Use TeamCity credentials to auth with NuGet.Server

Global.asax.cs

public class Global : System.Web.HttpApplication
    {
        private readonly string connectionString = ConfigurationManager.ConnectionStrings["teamCity"].ConnectionString;

        protected void Application_Start(object sender, EventArgs e)
        {

        }

        protected void Session_Start(object sender, EventArgs e)
        {

        }

        protected void Application_BeginRequest(object sender, EventArgs e)
        {

        }

        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {
            //check if requesting the web service - this is the only page
            //that should accept Basic Authentication
            HttpApplication app = (HttpApplication)sender;
            if (app.Context.Request.Headers.Get("X-NUGET-APIKEY") != null)
            {
                return;
            }

            if (app.Context.Request.Path.StartsWith("/nuget"))
            {
                if (HttpContext.Current.User == null)
                {
                    Console.WriteLine("Null user - use basic auth");

                    var ctx = HttpContext.Current;

                    var authenticated = false;

                    // look for authorization header
                    var authHeader = ctx.Request.Headers["Authorization"];

                    if (authHeader != null && authHeader.StartsWith("Basic"))
                    {
                        // extract credentials from header
                        var credentials = this.extractCredentials(authHeader);

                        if (this.ValidateUser(credentials[0], credentials[1]))
                        {
                            var id = new GenericIdentity(credentials[0], "CustomBasic");
                            var p = new GenericPrincipal(id, null);
                            ctx.User = p;

                            authenticated = true;
                        }
                    }

                    // emit the authenticate header to trigger client authentication
                    if (authenticated == false)
                    {
                        ctx.Response.StatusCode = 401;
                        ctx.Response.AddHeader(
                            "WWW-Authenticate", string.Format("Basic realm=\"{0}\"", app.Context.Request.Url.Host));
                        ctx.Response.Flush();
                        ctx.Response.Close();
                    }
                }
            }            
        }

        protected void Application_Error(object sender, EventArgs e)
        {

        }

        protected void Session_End(object sender, EventArgs e)
        {

        }

        protected void Application_End(object sender, EventArgs e)
        {

        }

        private bool ValidateUser(string username, string password)
        {
            using (var connection = new SqlConnection(connectionString))
            {
                connection.Open();
                using (var cmd = connection.CreateCommand())
                {
                    cmd.CommandText = @"
SELECT COUNT(*) FROM users AS u
WHERE LOWER(u.username) = LOWER(@userName)
AND u.password = LOWER(SUBSTRING(sys.fn_sqlvarbasetostr(HASHBYTES('md5',@password)),3,32))";
                    cmd.Parameters.AddWithValue("@userName", username);
                    cmd.Parameters.Add(new SqlParameter("@password", SqlDbType.VarChar) { Value = password });

                    return (int)cmd.ExecuteScalar() > 0;
                }
            }
        }

        private string[] extractCredentials(string authHeader)
        {
            // strip out the "basic"
            string encodedUserPass = authHeader.Substring(6).Trim();

            // that's the right encoding
            Encoding encoding = Encoding.GetEncoding("iso-8859-1");
            string userPass = encoding.GetString(Convert.FromBase64String(encodedUserPass));
            int separator = userPass.IndexOf(':');

            string[] credentials = new string[2];
            credentials[0] = userPass.Substring(0, separator);
            credentials[1] = userPass.Substring(separator + 1);

            return credentials;
        }
    }