godot/doc/classes/UDPServer.xml

<?xml version="1.0" encoding="UTF-8" ?>
<class name="UDPServer" inherits="RefCounted" version="4.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
	<brief_description>
		Helper class to implement a UDP server.
	</brief_description>
	<description>
		A simple server that opens a UDP socket and returns connected [PacketPeerUDP] upon receiving new packets. See also [method PacketPeerUDP.connect_to_host].
		After starting the server ([method listen]), you will need to [method poll] it at regular intervals (e.g. inside [method Node._process]) for it to process new packets, delivering them to the appropriate [PacketPeerUDP], and taking new connections.
		Below a small example of how it can be used:
		[codeblocks]
		[gdscript]
		# server_node.gd
		class_name ServerNode
		extends Node

		var server := UDPServer.new()
		var peers = []

		func _ready():
		    server.listen(4242)

		func _process(delta):
		    server.poll() # Important!
		    if server.is_connection_available():
		        var peer: PacketPeerUDP = server.take_connection()
		        var packet = peer.get_packet()
		        print("Accepted peer: %s:%s" % [peer.get_packet_ip(), peer.get_packet_port()])
		        print("Received data: %s" % [packet.get_string_from_utf8()])
		        # Reply so it knows we received the message.
		        peer.put_packet(packet)
		        # Keep a reference so we can keep contacting the remote peer.
		        peers.append(peer)

		    for i in range(0, peers.size()):
		        pass # Do something with the connected peers.
		[/gdscript]
		[csharp]
		// ServerNode.cs
		using Godot;
		using System.Collections.Generic;

		public partial class ServerNode : Node
		{
		    private UdpServer _server = new UdpServer();
		    private List&lt;PacketPeerUdp&gt; _peers  = new List&lt;PacketPeerUdp&gt;();

		    public override void _Ready()
		    {
		        _server.Listen(4242);
		    }

		    public override void _Process(double delta)
		    {
		        _server.Poll(); // Important!
		        if (_server.IsConnectionAvailable())
		        {
		            PacketPeerUdp peer = _server.TakeConnection();
		            byte[] packet = peer.GetPacket();
		            GD.Print($"Accepted Peer: {peer.GetPacketIP()}:{peer.GetPacketPort()}");
		            GD.Print($"Received Data: {packet.GetStringFromUtf8()}");
		            // Reply so it knows we received the message.
		            peer.PutPacket(packet);
		            // Keep a reference so we can keep contacting the remote peer.
		            _peers.Add(peer);
		        }
		        foreach (var peer in _peers)
		        {
		            // Do something with the peers.
		        }
		    }
		}
		[/csharp]
		[/codeblocks]
		[codeblocks]
		[gdscript]
		# client_node.gd
		class_name ClientNode
		extends Node

		var udp := PacketPeerUDP.new()
		var connected = false

		func _ready():
		    udp.connect_to_host("127.0.0.1", 4242)

		func _process(delta):
		    if !connected:
		        # Try to contact server
		        udp.put_packet("The answer is... 42!".to_utf8_buffer())
		    if udp.get_available_packet_count() &gt; 0:
		        print("Connected: %s" % udp.get_packet().get_string_from_utf8())
		        connected = true
		[/gdscript]
		[csharp]
		// ClientNode.cs
		using Godot;

		public partial class ClientNode : Node
		{
		    private PacketPeerUdp _udp = new PacketPeerUdp();
		    private bool _connected = false;

		    public override void _Ready()
		    {
		        _udp.ConnectToHost("127.0.0.1", 4242);
		    }

		    public override void _Process(double delta)
		    {
		        if (!_connected)
		        {
		            // Try to contact server
		            _udp.PutPacket("The Answer Is..42!".ToUtf8Buffer());
		        }
		        if (_udp.GetAvailablePacketCount() &gt; 0)
		        {
		            GD.Print($"Connected: {_udp.GetPacket().GetStringFromUtf8()}");
		            _connected = true;
		        }
		    }
		}
		[/csharp]
		[/codeblocks]
	</description>
	<tutorials>
	</tutorials>
	<methods>
		<method name="get_local_port" qualifiers="const">
			<return type="int" />
			<description>
				Returns the local port this server is listening to.
			</description>
		</method>
		<method name="is_connection_available" qualifiers="const">
			<return type="bool" />
			<description>
				Returns [code]true[/code] if a packet with a new address/port combination was received on the socket.
			</description>
		</method>
		<method name="is_listening" qualifiers="const">
			<return type="bool" />
			<description>
				Returns [code]true[/code] if the socket is open and listening on a port.
			</description>
		</method>
		<method name="listen">
			<return type="int" enum="Error" />
			<param index="0" name="port" type="int" />
			<param index="1" name="bind_address" type="String" default="&quot;*&quot;" />
			<description>
				Starts the server by opening a UDP socket listening on the given [param port]. You can optionally specify a [param bind_address] to only listen for packets sent to that address. See also [method PacketPeerUDP.bind].
			</description>
		</method>
		<method name="poll">
			<return type="int" enum="Error" />
			<description>
				Call this method at regular intervals (e.g. inside [method Node._process]) to process new packets. And packet from known address/port pair will be delivered to the appropriate [PacketPeerUDP], any packet received from an unknown address/port pair will be added as a pending connection (see [method is_connection_available], [method take_connection]). The maximum number of pending connection is defined via [member max_pending_connections].
			</description>
		</method>
		<method name="stop">
			<return type="void" />
			<description>
				Stops the server, closing the UDP socket if open. Will close all connected [PacketPeerUDP] accepted via [method take_connection] (remote peers will not be notified).
			</description>
		</method>
		<method name="take_connection">
			<return type="PacketPeerUDP" />
			<description>
				Returns the first pending connection (connected to the appropriate address/port). Will return [code]null[/code] if no new connection is available. See also [method is_connection_available], [method PacketPeerUDP.connect_to_host].
			</description>
		</method>
	</methods>
	<members>
		<member name="max_pending_connections" type="int" setter="set_max_pending_connections" getter="get_max_pending_connections" default="16">
			Define the maximum number of pending connections, during [method poll], any new pending connection exceeding that value will be automatically dropped. Setting this value to [code]0[/code] effectively prevents any new pending connection to be accepted (e.g. when all your players have connected).
		</member>
	</members>
</class>