System.Data.SqlClient.TdsParser.TryProcessLoginAck C# (CSharp) Method

        private bool TryProcessLoginAck(TdsParserStateObject stateObj, out SqlLoginAck sqlLoginAck)
        {
            SqlLoginAck a = new SqlLoginAck();

            sqlLoginAck = null;

            // read past interface type and version
            if (!stateObj.TrySkipBytes(1))
            {
                return false;
            }

            byte[] b = new byte[TdsEnums.VERSION_SIZE];
            if (!stateObj.TryReadByteArray(b, 0, b.Length))
            {
                return false;
            }
            a.tdsVersion = (UInt32)((((((b[0] << 8) | b[1]) << 8) | b[2]) << 8) | b[3]); // bytes are in motorola order (high byte first)
            UInt32 majorMinor = a.tdsVersion & 0xff00ffff;
            UInt32 increment = (a.tdsVersion >> 16) & 0xff;

            // Server responds:
            // 0x07000000 -> Sphinx         // Notice server response format is different for bwd compat
            // 0x07010000 -> Shiloh RTM     // Notice server response format is different for bwd compat
            // 0x71000001 -> Shiloh SP1
            // 0x72xx0002 -> Yukon RTM
            // information provided by S. Ashwin

            switch (majorMinor)
            {
                case TdsEnums.YUKON_MAJOR << 24 | TdsEnums.YUKON_RTM_MINOR:     // Yukon
                    if (increment != TdsEnums.YUKON_INCREMENT) { throw SQL.InvalidTDSVersion(); }
                    _isYukon = true;
                    break;
                case TdsEnums.KATMAI_MAJOR << 24 | TdsEnums.KATMAI_MINOR:
                    if (increment != TdsEnums.KATMAI_INCREMENT) { throw SQL.InvalidTDSVersion(); }
                    _isKatmai = true;
                    break;
                case TdsEnums.DENALI_MAJOR << 24 | TdsEnums.DENALI_MINOR:
                    if (increment != TdsEnums.DENALI_INCREMENT) { throw SQL.InvalidTDSVersion(); }
                    _isDenali = true;
                    break;
                default:
                    throw SQL.InvalidTDSVersion();
            }

            _isKatmai |= _isDenali;
            _isYukon |= _isKatmai;

            stateObj._outBytesUsed = stateObj._outputHeaderLen;
            byte len;
            if (!stateObj.TryReadByte(out len))
            {
                return false;
            }

            if (!stateObj.TrySkipBytes(len * ADP.CharSize))
            {
                return false;
            }
            if (!stateObj.TryReadByte(out a.majorVersion))
            {
                return false;
            }
            if (!stateObj.TryReadByte(out a.minorVersion))
            {
                return false;
            }
            byte buildNumHi, buildNumLo;
            if (!stateObj.TryReadByte(out buildNumHi))
            {
                return false;
            }
            if (!stateObj.TryReadByte(out buildNumLo))
            {
                return false;
            }

            a.buildNum = (short)((buildNumHi << 8) + buildNumLo);

            Debug.Assert(_state == TdsParserState.OpenNotLoggedIn, "ProcessLoginAck called with state not TdsParserState.OpenNotLoggedIn");
            _state = TdsParserState.OpenLoggedIn;

            {
                if (_fMARS)
                {
                    _resetConnectionEvent = new AutoResetEvent(true);
                }
            }

            // Fail if SSE UserInstance and we have not received this info.
            if (_connHandler.ConnectionOptions.UserInstance &&
                string.IsNullOrEmpty(_connHandler.InstanceName))
            {
                stateObj.AddError(new SqlError(0, 0, TdsEnums.FATAL_ERROR_CLASS, Server, SQLMessage.UserInstanceFailure(), "", 0));
                ThrowExceptionAndWarning(stateObj);
            }

            sqlLoginAck = a;
            return true;
        }