Question

通过我自己的BitReader捕获IP数据包（逐位读取）

public class BitReader
{
    int Index;
    byte Current;
    Stream Reader;

    public BitReader ( Stream Memory )
    {
        Reader = Memory;
    }

    public bool? ReadBit ( )
    {
        if ( Index == 8 )
        {
            Index = 0;
            Current = ( byte ) Reader . ReadByte ( );
        }

        if ( Current == -1 )
        {
            return null;
        }
        else
        {

            return ( Current & ( 1 << ( 7 - Index++ ) ) ) != 0;
         // return ( Current & ( 1 << Index++ ) ) != 0;
        }
    }
}

在IP v4数据包前接收ZERO未知字节，如下所示

00000000 01000101 00000000 00000101 11000000 01001001 00100110 01000000 00000000 10000000 00000110 10110010 01111110 11000000 10101000 00000001 00001010 01000101 10101011 11110010 00110101

编辑2：

private byte [ ] Buffer = new byte [ 4096 ];

                    _Socket = new Socket ( AddressFamily . InterNetwork , SocketType . Raw , ProtocolType . IP );

                    _Socket . Bind ( new IPEndPoint ( IPAddress . Parse ( Interface . Text ) , 0 ) );

                    _Socket . SetSocketOption ( SocketOptionLevel . IP , SocketOptionName . HeaderIncluded , true );

                    _Socket . IOControl ( IOControlCode . ReceiveAll , BitConverter . GetBytes ( 1 ) , BitConverter . GetBytes ( 1 ) );

                    _Socket . BeginReceive ( Buffer , 0 , Buffer . Length , SocketFlags . None , new AsyncCallback ( OnReceive ) , null );

编辑1：

MemoryStream _MemoryStream = new MemoryStream ( Buffer , 0 , Length );
BitReader _BitReader = new BitReader ( _MemoryStream );

            for ( int Loop = 0 ; Loop < 21 ; Loop++ )
            {
                bool? Result = _BitReader . ReadBit ( );

                if ( Loop % 8 == 0 && Loop != 0 )
                {
                    myTextBox . Invoke ( new Action ( delegate { myTextBox . Text += " "; } ) );
                }

                if ( Result . HasValue )
                {
                    myTextBox . Invoke ( new Action ( delegate { myTextBox . Text += Result . Value ? 1 : 0; } ) );
                }
            }

编辑3：

MemoryStream _MemoryStream = new MemoryStream(Buffer, 0, Length);
BinaryReader _BinaryReader = new BinaryReader(_MemoryStream );
private byte VersionAndHeaderLength;
VersionAndHeaderLength = _BinaryReader.ReadByte();

Answer 1

您从Index == 0开始，仅在Index == 8时读取下一个字节。这意味着您读取的第一个字节将始终为零。要解决此问题，请在构造函数中设置Index = 8。

此外，由于byte永远不能为-1，因此检查Current == -1是否始终为false并且您将在结束时获得无限1的条件该文件，因为这是将-1转换为byte时的结果。

收到未知字节

1 个答案: