WINHTTP_QUERY_URI在WinHTTP的用途？

Question

使用带有WINHTTP_QUERY_URI函数的WinHttpQueryHeaders标志确切地可以查询哪些HTTP标头？在阅读了它的描述之后，我觉得这个标志应该用来获取WinHttpOpenRequest函数中指定的请求的URI。然而，下面的程序给出了一个错误代码12019 ERROR_INTERNET_INCORRECT_HANDLE_STATE (如果我取消注释两行，则为12150 ERROR_HTTP_HEADER_NOT_FOUND )。

#include <cstdio>
#include <windows.h>
#include <winhttp.h>
#pragma comment(lib, "winhttp.lib")
int main()
{
    HINTERNET hSession = WinHttpOpen(nullptr, WINHTTP_ACCESS_TYPE_NO_PROXY, WINHTTP_NO_PROXY_NAME, WINHTTP_NO_PROXY_BYPASS, 0);
    HINTERNET hConnect = WinHttpConnect(hSession, L"www.ietf.org", INTERNET_DEFAULT_HTTP_PORT, 0);
    HINTERNET hRequest = WinHttpOpenRequest(hConnect, L"GET", L"/rfc/rfc2616.txt", nullptr, WINHTTP_NO_REFERER, nullptr, 0);

    //WinHttpSendRequest(hRequest, WINHTTP_NO_ADDITIONAL_HEADERS, 0, WINHTTP_NO_REQUEST_DATA, 0, 0, 0);
    //WinHttpReceiveResponse(hRequest, 0);

    wchar_t url[1024] = {};
    DWORD url_size = sizeof(url);
    auto success = WinHttpQueryHeaders(hRequest, WINHTTP_QUERY_URI, WINHTTP_HEADER_NAME_BY_INDEX, url, &url_size, WINHTTP_NO_HEADER_INDEX);
    auto error_code = GetLastError();
    wprintf(L"success=%d error_code=%u url=%s", success, error_code, url);

    WinHttpCloseHandle(hRequest);
    WinHttpCloseHandle(hConnect);
    WinHttpCloseHandle(hSession);
}

是的，我知道我可以使用WinHttpQueryOption和WINHTTP_OPTION_URL获得请求URI，无需指出这一点。

编辑。按照下面的队长Obvlious回答添加WINHTTP_QUERY_FLAG_REQUEST_HEADERS标志(如果WINHTTP_QUERY_URI确实应该返回请求URI，这完全是有意义的)：现在不管有没有WinHttpSendRequest和WinHttpReceiveResponse调用，WinHttpQueryHeaders函数都会产生错误代码12150 ERROR_HTTP_HEADER_NOT_FOUND。

Answer 1

您正在查询不包含URI的请求的响应头。您需要包含要从请求头检索的WINHTTP_QUERY_FLAG_REQUEST_HEADERS修饰符标志。

WinHttpQueryHeaders(
    hRequest,
    WINHTTP_QUERY_URI | WINHTTP_QUERY_FLAG_REQUEST_HEADERS,
    WINHTTP_HEADER_NAME_BY_INDEX,
    url,
    &url_size,
    WINHTTP_NO_HEADER_INDEX);