UDP client

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
using System.Threading;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        byte[] data = new byte[1024];
        string stringData;
        UdpClient server, client;
        IPEndPoint send, send1;

        public Form1()
        {
            InitializeComponent();
        }

        private void sendData(UdpClient s, string d)
        {
            System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();
            Byte[] data1 = encoding.GetBytes(d);
            s.Send(data1, data1.Length);
        }

        private string receiveData(UdpClient s, IPEndPoint e){
            Byte[] data1 = s.Receive(ref e);
            System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();
            return encoding.GetString(data1);
        }

        private void button1_Click(object sender, EventArgs e)
        {

            server = new UdpClient(textBox1.Text, Convert.ToInt32(textBox2.Text));

            send  = new IPEndPoint(IPAddress.Any, 2000);

            string test1 = "1|"+textBox8.Text;

            sendData(server,test1);

        }

        private void button3_Click(object sender, EventArgs e)
        {
            sendData(server,"2|" + textBox7.Text);
            Thread.Sleep(100);
            textBox4.AppendText(server.Available.ToString());
            string d = receiveData(server,send);
            //textBox4.AppendText();
            String[] a = d.Split('|');
            textBox6.Text = a[0];
            textBox5.Text = a[1];
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void button4_Click(object sender, EventArgs e)
        {
            client = new UdpClient(textBox6.Text, Convert.ToInt32(textBox5.Text));

            sendData(client, "HELLO!");
            timer1.Enabled = true;
            //string d = receiveData(client, send);
            //textBox4.AppendText(d);
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            if (client.Available > 0)
            {
                string d = receiveData(client, send);
                textBox4.AppendText(d);
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            sendData(client, textBox3.Text);
        }
    }
}