public void DepackFrameHeaderIfNesseary()

in sdk/Domain/SelectObjectStream.cs [55:162]
68 lines of code
11 McCabe index (conditional complexity)

        public void DepackFrameHeaderIfNesseary()
        {
            var buff = new byte[128];
            int readCnt = 0;

            //Version | Frame - Type | Payload Length | Header Checksum | Payload | Payload Checksum
            //<1 bytes> <--3 bytes-->   <-- 4 bytes --> <------4 bytes--> <variable><----4bytes------>
            //Payload 
            //<offset | data>
            //<8 bytes><variable>

            if (_payloadRemain > 0)
                return;

            if (_lastFrameType == 0x800001)
            {
                //Payload Checksum                
                readCnt = TryRead(buff, 0, 4);
                ensureReadSize(4, readCnt);
                uint serverCrc32 = OssUtils.ConvertBytesToUint(buff, 0, 4);

                //Payload Crc32 check  
                if (serverCrc32 != 0 && serverCrc32 != _payloadcrc32)
                {
                    throw new ClientException(string.Format("Payload checksum check fail server CRC {0}, client CRC {1}",
                        serverCrc32, _payloadcrc32));
                }
            }

            _lastFrameType = 0;
            _payloadRemain = 0;

            readCnt = TryRead(buff, 0, 12);

            if (_gotEndofStream)
                return;

            ensureReadSize(12, readCnt);

            //version

            //Frame - Type
            int frameType = OssUtils.ConvertBytesToInt(buff, 1, 3);
            _lastFrameType = frameType;

            //Payload Length
            int payloadLength = OssUtils.ConvertBytesToInt(buff, 4, 4);

            //Payload Length
            int headerCheckSum = OssUtils.ConvertBytesToInt(buff, 8, 4);

            switch (frameType)
            {
                case 0x800001:      //data frame
                    //offset
                    readCnt = TryRead(buff, 0, 8);
                    ensureReadSize(8, readCnt);
                    _payloadcrc32 = CRC32.GetCRC32Byte(buff, 8, 0);

                    //skip offset bytes
                    _payloadRemain = payloadLength - 8;
                    break;
                case 0x800005:      //Select object End Frame
                    //offset | total scanned bytes
                    readCnt = TryRead(buff, 0, 16);
                    ensureReadSize(16, readCnt);

                    //http status
                    readCnt = TryRead(buff, 0, 4);
                    ensureReadSize(4, readCnt);
                    StatusCode = OssUtils.ConvertBytesToInt(buff, 0, 4);

                    //error message
                    payloadLength = payloadLength - 20;

                    if (payloadLength > 0)
                    {
                        int len = Math.Min(buff.Length, payloadLength);
                        readCnt = TryRead(buff, 0, len);
                        ensureReadSize(len, readCnt);
                        ErrorMessage = System.Text.Encoding.Default.GetString(buff, 0, readCnt);

                        payloadLength -= len;
                        if (payloadLength > 0)
                        {
                            readCnt = TrySkip(payloadLength);
                            ensureReadSize(payloadLength, readCnt);
                        }
                    }

                    //skip payload Checksum
                    readCnt = TryRead(buff, 0, 4);
                    ensureReadSize(4, readCnt);

                    _gotEndFrame = true;
                    break;
                case 0x800004:      //Continuous Frame
                default:
                    //skip playload
                    readCnt = TrySkip(payloadLength);
                    ensureReadSize(payloadLength, readCnt);

                    //skip payload Checksum
                    readCnt = TryRead(buff, 0, 4);
                    ensureReadSize(4, readCnt);
                    break;
            }
        }