使用Wininet上传文件时如何添加正确的Content-Type？ （HTTP PUT）

Question

I am uploading a file with Wininet to a Sharepoint server with HTTP PUT. However, even when I specify a file name with .xlsx extension, I got on the Sharepoint server a file which says it's named .xlsx , but when downloading it, it gets a .zip extension. Also, on Sharepoint, the file does not get the little Excel icon next to it, but a more generic icon. I have tried every combination of setting the Content-type ("mime-type") with HttpAddRequestHeaders and at HttpSendRequest I could come up with.

The code below uploads the file, but Sharepoint gets the content-type wrong:

static int upload_file_to_sharepoint(LPCSTR filename, LPCSTR server, LPCSTR location)
{
    HINTERNET hIntrn = InternetOpenA(
        "magic", 
         INTERNET_OPEN_TYPE_PRECONFIG_WITH_NO_AUTOPROXY,
         NULL,
         NULL,
         0
    );
    if (!hIntrn)
        return printf("No Internet connection: %li.\n", GetLastError());

    HINTERNET hConn = InternetConnectA(
        hIntrn, 
        server,
        INTERNET_DEFAULT_HTTPS_PORT,
        NULL,
        NULL,
        INTERNET_SERVICE_HTTP,
        0,
        NULL
    );

    if (!hConn)
        return printf("Connection to update server failed: %li.\n", GetLastError());

    DWORD dwOpenRequestFlags =
        INTERNET_FLAG_KEEP_CONNECTION |
        INTERNET_FLAG_NO_COOKIES |
        INTERNET_FLAG_NO_CACHE_WRITE |
        INTERNET_FLAG_NO_UI |
        INTERNET_FLAG_RELOAD;

    PCSTR rgpszAcceptTypes[] = {
        "text/*",
        "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
        NULL
    };

    HINTERNET hReq = HttpOpenRequestA(
        hConn,
        "PUT",
        location,
        "HTTP/1.1",
        NULL,
        rgpszAcceptTypes,
        dwOpenRequestFlags,
        NULL
    );


    HANDLE hFile = CreateFileA(
        filename,
        GENERIC_READ,
        FILE_SHARE_READ,
        NULL,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        NULL
    );

    if (NULL == hFile) {
        ExitProcess(1);
    }

    HANDLE hMap = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
    if (NULL == hMap) {
        ExitProcess(1);
    }

    LPVOID lpvFile = MapViewOfFile(hMap, FILE_MAP_READ, 0, 0, 0);

    DWORD dwFileSize = GetFileSize(hFile, NULL);

    CHAR mimetype[1024];
    sprintf(
        mimetype,
        "Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
    //"Content-Type: application/vnd.ms-excel\r\n"
    );

    if (!HttpAddRequestHeadersA(hReq, mimetype, -1, HTTP_ADDREQ_FLAG_REPLACE)) {
        printf("Failed adding mime header\n");
    }

    if (!HttpSendRequestA(
        hReq,
        NULL,// "Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
        0, //-1,
        lpvFile,
        dwFileSize)) {
        printf("HttpSendRequest failed: %li.\n", GetLastError());
    }

    UnmapViewOfFile(lpvFile);
    CloseHandle(hMap);
    CloseHandle(hFile);

    printf("Uploaded file to http://%s%s\n", server, location);

    return 0;
}

I captured the headers with Fiddler, got this:

PUT http://x.com/CENSORED/a.xslx HTTP/1.1
Accept: text/*, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
Content-Disposition: attachment; filename="a.xlsx"
Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
User-Agent: magic
Host: censored
Content-Length: 772303
Connection: Keep-Alive
Pragma: no-cache


HTTP/1.1 200 OK
Cache-Control: private,max-age=0
Content-Length: 0
Expires: Tue, 15 Sep 2015 08:43:16 GMT
Last-Modified: Wed, 30 Sep 2015 08:43:16 GMT
ETag: "{0DC262D0-83AE-489A-90CD-EB23B284A3B3},14"
Server: Microsoft-IIS/7.5
SPRequestGuid: 6aba173e-41db-4b14-b7df-7714c54db282
X-SharePointHealthScore: 0
ResourceTag: rt:0DC262D0-83AE-489A-90CD-EB23B284A3B3@00000000014
Public-Extension: http://schemas.microsoft.com/repl-2
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 14.0.0.7145
X-MS-InvokeApp: 1; RequireReadOnly
ServerName: Xcensored
Date: Wed, 30 Sep 2015 08:43:16 GMT

Answer 1

So, it helps if you upload the file as .xlsx instead of .xslx ...

The code works now and looks something like this, no special headers necessary, which is consistent with other examples I have found on the web:

static int upload_file_to_sharepoint(LPCSTR filename, LPCSTR server, LPCSTR location)
{
    HINTERNET hIntrn = InternetOpenA(
        "magic", 
         INTERNET_OPEN_TYPE_PRECONFIG_WITH_NO_AUTOPROXY,
         NULL,
         NULL,
         0
    );
    if (!hIntrn)
        return printf("No Internet connection: %li.\n", GetLastError());

    HINTERNET hConn = InternetConnectA(
        hIntrn, 
        server,
        INTERNET_DEFAULT_HTTPS_PORT,
        NULL,
        NULL,
        INTERNET_SERVICE_HTTP,
        0,
        NULL
    );

    if (!hConn)
        return printf("Connection to update server failed: %li.\n", GetLastError());

    DWORD dwOpenRequestFlags =
        INTERNET_FLAG_KEEP_CONNECTION |
        INTERNET_FLAG_NO_COOKIES |
        INTERNET_FLAG_NO_CACHE_WRITE |
        INTERNET_FLAG_NO_UI |
        INTERNET_FLAG_RELOAD;

    HINTERNET hReq = HttpOpenRequestA(
        hConn,
        "PUT",
        location,
        "HTTP/1.1",
        NULL,
        NULL,
        dwOpenRequestFlags,
        NULL
    );


    HANDLE hFile = CreateFileA(
        filename,
        GENERIC_READ,
        FILE_SHARE_READ,
        NULL,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        NULL
    );

    if (NULL == hFile) {
        ExitProcess(1);
    }

    HANDLE hMap = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
    if (NULL == hMap) {
        ExitProcess(1);
    }

    LPVOID lpvFile = MapViewOfFile(hMap, FILE_MAP_READ, 0, 0, 0);

    DWORD dwFileSize = GetFileSize(hFile, NULL);    

    if (!HttpSendRequestA(
        hReq,
        NULL,
        0,
        lpvFile,
        dwFileSize)) {
        printf("HttpSendRequest failed: %li.\n", GetLastError());
    }

    UnmapViewOfFile(lpvFile);
    CloseHandle(hMap);
    CloseHandle(hFile);

    printf("Uploaded file to http://%s%s\n", server, location);

    return 0;
}