ASP.NET fast upload file to AWS using multipart/form-data without take memory

DisableFormValueModelBinding.cs

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
    public class DisableFormValueModelBindingAttribute : Attribute, IResourceFilter
    {
        public void OnResourceExecuting(ResourceExecutingContext context)
        {
            var factories = context.ValueProviderFactories;
            factories.RemoveType<FormValueProviderFactory>();
            factories.RemoveType<JQueryFormValueProviderFactory>();
        }

        public void OnResourceExecuted(ResourceExecutedContext context)
        {
        }
    }

Index.cshtml

<form action="upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file" />
    <input type="submit" value="Upload" />
</form>

UploadController.cs

    public class UploadController : Controller
    {
        [HttpPost]
        [DisableFormValueModelBinding]
        public async Task<IActionResult> Index()
        {
            if (!MediaTypeHeaderValue.TryParse(Request.ContentType, out var mt) ||
                !mt.MediaType.Equals("multipart/form-data", StringComparison.OrdinalIgnoreCase))
            {
                return BadRequest();
            }
            var boundary = HeaderUtilities.RemoveQuotes(mt.Boundary);
            var multipartReader = new MultipartReader(boundary.ToString(), Request.Body);
            var section = await multipartReader.ReadNextSectionAsync(HttpContext.RequestAborted);
            if (section == null)
            {
                return BadRequest($"No found any multipart section data.");
            }
            if (!ContentDispositionHeaderValue.TryParse(section.ContentDisposition, out var contentDisposition) ||
              !contentDisposition.IsFileDisposition())
            {
                return BadRequest();
            }
            // Geting current position in request body.
            var bufferOffsetield = typeof(BufferedReadStream).GetField("_bufferOffset", BindingFlags.NonPublic | BindingFlags.Instance);
            var innerStreamField = section.Body.GetType().GetField("_innerStream", BindingFlags.NonPublic | BindingFlags.Instance);
            var bufferedReadStream = innerStreamField.GetValue(section.Body);
            var offset = (int)bufferOffsetield.GetValue(bufferedReadStream);
            // the last line of boundary.
            var discardLength = "\r\n--".Length + boundary.Length + "--\r\n".Length;
            var fileLength = Request.ContentLength.Value - offset - discardLength;
            // Upload file to AWS3 Using a Presigned URL feature. 
            // https://docs.aws.amazon.com/AmazonS3/latest/dev/UploadObjectPreSignedURLDotNetSDK.html
            var endpointUrl = CreatePreSignedURL(contentDisposition.FileName.ToString());
            var request = new HttpRequestMessage(HttpMethod.Put, endpointUrl);
            request.Content = new StreamContent(section.Body);
            request.Content.Headers.ContentLength = fileLength;
            request.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
            var response = await new HttpClient().SendAsync(request);
            if (response.StatusCode != System.Net.HttpStatusCode.OK)
            {
                throw new AmazonS3Exception($"Upload file failed.{response.StatusCode}.");
            }
            return Ok();
        }

        private string CreatePreSignedURL(string key)
        {
            var request = new GetPreSignedUrlRequest()
            {
                BucketName = "BucketName",
                Key = key,
                Verb = HttpVerb.PUT,
                Expires = DateTime.Now.AddMinutes(5),
            };
            return new AmazonS3Client().GetPreSignedURL(request);
        }
    }

Uploading large files with streaming