Sample HttpMessageHandler doing async retrieval using .NET 4.5

SampleHandler.cs

using System;
using System.Net;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;

namespace SelfHost.MessageHandlers 
{
    /// <summary>
    /// This sample HttpMessageHandler illustrates how to perform an async operation as part of the 
    /// HTTP message handler pipeline using the async and await keywords from .NET 4.5
    /// </summary>
    public class SampleHandler : DelegatingHandler
    {
        private HttpClient _client;
        private Uri _address;

        public SampleHandler(Uri address)
        {
            if (address == null)
            {
                throw new ArgumentNullException("address");
            }

            if (!address.IsAbsoluteUri)
            {
                throw new ArgumentException("Value must be an absolute URI", "address");
            }
            _address = address;
            _client = new HttpClient();
        }

        /// <summary>
        /// We mark the SendAsync with 'async' so that we can await tasks without blocking in the method body.
        /// </summary>
        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            // Here I can inspect the request and do any pre-processing

            // Submit intermediate request and await response
            HttpResponseMessage intermediateResponse = await _client.GetAsync(_address);

            // If intermediate response is not successful then return a 500 status code
            if (!intermediateResponse.IsSuccessStatusCode)
            {
                return request.CreateResponse(HttpStatusCode.InternalServerError);
            }

            // Read intermediate response
            byte[] intermediateContent = await intermediateResponse.Content.ReadAsByteArrayAsync();

            // Now continue with the original request
            HttpResponseMessage response = await base.SendAsync(request, cancellationToken);

            // Here I can inspect the response and do any post-processing
            return response;
        }
    }
}

Is it safe to re-transfer a request multiple times? Does that depend of the kind of content in the request?

Thanks for your simple example. I want to implement same functionality into MVC project without using Owin, my understanding is that DelegatingHandlers are only invoked for API routes.

My requirement is whenever a new request comes I need to validate for specific request header and if that header is not in the request header then I will add that header to request header with a default value. I have achieved this functionality in WEB API project using DelegatingHandlers but couldn't able to find solution same for MVC project