gistfile1.cs

string filePath = Path.Combine(TempPath, file.FileName);
                /*Even though Jquery handles checking by doctypes, we have built checking on the server side
                 * To protect against javascript hacks
                 * 
                 * The jquery doesn't normalize the text in the file extension. We may choose to
                 * handle this ourselves when we come up with a standard naming scheme for consistency's sake later, 
                 * but for now, ToLower() the extension. */
                string checkValidExt = Path.GetExtension(filePath);
                if (checkValidExt.ToLower() != ".png" || checkValidExt.ToLower() != ".jpg")
                {
                    return "Please enter a valid file.";
                }
                System.IO.File.WriteAllBytes(filePath, ReadData(file.InputStream));
   

HttpContext.Current.Request.ContentLength should give us the length of the total content in the Request. That should be good enough to use to filter out bad requests. Since a lot of end user's have no idea what a large file is and we're saving thumbnails we should accept up to 10MB.