CODEWITHSUNDEEP
c#wcfapache-flexreststream
Ed Sinek
Ed Sinek

Reputation: 4987

How do I decode POST multipart/form-data?

In a Flex application communicating with a Windows Communication Foundation REST web service I am trying to upload a file from the Flex application to the server. I'm using FileReference to browse and upload the file.

I am then receiving the file as a stream (shows as System.ServiceModel.Dispatcher.StreamFormatter.MessageBodyStream in the debugger) using project type of Windows Communication Foundation 4 REST service.

[WebInvoke(Method = "POST", UriTemplate = "_test/upload")]
public void UploadImage(Stream data)
{
    // TODO: just hardcode filename for now
    var filepath = HttpContext.Current.Server.MapPath(@"~\_test\testfile.txt");
    using (Stream file = File.OpenWrite(filepath))
    {
        CopyStream(data, file);
    }
}
private static void CopyStream(Stream input, Stream output)
{
    var buffer = new byte[8 * 1024];
    int len;
    while ((len = input.Read(buffer, 0, buffer.Length)) > 0)
    {
        output.Write(buffer, 0, len);
    }
}

CopyStream method used from this post. The file contains more information than I would like (the source file only contained "THIS IS THE CONTENT OF THE FILE"):

------------ae0ae0Ef1ae0Ef1ae0gL6gL6Ij5cH2
Content-Disposition: form-data; name="Filename"

testfile.txt
------------ae0ae0Ef1ae0Ef1ae0gL6gL6Ij5cH2
Content-Disposition: form-data; name="Filedata"; filename="testfile.txt"
Content-Type: application/octet-stream

THIS IS THE CONTENT OF THE FILE
------------ae0ae0Ef1ae0Ef1ae0gL6gL6Ij5cH2
Content-Disposition: form-data; name="Upload"

Submit Query
------------ae0ae0Ef1ae0Ef1ae0gL6gL6Ij5cH2--

The contents look exactly like described in the Adobe documentation. Are there any facilities in C# to get the file contents from the stream? The Flex app is sending a multipart/form-data POST. How can I decode the multipart body data as represented by the Stream parameter and strip the pieces of the multipart body?

Upvotes: 5

Views: 10024

Answers (1)

Lorenzo Polidori
Lorenzo Polidori

Reputation: 10512

I open-sourced a C# Http form parser here.

This is slightly more flexible than the other one mentioned which is on CodePlex, since you can use it for both Multipart and non-Multipart form-data, and also it gives you other form parameters formatted in a Dictionary object.

This can be used as follows:

non-multipart

public void Login(Stream stream)
{
    string username = null;
    string password = null;

    HttpContentParser parser = new HttpContentParser(data);
    if (parser.Success)
    {
        username = HttpUtility.UrlDecode(parser.Parameters["username"]);
        password = HttpUtility.UrlDecode(parser.Parameters["password"]);
    }
}

multipart

public void Upload(Stream stream)
{
    HttpMultipartParser parser = new HttpMultipartParser(data, "image");

    if (parser.Success)
    {
        string user = HttpUtility.UrlDecode(parser.Parameters["user"]);
        string title = HttpUtility.UrlDecode(parser.Parameters["title"]);

        // Save the file somewhere
        File.WriteAllBytes(FILE_PATH + title + FILE_EXT, parser.FileContents);
    }
}

Upvotes: 6

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