Merge pull request #827 from Rhefew/feature/ip-connection-limit

feat(plugins): implement customizable maximum concurrent connections

(cherry picked from commit 0e30df9ae22a265c3486dea1eba259567631eb87)

src/GameLogic/IHasIpAddress.cs

@@ -0,0 +1,16 @@
+// <copyright file="IHasIpAddress.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameLogic;
+
+/// <summary>
+/// Interface for objects that expose a remote IP address.
+/// </summary>
+public interface IHasIpAddress
+{
+    /// <summary>
+    /// Gets the IP address of the remote connection.
+    /// </summary>
+    string? IpAddress { get; }
+}

src/GameLogic/Player.cs

@@ -203,6 +203,11 @@ public class Player : AsyncDisposable, IBucketMapObserver, IAttackable, IAttacke
     /// <inheritdoc/>
     public ushort Id { get; set; }
 
+    /// <summary>
+    /// Gets or sets a custom login result to override the default when login fails.
+    /// </summary>
+    public Views.Login.LoginResult? LoginResultOverride { get; set; }
+
     /// <inheritdoc cref="IPartyMember" />
     public string Name => this.SelectedCharacter?.Name ?? string.Empty;
 

src/GameLogic/PlayerActions/LoginAction.cs

@@ -189,7 +189,9 @@ public class LoginAction
 
     private async ValueTask HandleAlreadyConnectedAsync(Player player, string username)
     {
-        await player.InvokeViewPlugInAsync<IShowLoginResultPlugIn>(p => p.ShowLoginResultAsync(LoginResult.AccountAlreadyConnected)).ConfigureAwait(false);
+        var result = player.LoginResultOverride ?? LoginResult.AccountAlreadyConnected;
+        player.LoginResultOverride = null;
+        await player.InvokeViewPlugInAsync<IShowLoginResultPlugIn>(p => p.ShowLoginResultAsync(result)).ConfigureAwait(false);
         if (player.GameContext is IGameServerContext gameServerContext)
         {
             await gameServerContext.EventPublisher.PlayerAlreadyLoggedInAsync(gameServerContext.Id, username).ConfigureAwait(false);

src/GameLogic/PlugIns/MaximumConnectionsPerIpPlugIn.cs

@@ -0,0 +1,68 @@
+// <copyright file="MaximumConnectionsPerIpPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameLogic.PlugIns;
+
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// A plugin that limits the number of simultaneous active player sessions connected from the same IP address.
+/// </summary>
+[PlugIn]
+[Display(Name = "Maximum Connections Per IP", Description = "Limits the maximum number of parallel connections from the same IP address.")]
+[Guid("2C779F5E-379E-4CE0-BFCC-CA6455D757B3")]
+public class MaximumConnectionsPerIpPlugIn : IPlayerStateChangingPlugIn, ISupportCustomConfiguration<MaximumConnectionsPerIpPlugInConfiguration>, ISupportDefaultCustomConfiguration, IDisabledByDefault
+{
+    /// <inheritdoc />
+    public MaximumConnectionsPerIpPlugInConfiguration? Configuration { get; set; }
+
+    /// <inheritdoc />
+    public async ValueTask PlayerStateChangingAsync(Player player, StateMachine.StateChangeEventArgs eventArgs)
+    {
+        if (eventArgs.NextState != PlayerState.Authenticated)
+        {
+            return;
+        }
+
+        var ipAddress = (player as IHasIpAddress)?.IpAddress;
+        if (string.IsNullOrEmpty(ipAddress))
+        {
+            return;
+        }
+
+        var config = this.Configuration ?? CreateDefaultConfiguration();
+        var players = await player.GameContext.GetPlayersAsync().ConfigureAwait(false);
+        var sameIpCount = players.Count(p =>
+            (p as IHasIpAddress)?.IpAddress == ipAddress
+            && p != player
+            && p.PlayerState.CurrentState != PlayerState.Initial
+            && p.PlayerState.CurrentState != PlayerState.LoginScreen);
+
+        if (sameIpCount >= config.MaximumConnectionsPerIp)
+        {
+            player.Logger.LogWarning(
+                "Login request for IP '{IpAddress}' was cancelled. It exceeded the maximum connection limit of {Limit}.",
+                ipAddress,
+                config.MaximumConnectionsPerIp);
+            player.LoginResultOverride = Views.Login.LoginResult.ServerIsFull;
+            eventArgs.Cancel = true;
+        }
+    }
+
+    /// <inheritdoc />
+    public object CreateDefaultConfig()
+    {
+        return CreateDefaultConfiguration();
+    }
+
+    private static MaximumConnectionsPerIpPlugInConfiguration CreateDefaultConfiguration()
+    {
+        return new MaximumConnectionsPerIpPlugInConfiguration();
+    }
+}

src/GameLogic/PlugIns/MaximumConnectionsPerIpPlugInConfiguration.cs

@@ -0,0 +1,16 @@
+// <copyright file="MaximumConnectionsPerIpPlugInConfiguration.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameLogic.PlugIns;
+
+/// <summary>
+/// Configuration for the <see cref="MaximumConnectionsPerIpPlugIn"/>.
+/// </summary>
+public class MaximumConnectionsPerIpPlugInConfiguration
+{
+    /// <summary>
+    /// Gets or sets the maximum number of concurrent connections per IP address.
+    /// </summary>
+    public int MaximumConnectionsPerIp { get; set; } = 3;
+}

src/GameServer/RemoteView/RemotePlayer.cs

@@ -1,4 +1,4 @@
-// <copyright file="RemotePlayer.cs" company="MUnique">
+// <copyright file="RemotePlayer.cs" company="MUnique">
 // Licensed under the MIT License. See LICENSE file in the project root for full license information.
 // </copyright>
 
@@ -16,12 +16,14 @@ using MUnique.OpenMU.PlugIns;
 /// <summary>
 /// A player which is playing through a remote connection.
 /// </summary>
-public class RemotePlayer : Player, IClientVersionProvider
+public class RemotePlayer : Player, IClientVersionProvider, IHasIpAddress
 {
     private readonly byte[] _packetBuffer = new byte[0xFF];
 
     private ClientVersion _clientVersion;
 
+    private readonly string? _ipAddress;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="RemotePlayer"/> class.
     /// </summary>
@@ -33,6 +35,9 @@ public class RemotePlayer : Player, IClientVersionProvider
     {
         this.Connection = connection;
         this._clientVersion = clientVersion;
+        this._ipAddress = connection.EndPoint is System.Net.IPEndPoint ipEndPoint
+            ? (ipEndPoint.Address.IsIPv4MappedToIPv6 ? ipEndPoint.Address.MapToIPv4() : ipEndPoint.Address).ToString()
+            : null;
         this.MainPacketHandler = new MainPacketHandlerPlugInContainer(this, gameContext.PlugInManager, gameContext.LoggerFactory);
         this.MainPacketHandler.Initialize();
         this.Connection!.PacketReceived += this.PacketReceivedAsync;
@@ -42,6 +47,9 @@ public class RemotePlayer : Player, IClientVersionProvider
     /// <inheritdoc />
     public event EventHandler? ClientVersionChanged;
 
+    /// <inheritdoc />
+    public string? IpAddress => this._ipAddress;
+
     /// <summary>
     /// Gets the game server context.
     /// </summary>

tests/MUnique.OpenMU.Tests/MaximumConnectionsPerIpPlugInTests.cs

@@ -0,0 +1,200 @@
+// <copyright file="MaximumConnectionsPerIpPlugInTests.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.Tests;
+
+
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging.Abstractions;
+using Moq;
+using NUnit.Framework;
+using MUnique.OpenMU.AttributeSystem;
+using MUnique.OpenMU.DataModel.Configuration;
+using MUnique.OpenMU.DataModel.Configuration.Items;
+using MUnique.OpenMU.DataModel.Entities;
+using MUnique.OpenMU.GameLogic;
+using MUnique.OpenMU.GameLogic.Attributes;
+using MUnique.OpenMU.GameLogic.PlugIns;
+using MUnique.OpenMU.Persistence.InMemory;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// Unit tests for the <see cref="MaximumConnectionsPerIpPlugIn"/>.
+/// </summary>
+[TestFixture]
+public class MaximumConnectionsPerIpPlugInTests
+{
+    private GameContext _gameContext = null!;
+    private MaximumConnectionsPerIpPlugIn _plugin = null!;
+
+    [SetUp]
+    public async Task SetUp()
+    {
+        var dummyPlayer = await PlayerTestHelper.CreatePlayerAsync().ConfigureAwait(false);
+        this._gameContext = (GameContext)dummyPlayer.GameContext;
+        this._plugin = new MaximumConnectionsPerIpPlugIn
+        {
+            Configuration = new MaximumConnectionsPerIpPlugInConfiguration
+            {
+                MaximumConnectionsPerIp = 3
+            }
+        };
+    }
+
+    [Test]
+    public async ValueTask UnderLimitSucceedsAsync()
+    {
+        // Arrange
+        var player1 = new TestPlayer(this._gameContext);
+        player1.SetIpAddress("127.0.0.1");
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player1).ConfigureAwait(false);
+
+        var player2 = new TestPlayer(this._gameContext);
+        player2.SetIpAddress("127.0.0.1");
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player2).ConfigureAwait(false);
+
+        var joiningPlayer = new TestPlayer(this._gameContext);
+        joiningPlayer.SetIpAddress("127.0.0.1");
+        await joiningPlayer.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+
+        var eventArgs = new StateMachine.StateChangeEventArgs { NextState = PlayerState.Authenticated };
+
+        // Act
+        await this._plugin.PlayerStateChangingAsync(joiningPlayer, eventArgs).ConfigureAwait(false);
+
+        // Assert
+        Assert.That(eventArgs.Cancel, Is.False);
+    }
+
+    [Test]
+    public async ValueTask AtLimitCancelsTransitionAsync()
+    {
+        // Arrange
+        var player1 = new TestPlayer(this._gameContext);
+        player1.SetIpAddress("127.0.0.1");
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player1).ConfigureAwait(false);
+
+        var player2 = new TestPlayer(this._gameContext);
+        player2.SetIpAddress("127.0.0.1");
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player2).ConfigureAwait(false);
+
+        var player3 = new TestPlayer(this._gameContext);
+        player3.SetIpAddress("127.0.0.1");
+        await player3.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player3.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player3).ConfigureAwait(false);
+
+        var joiningPlayer = new TestPlayer(this._gameContext);
+        joiningPlayer.SetIpAddress("127.0.0.1");
+        await joiningPlayer.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+
+        var eventArgs = new StateMachine.StateChangeEventArgs { NextState = PlayerState.Authenticated };
+
+        // Act
+        await this._plugin.PlayerStateChangingAsync(joiningPlayer, eventArgs).ConfigureAwait(false);
+
+        // Assert
+        Assert.That(eventArgs.Cancel, Is.True);
+        Assert.That(joiningPlayer.LoginResultOverride, Is.EqualTo(GameLogic.Views.Login.LoginResult.ServerIsFull));
+    }
+
+    [Test]
+    public async ValueTask DifferentIpDoesNotCountAsync()
+    {
+        // Arrange
+        var player1 = new TestPlayer(this._gameContext);
+        player1.SetIpAddress("127.0.0.1");
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player1).ConfigureAwait(false);
+
+        var player2 = new TestPlayer(this._gameContext);
+        player2.SetIpAddress("127.0.0.1");
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player2).ConfigureAwait(false);
+
+        var player3 = new TestPlayer(this._gameContext);
+        player3.SetIpAddress("127.0.0.1");
+        await player3.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player3.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player3).ConfigureAwait(false);
+
+        var joiningPlayer = new TestPlayer(this._gameContext);
+        joiningPlayer.SetIpAddress(new System.Net.IPAddress(new byte[] { 192, 168, 1, 100 }).ToString());
+        await joiningPlayer.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+
+        var eventArgs = new StateMachine.StateChangeEventArgs { NextState = PlayerState.Authenticated };
+
+        // Act
+        await this._plugin.PlayerStateChangingAsync(joiningPlayer, eventArgs).ConfigureAwait(false);
+
+        // Assert
+        Assert.That(eventArgs.Cancel, Is.False);
+    }
+
+    [Test]
+    public async ValueTask LoginScreenAndInitialPlayersDoNotCountAsync()
+    {
+        // Arrange
+        var player1 = new TestPlayer(this._gameContext);
+        player1.SetIpAddress("127.0.0.1");
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player1.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player1).ConfigureAwait(false);
+
+        var player2 = new TestPlayer(this._gameContext);
+        player2.SetIpAddress("127.0.0.1");
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await player2.PlayerState.TryAdvanceToAsync(PlayerState.Authenticated).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player2).ConfigureAwait(false);
+
+        // This player is only at the login screen
+        var player3 = new TestPlayer(this._gameContext);
+        player3.SetIpAddress("127.0.0.1");
+        await player3.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+        await this._gameContext.AddPlayerAsync(player3).ConfigureAwait(false);
+
+        var joiningPlayer = new TestPlayer(this._gameContext);
+        joiningPlayer.SetIpAddress("127.0.0.1");
+        await joiningPlayer.PlayerState.TryAdvanceToAsync(PlayerState.LoginScreen).ConfigureAwait(false);
+
+        var eventArgs = new StateMachine.StateChangeEventArgs { NextState = PlayerState.Authenticated };
+
+        // Act
+        await this._plugin.PlayerStateChangingAsync(joiningPlayer, eventArgs).ConfigureAwait(false);
+
+        // Assert
+        Assert.That(eventArgs.Cancel, Is.False);
+    }
+
+    private class TestPlayer : Player, IHasIpAddress
+    {
+        private string? _ipAddress;
+
+        public TestPlayer(IGameContext gameContext)
+            : base(gameContext)
+        {
+        }
+
+        /// <inheritdoc />
+        public string? IpAddress => this._ipAddress;
+
+        /// <summary>Sets the IP address for testing purposes.</summary>
+        public void SetIpAddress(string? ip) => this._ipAddress = ip;
+
+        protected override ICustomPlugInContainer<GameLogic.Views.IViewPlugIn> CreateViewPlugInContainer()
+        {
+            return new MockViewPlugInContainer();
+        }
+    }
+}