Add sameiponlineclient limit

src/Impostor.Api/Config/AntiCheatConfig.cs

@@ -30,6 +30,9 @@ public class AntiCheatConfig
 
         public bool EnableTargetChecks { get; set; } = true;
 
+        // Set 0 = no limit
+        public int MaxOnlineFromSameIp { get; set; } = 1;
+
         public bool ForbidProtocolExtensions { get; set; } = true;
     }
 }

src/Impostor.Server/Net/Client.cs

@@ -37,7 +37,7 @@ public Client(ILogger<Client> logger, IOptions<AntiCheatConfig> antiCheatOptions
 
         public override async ValueTask<bool> ReportCheatAsync(CheatContext context, CheatCategory category, string message)
         {
-            if (!_antiCheatConfig.Enabled)
+            if (!_antiCheatConfig!.Enabled)
             {
                 return false;
             }

src/Impostor.Server/Net/ClientBase.cs

@@ -1,7 +1,5 @@
-using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
-using System.Text;
 using System.Threading.Tasks;
 using Impostor.Api;
 using Impostor.Api.Innersloth;

src/Impostor.Server/Net/Manager/ClientManager.cs

@@ -27,6 +27,7 @@ internal partial class ClientManager
         private int _idLast;
 
         public static Dictionary<string, string> _puids;
+        public static Dictionary<string, int> _onlineCount;
 
         public ClientManager(ILogger<ClientManager> logger, IEventManager eventManager, IClientFactory clientFactory, ICompatibilityManager compatibilityManager, IOptions<CompatibilityConfig> compatibilityConfig)
         {
@@ -35,6 +36,7 @@ public ClientManager(ILogger<ClientManager> logger, IEventManager eventManager,
             _clientFactory = clientFactory;
             _clients = new ConcurrentDictionary<int, ClientBase>();
             _puids = new Dictionary<string, string>();
+            _onlineCount = new Dictionary<string, int>();
             _compatibilityManager = compatibilityManager;
             _compatibilityConfig = compatibilityConfig.Value;
         }

src/Impostor.Server/Net/State/Game.Incoming.cs

@@ -174,6 +174,24 @@ private async ValueTask<GameJoinResult> AddClientSafeAsync(ClientBase client)
                 return GameJoinResult.FromError(GameJoinError.Banned);
             }
 
+            if (Client._antiCheatConfig!.MaxOnlineFromSameIp != 0)
+            {
+                if (ClientManager._onlineCount.TryGetValue(client.Connection.EndPoint.Address.ToString(), out var count))
+                {
+                    if (count >= Client._antiCheatConfig.MaxOnlineFromSameIp)
+                    {
+                        return GameJoinResult.CreateCustomError(string.Format("[Impostor Anticheat+]\nToo many clients from a same ip.\n({0}) x {1}", client.Connection.EndPoint.Address.ToString(), count));
+                    }
+
+                    ClientManager._onlineCount[client.Connection.EndPoint.Address.ToString()] = count + 1;
+                }
+                else
+                {
+                    ClientManager._onlineCount.TryAdd(client.Connection.EndPoint.Address.ToString(), 1);
+                    ClientManager._onlineCount[client.Connection.EndPoint.Address.ToString()] = 1;
+                }
+            }
+
             var player = client.Player;
 
             // Check if the player is running the same version as the host

src/Impostor.Server/Net/State/Game.State.cs

@@ -6,6 +6,7 @@
 using Impostor.Hazel;
 using Impostor.Server.Events;
 using Impostor.Server.Net.Hazel;
+using Impostor.Server.Net.Manager;
 using Microsoft.Extensions.Logging;
 
 namespace Impostor.Server.Net.State
@@ -36,6 +37,21 @@ private async ValueTask<bool> PlayerRemove(int playerId, bool isBan = false)
                 return false;
             }
 
+            if (Client._antiCheatConfig!.MaxOnlineFromSameIp != 0)
+            {
+                if (ClientManager._onlineCount.TryGetValue(player.Client.Connection.EndPoint.Address.ToString(), out var count))
+                {
+                    if (count == 1)
+                    {
+                        ClientManager._onlineCount.Remove(player.Client.Connection.EndPoint.Address.ToString());
+                    }
+                    else
+                    {
+                        ClientManager._onlineCount[player.Client.Connection.EndPoint.Address.ToString()]--;
+                    }
+                }
+            }
+
             _logger.LogInformation("{0} - Player {1} ({2}) has left. hashpuid : {3}", Code, player.Client.Name, playerId, player.Client.HashedPuid());
 
             if (GameState == GameStates.Starting || GameState == GameStates.Started || GameState == GameStates.NotStarted)