c++ - 如何在 C++ 中使用 WMI 从 WIN32_NetworkAdapter 检索值？我无法理解查询后用于访问值的 VARIANT

Question

1. Win_32 网络适配器、Win32_SignedDriver、如何在 C++ 中使用 WMI 从 WIN32_NetworkAdapter 检索值？我无法理解查询后用于访问值的 VARIANT。

Answer 1

MSDN 有很多关于 WMI and C++ 的资源, 此外，如果您不熟悉从 C++ 使用 WMI，则可以使用 WMI Delphi Code Creator它允许您生成 C++ 代码以访问 WMI 类、事件和方法。

尝试应用程序生成的示例代码

#include "stdafx.h"
#define _WIN32_DCOM
#include <iostream>
using namespace std;
#include <comdef.h>
#include <Wbemidl.h>
#pragma comment(lib, "wbemuuid.lib")

//CREDENTIAL structure
//http://msdn.microsoft.com/en-us/library/windows/desktop/aa374788%28v=vs.85%29.aspx
#define CRED_MAX_USERNAME_LENGTH            513
#define CRED_MAX_CREDENTIAL_BLOB_SIZE       512
#define CREDUI_MAX_USERNAME_LENGTH CRED_MAX_USERNAME_LENGTH
#define CREDUI_MAX_PASSWORD_LENGTH (CRED_MAX_CREDENTIAL_BLOB_SIZE / 2)


#pragma argsused
int main(int argc, char* argv[])
{
    wchar_t pszName[CREDUI_MAX_USERNAME_LENGTH+1] = L"user";
    wchar_t pszPwd[CREDUI_MAX_PASSWORD_LENGTH+1]  = L"password";
    BSTR strNetworkResource;
    //To use a WMI remote connection set localconn to false and configure the values of the pszName, pszPwd and the name of the remote machine in strNetworkResource
    bool localconn = true;  
    strNetworkResource = localconn ?  L"\\\\.\\root\\CIMV2" : L"\\\\remote--machine\\root\\CIMV2";

    COAUTHIDENTITY *userAcct =  NULL ;
    COAUTHIDENTITY authIdent;

    // Initialize COM. ------------------------------------------

    HRESULT hres;
    hres =  CoInitializeEx(0, COINIT_MULTITHREADED);
    if (FAILED(hres))
    {
        cout << "Failed to initialize COM library. Error code = 0x" << hex << hres << endl;
        cout << _com_error(hres).ErrorMessage() << endl;
        cout << "press enter to exit" << endl;
        cin.get();      
        return 1;                  // Program has failed.
    }

    // Set general COM security levels --------------------------

    if (localconn)
        hres =  CoInitializeSecurity(
            NULL,
            -1,                          // COM authentication
            NULL,                        // Authentication services
            NULL,                        // Reserved
            RPC_C_AUTHN_LEVEL_DEFAULT,   // Default authentication
            RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation
            NULL,                        // Authentication info
            EOAC_NONE,                   // Additional capabilities
            NULL                         // Reserved
            );
    else
        hres =  CoInitializeSecurity(
            NULL,
            -1,                          // COM authentication
            NULL,                        // Authentication services
            NULL,                        // Reserved
            RPC_C_AUTHN_LEVEL_DEFAULT,   // Default authentication
            RPC_C_IMP_LEVEL_IDENTIFY,    // Default Impersonation
            NULL,                        // Authentication info
            EOAC_NONE,                   // Additional capabilities
            NULL                         // Reserved
            );

    if (FAILED(hres))
    {
        cout << "Failed to initialize security. Error code = 0x" << hex << hres << endl;
        cout << _com_error(hres).ErrorMessage() << endl;
        CoUninitialize();
        cout << "press enter to exit" << endl;
        cin.get();      
        return 1;                    // Program has failed.
    }

    // Obtain the initial locator to WMI -------------------------

    IWbemLocator *pLoc = NULL;
    hres = CoCreateInstance(CLSID_WbemLocator, 0, CLSCTX_INPROC_SERVER, IID_IWbemLocator, (LPVOID *) &pLoc);

    if (FAILED(hres))
    {
        cout << "Failed to create IWbemLocator object." << " Err code = 0x" << hex << hres << endl;
        cout << _com_error(hres).ErrorMessage() << endl;
        CoUninitialize();       
        cout << "press enter to exit" << endl;
        cin.get();      
        return 1;                 // Program has failed.
    }

    // Connect to WMI through the IWbemLocator::ConnectServer method

    IWbemServices *pSvc = NULL;

    if (localconn)  
        hres = pLoc->ConnectServer(
             _bstr_t(strNetworkResource),      // Object path of WMI namespace
             NULL,                    // User name. NULL = current user
             NULL,                    // User password. NULL = current
             0,                       // Locale. NULL indicates current
             NULL,                    // Security flags.
             0,                       // Authority (e.g. Kerberos)
             0,                       // Context object
             &pSvc                    // pointer to IWbemServices proxy
             );
    else
        hres = pLoc->ConnectServer(
            _bstr_t(strNetworkResource),  // Object path of WMI namespace
            _bstr_t(pszName),             // User name
            _bstr_t(pszPwd),              // User password
            NULL,                // Locale
            NULL,                // Security flags
            NULL,                // Authority
            NULL,                // Context object
            &pSvc                // IWbemServices proxy
            );

    if (FAILED(hres))
    {
        cout << "Could not connect. Error code = 0x" << hex << hres << endl;    
        cout << _com_error(hres).ErrorMessage() << endl;
        pLoc->Release();
        CoUninitialize();
        cout << "press enter to exit" << endl;
        cin.get();          
        return 1;                // Program has failed.
    }

    cout << "Connected to root\\CIMV2 WMI namespace" << endl;

    // Set security levels on the proxy -------------------------
    if (localconn)
        hres = CoSetProxyBlanket(
           pSvc,                        // Indicates the proxy to set
           RPC_C_AUTHN_WINNT,           // RPC_C_AUTHN_xxx
           RPC_C_AUTHZ_NONE,            // RPC_C_AUTHZ_xxx
           NULL,                        // Server principal name
           RPC_C_AUTHN_LEVEL_CALL,      // RPC_C_AUTHN_LEVEL_xxx
           RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
           NULL,                        // client identity
           EOAC_NONE                    // proxy capabilities
        );
    else
    {
        // Create COAUTHIDENTITY that can be used for setting security on proxy
        memset(&authIdent, 0, sizeof(COAUTHIDENTITY));
        authIdent.PasswordLength = wcslen (pszPwd);
        authIdent.Password = (USHORT*)pszPwd;
        authIdent.User = (USHORT*)pszName;
        authIdent.UserLength = wcslen(pszName);
        authIdent.Domain = 0;
        authIdent.DomainLength = 0;
        authIdent.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE;
        userAcct = &authIdent;

        hres = CoSetProxyBlanket(
           pSvc,                           // Indicates the proxy to set
           RPC_C_AUTHN_DEFAULT,            // RPC_C_AUTHN_xxx
           RPC_C_AUTHZ_DEFAULT,            // RPC_C_AUTHZ_xxx
           COLE_DEFAULT_PRINCIPAL,         // Server principal name
           RPC_C_AUTHN_LEVEL_PKT_PRIVACY,  // RPC_C_AUTHN_LEVEL_xxx
           RPC_C_IMP_LEVEL_IMPERSONATE,    // RPC_C_IMP_LEVEL_xxx
           userAcct,                       // client identity
           EOAC_NONE                       // proxy capabilities
        );
    }

    if (FAILED(hres))
    {
        cout << "Could not set proxy blanket. Error code = 0x" << hex << hres << endl;
        cout << _com_error(hres).ErrorMessage() << endl;
        pSvc->Release();
        pLoc->Release();
        CoUninitialize();
        cout << "press enter to exit" << endl;
        cin.get();      
        return 1;               // Program has failed.
    }

    // Use the IWbemServices pointer to make requests of WMI ----

    IEnumWbemClassObject* pEnumerator = NULL;
    hres = pSvc->ExecQuery( L"WQL", L"SELECT * FROM Win32_NetworkAdapter",
    WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &pEnumerator);

    if (FAILED(hres))
    {
        cout << "ExecQuery failed" << " Error code = 0x"    << hex << hres << endl;
        cout << _com_error(hres).ErrorMessage() << endl;
        pSvc->Release();
        pLoc->Release();
        CoUninitialize();
        cout << "press enter to exit" << endl;
        cin.get();      
        return 1;               // Program has failed.
    }

    // Secure the enumerator proxy
    if (!localconn)
    {

        hres = CoSetProxyBlanket(
            pEnumerator,                    // Indicates the proxy to set
            RPC_C_AUTHN_DEFAULT,            // RPC_C_AUTHN_xxx
            RPC_C_AUTHZ_DEFAULT,            // RPC_C_AUTHZ_xxx
            COLE_DEFAULT_PRINCIPAL,         // Server principal name
            RPC_C_AUTHN_LEVEL_PKT_PRIVACY,  // RPC_C_AUTHN_LEVEL_xxx
            RPC_C_IMP_LEVEL_IMPERSONATE,    // RPC_C_IMP_LEVEL_xxx
            userAcct,                       // client identity
            EOAC_NONE                       // proxy capabilities
            );

        if (FAILED(hres))
        {
            cout << "Could not set proxy blanket on enumerator. Error code = 0x" << hex << hres << endl;
            cout << _com_error(hres).ErrorMessage() << endl;
            pEnumerator->Release();
            pSvc->Release();
            pLoc->Release();
            CoUninitialize();
            cout << "press enter to exit" << endl;
            cin.get();              
            return 1;               // Program has failed.
        }
    }

    // Get the data from the WQL sentence
    IWbemClassObject *pclsObj = NULL;
    ULONG uReturn = 0;

    while (pEnumerator)
    {
        HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1, &pclsObj, &uReturn);

        if(0 == uReturn || FAILED(hr))
          break;

        VARIANT vtProp;

                hr = pclsObj->Get(L"AdapterType", 0, &vtProp, 0, 0);// String
                if (!FAILED(hr))
                {
                  if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
                    wcout << "AdapterType : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
                  else
                    wcout << "AdapterType : " << vtProp.bstrVal << endl;
                }
                VariantClear(&vtProp);

                hr = pclsObj->Get(L"AdapterTypeId", 0, &vtProp, 0, 0);// Uint16
                if (!FAILED(hr))
                {
                  if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
                    wcout << "AdapterTypeId : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
                  else
                    wcout << "AdapterTypeId : " << vtProp.uiVal << endl;
                }
                VariantClear(&vtProp);

                hr = pclsObj->Get(L"Caption", 0, &vtProp, 0, 0);// String
                if (!FAILED(hr))
                {
                  if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
                    wcout << "Caption : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
                  else
                    wcout << "Caption : " << vtProp.bstrVal << endl;
                }
                VariantClear(&vtProp);

                hr = pclsObj->Get(L"Description", 0, &vtProp, 0, 0);// String
                if (!FAILED(hr))
                {
                  if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
                    wcout << "Description : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
                  else
                    wcout << "Description : " << vtProp.bstrVal << endl;
                }
                VariantClear(&vtProp);

                hr = pclsObj->Get(L"MACAddress", 0, &vtProp, 0, 0);// String
                if (!FAILED(hr))
                {
                  if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
                    wcout << "MACAddress : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
                  else
                    wcout << "MACAddress : " << vtProp.bstrVal << endl;
                }
                VariantClear(&vtProp);


        pclsObj->Release();
        pclsObj=NULL;
    }

    // Cleanup

    pSvc->Release();
    pLoc->Release();
    pEnumerator->Release();
    if (pclsObj!=NULL)
     pclsObj->Release();

    CoUninitialize();
    cout << "press enter to exit" << endl;
    cin.get();
    return 0;   // Program successfully completed.
}