Orchard/src/Orchard.Web/Modules/Orchard.MultiTenancy/Extensions/UrlHelperExtensions.cs

using System.Web.Mvc;
using Orchard.Environment.Configuration;

namespace Orchard.MultiTenancy.Extensions {
    public static class UrlHelperExtensions {
        public static string Tenant(this UrlHelper urlHelper, ShellSettings tenantShellSettings) {
            //info: (heskew) might not keep the port/vdir insertion around beyond...
            var port = string.Empty;
            string host = urlHelper.RequestContext.HttpContext.Request.Headers["Host"];

            if (host.Contains(":"))
                port = host.Substring(host.IndexOf(":"));

            var result = string.Format("{0}://{1}",
                                       urlHelper.RequestContext.HttpContext.Request.Url.Scheme,
                                       !string.IsNullOrEmpty(tenantShellSettings.RequestUrlHost)
                                           ? tenantShellSettings.RequestUrlHost + port : host);

            var applicationPath = urlHelper.RequestContext.HttpContext.Request.ApplicationPath;
            if (!string.IsNullOrEmpty(applicationPath) && !string.Equals(applicationPath, "/"))
                result += applicationPath;

            if (!string.IsNullOrEmpty(tenantShellSettings.RequestUrlPrefix))
                result += "/" + tenantShellSettings.RequestUrlPrefix;

            return result;
        }
    }
}