How can one simplify network byte-order conversion from a BinaryReader?

Question

System.IO.BinaryReader reads values in a little-endian format.

I have a C# application connecting to a proprietary networking library on the server side. The server-side sends everything down in network byte order, as one would expect, but I find that dealing with this on the client side is awkward, particularly for unsigned values.

UInt32 length = (UInt32)IPAddress.NetworkToHostOrder(reader.ReadInt32());

is the only way I've come up with to get a correct unsigned value out of the stream, but this seems both awkward and ugly, and I have yet to test if that's just going to clip off high-order values so that I have to do fun BitConverter stuff.

Is there some way I'm missing short of writing a wrapper around the whole thing to avoid these ugly conversions on every read? It seems like there should be an endian-ness option on the reader to make things like this simpler, but I haven't come across anything.

Answer 1

I built a custom BinaryReader to handle all of this. It's available as part of my Nextem library. It also has a very easy way of defining binary structs, which I think will help you here -- check out the Examples.

Note: It's only in SVN right now, but very stable. If you have any questions, email me at cody_dot_brocious_at_gmail_dot_com.

Answer 2

There is no built-in converter. Here's my wrapper (as you can see, I only implemented the functionality I needed but the structure is pretty easy to change to your liking):

/// <summary>
/// Utilities for reading big-endian files
/// </summary>
public class BigEndianReader
{
    public BigEndianReader(BinaryReader baseReader)
    {
        mBaseReader = baseReader;
    }

    public short ReadInt16()
    {
        return BitConverter.ToInt16(ReadBigEndianBytes(2), 0);
    }

    public ushort ReadUInt16()
    {
        return BitConverter.ToUInt16(ReadBigEndianBytes(2), 0);
    }

    public uint ReadUInt32()
    {
        return BitConverter.ToUInt32(ReadBigEndianBytes(4), 0);
    }

    public byte[] ReadBigEndianBytes(int count)
    {
        byte[] bytes = new byte[count];
        for (int i = count - 1; i >= 0; i--)
            bytes[i] = mBaseReader.ReadByte();

        return bytes;
    }

    public byte[] ReadBytes(int count)
    {
        return mBaseReader.ReadBytes(count);
    }

    public void Close()
    {
        mBaseReader.Close();
    }

    public Stream BaseStream
    {
        get { return mBaseReader.BaseStream;  }
    }

    private BinaryReader mBaseReader;
}

Basically, ReadBigEndianBytes does the grunt work, and this is passed to a BitConverter. There will be a definite problem if you read a large number of bytes since this will cause a large memory allocation.

Answer 3

It won't help now, but I created a connect ticket for BinaryReder/Writer to support Bigendian out the box. Go vote for it here.