SubdomainRoute class for ASP.NET MVC

SubdomainRoute.cs

public class SubdomainRoute : Route, IRouteWithArea
{
    private string[] namespaces;
    public string Subdomain { get; private set; }

    public SubdomainRoute(string subdomain, string url, object defaults, string[] namespaces)
        : base(url, new RouteValueDictionary(defaults), new MvcRouteHandler())
    {
        this.Subdomain = subdomain;
        this.namespaces = namespaces;
    }

    public string Area
    {
        get { return Convert.ToString(this.Defaults["area"]); }
    }

    public override RouteData GetRouteData(HttpContextBase httpContext)
    {
        string requestPath = httpContext.Request.AppRelativeCurrentExecutionFilePath.Substring(2) + httpContext.Request.PathInfo;
        string requestDomain = GetSubdomain(httpContext.Request.Headers["Host"]);

        RouteData data = null;
        Regex domainRegex = CreateRegex(this.Subdomain);
        Regex pathRegex = CreateRegex(this.Url);
        Match domainMatch = domainRegex.Match(requestDomain);
        Match pathMatch = pathRegex.Match(requestPath);

        if (domainMatch.Success && pathMatch.Success)
        {
            data = new RouteData(this, RouteHandler);

            if (Defaults != null)
            {
                foreach (KeyValuePair item in Defaults)
                    data.Values[item.Key] = item.Value;
            }

            for (int i = 0; i < pathMatch.Groups.Count; i++)
            {
                Group group = pathMatch.Groups[i];
                if (group.Success)
                {
                    string key = pathRegex.GroupNameFromNumber(i);

                    if (!string.IsNullOrEmpty(key) && !char.IsNumber(key, 0))
                    {
                        if (!string.IsNullOrEmpty(group.Value))
                        {
                            data.Values[key] = group.Value;
                        }
                    }
                }
            }

            data.DataTokens.Add("Area", data.Values["area"]);
            data.DataTokens.Add("namespaces", this.namespaces);
        }

        return data;
    }

    public static string GetSubdomain(string host)
    {
        if (host.IndexOf(":") >= 0)
            host = host.Substring(0, host.IndexOf(":"));

        Regex tldRegex = new Regex(@"\.[a-z]{2,3}\.[a-z]{2}$");
        host = tldRegex.Replace(host, "");
        tldRegex = new Regex(@"\.[a-z]{2,4}$");
        host = tldRegex.Replace(host, "");

        if (host.Split('.').Length > 1)
            return host.Substring(0, host.IndexOf("."));
        else
            return string.Empty;
    }

    private Regex CreateRegex(string source)
    {
        source = source.Replace("/", @"\/?");
        source = source.Replace(".", @"\.?");
        source = source.Replace("-", @"\-?");
        source = source.Replace("{", @"(?<");
        source = source.Replace("}", @">([a-zA-Z0-9_-]*))");
        return new Regex("^" + source + "$");
    }
}