如何在 .Net Core 中间件中获取当前子域？

Question

How can I get the current subdomain for the current request (in a middleware component) in asp.net 5.

I previously used the code below and looking for something similar.

public static string GetSubDomain()
        {
            string subDomain = String.Empty;

            if (HttpContext.Current.Request.Url.HostNameType == UriHostNameType.Dns)
            {
                subDomain = Regex.Replace(HttpContext.Current.Request.Url.Host, "((.*)(\\..*){2})|(.*)", "$2").Trim().ToLower();
            }

            if (subDomain == String.Empty)
            {

                subDomain = HttpContext.Current.Request.Headers["Host"].Split('.')[0];
            }

            return subDomain.Trim().ToLower();
        }

Answer 1

I have managed to work out my own answer in the meantime...comments appreciated.

private static string GetSubDomain(HttpContext httpContext)
        {
            var subDomain = string.Empty;

            var host = httpContext.Request.Host.Host;

            if (!string.IsNullOrWhiteSpace(host))
            {
                subDomain = host.Split('.')[0];
            }

            return subDomain.Trim().ToLower();
        }

Answer 2

If you're using Cross-Domain, the best option is to use the Origin from Request-Header. Something like:

Request.Headers.TryGetValue("Origin",  out var origin);

and then manipulate the value with split or whatever you like.