HttpMessageHandler for dealing with cookies in requests.

CookieMessageHandler.cs

public class CookieMessageHandler : DelegatingHandler
{
    private readonly CookieContainer _cookies = new CookieContainer();

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        request.Headers.Add("Cookie", _cookies.GetCookieHeader(request.RequestUri));

        var response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);

        if (response.Headers.TryGetValues("Set-Cookie", out var newCookies))
        {
            foreach (var item in SetCookieHeaderValue.ParseList(newCookies.ToList()))
            {
                var uri = new Uri(request.RequestUri, item.Path.Value);
                _cookies.Add(uri, new Cookie(item.Name.Value, item.Value.Value, item.Path.Value));
            }
        }

        return response;
    }
}