udp

using System.Collections.Generic;
using UnityEngine;
using System.Net.Sockets;
using System.Net;
using System;
using System.Text;

public class MinimalNet : MonoBehaviour
{

    public bool isHost, isOnline;

    public List<IPEndPoint> clients;

    IPEndPoint ownPoint, hostPoint, broadPoint;
    public string ownAddr;
    public int ownPort = 35000, hostPort;

    public string hostAddr;

    public List<string> lastReceivedMSGs;

    UdpClient udp;

    string message;

    byte[] sendBuff, recvBuff;

    object hostLock;

    private void Start() {
        GetOwnAddr();
        hostAddr = ownAddr;
        hostPort = ownPort;
        sendBuff = new byte[128];
        recvBuff = new byte[128];

        hostLock = new object();
        lastReceivedMSGs = new List<string>();
    }

    void ClearData() {
        if ( clients == null ) clients = new List<IPEndPoint>(); else clients.Clear();
    }

    private void OnGUI() {
        GUILayout.BeginHorizontal();
        GUILayout.Label( "Own Port" );
        string port = GUILayout.TextField( ownPort.ToString() );
        int.TryParse( port, out ownPort );
        GUILayout.EndHorizontal();

        if ( !isHost ) {
            GUILayout.BeginHorizontal();
            GUILayout.Label( "Host Address" );
            hostAddr = GUILayout.TextField( hostAddr );
            GUILayout.EndHorizontal();

            GUILayout.BeginHorizontal();
            GUILayout.Label( "Host Port" );
            string hPort = GUILayout.TextField( hostPort.ToString() );
            int.TryParse( hPort, out hostPort );
            GUILayout.EndHorizontal();
        }

        GUILayout.Box( string.Format( "Own Address: {0}:{1}", ownAddr, ownPort ) );
        GUILayout.Box( string.Format( "Online: {0}   Host: {1}", isOnline, isHost ) );
        if (!isOnline && GUILayout.Button( isHost ? "Become Client" : "Become Host")) { ToggleHost(); }
        GUILayout.Space( 30 );
        if ( GUILayout.Button( isOnline ? "Stop Online!" : "Go Online!" ) ) { ToggleOnline(); }
        GUILayout.Space( 30 );

        GUILayout.BeginHorizontal();
        message = GUILayout.TextField(message); if (GUILayout.Button("Send")) { SendUDPMessage( message ); message = ""; } if (isHost && isOnline && GUILayout.Button("Ping Broad")) { PingBroad(); }
        GUILayout.EndHorizontal();
        GUILayout.Space( 20 );
        string chat = "";
        for (int i = 0; i < lastReceivedMSGs.Count; i++ ) {
            chat += string.Format("{0}\n", lastReceivedMSGs[i]);
        }
        GUILayout.Box( chat );
    }

    //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

    void StartUDP(int port) {
        GetOwnAddr();
        hostPoint = new IPEndPoint( IPAddress.Parse( hostAddr ), hostPort );
        broadPoint = new IPEndPoint( IPAddress.Parse( "192.168.255.255" ), hostPort );
        udp = new UdpClient(port);

        lastReceivedMSGs.Add( "Started UDP: " + ownAddr + ":" + port );
        udp.BeginReceive( isHost ? new AsyncCallback( ReceiveAsHost ) : new AsyncCallback( ReceiveAsClient ), udp );
    }

    void ToggleOnline() {
        isOnline = !isOnline;
        ClearData();

        if (isOnline) {
            StartUDP( ownPort );
        } else {
            if (udp != null) udp.Close();
        }

    }

    IPEndPoint sender;

    void ReceiveAsHost( IAsyncResult ar ) {
        lock ( hostLock ) {
            try {
                recvBuff = udp.EndReceive( ar, ref sender );

                if ( !sender.Address.Equals( ownPoint.Address ) || sender.Port != ownPort) {
                    if ( !clients.Contains( sender ) ) {
                        clients.Add( sender );
                        lastReceivedMSGs.Add( "Added Client: " + sender.Address + ":" + sender.Port );
                    }

                    lastReceivedMSGs.Add( "Recv: " + Encoding.Unicode.GetString( recvBuff ) );
                }

            } catch ( Exception e ) {
                Debug.LogWarning( e.Message );
            }
        }

        udp.BeginReceive( new AsyncCallback( ReceiveAsHost ), udp );
    }

    void ReceiveAsClient( IAsyncResult ar ) {
        try {
            recvBuff = udp.EndReceive( ar, ref sender );
            lastReceivedMSGs.Add( "Recv: " + Encoding.Unicode.GetString( recvBuff ) );
        } catch (Exception e) {
            Debug.LogWarning( e.Message );
        }

        udp.BeginReceive( new AsyncCallback( ReceiveAsClient ), udp );
    }

    void SendUDPMessage( string txt ) {
        if ( !isOnline ) return;

        txt = string.Format( "{0:0.000}: {1}", Time.timeSinceLevelLoad, txt );

        sendBuff = Encoding.Unicode.GetBytes( txt );

        if (isHost) {
            for (int i = 0; i < clients.Count; i++ ) {
                udp.Send( sendBuff, sendBuff.Length, clients[i] );
            }
        } else {
            udp.Send( sendBuff, sendBuff.Length, hostPoint );
            txt += " to " + hostPoint.Address;
        }

        lastReceivedMSGs.Add( txt );
    }

    void PingBroad() {
        sendBuff = Encoding.Unicode.GetBytes( string.Format( "{0:0.000}: {1}", Time.timeSinceLevelLoad, "PING!" ) );
        udp.Send( sendBuff, sendBuff.Length, broadPoint );
    }

    //----------------------------------------------------------------------------------------------------------------

    void ToggleHost() {
        isHost = !isHost;
        ClearData();
    }

    void GetOwnAddr() {
        string hostName = Dns.GetHostName();
        IPHostEntry hostEn = Dns.GetHostEntry(hostName);

        ownPoint = null;

        for ( int i = 0; i < hostEn.AddressList.Length; i++ ) {

            if ( hostEn.AddressList[i].AddressFamily == AddressFamily.InterNetwork ) {
                print( hostEn.AddressList[i].ToString() );
            }
        }

        for ( int i = hostEn.AddressList.Length - 1; i >= 0; i-- ) {
            if ( hostEn.AddressList[i].AddressFamily == AddressFamily.InterNetwork ) {
                ownPoint = new IPEndPoint( hostEn.AddressList[i], ownPort );
                break;
            }
        }


        if (ownPoint != null) {
            ownAddr = ownPoint.Address.ToString();
        }

    }

    private void Update() {
        if ( lastReceivedMSGs.Count > 5 ) lastReceivedMSGs.RemoveAt( 0 );
    }
}