.put(ifaceName,  pnoScanEventHandler);wificondScanner.subscribePnoScanEvents(pnoScanEventHandler);} catch (RemoteException e) {Log.e(TAG, "Failed to refresh wificond scanner due to remote exception");}return clientInterface;}

system/connectivity/wificond/server.cpp

Status Server::createClientInterface(const std::string& iface_name,sp<IClientInterface>* created_interface) {InterfaceInfo interface;if (!SetupInterface(iface_name, &interface)) {return Status::ok();  // Logging was done internally}unique_ptr<ClientInterfaceImpl> client_interface(new ClientInterfaceImpl(wiphy_index_,interface.name,interface.index,interface.mac_address,if_tool_.get(),netlink_utils_,scan_utils_));*created_interface = client_interface->GetBinder();BroadcastClientInterfaceReady(client_interface->GetBinder());client_interfaces_[iface_name] = std::move(client_interface);return Status::ok();
}bool Server::SetupInterface(const std::string& iface_name,InterfaceInfo* interface) {if (!RefreshWiphyIndex()) {return false;}netlink_utils_->SubscribeRegDomainChange(wiphy_index_,std::bind(&Server::OnRegDomainChanged,this,_1));interfaces_.clear();if (!netlink_utils_->GetInterfaces(wiphy_index_, &interfaces_)) {LOG(ERROR) << "Failed to get interfaces info from kernel";return false;}for (const auto& iface : interfaces_) {if (iface.name == iface_name) {*interface = iface;return true;}}LOG(ERROR) << "No usable interface found";return false;
}

这边会从kernel获取所有的interface，然后对照name看有没有对应的，如果有的话，返回一个对应的iface.

看下interfaces是何时初始化的

netlink_utils_

bool NetlinkUtils::GetInterfaces(uint32_t wiphy_index,vector<InterfaceInfo>* interface_info) {NL80211Packet get_interfaces(netlink_manager_->GetFamilyId(),NL80211_CMD_GET_INTERFACE,netlink_manager_->GetSequenceNumber(),getpid());get_interfaces.AddFlag(NLM_F_DUMP);get_interfaces.AddAttribute(NL80211Attr<uint32_t>(NL80211_ATTR_WIPHY, wiphy_index));vector<unique_ptr<const NL80211Packet>> response;if (!netlink_manager_->SendMessageAndGetResponses(get_interfaces, &response)) {LOG(ERROR) << "NL80211_CMD_GET_INTERFACE dump failed";return false;}if (response.empty()) {LOG(ERROR) << "No interface is found";return false;}for (auto& packet : response) {if (packet->GetMessageType() == NLMSG_ERROR) {LOG(ERROR) << "Receive ERROR message: "<< strerror(packet->GetErrorCode());return false;}if (packet->GetMessageType() != netlink_manager_->GetFamilyId()) {LOG(ERROR) << "Wrong message type for new interface message: "<< packet->GetMessageType();return false;}if (packet->GetCommand() != NL80211_CMD_NEW_INTERFACE) {LOG(ERROR) << "Wrong command in response to "<< "an interface dump request: "<< static_cast<int>(packet->GetCommand());return false;}// In some situations, it has been observed that the kernel tells us// about a pseudo interface that does not have a real netdev.  In this// case, responses will have a NL80211_ATTR_WDEV, and not the expected// IFNAME/IFINDEX. In this case we just skip these pseudo interfaces.uint32_t if_index;if (!packet->GetAttributeValue(NL80211_ATTR_IFINDEX, &if_index)) {LOG(DEBUG) << "Failed to get interface index";continue;}// Today we don't check NL80211_ATTR_IFTYPE because at this point of time// driver always reports that interface is in STATION mode. Even when we// are asking interfaces infomation on behalf of tethering, it is still so// because hostapd is supposed to set interface to AP mode later.string if_name;if (!packet->GetAttributeValue(NL80211_ATTR_IFNAME, &if_name)) {LOG(WARNING) << "Failed to get interface name";continue;}vector<uint8_t> if_mac_addr;if (!packet->GetAttributeValue(NL80211_ATTR_MAC, &if_mac_addr)) {LOG(WARNING) << "Failed to get interface mac address";continue;}interface_info->emplace_back(if_index, if_name, if_mac_addr);}return true;
}

通过netlink_manager_发送包，然后依次解析返回回来的包得到if_index/if_name/if_mac_addr压栈到interface_info，最后封装成一个client_interface

这流程很熟悉，之前在（五十七）Android O WiFi的扫描流程梳理续——梳理java与c++之间的aidl-cpp通信梳理过