Question

MSDN states，WinInet不支持分块上传（“客户端代码必须执行分块。”）。对我而言，这意味着我可以手动切换传输。我的目的是通过HttpAddRequestHeaders添加“Transfer-Encoding：chunked”，通过HttpAddRequestHeaders HTTP_ADDREQ_FLAG_REPLACE删除Content-Length，然后在我的InternetWriteFile循环中，将数据写入分块编码块。问题是，我似乎无法说服WinInet不发送Content-Length。即使在删除后，它最终会向服务器发送“Content-Length：0”（除了“Transfer-Encoding：chunked”之外），这会使服务器感到困惑。

我也尝试在HttpSendRequestEx中设置HSR_CHUNKED标志。

有没有人有一个让WinInet跳过发送Content-Length的例子？

我知道WinHTTP声称支持分块上传，但我们对WinInet有其他依赖，这就是为什么我希望尽可能解决问题。

以下是我尝试过的代码示例：

#include <windows.h>
#include <wininet.h>
#include <tchar.h>
#include <stdio.h>

bool http_putfile(HINTERNET hConnection, TCHAR* resource);

#define HOST  _T("www.website.com")
#define RESOURCE _T("/path/for/resource")

int _tmain(int argc, TCHAR* argv[])
{
    LPCTSTR lpszHostName = HOST;
    INTERNET_PORT nServerPort = INTERNET_DEFAULT_HTTP_PORT;
    DWORD dwService = INTERNET_SERVICE_HTTP;
    DWORD dwFlags = NULL;
    DWORD dwContext = 0;

    HINTERNET hSession = InternetOpen(
        argv[0],
        INTERNET_OPEN_TYPE_DIRECT, 
        NULL,
        NULL,
        NULL);

    if(hSession != NULL)
    {
        HINTERNET hConnection = InternetConnect(
            hSession,
            lpszHostName,
            nServerPort,
            NULL,
            NULL,
            dwService,
            dwFlags,
            dwContext);

        if(hConnection != NULL)
        {
            http_putfile(hConnection, RESOURCE);

            InternetCloseHandle(hConnection);
        }
        else
        {
            printf("InternetConnect failed: %d\n", GetLastError());
        }

        InternetCloseHandle(hSession);
    }
    else
    {
        printf("InternetOpen failed: %d\n", GetLastError());
    }

    return 0;
}

bool http_putfile(HINTERNET hConnection, TCHAR* resource)
{
    bool result = false;

    HINTERNET hRequest = HttpOpenRequest(
        hConnection,
        _T("PUT"),
        resource,
        NULL,
        NULL,
        NULL,
        INTERNET_FLAG_RELOAD | INTERNET_FLAG_EXISTING_CONNECT | INTERNET_FLAG_NO_CACHE_WRITE,
        0);

    if(hRequest != NULL)
    {
        HttpAddRequestHeaders(
            hRequest,
            _T("Transfer-Encoding: chunked\r\n"),
            -1L,
            HTTP_ADDREQ_FLAG_ADD | HTTP_ADDREQ_FLAG_REPLACE);

        // have tried:
        // Content-Length
        // Content-Length:
        // Content-Length\r\n
        // Content-Length:\r\n
        // all with/without HTTP_ADDREQ_FLAG_ADD.  Have even tried adding in a Content-Length
        // and then removing it.  All results show "Content-Length: 0" in the header on the wire.
        if(HttpAddRequestHeaders(
            hRequest,
            _T("Content-Length"),
            -1L,
            HTTP_ADDREQ_FLAG_ADD | HTTP_ADDREQ_FLAG_REPLACE) == FALSE)
        {
            DWORD err = GetLastError();
        }

        // have tried both 0 here for flags as documented on msdn
        // http://msdn.microsoft.com/en-us/library/windows/desktop/aa384318%28v=vs.85%29.aspx
        // as well as other combinations of INITIATE/CHUNKED
        if(HttpSendRequestEx(hRequest, NULL, NULL, HSR_INITIATE | HSR_CHUNKED /* 0 */, NULL))
        {
            DWORD wrote = 0;
            char* chunks = "5\r\nCHUNK0\r\n";

            if(InternetWriteFile(
                    hRequest,
                    chunks,
                    strlen(chunks),
                    &wrote) == FALSE)
            {
                printf("InternetWriteFile failed: %d\n", GetLastError());
            }

            HttpEndRequest(hRequest, NULL, 0, NULL);
        }
        else
        {
            printf("HttpSendRequestEx failed: %d\n", GetLastError);
        }

        InternetCloseHandle(hRequest);
    }
    else
    {
        printf("HttpOpenRequest failed: %d\n", GetLastError());
    }

    return result;
}

Answer 1

好吧，看起来你是对的。事实上，我没有看到任何迹象表明WinINet支持分块上传; only WinHTTP does。查看Wine source code（往往非常准确），“Content-Length”标题始终附加到“GET”以外的任何方法的请求中。

根据HTTP specs，如果存在非身份“Transfer-Encoding”标头，则认为该消息被分块。如果还存在“Content-Length”标题，则必须忽略它。如果虚假的“Content-Length：0”标题导致您出现问题，那么可能会认为这是服务器的问题。我会试试WinHTTP，看看它是否解决了这个问题。

Answer 2

很好的问题，我在很长一段时间内对此感到沮丧。

你对HTTP_ADDREQ_FLAG_REPLACE的直觉证明是正确的......但是，你必须很晚才打电话。具体而言，您需要register a status callback，并且当您使用INTERNET_STATUS_CONNECTED_TO_SERVER调用回调时，是您删除标题的时候：

// Inside InternetStatusCallback
//
if (dwInternetStatus == INTERNET_STATUS_CONNECTED_TO_SERVER)
{
  HttpAddRequestHeaders(Handle, L"Content-Length", -1, HTTP_ADDREQ_FLAG_REPLACE);
}

WinInet - 无法从标头中删除Content-Length以手动分块上传

2 个答案: