Securing Large Downloads Using C# and IIS 7

.net, c#, download, iis

Solution

You know what? The KB article is poo. Here is my official recommendation:

public void StreamFile(string filePath)
{
    string fileName = Path.GetFileName(filePath);

    using (var fStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read))
    {
        var contentLength = fStream.Length;

        if (Request.UserAgent.Contains("MSIE"))
        {
            Response.AddHeader("Content-Transfer-Encoding", "binary");
        }

        Response.ContentType = "application/octet-stream";
        Response.AddHeader("Content-Length", contentLength.ToString());

        // Even though "Content-Disposition" should have an upper-case "d", as per http://www.ietf.org/rfc/rfc2183.txt
        // IE fails to recognize this if the "d" is upper-cased.
        Response.AddHeader("Content-disposition", "attachment; filename=" + fileName);

        var buffer = new byte[8192];

        while (Response.IsClientConnected)
        {
            var count = fStream.Read(buffer, 0, buffer.Length);
            if (count == 0)
            {
                break;
            }

            Response.OutputStream.Write(buffer, 0, count);
            Response.Flush();
        }
    }

    Response.Close();
}

Problem

Original source

Related problems

• ASP.net memory usage during download