Hello request in flight body

gistfile1.cs

        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
        {
            if (request.Headers.Date == null)
            {
                request.Headers.Date = DateTime.UtcNow;
            }

            // Check if we have request content, if we do then we need to add a Content-MD5 header.
            if (request.Content != null && request.Content.Headers.ContentMD5 == null)
            {
                await request.Content.LoadIntoBufferAsync().ConfigureAwait(false);
                using (var bodyStream = new MemoryStream())
                {
                    await request.Content.CopyToAsync(bodyStream).ConfigureAwait(false);
                    bodyStream.Position = 0;
                    using (var md5 = new MD5CryptoServiceProvider())
                    {
                        request.Content.Headers.ContentMD5 = md5.ComputeHash(bodyStream);
                    }
                }
            }

            byte[] hash = SharedKeySignature.Calculate(request, this.accountName, this.sharedSecret);
            request.Headers.Authorization = new AuthenticationHeaderValue(
                SharedKeyAuthentication.Scheme,
                string.Format(CultureInfo.InvariantCulture, "{0}:{1}", this.accountName, Convert.ToBase64String(hash)));

            // And finally hand off the request to the InnerHandler.
            return await base.SendAsync(request, cancellationToken);
        }