以编程方式检查我的机器是否具有Internet访问权限

Question

如何以编程方式检查我的机器是否具有使用C/C++的Internet访问权限,是否仅仅是ping IP？NIC如何做到这一点？我的意思是:

我使用的是Windows 7.

Answer 1

如果你在Windows上工作,试试这个

#include <iostream>
#include <windows.h> 
#include <wininet.h>
using namespace std;

int main(){

if(InternetCheckConnection(L"http://www.google.com",FLAG_ICC_FORCE_CONNECTION,0))
{
        cout << "connected to internet";
}

return 0;
}

Answer 2

根据 Microsoft API 文档，InternetCheckConnection已被弃用。

[InternetCheckConnection 可用于“要求”部分中指定的操作系统。在后续版本中可能会更改或不可用。相反，请使用 NetworkInformation.GetInternetConnectionProfile 或 NLM 接口。]

对于 Windows 平台，我们可以使用INetworkListManager接口来检查 Internet 是否已连接，而不是使用此 API。

下面是 win32 代码库：

#include <iostream>
#include <ObjBase.h>      // include the base COM header
#include <Netlistmgr.h>

// Instruct linker to link to the required COM libraries
#pragma comment(lib, "ole32.lib")

using namespace std;

enum class INTERNET_STATUS
{
    CONNECTED,
    DISCONNECTED,
    CONNECTED_TO_LOCAL,
    CONNECTION_ERROR
};

INTERNET_STATUS IsConnectedToInternet();

int main()
{
    INTERNET_STATUS connectedStatus = INTERNET_STATUS::CONNECTION_ERROR;
    connectedStatus = IsConnectedToInternet();
    switch (connectedStatus)
    {
    case INTERNET_STATUS::CONNECTED:
        cout << "Connected to the internet" << endl;
        break;
    case INTERNET_STATUS::DISCONNECTED:
        cout << "Internet is not available" << endl;
        break;
    case INTERNET_STATUS::CONNECTED_TO_LOCAL:
        cout << "Connected to the local network." << endl;
        break;
    case INTERNET_STATUS::CONNECTION_ERROR:
    default:
        cout << "Unknown error has been occurred." << endl;
        break;
    }
}

INTERNET_STATUS IsConnectedToInternet()
{
    INTERNET_STATUS connectedStatus = INTERNET_STATUS::CONNECTION_ERROR;
    HRESULT hr = S_FALSE;

    try
    {
        hr = CoInitialize(NULL);
        if (SUCCEEDED(hr))
        {
            INetworkListManager* pNetworkListManager;
            hr = CoCreateInstance(CLSID_NetworkListManager, NULL, CLSCTX_ALL, __uuidof(INetworkListManager), (LPVOID*)&pNetworkListManager);
            if (SUCCEEDED(hr))
            {
                NLM_CONNECTIVITY nlmConnectivity = NLM_CONNECTIVITY::NLM_CONNECTIVITY_DISCONNECTED;
                VARIANT_BOOL isConnected = VARIANT_FALSE;
                hr = pNetworkListManager->get_IsConnectedToInternet(&isConnected);
                if (SUCCEEDED(hr))
                {
                    if (isConnected == VARIANT_TRUE)
                        connectedStatus = INTERNET_STATUS::CONNECTED;
                    else
                        connectedStatus = INTERNET_STATUS::DISCONNECTED;
                }

                if (isConnected == VARIANT_FALSE && SUCCEEDED(pNetworkListManager->GetConnectivity(&nlmConnectivity)))
                {
                    if (nlmConnectivity & (NLM_CONNECTIVITY_IPV4_LOCALNETWORK | NLM_CONNECTIVITY_IPV4_SUBNET | NLM_CONNECTIVITY_IPV6_LOCALNETWORK | NLM_CONNECTIVITY_IPV6_SUBNET))
                    {
                        connectedStatus = INTERNET_STATUS::CONNECTED_TO_LOCAL;
                    }
                }

                pNetworkListManager->Release();
            }
        }

        CoUninitialize();
    }
    catch (...)
    {
        connectedStatus = INTERNET_STATUS::CONNECTION_ERROR;
    }

    return connectedStatus;
}

Answer 3

除了 InternetCheckConnection() 函数之外，Win32 API 还有一个函数 ( InternetGetConnectedState() )，它返回某种形式的 Internet 连接（可用性）的 true/false：

https://msdn.microsoft.com/en-us/library/windows/desktop/aa384702(v=vs.85).aspx

它还告诉您您拥有什么类型的互联网连接（LAN、调制解调器、代理等）——这通常很容易知道。