In C#, how can I send a binary packet structure with Socket.Send?

Question

Hello,

I am trying to send a binary packet structure using Socket.send.  I have defined the packet using "StructLayout" and "FieldOffset" in a manner similar to the following:

[StructLayout(LayoutKind.Explicit, Size = 6)]

public class PacketHdr

{ [FieldOffset(0)]public short PacketType;

[FieldOffset(2)]public int PacketLength; }

After I create an instance of PacketHdr, I need to reference it as "byte [ ]" to send it out using "Socket.Send", since the buffer parameter of Socket.Send is defined as "byte [ ]" as follows:

     int Socket.Send(byte [ ] buffer, int offset, int size, ...

How can I reference the packet as "byte [ ]"?

This is trivial in C++, but I have not been able to find an example in C#.

Thank you for your help.

Bill Welch

 

 

Answer 1

Hi

Serialize your object to get byte[] using the following code

MemoryStream ms = new MemoryStream(); BinaryFormatter formatter = new BinaryFormatter(); formatter.AssemblyFormat = FormatterAssemblyStyle.Simple; formatter.TypeFormat = FormatterTypeStyle.TypesWhenNeeded; formatter.Serialize(ms,<objPacketHdr>); return ms.GetBuffer(); //THIS WILL RETURN BYTE[] WHICH YOU WANT

Then when you receive this byte[] then Deseiralize it to get actual object,

MemoryStream ms = new MemoryStream(bytes, offset, count); //HERE BYTES IS BYTE[] YOU HAVE RECEIVED BinaryFormatter formatter = new BinaryFormatter(); formatter.AssemblyFormat = FormatterAssemblyStyle.Simple; formatter.TypeFormat = FormatterTypeStyle.TypesWhenNeeded; PacketHdr objPacketHdr = (PacketHdr)formatter.Deserialize(ms);

PLEASE NOTE: You will need to mark your class with [Serializable] attribute to serialize it.

HTH,

Answer 2

include these 2 lines at the top of the class file:

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatter.Binary;

Here your class goes:

[Serializable]
    public class PacketHdr
    {
        private short packetType;
        private int packetLength;

        public PacketHdr(short packetType, int packetLength)
        {
            this.packetType = packetType;
            this.packetLength = packetLength;
        }
    }

 

Here Function to do the Conversion:

From object to bytes:

private byte[] GetPacketBytes(PacketHdr packetHdr)
        {
            MemoryStream ms = new MemoryStream();
            BinaryFormatter formatter = new BinaryFormatter();
            formatter.Serialize(ms, packetHdr);
            return ms.ToArray();
        }

From Byes to object:

        private PacketHdr GetPacketObject(byte[] packetBytes)
        {
            MemoryStream ms = new MemoryStream();
            ms.Write(packetBytes, 0, packetBytes.Length);
            ms.Position = 0;
            BinaryFormatter formatter = new BinaryFormatter();
            return formatter.Deserialize(ms) as PacketHdr;
        }

Usage:

PacketHdr p = new PacketHdr(1, 2);

byte[] packetBytes = GetPacketBytes(p); // Write these bytes on Network;

Read the bytes from the Network and contruct the object from the following line:

PacketHdr p1 = GetPacketObject(packetBytes);

Make sure to Receive all the bytes from the Network before you Decerialize bytes back to object otherwise wou;ll get an exception. So you have to make a check that how many bytes are sending and how many bytes you have to receive for a successful deserialization.

I hope this will help.

Best Regards,

Rizwan aka RizwanSharp