From 5455af24d799afeb69f68b5fc9e215678a5ad44b Mon Sep 17 00:00:00 2001
From: Regalis <regalis@undertowgames.com>
Date: Thu, 1 Jun 2017 19:37:08 +0300
Subject: [PATCH] Readded spam filter

---
 Subsurface/Source/Networking/ChatMessage.cs | 56 ++++++++++++++++++---
 Subsurface/Source/Networking/Client.cs      |  4 ++
 Subsurface/Source/Networking/GameServer.cs  | 19 ++++---
 3 files changed, 65 insertions(+), 14 deletions(-)

diff --git a/Subsurface/Source/Networking/ChatMessage.cs b/Subsurface/Source/Networking/ChatMessage.cs
index c2ef0099d..27c0eb21b 100644
--- a/Subsurface/Source/Networking/ChatMessage.cs
+++ b/Subsurface/Source/Networking/ChatMessage.cs
@@ -134,23 +134,65 @@ namespace Barotrauma.Networking
             msg.Write(Text);
         }
 
-        static public void ServerRead(NetIncomingMessage msg, Client c)
+        public static void ServerRead(NetIncomingMessage msg, Client c)
         {
             UInt16 ID = msg.ReadUInt16();
             string txt = msg.ReadString();
-
             if (txt.Length > MaxLength)
             {
                 txt = txt.Substring(0, MaxLength);
             }
 
-            if (NetIdUtils.IdMoreRecent(ID, c.lastSentChatMsgID))
+            if (!NetIdUtils.IdMoreRecent(ID, c.lastSentChatMsgID)) return;
+
+            c.lastSentChatMessages.Add(txt);
+            if (c.lastSentChatMessages.Count > 10)
             {
-                //this chat message is new to the server
-                GameMain.Server.SendChatMessage(txt, null, c);
-                //GameMain.Server.AddChatMessage(txt, ChatMessageType.Default, c.name);
-                c.lastSentChatMsgID = ID;
+                c.lastSentChatMessages.RemoveRange(0, c.lastSentChatMessages.Count-10);
             }
+
+
+            c.lastSentChatMsgID = ID;
+
+            //SPAM FILTER
+            if (c.ChatSpamTimer > 0.0f)
+            {
+                //player has already been spamming, stop again
+                ChatMessage denyMsg = ChatMessage.Create("", "You have been blocked by the spam filter. Try again after 10 seconds.", ChatMessageType.Server, null);
+                c.ChatSpamTimer = 10.0f;
+                GameMain.Server.SendChatMessage(denyMsg, c);
+                return;
+            }
+
+            float similarity = 0.0f;
+            for (int i = 0; i < c.lastSentChatMessages.Count; i++)
+            {
+                float closeFactor = 1.0f / (c.lastSentChatMessages.Count - i);
+                int levenshteinDist = ToolBox.LevenshteinDistance(txt, c.lastSentChatMessages[i]);
+                similarity += Math.Max((txt.Length - levenshteinDist) / (float)txt.Length * closeFactor, 0.0f);
+            }
+
+            if (similarity + c.ChatSpamSpeed > 5.0f)
+            {
+                c.ChatSpamCount++;
+
+                if (c.ChatSpamCount > 3)
+                {
+                    //kick for spamming too much
+                    GameMain.Server.KickClient(c);
+                }
+                else
+                {
+                    ChatMessage denyMsg = ChatMessage.Create("", "You have been blocked by the spam filter. Try again after 10 seconds.", ChatMessageType.Server, null);
+                    c.ChatSpamTimer = 10.0f;
+                    GameMain.Server.SendChatMessage(denyMsg, c);
+                }
+                return;
+            }
+
+            c.ChatSpamSpeed += similarity;
+
+            GameMain.Server.SendChatMessage(txt, null, c);
         }
 
         public void ServerWrite(NetOutgoingMessage msg, Client c)
diff --git a/Subsurface/Source/Networking/Client.cs b/Subsurface/Source/Networking/Client.cs
index bec8eb339..dce365954 100644
--- a/Subsurface/Source/Networking/Client.cs
+++ b/Subsurface/Source/Networking/Client.cs
@@ -39,6 +39,10 @@ namespace Barotrauma.Networking
         
         public List<ChatMessage> chatMsgQueue = new List<ChatMessage>();
         public UInt16 lastChatMsgQueueID;
+
+
+        //latest chat messages sent by this client
+        public List<string> lastSentChatMessages = new List<string>(); 
         public float ChatSpamSpeed;
         public float ChatSpamTimer;
         public int ChatSpamCount;
diff --git a/Subsurface/Source/Networking/GameServer.cs b/Subsurface/Source/Networking/GameServer.cs
index 8f4055560..d84098147 100644
--- a/Subsurface/Source/Networking/GameServer.cs
+++ b/Subsurface/Source/Networking/GameServer.cs
@@ -1451,7 +1451,17 @@ namespace Barotrauma.Networking
                 if (c.Character == null || !c.inGame) continue;
             }
         }
-        
+
+        public void SendChatMessage(ChatMessage msg, Client recipient)
+        {
+            msg.NetStateID = recipient.chatMsgQueue.Count > 0 ?
+                (ushort)(recipient.chatMsgQueue.Last().NetStateID + 1) :
+                (ushort)(recipient.lastRecvChatMsgID + 1);
+
+            recipient.chatMsgQueue.Add(msg);
+            recipient.lastChatMsgQueueID = msg.NetStateID;
+        }
+
         /// <summary>
         /// Add the message to the chatbox and pass it to all clients who can receive it
         /// </summary>
@@ -1628,13 +1638,8 @@ namespace Barotrauma.Networking
                     modifiedMessage, 
                     (ChatMessageType)type,
                     senderCharacter);
-                
-                chatMsg.NetStateID = client.chatMsgQueue.Count > 0 ?
-                    (ushort)(client.chatMsgQueue.Last().NetStateID + 1) :
-                    (ushort)(client.lastRecvChatMsgID + 1);
 
-                client.chatMsgQueue.Add(chatMsg);
-                client.lastChatMsgQueueID = chatMsg.NetStateID;
+                SendChatMessage(chatMsg, client);
             }
 
             string myReceivedMessage = message;