Downloaded.cpp

Here's the updated DLL code that includes proxy authentication. I'll modify it to include proxy settings and credentials:

```cpp
// FileDownloadDLL.cpp
#include <windows.h>
#include <winhttp.h>
#include <string>
#pragma comment(lib, "winhttp.lib")

#ifdef FILEDOWNLOADDLL_EXPORTS
#define FILEDOWNLOADDLL_API __declspec(dllexport)
#else
#define FILEDOWNLOADDLL_API __declspec(dllimport)
#endif

// Structure to hold proxy credentials
struct ProxyConfig {
    const wchar_t* proxyAddress;    // e.g., L"proxy.mydomain.com:8080"
    const wchar_t* username;        // Proxy username
    const wchar_t* password;        // Proxy password
};

// Function to download file with proxy authentication
extern "C" FILEDOWNLOADDLL_API BOOL DownloadFileWithProxy(
    const wchar_t* url, 
    const wchar_t* outputPath,
    const ProxyConfig* proxyConfig)
{
    BOOL bResult = FALSE;
    HINTERNET hSession = NULL;
    HINTERNET hConnect = NULL;
    HINTERNET hRequest = NULL;
    HANDLE hFile = INVALID_HANDLE_VALUE;

    // Initialize WinHTTP with proxy settings
    hSession = WinHttpOpen(L"FileDownloadDLL/1.0",
                          WINHTTP_ACCESS_TYPE_NAMED_PROXY,
                          proxyConfig->proxyAddress,
                          WINHTTP_NO_PROXY_BYPASS,
                          0);
    if (!hSession) goto cleanup;

    // Set proxy credentials if provided
    if (proxyConfig->username && proxyConfig->password) {
        WinHttpSetCredentials(hSession,
                            WINHTTP_AUTH_TARGET_PROXY,
                            WINHTTP_AUTH_SCHEME_BASIC,
                            proxyConfig->username,
                            proxyConfig->password,
                            NULL);
    }

    // Parse URL components
    URL_COMPONENTS urlComp = {0};
    urlComp.dwStructSize = sizeof(urlComp);
    urlComp.dwSchemeLength = (DWORD)-1;
    urlComp.dwHostNameLength = (DWORD)-1;
    urlComp.dwUrlPathLength = (DWORD)-1;

    if (!WinHttpCrackUrl(url, 0, 0, &urlComp)) goto cleanup;

    // Extract hostname
    std::wstring hostName(urlComp.lpszHostName, urlComp.dwHostNameLength);
    
    // Connect to server through proxy
    hConnect = WinHttpConnect(hSession, hostName.c_str(), INTERNET_DEFAULT_HTTP_PORT, 0);
    if (!hConnect) goto cleanup;

    // Create HTTP request
    std::wstring urlPath(urlComp.lpszUrlPath, urlComp.dwUrlPathLength);
    hRequest = WinHttpOpenRequest(hConnect,
                                L"GET",
                                urlPath.c_str(),
                                NULL,
                                WINHTTP_NO_REFERER,
                                WINHTTP_DEFAULT_ACCEPT_TYPES,
                                0);
    if (!hRequest) goto cleanup;

    // Send request
    if (!WinHttpSendRequest(hRequest,
                           WINHTTP_NO_ADDITIONAL_HEADERS,
                           0,
                           WINHTTP_NO_REQUEST_DATA,
                           0,
                           0,
                           0)) {
        // Handle proxy authentication if required
        DWORD dwStatusCode = 0;
        DWORD dwStatusCodeSize = sizeof(dwStatusCode);
        WinHttpQueryHeaders(hRequest,
                          WINHTTP_QUERY_STATUS_CODE | WINHTTP_QUERY_FLAG_NUMBER,
                          WINHTTP_HEADER_NAME_BY_INDEX,
                          &dwStatusCode,
                          &dwStatusCodeSize,
                          WINHTTP_NO_HEADER_INDEX);

        if (dwStatusCode == HTTP_STATUS_PROXY_AUTH_REQ) {
            if (!proxyConfig->username || !proxyConfig->password) {
                goto cleanup;  // No credentials provided
            }
            // Retry with credentials
            WinHttpSetCredentials(hRequest,
                                WINHTTP_AUTH_TARGET_PROXY,
                                WINHTTP_AUTH_SCHEME_BASIC,
                                proxyConfig->username,
                                proxyConfig->password,
                                NULL);

            if (!WinHttpSendRequest(hRequest,
                                  WINHTTP_NO_ADDITIONAL_HEADERS,
                                  0,
                                  WINHTTP_NO_REQUEST_DATA,
                                  0,
                                  0,
                                  0)) {
                goto cleanup;
            }
        } else {
            goto cleanup;
        }
    }

    // Receive response
    if (!WinHttpReceiveResponse(hRequest, NULL)) goto cleanup;

    // Create output file
    hFile = CreateFileW(outputPath,
                       GENERIC_WRITE,
                       0,
                       NULL,
                       CREATE_ALWAYS,
                       FILE_ATTRIBUTE_NORMAL,
                       NULL);
    if (hFile == INVALID_HANDLE_VALUE) goto cleanup;

    // Download and write file
    DWORD dwSize = 0;
    DWORD dwDownloaded = 0;
    BYTE buffer[4096];

    do {
        if (!WinHttpQueryDataAvailable(hRequest, &dwSize)) break;
        if (dwSize == 0) break;
        if (!WinHttpReadData(hRequest, buffer, dwSize, &dwDownloaded)) break;
        DWORD dwWritten;
        WriteFile(hFile, buffer, dwDownloaded, &dwWritten, NULL);
    } while (dwSize > 0);

    bResult = TRUE;

cleanup:
    if (hFile != INVALID_HANDLE_VALUE) CloseHandle(hFile);
    if (hRequest) WinHttpCloseHandle(hRequest);
    if (hConnect) WinHttpCloseHandle(hConnect);
    if (hSession) WinHttpCloseHandle(hSession);

    return bResult;
}

// DLL entry point
BOOL APIENTRY DllMain(HMODULE hModule,
                     DWORD  ul_reason_for_call,
                     LPVOID lpReserved)
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}
```

Updated header file:

```cpp
// FileDownloadDLL.h
#pragma once

#ifdef FILEDOWNLOADDLL_EXPORTS
#define FILEDOWNLOADDLL_API __declspec(dllexport)
#else
#define FILEDOWNLOADDLL_API __declspec(dllimport)
#endif

struct ProxyConfig {
    const wchar_t* proxyAddress;
    const wchar_t* username;
    const wchar_t* password;
};

extern "C" FILEDOWNLOADDLL_API BOOL DownloadFileWithProxy(
    const wchar_t* url,
    const wchar_t* outputPath,
    const ProxyConfig* proxyConfig);
```

Example usage:

```cpp
#include "FileDownloadDLL.h"

int main()
{
    ProxyConfig proxy = {
        L"proxy.mydomain.com:8080",  // Proxy address and port
        L"proxyUsername",           // Proxy username
        L"proxyPassword"           // Proxy password
    };

    BOOL result = DownloadFileWithProxy(
        L"http://myserver.com",
        L"C:\\path\\to\\output.bin",
        &proxy);
    
    return result ? 0 : 1;
}
```

Key changes and features:
1. Changed access type to `WINHTTP_ACCESS_TYPE_NAMED_PROXY`
2. Added `ProxyConfig` structure to pass proxy details
3. Added proxy authentication support using `WinHttpSetCredentials`
4. Handles proxy authentication challenges (HTTP 407)
5. Supports BASIC authentication scheme (most common for proxies)
6. Maintains the original file download functionality

Notes:
- Replace "proxy.mydomain.com:8080" with your actual proxy address and port
- Use your actual proxy username and password
- This uses BASIC authentication; some proxies might require NTLM or other schemes
- For HTTPS proxies, you might need to add `WINHTTP_FLAG_SECURE` to `WinHttpOpenRequest`
- Error handling could be enhanced to provide specific proxy-related error codes
- The proxy credentials are optional - if NULL, it will attempt without authentication first

To compile, follow the same steps as before, ensuring `FILEDOWNLOADDLL_EXPORTS` is defined in the project settings and linking against `winhttp.lib`.