System.Net.WebSockets.ManagedWebSocket.IsValidCloseStatus C# (CSharp) Method

        private static bool IsValidCloseStatus(WebSocketCloseStatus closeStatus)
        {
            // 0-999: "not used"
            // 1000-2999: reserved for the protocol; we need to check individual codes manually
            // 3000-3999: reserved for use by higher-level code
            // 4000-4999: reserved for private use
            // 5000-: not mentioned in RFC

            if (closeStatus < (WebSocketCloseStatus)1000 || closeStatus >= (WebSocketCloseStatus)5000)
            {
                return false;
            }

            if (closeStatus >= (WebSocketCloseStatus)3000)
            {
                return true;
            }

            switch (closeStatus) // check for the 1000-2999 range known codes
            {
                case WebSocketCloseStatus.EndpointUnavailable:
                case WebSocketCloseStatus.InternalServerError:
                case WebSocketCloseStatus.InvalidMessageType:
                case WebSocketCloseStatus.InvalidPayloadData:
                case WebSocketCloseStatus.MandatoryExtension:
                case WebSocketCloseStatus.MessageTooBig:
                case WebSocketCloseStatus.NormalClosure:
                case WebSocketCloseStatus.PolicyViolation:
                case WebSocketCloseStatus.ProtocolError:
                    return true;

                default:
                    return false;
            }
        }