multi-threaded chess using winsock

I've been working on a small network based chess application. I managed to create a server that can handle multiple connections, however I don't know how to send data from one client to another through the server. With this setup, it only send the message to one client.
I can also send you the solution file. Any help would be appreciated. Thanks

Here is the partial Server implementation;
Basically it creates new thread for each new client;

Code:

//function to handle our Socket on its own thread.
//param- SOCKET* that is connected to a client
DWORD WINAPI HandleSocket(void* param)
{
string test;

SOCKET s = (SOCKET)param;
User temp;
temp._socket = (SOCKET)param;
temp._inGame = false;
userlist.add(&temp);

std::cout<<"connection"<<endl;
int bytesread = 0;  
int byteswrite=0;

while(true)
{
    //receive
    bytesread = recv(s, reinterpret_cast<char*>(test.c_str()), BUF_LEN, 0);

    //error check   
    if(bytesread == SOCKET_ERROR)
    {
        std::cout << WSAGetLastError();
        //shutdown and close on error
        shutdown(s, SD_BOTH);
        closesocket(s);
        return 0;
    }


    //check for socket being closed by the client
    if(bytesread == 0)
    {
        //shutdown our socket, it closed
        shutdown(s, SD_BOTH);
        closesocket(s);
        return 0;
    }

    byteswrite = send(s, "test" , 255 , 0);
    if(byteswrite == SOCKET_ERROR)
    {
        std::cout << WSAGetLastError();
        //shutdown and close on error
        shutdown(s, SD_BOTH);
        closesocket(s);
        return 0;
    }

    test.clear();
 }
}

> bytesread = recv(s, reinterpret_cast<char*>(test.c_str()), BUF_LEN, 0);
Two things wrong here
1. c_str() is supposed to be 'const', which means you shouldn't be modifying it.
2. How do you know you have BUF_LEN of it anyway?

> byteswrite = send(s, "test" , 255 , 0);
Also, this sends 250 bytes of garbage, assuming it doesn't first run off the end of memory and generate a segfault.

thanks for the answer I corrected those parts, but still don't know how to send a data from one client to another client through the server.

You do a recv() from one client, and a send() to the other client.

yes I know that, but the problem is recv() blocks the code, so its impossible to loop between different client sockets. it keeps waiting on the first client socket, which makes it impossible to receive data from others.

Originally Posted by akurdas

yes I know that, but the problem is recv() blocks the code, so its impossible to loop between different client sockets. it keeps waiting on the first client socket, which makes it impossible to receive data from others.

Look into either threads or making the socket asynchronous(using select).

I've been working on it since yesterday, but no result.
All the files are inside the attachment maybe someone can point me to the right direction. All I need to do is sending data from one client to another.

Rather than post your completed game (to date), which has a lot of stuff in it which is of no interest to us, write a separate simple test program where you can focus on experimenting with just this one issue.

A server that just waits for connections, and echoes everything it receives to all connected clients.
A client (which you run several instances of) which send a single string (and perhaps a process ID) to the server, and echoes anything the server sends back.

When you understand how all this works, then apply that idea to your real code.

I know I have to communicate with all of the other client threads connected. What I don't know and need help with is how to communicate with all of the client threads to send the message out

Each user gets a new thread??