Packet issues

see_seA

I've highly modified the code found here http://www.codeproject.com/KB/IP/ChatAsynchTCPSockets.aspx. When creating a packet, I give the following class the info it needs onto which is converts it into a byte[] and visa versa which can then be sent and received by a socket respectively.

public class Data
{
    //Default constructor
    public Command cmdCommand; //Command type (login, logout, send message, etcetera)
    public string strMessage; //Message text
    public string strName; //Name by which the client logs into the room

    public Data()
    {
        cmdCommand = Command.Null;
        strMessage = null;
        strName = null;
    }

    //Converts the bytes into an object of type Data
    public Data(byte\[\] data)
    {
        //The first four bytes are for the Command
        cmdCommand = (Command)BitConverter.ToInt32(data, 0);

        //The next four store the length of the name
        int nameLen = BitConverter.ToInt32(data, 4);

        //The next four store the length of the message
        int msgLen = BitConverter.ToInt32(data, 8);

        //This check makes sure that strName has been passed in the array of bytes
        if (nameLen > 0)
            strName = Encoding.UTF8.GetString(data, 12, nameLen);
        else
            strName = null;

        //This checks for a null message field
        if (msgLen > 0)
            strMessage = Encoding.UTF8.GetString(data, 12 + nameLen, msgLen);
        else
            strMessage = null;
    }

    //Converts the Data structure into an array of bytes
    public byte\[\] ToByte()
    {
        List result = new List();

        //First four are for the Command
        result.AddRange(BitConverter.GetBytes((int)cmdCommand));

        //Add the length of the name
        if (strName != null)
            result.AddRange(BitConverter.GetBytes(strName.Length));
        else
            result.AddRange(BitConverter.GetBytes(0));

        //Length of the message
        if (strMessage != null)
            result.AddRange(BitConverter.GetBytes(Encoding.UTF8.GetByteCount(strMessage)));
        else
            result.AddRange(BitConverter.GetBytes(0));

        //Add the name
        if (strName !=

leppie

Please fix the generics in the post. I am pretty sure that is a List of byte.

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 alpha 4a out now (29 May 2008)

leppie

At which point do you get this error? I suspect, the byte[] you pass to the constructor does not contain the correct data. Add a check in the beginning of the constructor to ensure the byte[] is long enough at least.

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 alpha 4a out now (29 May 2008)

see_seA

As far as I can tell, I get the error after executing the following commands: In the OnAccept method..

            byte\[\] bufData = new byte\[1024\];
            clientSocket.BeginReceive(bufData, 0, bufData.Length, SocketFlags.None, new AsyncCallback(OnReceive),
                                      new object\[\] {clientSocket, bufData});

In the OnReceive method..

Socket clientSocket = null;
Data msgReceived = null;
byte[] bufData = new byte[1024];
bool bypass = false;
ClientInfo cInfo = null;

        try
        {
            bool blInvalidClient = false;

            try
            {
                object\[\] oData = (object\[\]) ar.AsyncState;
                clientSocket = (Socket) oData\[0\];
                bufData = (byte\[\]) oData\[1\];
                clientSocket.EndReceive(ar);

                //Console.WriteLine(clientList.Count);
            }
            catch (SocketException)
            {
                blInvalidClient = true;
            }

            if (!blInvalidClient)
            {
                //Transform the array of bytes received from the user into an
                //intelligent form of object Data
                msgReceived = Packet.PacketReceived(bufData);

...

The Packet.PacketReceived method returns new Data(bufData). I've added traces in that constructor and there is something incorrect happening. All clients that communicate use the same Data class to convert the info into a byte[] so it's not as if I'm sending an arb string of bytes to the socket. But the weird thing is that this only ever happens when I sent lots of packets to the socket at once.

see_seA

Problem seems to be here. Not sure I understand why...

            if (nameLen > 0)
                strName = Encoding.UTF8.GetString(data, 12, nameLen);
            else
                strName = null;

leppie

It probably does not allow you to read zero strings (assuming it needs a 0 terminator).

xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 alpha 4a out now (29 May 2008)

see_seA

Packets are lost due to this under high load. I'm out of ideas.

see_seA

Hmmm. I increased the buffer size from 1024 to 4096 and everything seems to work perfectly now.