HTTP Upload Corrupts Zip File?

Question

I have a zip file that I can read with DotNetZipLib from the file system. However, when I POST it via a form to my MVC application it can't be read as a stream. My best guess at the moment is that the HTTP upload is somehow corrupting the zip file. There's no shortage of questions with the same problem, and I thought I'd accounted for the stream properly but perhaps I'm not using the .NET object(s) here as intended.

Here's my WebAPI POST handler:

public void Post(HttpRequestMessage request)
{
    using(var fileData = request.Content.ReadAsStreamAsync().Result)
        if (fileData.Length > 0)
        {
            var zip = ZipFile.Read(fileData); // exception
        }
}

The exception, of course, is from the DotNetZipLib ZipFile just saying that the stream can't be read as a zip. If I replace fileData with just a path to the file (this is all being tested on the same machine) then it reads it, so it has to be the HTTP upload.

In FireBug, the headers for the POST are:

Response Headers:
    Cache-Control       no-cache
    Content-Length      1100
    Content-Type        application/xml; charset=utf-8
    Date                Sat, 01 Feb 2014 23:18:32 GMT
    Expires             -1
    Pragma              no-cache
    Server              Microsoft-IIS/8.0
    X-AspNet-Version    4.0.30319
    X-Powered-By        ASP.NET
    X-SourceFiles       =?UTF-8?B?QzpcRGF0YVxDb2RlXE9yZ1BvcnRhbFxPcmdQb3J0YWxTZXJ2ZXJcYXBpXGFwcHg=?=

Request Headers
    Accept              text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    Accept-Encoding     gzip, deflate
    Accept-Language     en-US,en;q=0.5
    Connection          keep-alive
    Cookie              uvts=ENGUn8FXEnEQFeS
    Host                localhost:48257
    Referer             http://localhost:48257/Home/Test
    User-Agent          Mozilla/5.0 (Windows NT 6.3; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0

Request Headers From Upload Stream
    Content-Length      31817
    Content-Type        multipart/form-data; boundary=---------------------------265001916915724

And the form is simple enough:

<form action="/api/appx" method="post" enctype="multipart/form-data">
    <input name="postedFile" type="file" />
    <input type="submit" />
</form>

Am I doing something wrong with the steam? Pulling data from the HttpRequestMessage incorrectly? Or perhaps I should be receiving the upload in an entirely different way?

Answer 1

When you post a file using a HTML form the media type is multipart/form-data which has some special formatting syntax, as you can see from your Firebug details. You can't just read it as a stream and expect it to match the file that was sent. There are a set of ReadAsMultipartAsync extension methods for handling this media type.

Answer 2

The below code worked fine for both Zip and Text file. you may try this out

        public HttpStatusCode Post(string fileName)
        {
                    var task = this.Request.Content.ReadAsStreamAsync();
                    task.Wait();
                    Stream requestStream = task.Result;

                    try
                    {
                        Stream fileStream =    File.Create(HttpContext.Current.Server.MapPath("~/" + fileName));
                        requestStream.CopyTo(fileStream);
                        fileStream.Close();
                        requestStream.Close();
                    }
                    catch (IOException)
                    {
                        throw new HttpResponseException(HttpStatusCode.InternalServerError);
                    }

                    HttpResponseMessage response = new HttpResponseMessage();
                    response.StatusCode = HttpStatusCode.Created;
                    return response.StatusCode;

        }