Add anti-flood protection

OpenRA.Game/Server/PlayerMessageTracker.cs

@@ -0,0 +1,86 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2022 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+
+namespace OpenRA.Server
+{
+	class PlayerMessageTracker
+	{
+		[TranslationReference("remaining")]
+		static readonly string ChatDisabled = "chat-disabled";
+
+		readonly Dictionary<int, List<long>> messageTracker = new Dictionary<int, List<long>>();
+		readonly Server server;
+		readonly Action<Connection, int, int, byte[]> dispatchOrdersToClient;
+		readonly Action<Connection, string, Dictionary<string, object>> sendLocalizedMessageTo;
+
+		public PlayerMessageTracker(Server server, Action<Connection, int, int, byte[]> dispatchOrdersToClient, Action<Connection, string, Dictionary<string, object>> sendLocalizedMessageTo)
+		{
+			this.server = server;
+			this.dispatchOrdersToClient = dispatchOrdersToClient;
+			this.sendLocalizedMessageTo = sendLocalizedMessageTo;
+		}
+
+		public void DisableChatUI(Connection conn, int time)
+		{
+			dispatchOrdersToClient(conn, 0, 0, new Order("DisableChatEntry", null, false) { ExtraData = (uint)time }.Serialize());
+		}
+
+		public bool IsPlayerAtFloodLimit(Connection conn)
+		{
+			if (!messageTracker.ContainsKey(conn.PlayerIndex))
+				messageTracker.Add(conn.PlayerIndex, new List<long>());
+
+			var isAdmin = server.GetClient(conn)?.IsAdmin ?? false;
+			var settings = server.Settings;
+			var time = conn.ConnectionTimer.ElapsedMilliseconds;
+			var tracker = messageTracker[conn.PlayerIndex];
+			tracker.RemoveAll(t => t + settings.FloodLimitInterval < time);
+
+			long CalculateRemaining(long cooldown)
+			{
+				return (cooldown - time + 999) / 1000;
+			}
+
+			// Block messages until join cooldown times out
+			if (!isAdmin && time < settings.FloodLimitJoinCooldown)
+			{
+				var remaining = CalculateRemaining(settings.FloodLimitJoinCooldown);
+				sendLocalizedMessageTo(conn, ChatDisabled, Translation.Arguments("remaining", remaining));
+				return true;
+			}
+
+			// Block messages if above flood limit
+			if (tracker.Count >= settings.FloodLimitMessageCount)
+			{
+				var remaining = CalculateRemaining(tracker[0] + settings.FloodLimitInterval);
+				sendLocalizedMessageTo(conn, ChatDisabled, Translation.Arguments("remaining", remaining));
+				return true;
+			}
+
+			tracker.Add(time);
+
+			// Disable chat when player has reached the flood limit
+			if (tracker.Count >= settings.FloodLimitMessageCount)
+			{
+				var cooldownDelta = Math.Max(0, settings.FloodLimitCooldown - settings.FloodLimitInterval);
+				for (var i = 0; i < tracker.Count; i++)
+					tracker[i] = time + cooldownDelta;
+
+				DisableChatUI(conn, settings.FloodLimitCooldown);
+			}
+
+			return false;
+		}
+	}
+}

OpenRA.Game/Server/Server.cs

@@ -79,6 +79,7 @@ namespace OpenRA.Server
 		GameInformation gameInfo;
 		readonly List<GameInformation.Player> worldPlayers = new List<GameInformation.Player>();
 		readonly Stopwatch pingUpdated = Stopwatch.StartNew();
+		readonly PlayerMessageTracker playerMessageTracker;
 
 		[TranslationReference]
 		static readonly string CustomRules = "custom-rules";
@@ -128,9 +129,6 @@ namespace OpenRA.Server
 		[TranslationReference("command")]
 		static readonly string UnknownServerCommand = "unknown-server-command";
 
-		[TranslationReference("remaining")]
-		static readonly string ChatDisabled = "chat-disabled";
-
 		[TranslationReference("player")]
 		static readonly string LobbyDisconnected = "lobby-disconnected";
 
@@ -316,6 +314,8 @@ namespace OpenRA.Server
 			Map = ModData.MapCache[settings.Map];
 			MapStatusCache = new MapStatusCache(modData, MapStatusChanged, type == ServerType.Dedicated && settings.EnableLintChecks);
 
+			playerMessageTracker = new PlayerMessageTracker(this, DispatchOrdersToClient, SendLocalizedMessageTo);
+
 			LobbyInfo = new Session
 			{
 				GlobalSettings =
@@ -558,8 +558,8 @@ namespace OpenRA.Server
 						newConn.Validated = true;
 
 						// Disable chat UI to stop the client sending messages that we know we will reject
-						if (!client.IsAdmin && Settings.JoinChatDelay > 0)
-							DispatchOrdersToClient(newConn, 0, 0, new Order("DisableChatEntry", null, false) { ExtraData = (uint)Settings.JoinChatDelay }.Serialize());
+						if (!client.IsAdmin && Settings.FloodLimitJoinCooldown > 0)
+							playerMessageTracker.DisableChatUI(newConn, Settings.FloodLimitJoinCooldown);
 
 						Log.Write("server", $"Client {newConn.PlayerIndex}: Accepted connection from {newConn.EndPoint}.");
 
@@ -1006,14 +1006,7 @@ namespace OpenRA.Server
 
 					case "Chat":
 						{
-							var isAdmin = GetClient(conn)?.IsAdmin ?? false;
-							var connected = conn.ConnectionTimer.ElapsedMilliseconds;
-							if (!isAdmin && connected < Settings.JoinChatDelay)
-							{
-								var remaining = (Settings.JoinChatDelay - connected + 999) / 1000;
-								SendLocalizedMessageTo(conn, ChatDisabled, Translation.Arguments("remaining", remaining));
-							}
-							else
+							if (Type == ServerType.Local || !playerMessageTracker.IsPlayerAtFloodLimit(conn))
 								DispatchOrdersToClients(conn, 0, o.Serialize());
 
 							break;

OpenRA.Game/Settings.cs

@@ -103,7 +103,16 @@ namespace OpenRA
 		public bool EnableLintChecks = true;
 
 		[Desc("Delay in milliseconds before newly joined players can send chat messages.")]
-		public int JoinChatDelay = 5000;
+		public int FloodLimitJoinCooldown = 5000;
+
+		[Desc("Amount of miliseconds player chat messages are tracked for.")]
+		public int FloodLimitInterval = 5000;
+
+		[Desc("Amount of chat messages per FloodLimitInterval a players can send before flood is detected.")]
+		public int FloodLimitMessageCount = 5;
+
+		[Desc("Delay in milliseconds before players can send chat messages after flood was detected.")]
+		public int FloodLimitCooldown = 15000;
 
 		public ServerSettings Clone()
 		{

mods/common/languages/en.ftl

@@ -8,11 +8,6 @@ no-start-until-required-slots-full = Unable to start the game until required slo
 no-start-without-players = Unable to start the game with no players.
 insufficient-enabled-spawnPoints = Unable to start the game until more spawn points are enabled.
 malformed-command = Malformed { $command } command
-chat-disabled =
-    { $remaining ->
-        [one] Chat is disabled. Please try again in { $remaining } second.
-       *[other] Chat is disabled. Please try again in { $remaining } seconds.
-    }
 state-unchanged-ready = Cannot change state when marked as ready.
 invalid-faction-selected = Invalid faction selected: { $faction }
 supported-factions = Supported values: { $factions }
@@ -91,6 +86,13 @@ game-started = Game started
 ## Server also LobbyUtils
 bots-disabled = Bots Disabled
 
+## PlayerMessageTracker
+chat-disabled =
+    { $remaining ->
+        [one] Chat is disabled. Please try again in { $remaining } second.
+       *[other] Chat is disabled. Please try again in { $remaining } seconds.
+    }
+
 ## ActorEditLogic
 duplicate-actor-id = Duplicate Actor ID
 enter-actor-id = Enter an Actor ID