System.Net.Sockets.Socket.BeginSendTo C# (CSharp) Method

        public IAsyncResult BeginSendTo(byte[] buffer, int offset, int size, SocketFlags socketFlags, EndPoint remoteEP, AsyncCallback callback, object state)
        {
            if (NetEventSource.IsEnabled) NetEventSource.Enter(this);
            if (CleanedUp)
            {
                throw new ObjectDisposedException(this.GetType().FullName);
            }

            // Validate input parameters.
            if (buffer == null)
            {
                throw new ArgumentNullException(nameof(buffer));
            }
            if (remoteEP == null)
            {
                throw new ArgumentNullException(nameof(remoteEP));
            }
            if (offset < 0 || offset > buffer.Length)
            {
                throw new ArgumentOutOfRangeException(nameof(offset));
            }
            if (size < 0 || size > buffer.Length - offset)
            {
                throw new ArgumentOutOfRangeException(nameof(size));
            }

            // This will check the permissions for connect.
            EndPoint endPointSnapshot = remoteEP;
            Internals.SocketAddress socketAddress = CheckCacheRemote(ref endPointSnapshot, false);

            // Set up the async result and indicate to flow the context.
            OverlappedAsyncResult asyncResult = new OverlappedAsyncResult(this, state, callback);
            asyncResult.StartPostingAsyncOp(false);

            // Post the send.
            DoBeginSendTo(buffer, offset, size, socketFlags, endPointSnapshot, socketAddress, asyncResult);

            // Finish, possibly posting the callback.  The callback won't be posted before this point is reached.
            asyncResult.FinishPostingAsyncOp(ref Caches.SendClosureCache);

            if (NetEventSource.IsEnabled) NetEventSource.Exit(this, asyncResult);
            return asyncResult;
        }

        private void btnOK_Click(object sender, EventArgs e)
        {
            strName = txtName.Text;
            try
            {
                //Using UDP sockets
                clientSocket = new Socket(AddressFamily.InterNetwork,
                    SocketType.Dgram, ProtocolType.Udp);

                //IP address of the server machine
                IPAddress ipAddress = IPAddress.Parse(txtServerIP.Text);
                //Server is listening on port 1000
                IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, 1000);

                epServer = (EndPoint)ipEndPoint;

                Data msgToSend = new Data ();
                msgToSend.cmdCommand = Command.Login;
                msgToSend.strMessage = null;
                msgToSend.strName = strName;

                byte[] byteData = msgToSend.ToByte();

                //Login to the server
                clientSocket.BeginSendTo(byteData, 0, byteData.Length,
                    SocketFlags.None, epServer, new AsyncCallback(OnSend), null);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "SGSclient",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }