背景
把Windows网络托盘小图标移植到应用程序中来。使得应用界面显示网络状态，状态包括无网络、有线网、无线网(需要显示WiFi信号强度)
方案
- 动态监测托盘图标变化(没有采用)
- 动态监测网络状态变化(利用Windows的API和COM接口，也可以采用轮询)
问题点
- 获取Windows网络的活动连接列表
- 获取活动连接的网络适配器类型
- 注册网络状态变化的通知，避免轮询
- 获取WiFi信号强度
- 注册WiFi信号强度变化的通知，避免轮询
获取Windows网络的活动连接列表
使用的API头文件是<netlistmgr.h> https://docs.microsoft.com/en-us/windows/win32/api/netlistmgr/
先用GetNetworkConnectios拿到一个网络连接的枚举器IEnumNetworkConnections；然后进行枚举活动网络连接INetworkConnection https://docs.microsoft.com/en-us/windows/win32/api/netlistmgr/nn-netlistmgr-inetworkconnection。
可以查看下这里面的方法，通过get_IsConnectedToInternet函数可以过滤掉没有连上网的连接；再通过GetAdapterId拿到网络适配器的GUID，这个很重要，因为要通过这个GUID来判断网络适配器的类型，同时在获取WiFi信号的时候也要用到这个GUID。
获取活动连接的网络适配器类型
使用的API头文件是<iphlpapi.h> https://docs.microsoft.com/en-us/windows/win32/api/iphlpapi/
使用GetAdaptersInfo https://docs.microsoft.com/zh-cn/windows/win32/api/iphlpapi/nf-iphlpapi-getadaptersinfo 可以拿到所有网络适配器的信息IP_ADAPTER_INFO https://docs.microsoft.com/en-us/windows/win32/api/iptypes/ns-iptypes-ip_adapter_info，这里面有个字段AdapterName，里面的信息就是之前提到的GUID，通过这个可以定位到活动网络连接对应的网络适配器；里面还有个字段Type，需要关心的类型含义如下：
MIB_IF_TYPE_ETHERNET以太网，就是有线网MIB_IF_TYPE_LOOPBACK环回地址，过滤掉IF_TYPE_IEEE80211无线网
显示的规则如下：
同时存在有线和无线，优先显示有线；只存在其一则正常显示；如果都没有那么就显示断网。
注册网络状态变化的通知
使用事件INetworkConnectionEvents https://docs.microsoft.com/en-us/windows/win32/api/netlistmgr/nn-netlistmgr-inetworkconnectionevents；实现这个纯虚类，这里面有个接口NetworkConnectionConnectivityChanged，这个函数会在网络状态发生变化的时候回调。
注意，之前使用了INetworkListManagerEvents，里面有个函数ConnectivityChanged，这个函数在网络状态发生变化的时候也会回调，但是不敏感，举个例子：假设你有一个有线网卡和一个无线网卡，两个都连上网了，这个时候断开有线网，这个函数是不会回调的，但是NetworkConnectionConnectivityChanged会回调。因此优先使用上一个事件。
MSDN上有一个例子可以参考，https://docs.microsoft.com/zh-cn/previous-versions/windows/desktop/mpc/network-awareness-on-windows-vista-and-windows-7
在网络状态变化回调时获取一次活动网络连接，把结果进行显示即可。
获取WiFi信号强度
MSDN上有一个例子，https://docs.microsoft.com/zh-cn/windows/win32/api/wlanapi/nf-wlanapi-wlanqueryinterface；
有可能存在很多WiFi网卡，因此上文中提到的GUID又起作用了。
获取wlanSignalQuality可线性转换为RSSI。这里参考了https://www.netspotapp.com/what-is-rssi-level.html，把信号强度分成了四个等级。
注册WiFi信号强度变化的通知
使用API WlanRegisterNotification https://docs.microsoft.com/en-us/windows/win32/api/wlanapi/nf-wlanapi-wlanregisternotification 注册回调 WLAN_NOTIFICATION_CALLBACK，里面有个参数NotificationSource和NotificationCode，只有当这两个参数满足NotificationSource == WLAN_NOTIFICATION_SOURCE_MSM && NotificationCode == wlan_notification_msm_signal_quality_change时，回调的内容才是WiFi信号发生了改变，可以把pData转成WLAN_SIGNAL_QUALITY，注意，这个值是不能用的，根本就不是WiFi信号强度，因此这里就改成回调时再获取一次WiFi信号强度即可。
整个流程就过完了，下面就上代码吧。有些细节需要自己揣摩下。
#include <string>
#include <iostream>
#include <memory>
#include <thread>
#include <vector>
#include <algorithm>
#include <locale>
#include <codecvt>
#include <Windows.h>
#include <netlistmgr.h>
#include <atlbase.h>
#include <objbase.h>
#include <wtypes.h>
#include <wlanapi.h>
#include <IPHlpApi.h>
#pragma comment(lib, "ole32.lib")
#pragma comment(lib, "wlanapi.lib")
#pragma comment(lib, "Iphlpapi.lib")
static std::wstring GUIDToString(const GUID & guid)
{
OLECHAR guidString[40] = { 0 };
::StringFromGUID2(guid, guidString, sizeof(guidString));
return guidString;
}
static std::string UnicodeToUTF8(const std::wstring & wstr)
{
std::string ret;
try
{
std::wstring_convert< std::codecvt_utf8<wchar_t> > wcv;
ret = wcv.to_bytes(wstr);
}
catch (const std::exception & e)
{
std::cerr << e.what() << std::endl;
}
return ret;
}
class NetWorkEvent : public INetworkConnectionEvents
{
private:
LONG _ref;
std::function<void()> _callback;
public:
NetWorkEvent(const std::function<void()> & cb);
virtual HRESULT STDMETHODCALLTYPE NetworkConnectionConnectivityChanged(
/* [in] */ GUID connectionId,
/* [in] */ NLM_CONNECTIVITY newConnectivity);
virtual HRESULT STDMETHODCALLTYPE NetworkConnectionPropertyChanged(
/* [in] */ GUID connectionId,
/* [in] */ NLM_CONNECTION_PROPERTY_CHANGE flags);
STDMETHODIMP QueryInterface(REFIID refIID, void **pIFace);
virtual ULONG __stdcall AddRef(void);
virtual ULONG __stdcall Release(void);
};
NetWorkEvent::NetWorkEvent(const std::function<void()>& cb)
: _callback(cb)
{
}
HRESULT NetWorkEvent::NetworkConnectionConnectivityChanged(GUID connectionId, NLM_CONNECTIVITY newConnectivity)
{
std::wcout << GUIDToString(connectionId) << " | NUL_CONNECTIVITY : " << newConnectivity << std::endl;
if (_callback)
{
_callback();
}
return S_OK;
}
HRESULT NetWorkEvent::NetworkConnectionPropertyChanged(GUID connectionId, NLM_CONNECTION_PROPERTY_CHANGE flags)
{
return S_OK;
}
STDMETHODIMP NetWorkEvent::QueryInterface(REFIID refIID, void ** pIFace)
{
HRESULT hr = S_OK;
*pIFace = NULL;
if (IsEqualIID(refIID, IID_IUnknown))
{
*pIFace = (IUnknown *)this;
((IUnknown *)*pIFace)->AddRef();
}
else if (IsEqualIID(refIID, IID_INetworkConnectionEvents))
{
*pIFace = (INetworkConnectionEvents *)this;
((IUnknown *)*pIFace)->AddRef();
}
else
{
hr = E_NOINTERFACE;
}
return hr;
}
ULONG NetWorkEvent::AddRef(void)
{
return (ULONG)InterlockedIncrement(&_ref);
}
ULONG NetWorkEvent::Release(void)
{
LONG Result = InterlockedDecrement(&_ref);
if (Result == 0)
delete this;
return (ULONG)Result;
}
enum NetworkType
{
NotNetwork,
Ethernet,
Wlan,
};
enum WiFiQuality
{
Weak, // (-INF, -70dBm)
Fair, // [-70dBm, -60dBm)
Good, // [-60dBm, -50dBm)
Excellent // [-50dBm, +INF)
};
struct ConnectionInfo
{
std::wstring guid;
NetworkType type;
};
class NetworkMonitor
{
friend void OnNotificationCallback(PWLAN_NOTIFICATION_DATA Data, PVOID context);
public:
NetworkMonitor();
~NetworkMonitor();
std::vector<ConnectionInfo> GetNetworkConnections();
NetworkType GetNetAdpaterType(const std::wstring &guid);
void OnNetworkStatusChange();
WiFiQuality GetWiFiSignalQuality(const std::wstring &guid);
void OnWiFiQualityChange(const GUID & guid);
void ShowNetworkStatus();
private:
std::unique_ptr<NetWorkEvent> _networkEvent;
DWORD _cookie;
CComPtr<INetworkListManager> _pNLM;
CComPtr<IConnectionPointContainer> _pCpc;
CComPtr<IConnectionPoint> _pConnectionPoint;
HANDLE _wlanHandle;
};
static NetworkMonitor * InstanceOfNetworkMonitor()
{
static NetworkMonitor instance;
return &instance;
}
NetworkMonitor::NetworkMonitor()
{
CoInitializeEx(NULL, COINIT_MULTITHREADED | COINIT_DISABLE_OLE1DDE);
HRESULT hr = CoCreateInstance(CLSID_NetworkListManager, NULL, CLSCTX_ALL, IID_INetworkListManager, (LPVOID *)&_pNLM);
hr = _pNLM->QueryInterface(IID_IConnectionPointContainer, (void **)&_pCpc);
hr = _pCpc->FindConnectionPoint(IID_INetworkConnectionEvents, &_pConnectionPoint);
_networkEvent = std::make_unique<NetWorkEvent>(std::bind(&NetworkMonitor::OnNetworkStatusChange, this));
hr = _pConnectionPoint->Advise((IUnknown *)_networkEvent.get(), &_cookie);
}
NetworkMonitor::~NetworkMonitor()
{
if (_pConnectionPoint)
{
_pConnectionPoint->Unadvise(_cookie);
}
CloseHandle(_wlanHandle);
CoUninitialize();
}
void OnNotificationCallback(PWLAN_NOTIFICATION_DATA Data, PVOID context)
{
if (Data != NULL &&
Data->NotificationSource == WLAN_NOTIFICATION_SOURCE_MSM &&
Data->NotificationCode == wlan_notification_msm_signal_quality_change)
{
WLAN_SIGNAL_QUALITY Qality = (WLAN_SIGNAL_QUALITY)Data->pData;
std::cout << "WiFi OnNotification Qality : " << Qality << std::endl;
InstanceOfNetworkMonitor()->OnWiFiQualityChange(Data->InterfaceGuid);
}
}
std::vector<ConnectionInfo> NetworkMonitor::GetNetworkConnections()
{
std::vector<ConnectionInfo> result;
CComPtr<IEnumNetworkConnections> enumConnectons;
if (FAILED(_pNLM->GetNetworkConnections(&enumConnectons)))
{
std::cerr << "GetNetworkConnections error : " << GetLastError() << std::endl;
return result;
}
if (enumConnectons)
{
ULONG lFetch;
INetworkConnection *connection = nullptr;
while (SUCCEEDED(enumConnectons->Next(1, &connection, &lFetch)) && nullptr != connection)
{
VARIANT_BOOL isConnectInternet = VARIANT_FALSE;
connection->get_IsConnectedToInternet(&isConnectInternet);
if (isConnectInternet == VARIANT_FALSE)
{
continue;
}
ConnectionInfo item;
GUID guid;
connection->GetAdapterId(&guid);
item.guid = GUIDToString(guid);
result.push_back(item);
}
if (connection)
{
connection->Release();
}
}
for (auto it = result.begin(); it != result.end(); ++it)
{
it->type = GetNetAdpaterType(it->guid);
}
std::partition(result.begin(), std::partition(result.begin(), result.end(), [](const ConnectionInfo & info)
{
return info.type != NetworkType::NotNetwork;
}), [](const ConnectionInfo & info)
{
return info.type == NetworkType::Ethernet;
});
for (auto it = result.begin(); it != result.end(); ++it)
{
std::wcout << "connect network guid : " << it->guid << " | type : " << it->type << std::endl;
}
return result;
}
NetworkType NetworkMonitor::GetNetAdpaterType(const std::wstring & guid)
{
unsigned long unSize = sizeof(IP_ADAPTER_INFO);
std::unique_ptr<uint8_t[]> data = std::make_unique<uint8_t[]>(unSize);
bool find = false;
unsigned long unResult = GetAdaptersInfo(reinterpret_cast<PIP_ADAPTER_INFO>(data.get()), &unSize);
if (ERROR_BUFFER_OVERFLOW == unResult)
{
data = std::make_unique<uint8_t[]>(unSize);
unResult = GetAdaptersInfo(reinterpret_cast<PIP_ADAPTER_INFO>(data.get()), &unSize);
}
if (ERROR_SUCCESS == unResult)
{
PIP_ADAPTER_INFO pIpAdapterInfo = reinterpret_cast<PIP_ADAPTER_INFO>(data.get());
while (pIpAdapterInfo)
{
if (UnicodeToUTF8(guid) == pIpAdapterInfo->AdapterName)
{
return MIB_IF_TYPE_ETHERNET == pIpAdapterInfo->Type ? NetworkType::Ethernet :
IF_TYPE_IEEE80211 == pIpAdapterInfo->Type ? NetworkType::Wlan : NetworkType::NotNetwork;
}
pIpAdapterInfo = pIpAdapterInfo->Next;
}
}
return NetworkType::NotNetwork;
}
void NetworkMonitor::OnNetworkStatusChange()
{
ShowNetworkStatus();
}
WiFiQuality NetworkMonitor::GetWiFiSignalQuality(const std::wstring & guid)
{
WiFiQuality result = WiFiQuality::Weak;
DWORD dwMaxClient = 2;
DWORD dwCurVersion = 0;
DWORD dwResult = 0;
unsigned int i, j;
PWLAN_INTERFACE_INFO_LIST pIfList = NULL;
PWLAN_INTERFACE_INFO pIfInfo = NULL;
PWLAN_AVAILABLE_NETWORK_LIST pBssList = NULL;
PWLAN_AVAILABLE_NETWORK pBssEntry = NULL;
int iRSSI = 0;
if (_wlanHandle == NULL)
{
dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &_wlanHandle);
if (dwResult != ERROR_SUCCESS)
{
std::cerr << "WlanOpenHandle failed with error: " << dwResult << std::endl;
return result;
}
dwResult = WlanRegisterNotification(_wlanHandle, WLAN_NOTIFICATION_SOURCE_ALL, TRUE, WLAN_NOTIFICATION_CALLBACK(OnNotificationCallback), NULL, NULL, NULL);
if (dwResult != ERROR_SUCCESS)
{
std::cerr << "WlanRegisterNotification failed with error: " << dwResult << std::endl;
return result;
}
}
dwResult = WlanEnumInterfaces(_wlanHandle, NULL, &pIfList);
if (dwResult != ERROR_SUCCESS)
{
std::cerr << "WlanEnumInterfaces failed with error: " << dwResult << std::endl;
return result;
}
for (i = 0; i < (int)pIfList->dwNumberOfItems; i++)
{
pIfInfo = (WLAN_INTERFACE_INFO *)&pIfList->InterfaceInfo[i];
if (guid != GUIDToString(pIfInfo->InterfaceGuid) || pIfInfo->isState != wlan_interface_state_connected)
{
continue;
}
dwResult = WlanGetAvailableNetworkList(_wlanHandle,
&pIfInfo->InterfaceGuid,
0,
NULL,
&pBssList);
if (dwResult != ERROR_SUCCESS)
{
std::cerr << "WlanGetAvailableNetworkList failed with error:" << dwResult << std::endl;
return result;
}
for (j = 0; j < pBssList->dwNumberOfItems; j++)
{
pBssEntry = (WLAN_AVAILABLE_NETWORK *)& pBssList->Network[j];
if (pBssEntry->bNetworkConnectable && (pBssEntry->dwFlags & WLAN_AVAILABLE_NETWORK_CONNECTED))
{
if (pBssEntry->wlanSignalQuality == 0)
iRSSI = -100;
else if (pBssEntry->wlanSignalQuality == 100)
iRSSI = -50;
else
iRSSI = -100 + (pBssEntry->wlanSignalQuality / 2);
std::cout << "Signal Quality:\t " << pBssEntry->wlanSignalQuality << " (RSSI: " << iRSSI << " dBm)" << std::endl;
result = iRSSI < -70 ? WiFiQuality::Weak :
iRSSI < -60 ? WiFiQuality::Fair :
iRSSI < -50 ? WiFiQuality::Good : WiFiQuality::Excellent;
}
}
}
if (pBssList != NULL)
{
WlanFreeMemory(pBssList);
pBssList = NULL;
}
if (pIfList != NULL)
{
WlanFreeMemory(pIfList);
pIfList = NULL;
}
return result;
}
void NetworkMonitor::OnWiFiQualityChange(const GUID & guid)
{
auto nowQuality = GetWiFiSignalQuality(GUIDToString(guid));
std::cout << "WiFi signal quality now : " << nowQuality << std::endl;
ShowNetworkStatus();
}
void NetworkMonitor::ShowNetworkStatus()
{
NetworkType type;
WiFiQuality quality;
auto connections = GetNetworkConnections();
if (connections.empty())
{
type = NetworkType::NotNetwork;
}
else
{
type = connections.front().type;
if (type == NetworkType::Wlan)
{
quality = GetWiFiSignalQuality(connections.front().guid);
}
}
std::cout << "====== Notify ======" << std::endl;
std::cout << "* Type : " << (type == NetworkType::NotNetwork ? "NetworkError" : type == NetworkType::Ethernet ? "Ethernet" : "WiFi") << std::endl;
if (type == NetworkType::Wlan)
{
std::cout << "* Signal : " << quality + 1 << std::endl;
}
std::cout << std::endl;
}
int main()
{
InstanceOfNetworkMonitor()->ShowNetworkStatus();
while (true) std::this_thread::sleep_for(std::chrono::hours(10));
return 0;
}
