Merge pull request #1642 from AxeelAnder/npc-buff-bouncer

Add cheat detection on NPCAddBuff

CHANGELOG.md

@@ -90,6 +90,7 @@ This is the rolling changelog for TShock for Terraria. Use past tense when addin
 * Added filtering and validation on packet 96 (Teleport player through portal) (@QuiCM)
 * Update tracker now uses TLS (@pandabear41) 
 * When deleting an user account, any player logged in to that account is now logged out properly (@Enerdy)
+* Add NPCAddBuff data handler and bouncer (@AxeelAnder)
 
 ## TShock 4.3.25
 * Fixed a critical exploit in the Terraria protocol that could cause massive unpreventable world corruption as well as a number of other problems. Thanks to @bartico6 for reporting. Fixed by the efforts of @QuiCM, @hakusaro, and tips in the right directioon from @bartico6.

TShockAPI/Bouncer.cs

@@ -36,6 +36,31 @@ namespace TShockAPI
 	/// <summary>Bouncer is the TShock anti-hack and anti-cheat system.</summary>
 	internal sealed class Bouncer
 	{
+		static Dictionary<byte, short> NPCAddBuffTimeMax = new Dictionary<byte, short>()
+		{
+			{ BuffID.Poisoned, 3600 },
+			{ BuffID.OnFire, 1200 },
+			{ BuffID.CursedInferno, 420 },
+			{ BuffID.Frostburn, 900 },
+			{ BuffID.Ichor, 1200 },
+			{ BuffID.Venom, 1260 },
+			{ BuffID.Midas, 120 },
+			{ BuffID.Wet, 1500 },
+			{ BuffID.Slimed, 1500 },
+			{ BuffID.Lovestruck, 1800 },
+			{ BuffID.Stinky, 1800 },
+			{ BuffID.SoulDrain, 30 },
+			{ BuffID.ShadowFlame, 660 },
+			{ BuffID.DryadsWard, 120 },
+			{ BuffID.BoneJavelin, 900 },
+			{ BuffID.StardustMinionBleed, 900 },
+			{ BuffID.DryadsWardDebuff, 120 },
+			{ BuffID.Daybreak, 300 },
+			{ BuffID.BetsysCurse, 600 },
+			{ BuffID.Oiled, 540 }
+		};
+
+
 		/// <summary>Constructor call initializes Bouncer and related functionality.</summary>
 		/// <returns>A new Bouncer.</returns>
 		internal Bouncer()
@@ -49,6 +74,7 @@ namespace TShockAPI
 			GetDataHandlers.PlayerAnimation += OnPlayerAnimation;
 			GetDataHandlers.NPCStrike += OnNPCStrike;
 			GetDataHandlers.ItemDrop += OnItemDrop;
+			GetDataHandlers.NPCAddBuff += OnNPCAddBuff;
 			GetDataHandlers.PlayerBuff += OnPlayerBuff;
 			GetDataHandlers.ChestItemChange += OnChestItemChange;
 			GetDataHandlers.NPCHome += OnUpdateNPCHome;
@@ -454,6 +480,65 @@ namespace TShockAPI
 			}
 		}
 
+		/// <summary>Handles NPCAddBuff events.</summary>
+		/// <param name="sender">The object that triggered the event.</param>
+		/// <param name="args">The packet arguments that the event has.</param>
+		internal void OnNPCAddBuff(object sender, GetDataHandlers.NPCAddBuffEventArgs args)
+		{
+			short id = args.ID;
+			byte type = args.Type;
+			short time = args.Time;
+
+			if (id >= Main.npc.Length)
+			{
+				args.Handled = true;
+				return;
+			}
+
+			NPC npc = Main.npc[id];
+
+			if (npc == null)
+			{
+				args.Handled = true;
+				return;
+			}
+
+			if (args.Player.IsBeingDisabled())
+			{
+				args.Handled = true;
+				return;
+			}
+
+			bool detectedNPCBuffTimeCheat = false;
+
+			if (NPCAddBuffTimeMax.ContainsKey(type))
+			{
+				if (time > NPCAddBuffTimeMax[type])
+				{
+					detectedNPCBuffTimeCheat = true;
+				}
+
+				if (npc.townNPC && npc.netID != NPCID.Guide && npc.netID != NPCID.Clothier)
+				{
+					if (type != BuffID.Lovestruck && type != BuffID.Stinky && type != BuffID.DryadsWard &&
+						type != BuffID.Wet && type != BuffID.Slimed)
+					{
+						detectedNPCBuffTimeCheat = true;
+					}
+				}
+			}
+			else
+			{
+				detectedNPCBuffTimeCheat = true;
+			}
+
+			if (detectedNPCBuffTimeCheat)
+			{
+				args.Player.Kick("Added buff to NPC abnormally.", true);
+				args.Handled = true;
+			}
+		}
+
 		/// <summary>Handles Buff events.</summary>
 		/// <param name="sender">The object that triggered the event.</param>
 		/// <param name="args">The packet arguments that the event has.</param>

TShockAPI/GetDataHandlers.cs

@@ -1003,6 +1003,46 @@ namespace TShockAPI
 			NPCHome.Invoke(null, args);
 			return args.Handled;
 		}
+		
+		/// <summary>
+		/// For use in a NPCAddBuff event
+		/// </summary>
+		public class NPCAddBuffEventArgs : GetDataHandledEventArgs
+		{
+			/// <summary>
+			/// The ID of the npc
+			/// </summary>
+			public short ID { get; set; }
+			/// <summary>
+			/// Buff Type
+			/// </summary>
+			public byte Type { get; set; }
+			/// <summary>
+			/// Time the buff lasts
+			/// </summary>
+			public short Time { get; set; }
+		}
+		/// <summary>
+		/// NPCAddBuff - Called when a npc is buffed
+		/// </summary>
+		public static HandlerList<NPCAddBuffEventArgs> NPCAddBuff = new HandlerList<NPCAddBuffEventArgs>();
+
+		private static bool OnNPCAddBuff(TSPlayer player, MemoryStream data, short id, byte type, short time)
+		{
+			if (NPCAddBuff == null)
+				return false;
+
+			var args = new NPCAddBuffEventArgs
+			{
+				Player = player,
+				Data = data,
+				ID = id,
+				Type = type,
+				Time = time
+			};
+			NPCAddBuff.Invoke(null, args);
+			return args.Handled;
+		}
 
 		/// <summary>
 		/// For use in a PlayerBuff event
@@ -1455,6 +1495,7 @@ namespace TShockAPI
 					{ PacketTypes.PlayerSlot, HandlePlayerSlot },
 					{ PacketTypes.TileGetSection, HandleGetSection },
 					{ PacketTypes.UpdateNPCHome, UpdateNPCHome },
+					{ PacketTypes.NpcAddBuff, HandleNPCAddBuff },
 					{ PacketTypes.PlayerAddBuff, HandlePlayerAddBuff },
 					{ PacketTypes.ItemDrop, HandleItemDrop },
 					{ PacketTypes.UpdateItemDrop, HandleItemDrop },
@@ -2627,6 +2668,18 @@ namespace TShockAPI
 			}
 			return false;
 		}
+		
+		private static bool HandleNPCAddBuff(GetDataHandlerArgs args)
+		{
+			var id = args.Data.ReadInt16();
+			var type = args.Data.ReadInt8();
+			var time = args.Data.ReadInt16();
+
+			if (OnNPCAddBuff(args.Player, args.Data, id, type, time))
+				return true;
+			
+			return false;
+		}
 
 		private static bool HandlePlayerAddBuff(GetDataHandlerArgs args)
 		{