How to defense attack of the WSAAsyncSelect TCP Server ?

BOOL CServerDlg::InitSocket()
{
	WSADATA	wsaData; 
	int		iErrorCode; 
	if(WSAStartup(MAKEWORD(2,2),&wsaData))
	{
		CString strError;
		strError.Format(_T("WSAStartup failed: %d"),GetLastError());
		AddSEHLog(strError);
		WSACleanup(); 
		return   FALSE; 
	} 

	m_socket=WSASocket(PF_INET,SOCK_STREAM,0,NULL,0,0);
	if(m_socket==INVALID_SOCKET) 
	{
		CString strError;
		strError.Format(_T("WSASocket failed: %d"),GetLastError());
		AddSEHLog(strError);
		WSACleanup(); 
		return FALSE; 
	}

	SOCKADDR_IN sockServerAddr;
	DWORD		dwPort = GetListenPort();

	sockServerAddr.sin_family =AF_INET; 
	sockServerAddr.sin_addr.s_addr=htonl(INADDR_ANY);
	sockServerAddr.sin_port= htons(dwPort); 
	
	if(bind(m_socket,(LPSOCKADDR)&sockServerAddr,sizeof(sockServerAddr)) == SOCKET_ERROR)
	{
		CString strError;
		strError.Format(_T("bind failed: %d"),GetLastError());
		AddSEHLog(strError);

		closesocket(m_socket); 
		WSACleanup(); 
		return FALSE; 
	}

	if(listen(m_socket,64) == SOCKET_ERROR)   
	{
		CString strError;
		strError.Format(_T("list failed: %d"),GetLastError());
		AddSEHLog(strError);
		return FALSE; 
	}

    // this is the custom message : WM_SERVER_ACCEPT
	iErrorCode = WSAAsyncSelect(m_socket,m_hWnd,WM_SERVER_ACCEPT,FD_ACCEPT); 
	if(iErrorCode == SOCKET_ERROR)   
	{
		CString strError;
		strError.Format(_T("WSAAsyncSelect failed: %d"),GetLastError());
		AddSEHLog(strError);
		return FALSE; 
	} 

	AddSEHLog(_T("server start success !"));
	return TRUE; 
}

LRESULT CServerDlg::OnAccept(WPARAM wParam, LPARAM lParam)
{
    if(WSAGETSELECTERROR(wParam)) 
	{
		DeleteClient(wParam);
		ReFreshClient();
		return 0L; 
	} 
	
	if(WSAGETSELECTEVENT(lParam) == FD_ACCEPT)
	{
		SOCKADDR_IN	m_sockClientAddr; 
		int			nCount = 100;
		int			len=sizeof(m_sockClientAddr); 
		CString		strIP = _T("");
		CString		strPort = _T("");
		int			nLen;
		HANDLE		hThread = INVALID_HANDLE_VALUE;

        SOCKET		Client   =   accept(m_socket,(LPSOCKADDR)&m_sockClientAddr,&nCount); 
		RECVPARAM   recvParam;

		recvParam.m_sock = Client; 
		recvParam.m_hWnd = m_hWnd;

		m_cArrayList.Add(recvParam);

		hThread = CreateThread(NULL,0,RecvProc,(LPVOID)&recvParam,CREATE_SUSPENDED,NULL);
		SetThreadPriority(hThread,THREAD_PRIORITY_NORMAL);
		ResumeThread(hThread);
		WaitForSingleObject(hThread,INFINITE);

		CloseHandle(hThread); 
		ReFreshClient();
	} 
	
    return 0L; 
}

LRESULT CServerDlg::OnReadClose(WPARAM wParam, LPARAM lParam)
{
	if(WSAGETSELECTERROR(lParam))
	{
		DeleteClient(sockClient);
		ReFreshClient();
		return -1;
	}

	//////////////////////////////////////////////////////////////////////////
	switch (WSAGETSELECTEVENT(lParam)) 
	{ 
	case FD_READ: 
		{
			RECVPARAM *pRecvParam  = new RECVPARAM; 
			pRecvParam->m_sock     = sockClient; 
			pRecvParam->m_hWnd     = m_hWnd;
			pRecvParam->m_pMainDlg = this;
			
			HANDLE   hThread = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)ReadThreadProc,pRecvParam,CREATE_SUSPENDED,NULL);
			SetThreadPriority(hThread,THREAD_PRIORITY_NORMAL);
			ResumeThread(hThread);
			Sleep(100);
			CloseHandle(hThread);
		}
		break; 

	case FD_CLOSE: 
		{
			DeleteClient(sockClient);
			ReFreshClient();
		} 
		break; 
	}

	return 0L; 
}

//////////////////////////////////////////////////////////////////////////
// Here is to read the buffer from client
// Paser the packets.
DWORD CServerDlg::ReadThreadProc(LPVOID pParam)
{
	RECVPARAM	*pRecvParam = (RECVPARAM *)pParam;
	SOCKET		sock  = pRecvParam->m_sock; 
	HWND		hwnd  = pRecvParam->m_hWnd; 
	CServerDlg	*pDlg = (CServerDlg *)((RECVPARAM*)pParam)->m_pMainDlg; 

	if(MyWSARecvFrom(sock,&wsabufRecv,1,&dwRead,&dwFlag,(SOCKADDR*)&addrFrom,&len,NULL,NULL)== SOCKET_ERROR)
	{
		::PostMessage(hwnd,WM_RECVDATA,0,(LPARAM)wsabufRecv.buf); 
		delete[] wsabufRecv.buf;
		delete pRecvParam;
		return -1; 
	}

	::PostMessage(hwnd,WM_RECVDATA,(WPARAM)sock,(LPARAM)wsabufRecv.buf); 

	//////////////////////////////////////////////////////////////////////////
	// Paser the packets
	pszRecv = clientCMD.PaserData(sock,wsabufRecv.buf);
	delete pRecvParam;
	delete [] wsabufRecv.buf;
	wsabufRecv.buf = NULL;
	return 0;   
}