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thanatos-tshock · Oct 7, 2017 · 4d2c314 · 4d2c314
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diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,7 @@
+/Connection.Limit/bin
+/Connection.Limit/obj
+*.suo
+/*.user
+packages/
+References/
+.vs/
diff --git a/Connection.Limit.sln b/Connection.Limit.sln
@@ -0,0 +1,22 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 15
+VisualStudioVersion = 15.0.26430.16
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Connection.Limit", "Connection.Limit\Connection.Limit.csproj", "{2C05B111-C1E5-4BF3-988F-AA3AA42F0FC1}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{2C05B111-C1E5-4BF3-988F-AA3AA42F0FC1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2C05B111-C1E5-4BF3-988F-AA3AA42F0FC1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2C05B111-C1E5-4BF3-988F-AA3AA42F0FC1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2C05B111-C1E5-4BF3-988F-AA3AA42F0FC1}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+EndGlobal
diff --git a/Connection.Limit/Config.cs b/Connection.Limit/Config.cs
@@ -0,0 +1,32 @@
+using Newtonsoft.Json;
+using System;
+
+namespace Connection.Limit
+{
+	public class Config
+	{
+		[JsonProperty("enabled")]
+		public bool Enabled { get; set; } = true;
+
+		[JsonProperty("max-connections-per-ip")]
+		public int MaxConnectionsPerIp { get; set; } = 1;
+
+		[JsonProperty("recalibration-time-milliseconds")]
+		public int RecalibrationTimeMilliseconds { get; set; } = 1000;
+
+		public void Verify()
+		{
+			if (MaxConnectionsPerIp < 1)
+			{
+				Console.WriteLine($"{MaxConnectionsPerIp} is an invalid value for config property: max-connections-per-ip. Minimum value is 1.");
+				MaxConnectionsPerIp = 1;
+			}
+
+			if (RecalibrationTimeMilliseconds < 1000)
+			{
+				Console.WriteLine($"{RecalibrationTimeMilliseconds} is an invalid value for config property: recalibration-time-milliseconds. Minimum value is 1000.");
+				RecalibrationTimeMilliseconds = 1000;
+			}
+		}
+	}
+}
diff --git a/Connection.Limit/Connection.Limit.csproj b/Connection.Limit/Connection.Limit.csproj
@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{2C05B111-C1E5-4BF3-988F-AA3AA42F0FC1}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>Connection.Limit</RootNamespace>
+    <AssemblyName>xxConnection.Limit</AssemblyName>
+    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="Newtonsoft.Json, Version=6.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\..\..\..\..\..\..\TShock_Testing\Newtonsoft.Json.dll</HintPath>
+    </Reference>
+    <Reference Include="OTAPI">
+      <HintPath>..\..\..\..\..\..\..\TShock_Testing\OTAPI.dll</HintPath>
+    </Reference>
+    <Reference Include="System" />
+    <Reference Include="System.Core" />
+    <Reference Include="System.Xml.Linq" />
+    <Reference Include="System.Data.DataSetExtensions" />
+    <Reference Include="Microsoft.CSharp" />
+    <Reference Include="System.Data" />
+    <Reference Include="System.Net.Http" />
+    <Reference Include="System.Xml" />
+    <Reference Include="TerrariaServer">
+      <HintPath>..\..\..\..\..\..\..\TShock_Testing\TerrariaServer.exe</HintPath>
+    </Reference>
+    <Reference Include="TShockAPI">
+      <HintPath>..\..\..\..\..\..\..\TShock_Testing\ServerPlugins\TShockAPI.dll</HintPath>
+    </Reference>
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Config.cs" />
+    <Compile Include="ConnectionLimitPlugin.cs" />
+    <Compile Include="Limiter.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="TcpSocket.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <PropertyGroup>
+    <PostBuildEvent>
+    </PostBuildEvent>
+  </PropertyGroup>
+</Project>
diff --git a/Connection.Limit/Connection.Limit.csproj.user b/Connection.Limit/Connection.Limit.csproj.user
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'">
+    <StartArguments>
+    </StartArguments>
+    <StartAction>Program</StartAction>
+    <StartProgram>
+    </StartProgram>
+    <StartWorkingDirectory>
+    </StartWorkingDirectory>
+  </PropertyGroup>
+</Project>
diff --git a/Connection.Limit/ConnectionLimitPlugin.cs b/Connection.Limit/ConnectionLimitPlugin.cs
@@ -0,0 +1,95 @@
+using Newtonsoft.Json;
+using OTAPI;
+using System;
+using System.IO;
+using Terraria;
+using TerrariaApi.Server;
+using TShockAPI;
+
+namespace Connection.Limit
+{
+	[ApiVersion(2, 1)]
+	public class ConnectionLimitPlugin : TerrariaPlugin
+	{
+		internal const String PluginName = "Connection.Limit";
+		internal const String ConsoleTag = "[" + PluginName + "]: ";
+
+		public override string Author => "thanatos";
+		public override string Description => "Limits the amount of connections per ip";
+		public override string Name => PluginName;
+		public override Version Version => typeof(ConnectionLimitPlugin).Assembly.GetName().Version;
+
+		private Config _config;
+		private TcpSocket _socket;
+
+		public ConnectionLimitPlugin(Main game) : base(game)
+		{
+			this.Order = 1000;
+		}
+
+		void LoadConfig()
+		{
+			string
+				directory = Path.Combine("tshock", "connection_limit"),
+				filepath = Path.Combine(directory, "config.json")
+			;
+			Directory.CreateDirectory(directory);
+
+			if (File.Exists(filepath))
+			{
+				_config = JsonConvert.DeserializeObject<Config>(File.ReadAllText(filepath));
+			}
+			else
+			{
+				var config = new Config();
+				File.WriteAllText(filepath, JsonConvert.SerializeObject(config, Formatting.Indented));
+				_config = config;
+			}
+
+			_config.Verify();
+		}
+
+		public override void Initialize()
+		{
+			LoadConfig();
+
+			if (!_config.Enabled)
+			{
+				Console.WriteLine($"{ConsoleTag} disabled by configuration file.");
+				return;
+			}
+
+			Commands.ChatCommands.Add(new Command("connection.limit.toggle", (CommandArgs args) =>
+			{
+				this._config.Enabled = !this._config.Enabled;
+				args.Player.SendInfoMessage($"{PluginName} is {(this._config.Enabled ? "enabled" : "disabled")}");
+			}, new[]
+			{
+				"cl-toggle"
+			}));
+			Commands.ChatCommands.Add(new Command("connection.limit.stats", (CommandArgs args) =>
+			{
+				long accepted = _socket?.Limiter?.AcceptedConnections ?? 0L;
+				long blocked = _socket?.Limiter?.BlockedConnections ?? 0L;
+				Console.WriteLine($"{ConsoleTag} Accepted connections for current session: {accepted}");
+				Console.WriteLine($"{ConsoleTag} Blocked connections for current session: {blocked}");
+			}, new[]
+			{
+				"cl-stats"
+			}));
+
+			Hooks.World.IO.PreLoadWorld = (ref bool loadFromCloud) =>
+			{
+				Hooks.Net.Socket.Create = CreateSocket;
+				return HookResult.Continue;
+			};
+
+			Console.WriteLine($"{ConsoleTag} initialised");
+		}
+
+		TcpSocket CreateSocket()
+		{
+			return _socket ?? (_socket = new TcpSocket(_config));
+		}
+	}
+}
diff --git a/Connection.Limit/Limiter.cs b/Connection.Limit/Limiter.cs
@@ -0,0 +1,129 @@
+using System;
+using System.Collections.Generic;
+
+namespace Connection.Limit
+{
+	public class Limiter
+	{
+		private Dictionary<string, int> _registry = new Dictionary<string, int>();
+		private Config _config;
+		private DateTime? _lastCalibration;
+
+		private long _blockedConnections = 0;
+		public long BlockedConnections
+		{
+			get
+			{
+				return System.Threading.Interlocked.Read(ref _blockedConnections);
+			}
+		}
+
+		private long _acceptedConnections = 0;
+		public long AcceptedConnections
+		{
+			get
+			{
+				return System.Threading.Interlocked.Read(ref _acceptedConnections);
+			}
+		}
+
+		public Limiter(Config config)
+		{
+			_config = config;
+		}
+
+		public bool Register(string ip)
+		{
+			bool allow = true;
+
+			if (CanRecalibrate())
+				Recalibrate();
+
+			lock (_registry)
+			{
+				int number;
+				if (_registry.TryGetValue(ip, out number))
+				{
+					allow = number < _config.MaxConnectionsPerIp;
+
+					if (allow)
+					{
+						_registry[ip]++;
+					}
+				}
+				else
+				{
+					_registry.Add(ip, 1);
+				}
+			}
+
+			if (allow)
+			{
+				System.Threading.Interlocked.Increment(ref _acceptedConnections);
+			}
+			else
+			{
+				System.Threading.Interlocked.Increment(ref _blockedConnections);
+			}
+
+			return allow;
+		}
+
+		public void Unregister(string ip)
+		{
+			lock (_registry)
+			{
+				int number;
+				if (_registry.TryGetValue(ip, out number))
+				{
+					if (number <= 0)
+					{
+						System.Diagnostics.Debug.WriteLine("Tried decreasing an ip limit when the number is already 0");
+					}
+					else
+					{
+						_registry[ip]--;
+					}
+				}
+				else
+				{
+					System.Diagnostics.Debug.WriteLine("Tried decreasing an ip limit when there was no registration");
+				}
+			}
+		}
+
+		public bool CanRecalibrate() => _lastCalibration == null || (DateTime.Now - _lastCalibration.Value).TotalMilliseconds >= _config.RecalibrationTimeMilliseconds;
+
+		public void Recalibrate()
+		{
+			System.Diagnostics.Debug.WriteLine("Recalibrating");
+			lock (_registry)
+			{
+				_registry.Clear();
+
+				foreach (var client in Terraria.Netplay.Clients)
+				{
+					if (client != null && client.IsActive)
+					{
+						var socket = client.Socket as TcpSocket;
+						if (socket != null)
+						{
+							var ip = socket.IpAddress;
+							int number;
+							if (_registry.TryGetValue(ip, out number))
+							{
+								_registry[ip]++;
+							}
+							else
+							{
+								_registry.Add(ip, 1);
+							}
+						}
+					}
+				}
+
+				_lastCalibration = DateTime.Now;
+			}
+		}
+	}
+}