How to Convert Structure to byte array in C# ?

Question

Hi,

How to Convert Structure to byte array in C# ?

I have defined a structure like this :

        public struct CIFSPacket
        {
            public uint protocolIdentifier;//the value must be "0xFF+'SMB'"
            public byte command;

            public byte errorClass;
            public byte reserved;
            public ushort error;

            public byte flags;


            //here there are 14 bytes of data which is used differently among different dialects.
            //I do want the flags2 however so I'll try parsing them
            public ushort flags2;

            public ushort treeId;
            public ushort processId;
            public ushort userId;
            public ushort multiplexId;
            //trans request
            public byte wordCount;//Count of parameter words defining the data portion of the packet.
            //from here it might be undefined...

            public int parametersStartIndex;

            public ushort byteCount;//buffer length
            public int bufferStartIndex;

            public string Buffer;


        }

In my main method i create a instance of it and assign values to it

            CIFSPacket packet = new CIFSPacket();
            packet.protocolIdentifier = 0xff;
            packet.command = (byte)CommandTypes.SMB_COM_NEGOTIATE; 
            packet.errorClass = 0xff;
            packet.error = 0;
            packet.flags = 0x00;
            packet.flags2 = 0x0001;
            packet.multiplexId = 22; 
            packet.wordCount = 0; 
            packet.byteCount = 119;    

            packet.Buffer = "NT LM 0.12";

Now i want send this Packet by socket for that i need to convert Structute to byte array ..How i can do it ??

My full code is as follows :

        static void Main(string[] args)
        {

          Socket MyPing = new Socket(AddressFamily.InterNetwork,
          SocketType.Stream , ProtocolType.Unspecified ) ;


          MyPing.Connect("172.24.18.240", 139);  

            //Fake an IP Address so I can send with SendTo
            IPAddress IP = new IPAddress(new byte[] { 172,24,18,240 });
            IPEndPoint IPEP = new IPEndPoint(IP, 139);

            //Local IP for Receiving
            IPEndPoint Local = new IPEndPoint(IPAddress.Any, 0);
            EndPoint EP = (EndPoint)Local;

            CIFSPacket packet = new CIFSPacket();
            packet.protocolIdentifier = 0xff;
            packet.command = (byte)CommandTypes.SMB_COM_NEGOTIATE; 
            packet.errorClass = 0xff;
            packet.error = 0;
            packet.flags = 0x00;
            packet.flags2 = 0x0001;
            packet.multiplexId = 22; 
            packet.wordCount = 0; 
            packet.byteCount = 119;    

            packet.Buffer = "NT LM 0.12";






            MyPing.SendTo(It takes byte array as parameter);



        }

Any code snippet pls

Answer 1

I would take a look at the BinaryReader and BinaryWriter classes. I recently had to serialize data to a byte array (and back) and only found these classes after I'd basically rewritten them myself.

http://msdn.microsoft.com/en-us/library/system.io.binarywriter.aspx

There is a good example on that page too.

Answer 2

Quote from Wikipedia - In computer science, in the context of data storage and transmission, serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be "resurrected" later in the same or another computer environment.

For introduction in serialization in C# look here. You should use a BinaryFormatter with a MemoryStream like here to get the byte array.

Answer 3

Looks like a predefined (C level) structure for some external library. Marshal is your friend. Check:

http://geekswithblogs.net/taylorrich/archive/2006/08/21/88665.aspx

for a starter how to deal with this. Note that you can - with attributes - define things like byte layout and string handling. VERY nice approach, actually.

Neither BinaryFormatter Nor MemoryStream are done for that.

Answer 4

Have a look at these methods:

byte [] StructureToByteArray(object obj)
{
int len = Marshal.SizeOf(obj);

byte [] arr = new byte[len];

IntPtr ptr = Marshal.AllocHGlobal(len);

Marshal.StructureToPtr(obj, ptr, true);

Marshal.Copy(ptr, arr, 0, len);

Marshal.FreeHGlobal(ptr);

return arr;
}
void ByteArrayToStructure(byte [] bytearray, ref object obj)
{

int len = Marshal.SizeOf(obj);

IntPtr i = Marshal.AllocHGlobal(len);

Marshal.Copy(bytearray,0, i,len);

obj = Marshal.PtrToStructure(i, obj.GetType());

Marshal.FreeHGlobal(i);

}

This is a shameless copy of another thread which I found upon Googling!

Update : For more details, check the source

Answer 5

This is fairly easy, using marshalling.

Top of file

using System.Runtime.InteropServices

Function

byte[] getBytes(CIFSPacket str) {
    int size = Marshal.SizeOf(str);
    byte[] arr = new byte[size];
    IntPtr ptr = Marshal.AllocHGlobal(size);

    Marshal.StructureToPtr(str, ptr, true);
    Marshal.Copy(ptr, arr, 0, size);
    Marshal.FreeHGlobal(ptr);

    return arr;
}

And to convert it back:

CIFSPacket fromBytes(byte[] arr) {
    CIFSPacket str = new CIFSPacket();

    int size = Marshal.SizeOf(str);
    IntPtr ptr = Marshal.AllocHGlobal(size);

    Marshal.Copy(arr, 0, ptr, size);

    str = (CIFSPacket)Marshal.PtrToStructure(ptr, str.GetType());
    Marshal.FreeHGlobal(ptr);

    return str;
}

In your structure, you will need to put this before a string

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
public string Buffer;

And make sure SizeConst is as big as your biggest possible string.

And you should probably read this: http://msdn.microsoft.com/en-us/library/4ca6d5z7.aspx

Answer 6

You can use Marshal (StructureToPtr, ptrToStructure), and Marshal.copy but this is plataform dependent.

---

Serialization includes Functions to Custom Serialization.

public virtual void GetObjectData(SerializationInfo info, StreamingContext context)
Protected Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext) 

SerializationInfo include functions to serialize each member.

---

BinaryWriter and BinaryReader also contains methods to Save / Load to Byte Array (Stream).

Note that you can create a MemoryStream from a Byte Array or a Byte Array from a MemoryStream.

You can create a method Save and a method New on your structure:

   Save(Bw as BinaryWriter)
   New (Br as BinaryReader)

Then you select members to Save / Load to Stream -> Byte Array.