windows凭据提示出现问题，CredUnPackAuthenticationBuffer错误50

Question

我正在尝试显示Windows默认凭证提示，并将用户名、密码和域检索为字符串。

我正在使用这些文档：

CredUIPromptForWindowsCredentialsW

CredUnPackAuthenticationBufferW

当提示符显示时，我输入随机用户名和密码(例如，用户名: test，密码: test123)，点击enter和函数CredUnPackAuthenticationBuffer()失败。

代码：

#include <Windows.h>
#include <wincred.h> //Link library Credui.lib for CredUIPromptForWindowsCredentials() to work
#include <iostream>
#include <string>

//Display error in console and close application
void DisplayConsoleError(const WCHAR* errorMessage, const WCHAR* fName);

int wmain(int argc, WCHAR* argv[])
{
        CREDUI_INFO cuiInfo;
    cuiInfo.cbSize = sizeof(CREDUI_INFO);
    cuiInfo.hbmBanner = nullptr;
    cuiInfo.hwndParent = nullptr;
    cuiInfo.pszCaptionText = L"CaptionText";
    cuiInfo.pszMessageText = L"MessageText";

    DWORD dwAuthError = 0;
    ULONG dwAuthPackage = 0;

    LPVOID outCredBuffer = nullptr;
    ULONG outCredBufferSize = 0;
    BOOL credSaveCheckbox = false;

    DWORD dwError = 0;
    DWORD lastError = 0;

    dwError = CredUIPromptForWindowsCredentials(
        &cuiInfo, 
        dwAuthError, 
        &dwAuthPackage, 
        nullptr, 
        NULL, 
        &outCredBuffer, 
        &outCredBufferSize, 
        &credSaveCheckbox, 
        CREDUIWIN_CHECKBOX | CREDUIWIN_GENERIC);

    if (dwError == ERROR_SUCCESS)
    {
        DWORD maxUserNameSize = CREDUI_MAX_USERNAME_LENGTH;
        DWORD maxDomainNameSize = CREDUI_MAX_DOMAIN_TARGET_LENGTH;
        DWORD maxPasswordLength = CREDUI_MAX_PASSWORD_LENGTH;

        LPWSTR szUserName = new WCHAR[maxUserNameSize];
        LPWSTR szDomain = new WCHAR[maxDomainNameSize];
        LPWSTR szPassword = new WCHAR[maxPasswordLength];

        DWORD dwCredBufferSize = outCredBufferSize;     //ULONG to DWORD

        DWORD lastError = 0;
        dwError = CredUnPackAuthenticationBuffer(
            CRED_PACK_GENERIC_CREDENTIALS,
            &outCredBuffer,
            dwCredBufferSize,
            szUserName,
            &maxUserNameSize,
            szDomain,
            &maxDomainNameSize,
            szPassword,
            &maxPasswordLength
        );
        lastError = GetLastError();

        //Check for error
        if (dwError == FALSE)
        {
            DisplayConsoleError(L"Blah", L"CredUnPackAuthenticationBuffer", lastError);
        }
        else
        {
            std::wcout << L"username " << szUserName << std::endl;
            std::wcout << L"domain " << szDomain << std::endl;
            std::wcout << L"password " << szPassword << std::endl;
        }

    }
    else
    {
        lastError = dwError;
    }

    SecureZeroMemory(outCredBuffer, outCredBufferSize);
    CoTaskMemFree(outCredBuffer);

    return lastError;
} 

此外，在CredUIPromptForWindowsCredentials()中调试VS2019失败(加载符号问题？)，但编译的.exe工作正常。作为解决办法，我附加调试器来处理。

我是winapi的初学者，所以如果有人能解释为什么会出现这个错误，我做错了什么，以及如何修复这段代码，我将不胜感激。

编辑将错误检查移至SecureZeroMemory()和CoTaskMemFree()函数之上，以避免在检查错误消息之前调用其他API函数，但错误保持不变。

DisplayConsoleError：

void DisplayConsoleError(const WCHAR* errorMessage, const WCHAR* fName, DWORD lastError)
{
    std::cout << std::endl;
    std::cout << "Error\t" << std::endl;
    std::wcout << L"In function:\t" << fName << std::endl;
    std::cout << "Code:\t" << lastError << std::endl;
    std::cout << std::endl;
}

考虑@RemyLebeau反馈对代码的编辑2更改

Answer 1

在代码中查看此函数：

CredUnPackAuthenticationBuffer(
            CRED_PACK_GENERIC_CREDENTIALS,
            &outCredBuffer,
            dwCredBufferSize,
            szUserName,
            &maxUserNameSize,
            szDomain,
            &maxDomainNameSize,
            szPassword,
            &maxPasswordLength
        );

您需要将&outCredBuffer 更改为 outCredBuffer**.**

#include <Windows.h>
#include <wincred.h> //Link library Credui.lib for CredUIPromptForWindowsCredentials() to work
#include <iostream>
#include <string>

//Display error in console and close application
void DisplayConsoleError(const WCHAR* errorMessage, const WCHAR* fName, DWORD lastError)
{
    std::cout << std::endl;
    std::cout << "Error\t" << std::endl;
    std::wcout << L"In function:\t" << fName << std::endl;
    std::cout << "Code:\t" << lastError << std::endl;
    std::cout << std::endl;
}

int wmain(int argc, WCHAR* argv[])
{
    CREDUI_INFO cuiInfo;
    cuiInfo.cbSize = sizeof(CREDUI_INFO);
    cuiInfo.hbmBanner = nullptr;
    cuiInfo.hwndParent = nullptr;
    cuiInfo.pszCaptionText = L"CaptionText";
    cuiInfo.pszMessageText = L"MessageText";

    DWORD dwAuthError = 0;
    ULONG dwAuthPackage = 0;

    LPVOID outCredBuffer = nullptr;
    ULONG outCredBufferSize = 0;
    BOOL credSaveCheckbox = false;

    DWORD dwError = 0;
    DWORD lastError = 0;

    dwError = CredUIPromptForWindowsCredentials(
        &cuiInfo,
        dwAuthError,
        &dwAuthPackage,
        nullptr,
        NULL,
        &outCredBuffer,
        &outCredBufferSize,
        &credSaveCheckbox,
        CREDUIWIN_CHECKBOX | CREDUIWIN_GENERIC);

    if (dwError == ERROR_SUCCESS)
    {
        DWORD maxUserNameSize = CREDUI_MAX_USERNAME_LENGTH;
        DWORD maxDomainNameSize = CREDUI_MAX_DOMAIN_TARGET_LENGTH;
        DWORD maxPasswordLength = CREDUI_MAX_PASSWORD_LENGTH;

        LPWSTR szUserName = new WCHAR[maxUserNameSize];
        LPWSTR szDomain = new WCHAR[maxDomainNameSize];
        LPWSTR szPassword = new WCHAR[maxPasswordLength];

        DWORD dwCredBufferSize = outCredBufferSize;     //ULONG to DWORD

        DWORD lastError = 0;
        dwError = CredUnPackAuthenticationBuffer(
            CRED_PACK_GENERIC_CREDENTIALS,
            outCredBuffer,
            dwCredBufferSize,
            szUserName,
            &maxUserNameSize,
            szDomain,
            &maxDomainNameSize,
            szPassword,
            &maxPasswordLength
        );
        lastError = GetLastError();

        //Check for error
        if (dwError == FALSE)
        {
            DisplayConsoleError(L"Blah", L"CredUnPackAuthenticationBuffer", lastError);
        }
        else
        {
            std::wcout << L"username " << szUserName << std::endl;
            std::wcout << L"domain " << szDomain << std::endl;
            std::wcout << L"password " << szPassword << std::endl;
        }

    }
    else
    {
        lastError = dwError;
    }

    SecureZeroMemory(outCredBuffer, outCredBufferSize);
    CoTaskMemFree(outCredBuffer);

    return lastError;
}