Add ldn:u implementation, INetworkClient interface and DisabledLdnClient (#5652)

* Impl first attempt to LDN

* Make this work.

- Endianness swap on all IPs.
- Use local network IP for connections, rather than 127.0.0.1. This is to be changed when tunnelling or whatever.
- Mac addresses are now randomly assigned on the server. (fixes joining lobbies)
- Fixed the "connected" handler for stations to actually find a
- Added info retrieval when connected to a station.
- Users that disconnect are now removed from rooms they were in. (still need to broadcast tho)
- The communication service does a bit better with being closed now.
- Some locking around the game instance dictionary.

* We may just be "initialized". Ignore this for now.

* Lots of WIP

* Add Disconnect packet

* Improve signalling of internal events.

* Fix scan.

* Fix some more stupid things.

* Enable NoDelay on all sockets.

* Add station accept policy, disconnect function.

* Limit max number of games.

* Split out networking stuff from HLE, so it can be swapped.

* Update logging calls.

* Missed a spot.

* Call SignalDisconnect instead of SetState

* Add comment to GetNetworkInfo

* Update configuration + UI

Now has its own tab, more options.

* Refactoring IUserLocalCommunicationService

( Expected new issues :'( )

* some cleanup

* More fix

* Correctly handle errors when connecting.

* Disable *Private call and clean symbols

* Structs cleanup

* Big cleanup

* Fix InvalidHandle (in MK8D and other games)

* Add Reject and Private Network support (v1)

RyuLdn Version bumped to 1.

* Add Initialize Packet

Allows users to keep Mac Addresses assigned by the server.

* Add SetWirelessControllerRestriction and some cleanup

* LDN-2 Initial Rebase

Make this work.

- Endianness swap on all IPs.
- Use local network IP for connections, rather than 127.0.0.1. This is to be changed when tunnelling or whatever.
- Fixed the "connected" handler for stations to actually find a
- The communication service does a bit better with being closed now.
- Some locking around the game instance dictionary.

We may just be "initialized". Ignore this for now.

Lots of WIP

Implement scan filter.

Improve signalling of internal events.

Fix scan.

Fix 0 width data, scan reply end delay removed.

Fix some more stupid things.

Enable NoDelay on all sockets.

Add station accept policy, disconnect function.

Limit max number of games.

Split out networking stuff from HLE, so it can be swapped.

Update logging calls.

Missed a spot.

SetAdvertiseData when open, don't return games that have accept policy 1

Update configuration + UI

Now has its own tab, more options.

Don't Keepalive, it causes problems.

Refactoring IUserLocalCommunicationService

( Expected new issues :'( )

some cleanup

More fix

Correctly handle errors when connecting.

Disable *Private call and clean symbols

Structs cleanup

Big cleanup

Fix InvalidHandle (in MK8D and other games)

Add Reject and Private Network support (v1)

Disable TcpNoDelay option on linux.

Add SetWirelessControllerRestriction and some cleanup

Misc cleanup, implement broadcast flag.

* Misc Changes

* Fix GetNetworkInfo

* Fix some small issues

* Implement GetNetworkInfoLatestUpdate

* Hotfix when LocalCommunicationId = 0xFFFFFFFFFFFFFFFF

* Fix ARMS Scan (and other games using wrong LocalCommunicationId

* Fix latest update when host leaves

* Revert "Fix ARMS Scan (and other games using wrong LocalCommunicationId"

This reverts commit 519c283d3993e2fdfafb8ac6b4e0a98231f6fb75.

* Fix the localCommunicationId = -1

* Don't set Connect flag for nodes already in the room before joining.

* Make IUserLocalCommunicationService disposable

* Don't dispose if there's no client.

* LDN-2-2 Rebase

Make this work.

- Endianness swap on all IPs.
- Use local network IP for connections, rather than 127.0.0.1. This is to be changed when tunnelling or whatever.
- Fixed the "connected" handler for stations to actually find a
- The communication service does a bit better with being closed now.
- Some locking around the game instance dictionary.

We may just be "initialized". Ignore this for now.

Put sockets behind an interface, so that they can be swapped for something proxyable

Lots of WIP

Implement scan filter.

Improve signalling of internal events.

Fix scan.

Fix 0 width data, scan reply end delay removed.

Fix some more stupid things.

Enable NoDelay on all sockets.

Add station accept policy, disconnect function.

Limit max number of games.

Split out networking stuff from HLE, so it can be swapped.

Update logging calls.

Missed a spot.

SetAdvertiseData when open, don't return games that have accept policy 1

Update configuration + UI

Now has its own tab, more options.

Don't Keepalive, it causes problems.

Refactoring IUserLocalCommunicationService

( Expected new issues :'( )

some cleanup

More fix

Correctly handle errors when connecting.

Disable *Private call and clean symbols

Structs cleanup

Big cleanup

Fix InvalidHandle (in MK8D and other games)

Add Reject and Private Network support (v1)

Disable TcpNoDelay option on linux.

Add SetWirelessControllerRestriction and some cleanup

Misc cleanup, implement broadcast flag.

Misc Changes

Fix GetNetworkInfo

Fix some small issues

Disable LAN by default til the config is added.

Fix Splatoon 2

- Stub nfp IUser::StartDetection / IUser::StopDetection.
- Stub ntc IEnsureNetworkClockAvailabilityService and needed calls.

Cleanup previous fixes

Stub IAudioInManager/IAudioIn for Splatoon 2 LAN

Add LAN settings to multiplayer tab

LAN Play > LAN Mode

Implement GetNetworkInfoLatestUpdate

Hotfix when LocalCommunicationId = 0xFFFFFFFFFFFFFFFF

Fix ARMS Scan (and other games using wrong LocalCommunicationId

Fix latest update when host leaves

Revert "Fix ARMS Scan (and other games using wrong LocalCommunicationId"

This reverts commit 519c283d3993e2fdfafb8ac6b4e0a98231f6fb75.

Fix the localCommunicationId = -1

Don't set Connect flag for nodes already in the room before joining.

Make IUserLocalCommunicationService disposable

Fix crash when using LAN mode on linux.

Actually use that call

Don't dispose if there's no client.

Fix the settings window crash

Fix configurationFileUpdated

* Make LDN compatible with Ryujinx/Ryujinx#3805

* Ava: Add Ldn options to SettingsNetworkTab

* Ava: Add update events for multiplayer options

* Apply formatting

* Remove LdnHelper

* ldn: Fix hardcoded /24 subnet mask

* Fix naming rule violations

* Add missing summary doc tag

* Remove NetCoreServer dependency

* Address code style issues and typos

Co-authored-by: gdkchan <gab.dark.100@gmail.com>

* Call CloseStation/CloseAccessPoint to reduce code duplication

* Fix typo

Co-authored-by: gdkchan <gab.dark.100@gmail.com>

* Fix missing trailing commas

* Extract AddressList from AddressEntry

* Use AcceptPolicy as a type for LdnNetworkInfo.StationAcceptPolicy

* Add Flags attribute to ScanFilterFlag

* Rename struct members for LdnNetworkInfo

* Remove extra line

Co-authored-by: Ac_K <Acoustik666@gmail.com>

* Extract NetworkErrorMessage from NetworkError

* Fix missing trailing commas

---------

Co-authored-by: Ac_K <Acoustik666@gmail.com>
Co-authored-by: riperiperi <rhy3756547@hotmail.com>
Co-authored-by: gdkchan <gab.dark.100@gmail.com>

src/Ryujinx.Ava/AppHost.cs

@@ -21,6 +21,7 @@ using Ryujinx.Ava.UI.ViewModels;
 using Ryujinx.Ava.UI.Windows;
 using Ryujinx.Common;
 using Ryujinx.Common.Configuration;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Common.Logging;
 using Ryujinx.Common.SystemInterop;
 using Ryujinx.Graphics.GAL;
@@ -191,6 +192,7 @@ namespace Ryujinx.Ava
             ConfigurationState.Instance.Graphics.EnableColorSpacePassthrough.Event += UpdateColorSpacePassthrough;
 
             ConfigurationState.Instance.Multiplayer.LanInterfaceId.Event += UpdateLanInterfaceIdState;
+            ConfigurationState.Instance.Multiplayer.Mode.Event += UpdateMultiplayerModeState;
 
             _gpuCancellationTokenSource = new CancellationTokenSource();
             _gpuDoneEvent = new ManualResetEvent(false);
@@ -412,6 +414,11 @@ namespace Ryujinx.Ava
             Device.Configuration.MultiplayerLanInterfaceId = e.NewValue;
         }
 
+        private void UpdateMultiplayerModeState(object sender, ReactiveEventArgs<MultiplayerMode> e)
+        {
+            Device.Configuration.MultiplayerMode = e.NewValue;
+        }
+
         public void Stop()
         {
             _isActive = false;
@@ -782,7 +789,8 @@ namespace Ryujinx.Ava
                                                      ConfigurationState.Instance.Graphics.AspectRatio,
                                                      ConfigurationState.Instance.System.AudioVolume,
                                                      ConfigurationState.Instance.System.UseHypervisor,
-                                                     ConfigurationState.Instance.Multiplayer.LanInterfaceId.Value);
+                                                     ConfigurationState.Instance.Multiplayer.LanInterfaceId.Value,
+                                                     ConfigurationState.Instance.Multiplayer.Mode);
 
             Device = new Switch(configuration);
         }

src/Ryujinx.Ava/Assets/Locales/en_US.json

@@ -652,5 +652,8 @@
   "NetworkInterfaceDefault": "Default",
   "PackagingShaders": "Packaging Shaders",
   "AboutChangelogButton": "View Changelog on GitHub",
-  "AboutChangelogButtonTooltipMessage": "Click to open the changelog for this version in your default browser."
+  "AboutChangelogButtonTooltipMessage": "Click to open the changelog for this version in your default browser.",
+  "SettingsTabNetworkMultiplayer": "Multiplayer",
+  "MultiplayerMode": "Mode:",
+  "MultiplayerModeTooltip": "Change multiplayer mode"
 }

src/Ryujinx.Ava/Common/ApplicationHelper.cs

@@ -15,7 +15,6 @@ using LibHac.Tools.FsSystem.NcaUtils;
 using Ryujinx.Ava.Common.Locale;
 using Ryujinx.Ava.UI.Controls;
 using Ryujinx.Ava.UI.Helpers;
-using Ryujinx.Ava.UI.Windows;
 using Ryujinx.Common.Logging;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS.Services.Account.Acc;
@@ -36,11 +35,9 @@ namespace Ryujinx.Ava.Common
         private static HorizonClient _horizonClient;
         private static AccountManager _accountManager;
         private static VirtualFileSystem _virtualFileSystem;
-        private static StyleableWindow _owner;
 
-        public static void Initialize(VirtualFileSystem virtualFileSystem, AccountManager accountManager, HorizonClient horizonClient, StyleableWindow owner)
+        public static void Initialize(VirtualFileSystem virtualFileSystem, AccountManager accountManager, HorizonClient horizonClient)
         {
-            _owner = owner;
             _virtualFileSystem = virtualFileSystem;
             _horizonClient = horizonClient;
             _accountManager = accountManager;

src/Ryujinx.Ava/UI/ViewModels/SettingsViewModel.cs

@@ -10,6 +10,7 @@ using Ryujinx.Ava.UI.Helpers;
 using Ryujinx.Ava.UI.Windows;
 using Ryujinx.Common.Configuration;
 using Ryujinx.Common.Configuration.Hid;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Common.GraphicsDriver;
 using Ryujinx.Common.Logging;
 using Ryujinx.Graphics.Vulkan;
@@ -54,6 +55,7 @@ namespace Ryujinx.Ava.UI.ViewModels
         public event Action CloseWindow;
         public event Action SaveSettingsEvent;
         private int _networkInterfaceIndex;
+        private int _multiplayerModeIndex;
 
         public int ResolutionScale
         {
@@ -251,6 +253,11 @@ namespace Ryujinx.Ava.UI.ViewModels
             get => new(_networkInterfaces.Keys);
         }
 
+        public AvaloniaList<string> MultiplayerModes
+        {
+            get => new(Enum.GetNames<MultiplayerMode>());
+        }
+
         public KeyboardHotkeys KeyboardHotkeys
         {
             get => _keyboardHotkeys;
@@ -272,6 +279,16 @@ namespace Ryujinx.Ava.UI.ViewModels
             }
         }
 
+        public int MultiplayerModeIndex
+        {
+            get => _multiplayerModeIndex;
+            set
+            {
+                _multiplayerModeIndex = value;
+                ConfigurationState.Instance.Multiplayer.Mode.Value = (MultiplayerMode)_multiplayerModeIndex;
+            }
+        }
+
         public SettingsViewModel(VirtualFileSystem virtualFileSystem, ContentManager contentManager) : this()
         {
             _virtualFileSystem = virtualFileSystem;
@@ -478,6 +495,8 @@ namespace Ryujinx.Ava.UI.ViewModels
             EnableFsAccessLog = config.Logger.EnableFsAccessLog;
             FsGlobalAccessLogMode = config.System.FsGlobalAccessLogMode;
             OpenglDebugLevel = (int)config.Logger.GraphicsDebugLevel.Value;
+
+            MultiplayerModeIndex = (int)config.Multiplayer.Mode.Value;
         }
 
         public void SaveSettings()
@@ -579,6 +598,7 @@ namespace Ryujinx.Ava.UI.ViewModels
             config.Logger.GraphicsDebugLevel.Value = (GraphicsDebugLevel)OpenglDebugLevel;
 
             config.Multiplayer.LanInterfaceId.Value = _networkInterfaces[NetworkInterfaceList[NetworkInterfaceIndex]];
+            config.Multiplayer.Mode.Value = (MultiplayerMode)MultiplayerModeIndex;
 
             config.ToFileFormat().SaveConfig(Program.ConfigurationPath);
 

src/Ryujinx.Ava/UI/Views/Settings/SettingsNetworkView.axaml

@@ -23,21 +23,34 @@
                 HorizontalAlignment="Stretch"
                 Orientation="Vertical"
                 Spacing="10">
+                <TextBlock Classes="h1" Text="{locale:Locale SettingsTabNetworkMultiplayer}" />
+                <StackPanel Margin="10,0,0,0" Orientation="Horizontal">
+                    <TextBlock VerticalAlignment="Center"
+                        Text="{locale:Locale MultiplayerMode}"
+                        ToolTip.Tip="{locale:Locale MultiplayerModeTooltip}"
+                        Width="200" />
+                    <ComboBox SelectedIndex="{Binding MultiplayerModeIndex}"
+                        ToolTip.Tip="{locale:Locale MultiplayerModeTooltip}"
+                        HorizontalContentAlignment="Left"
+                        ItemsSource="{Binding MultiplayerModes}"
+                        Width="250" />
+                </StackPanel>
+                <Separator Height="1" />
                 <TextBlock Classes="h1" Text="{locale:Locale SettingsTabNetworkConnection}" />
                 <CheckBox Margin="10,0,0,0" IsChecked="{Binding EnableInternetAccess}">
                     <TextBlock Text="{locale:Locale SettingsTabSystemEnableInternetAccess}"
-                               ToolTip.Tip="{locale:Locale EnableInternetAccessTooltip}" />
+                        ToolTip.Tip="{locale:Locale EnableInternetAccessTooltip}" />
                 </CheckBox>
                 <StackPanel Margin="10,0,0,0" Orientation="Horizontal">
                     <TextBlock VerticalAlignment="Center"
-                               Text="{locale:Locale SettingsTabNetworkInterface}"
+                        Text="{locale:Locale SettingsTabNetworkInterface}"
-                               ToolTip.Tip="{locale:Locale NetworkInterfaceTooltip}"
+                        ToolTip.Tip="{locale:Locale NetworkInterfaceTooltip}"
-                               Width="200" />
+                        Width="200" />
                     <ComboBox SelectedIndex="{Binding NetworkInterfaceIndex}"
-                              ToolTip.Tip="{locale:Locale NetworkInterfaceTooltip}"
+                        ToolTip.Tip="{locale:Locale NetworkInterfaceTooltip}"
-                              HorizontalContentAlignment="Left"
+                        HorizontalContentAlignment="Left"
-                              ItemsSource="{Binding NetworkInterfaceList}"
+                        ItemsSource="{Binding NetworkInterfaceList}"
-                              Width="250" />
+                        Width="250" />
                 </StackPanel>
             </StackPanel>
         </Border>

src/Ryujinx.Ava/UI/Windows/MainWindow.axaml.cs

@@ -15,6 +15,7 @@ using Ryujinx.Graphics.Gpu;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS;
 using Ryujinx.HLE.HOS.Services.Account.Acc;
+using Ryujinx.Input.HLE;
 using Ryujinx.Input.SDL2;
 using Ryujinx.Modules;
 using Ryujinx.Ui.App.Common;
@@ -25,7 +26,6 @@ using System;
 using System.IO;
 using System.Runtime.Versioning;
 using System.Threading.Tasks;
-using InputManager = Ryujinx.Input.HLE.InputManager;
 
 namespace Ryujinx.Ava.UI.Windows
 {
@@ -251,7 +251,7 @@ namespace Ryujinx.Ava.UI.Windows
 
             VirtualFileSystem.ReloadKeySet();
 
-            ApplicationHelper.Initialize(VirtualFileSystem, AccountManager, LibHacHorizonManager.RyujinxClient, this);
+            ApplicationHelper.Initialize(VirtualFileSystem, AccountManager, LibHacHorizonManager.RyujinxClient);
         }
 
         [SupportedOSPlatform("linux")]

src/Ryujinx.Common/Configuration/Multiplayer/MultiplayerMode.cs

@@ -0,0 +1,7 @@
+namespace Ryujinx.Common.Configuration.Multiplayer
+{
+    public enum MultiplayerMode
+    {
+        Disabled,
+    }
+}

src/Ryujinx.Common/Memory/StructArrayHelpers.cs

@@ -791,5 +791,34 @@ namespace Ryujinx.Common.Memory
         [Pure]
         public Span<T> AsSpan() => MemoryMarshal.CreateSpan(ref _e0, Length);
     }
+
+    public struct Array140<T> : IArray<T> where T : unmanaged
+    {
+        T _e0;
+        Array64<T> _other;
+        Array64<T> _other2;
+        Array11<T> _other3;
+        public readonly int Length => 140;
+        public ref T this[int index] => ref AsSpan()[index];
+
+        [Pure]
+        public Span<T> AsSpan() => MemoryMarshal.CreateSpan(ref _e0, Length);
+    }
+
+    public struct Array384<T> : IArray<T> where T : unmanaged
+    {
+        T _e0;
+        Array64<T> _other;
+        Array64<T> _other2;
+        Array64<T> _other3;
+        Array64<T> _other4;
+        Array64<T> _other5;
+        Array63<T> _other6;
+        public readonly int Length => 384;
+        public ref T this[int index] => ref AsSpan()[index];
+
+        [Pure]
+        public Span<T> AsSpan() => MemoryMarshal.CreateSpan(ref _e0, Length);
+    }
 }
 #pragma warning restore CS0169, IDE0051

src/Ryujinx.Common/Utilities/NetworkHelpers.cs

@@ -1,4 +1,6 @@
-using System.Net.NetworkInformation;
+using System.Buffers.Binary;
+using System.Net;
+using System.Net.NetworkInformation;
 
 namespace Ryujinx.Common.Utilities
 {
@@ -62,5 +64,15 @@ namespace Ryujinx.Common.Utilities
 
             return (targetProperties, targetAddressInfo);
         }
+
+        public static uint ConvertIpv4Address(IPAddress ipAddress)
+        {
+            return BinaryPrimitives.ReadUInt32BigEndian(ipAddress.GetAddressBytes());
+        }
+
+        public static uint ConvertIpv4Address(string ipAddress)
+        {
+            return ConvertIpv4Address(IPAddress.Parse(ipAddress));
+        }
     }
 }

src/Ryujinx.HLE/HLEConfiguration.cs

@@ -1,6 +1,7 @@
 using LibHac.Tools.FsSystem;
 using Ryujinx.Audio.Integration;
 using Ryujinx.Common.Configuration;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Graphics.GAL;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS;
@@ -158,6 +159,11 @@ namespace Ryujinx.HLE
         /// </summary>
         public string MultiplayerLanInterfaceId { internal get; set; }
 
+        /// <summary>
+        /// Multiplayer Mode
+        /// </summary>
+        public MultiplayerMode MultiplayerMode { internal get; set; }
+
         /// <summary>
         /// An action called when HLE force a refresh of output after docked mode changed.
         /// </summary>
@@ -187,7 +193,8 @@ namespace Ryujinx.HLE
                                 AspectRatio aspectRatio,
                                 float audioVolume,
                                 bool useHypervisor,
-                                string multiplayerLanInterfaceId)
+                                string multiplayerLanInterfaceId,
+                                MultiplayerMode multiplayerMode)
         {
             VirtualFileSystem = virtualFileSystem;
             LibHacHorizonManager = libHacHorizonManager;
@@ -214,6 +221,7 @@ namespace Ryujinx.HLE
             AudioVolume = audioVolume;
             UseHypervisor = useHypervisor;
             MultiplayerLanInterfaceId = multiplayerLanInterfaceId;
+            MultiplayerMode = multiplayerMode;
         }
     }
 }

src/Ryujinx.HLE/HOS/Horizon.cs

@@ -88,6 +88,7 @@ namespace Ryujinx.HLE.HOS
         internal ServerBase ViServer { get; private set; }
         internal ServerBase ViServerM { get; private set; }
         internal ServerBase ViServerS { get; private set; }
+        internal ServerBase LdnServer { get; private set; }
 
         internal KSharedMemory HidSharedMem { get; private set; }
         internal KSharedMemory FontSharedMem { get; private set; }
@@ -319,6 +320,7 @@ namespace Ryujinx.HLE.HOS
             ViServer = new ServerBase(KernelContext, "ViServerU");
             ViServerM = new ServerBase(KernelContext, "ViServerM");
             ViServerS = new ServerBase(KernelContext, "ViServerS");
+            LdnServer = new ServerBase(KernelContext, "LdnServer");
 
             StartNewServices();
         }

src/Ryujinx.HLE/HOS/Services/Ldn/IUserServiceCreator.cs

@@ -5,7 +5,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn
     [Service("ldn:u")]
     class IUserServiceCreator : IpcService
     {
-        public IUserServiceCreator(ServiceCtx context) { }
+        public IUserServiceCreator(ServiceCtx context) : base(context.Device.System.LdnServer) { }
 
         [CommandCmif(0)]
         // CreateUserLocalCommunicationService() -> object<nn::ldn::detail::IUserLocalCommunicationService>

src/Ryujinx.HLE/HOS/Services/Ldn/ResultCode.cs

@@ -7,10 +7,18 @@ namespace Ryujinx.HLE.HOS.Services.Ldn
 
         Success = 0,
 
+        DeviceNotAvailable = (16 << ErrorCodeShift) | ModuleId,
         DeviceDisabled = (22 << ErrorCodeShift) | ModuleId,
         InvalidState = (32 << ErrorCodeShift) | ModuleId,
-        Unknown1 = (48 << ErrorCodeShift) | ModuleId,
+        NodeNotFound = (48 << ErrorCodeShift) | ModuleId,
+        ConnectFailure = (64 << ErrorCodeShift) | ModuleId,
+        ConnectNotFound = (65 << ErrorCodeShift) | ModuleId,
+        ConnectTimeout = (66 << ErrorCodeShift) | ModuleId,
+        ConnectRejected = (67 << ErrorCodeShift) | ModuleId,
         InvalidArgument = (96 << ErrorCodeShift) | ModuleId,
         InvalidObject = (97 << ErrorCodeShift) | ModuleId,
+        VersionTooLow = (113 << ErrorCodeShift) | ModuleId,
+        VersionTooHigh = (114 << ErrorCodeShift) | ModuleId,
+        TooManyPlayers = (144 << ErrorCodeShift) | ModuleId,
     }
 }

src/Ryujinx.HLE/HOS/Services/Ldn/Types/AcceptPolicy.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    enum AcceptPolicy : byte
+    {
+        AcceptAll,
+        RejectAll,
+        BlackList,
+        WhiteList,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/AddressEntry.cs

@@ -0,0 +1,13 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0xC)]
+    struct AddressEntry
+    {
+        public uint Ipv4Address;
+        public Array6<byte> MacAddress;
+        public ushort Reserved;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/AddressList.cs

@@ -0,0 +1,11 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x60)]
+    struct AddressList
+    {
+        public Array8<AddressEntry> Addresses;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/CommonNetworkInfo.cs

@@ -0,0 +1,16 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x30)]
+    struct CommonNetworkInfo
+    {
+        public Array6<byte> MacAddress;
+        public Ssid Ssid;
+        public ushort Channel;
+        public byte LinkLevel;
+        public byte NetworkType;
+        public uint Reserved;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/DisconnectReason.cs

@@ -0,0 +1,13 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    enum DisconnectReason : uint
+    {
+        None,
+        DisconnectedByUser,
+        DisconnectedBySystem,
+        DestroyedByUser,
+        DestroyedBySystem,
+        Rejected,
+        SignalLost,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/IntentId.cs

@@ -0,0 +1,13 @@
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x10)]
+    struct IntentId
+    {
+        public long LocalCommunicationId;
+        public ushort Reserved1;
+        public ushort SceneId;
+        public uint Reserved2;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/LdnNetworkInfo.cs

@@ -0,0 +1,23 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x430)]
+    struct LdnNetworkInfo
+    {
+        public Array16<byte> SecurityParameter;
+        public ushort SecurityMode;
+        public AcceptPolicy StationAcceptPolicy;
+        public byte Reserved1;
+        public ushort Reserved2;
+        public byte NodeCountMax;
+        public byte NodeCount;
+        public Array8<NodeInfo> Nodes;
+        public ushort Reserved3;
+        public ushort AdvertiseDataSize;
+        public Array384<byte> AdvertiseData;
+        public Array140<byte> Reserved4;
+        public ulong AuthenticationId;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NetworkConfig.cs

@@ -0,0 +1,16 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x20)]
+    struct NetworkConfig
+    {
+        public IntentId IntentId;
+        public ushort Channel;
+        public byte NodeCountMax;
+        public byte Reserved1;
+        public ushort LocalCommunicationVersion;
+        public Array10<byte> Reserved2;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NetworkId.cs

@@ -0,0 +1,12 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x20)]
+    struct NetworkId
+    {
+        public IntentId IntentId;
+        public Array16<byte> SessionId;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NetworkInfo.cs

@@ -0,0 +1,12 @@
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x480)]
+    struct NetworkInfo
+    {
+        public NetworkId NetworkId;
+        public CommonNetworkInfo Common;
+        public LdnNetworkInfo Ldn;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NetworkType.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    enum NetworkType : uint
+    {
+        None,
+        General,
+        Ldn,
+        All,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NodeInfo.cs

@@ -0,0 +1,18 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x40)]
+    struct NodeInfo
+    {
+        public uint Ipv4Address;
+        public Array6<byte> MacAddress;
+        public byte NodeId;
+        public byte IsConnected;
+        public Array33<byte> UserName;
+        public byte Reserved1;
+        public ushort LocalCommunicationVersion;
+        public Array16<byte> Reserved2;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NodeLatestUpdate.cs

@@ -0,0 +1,62 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 8)]
+    struct NodeLatestUpdate
+    {
+        public NodeLatestUpdateFlags State;
+        public Array7<byte> Reserved;
+    }
+
+    static class NodeLatestUpdateHelper
+    {
+        private static readonly object _lock = new();
+
+        public static void CalculateLatestUpdate(this Array8<NodeLatestUpdate> array, Array8<NodeInfo> beforeNodes, Array8<NodeInfo> afterNodes)
+        {
+            lock (_lock)
+            {
+                for (int i = 0; i < 8; i++)
+                {
+                    if (beforeNodes[i].IsConnected == 0)
+                    {
+                        if (afterNodes[i].IsConnected != 0)
+                        {
+                            array[i].State |= NodeLatestUpdateFlags.Connect;
+                        }
+                    }
+                    else
+                    {
+                        if (afterNodes[i].IsConnected == 0)
+                        {
+                            array[i].State |= NodeLatestUpdateFlags.Disconnect;
+                        }
+                    }
+                }
+            }
+        }
+
+        public static NodeLatestUpdate[] ConsumeLatestUpdate(this Array8<NodeLatestUpdate> array, int number)
+        {
+            NodeLatestUpdate[] result = new NodeLatestUpdate[number];
+
+            lock (_lock)
+            {
+                for (int i = 0; i < number; i++)
+                {
+                    result[i].Reserved = new Array7<byte>();
+
+                    if (i < 8)
+                    {
+                        result[i].State = array[i].State;
+                        array[i].State = NodeLatestUpdateFlags.None;
+                    }
+                }
+            }
+
+            return result;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/NodeLatestUpdateFlags.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [Flags]
+    enum NodeLatestUpdateFlags : byte
+    {
+        None = 0,
+        Connect = 1 << 0,
+        Disconnect = 1 << 1,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/ScanFilter.cs

@@ -0,0 +1,16 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x60)]
+    struct ScanFilter
+    {
+        public NetworkId NetworkId;
+        public NetworkType NetworkType;
+        public Array6<byte> MacAddress;
+        public Ssid Ssid;
+        public Array16<byte> Reserved;
+        public ScanFilterFlag Flag;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/ScanFilterFlag.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [Flags]
+    enum ScanFilterFlag : byte
+    {
+        LocalCommunicationId = 1 << 0,
+        SessionId = 1 << 1,
+        NetworkType = 1 << 2,
+        MacAddress = 1 << 3,
+        Ssid = 1 << 4,
+        SceneId = 1 << 5,
+        IntentId = LocalCommunicationId | SceneId,
+        NetworkId = IntentId | SessionId,
+        All = NetworkType | IntentId | SessionId | MacAddress | Ssid,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/SecurityConfig.cs

@@ -0,0 +1,13 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x44)]
+    struct SecurityConfig
+    {
+        public SecurityMode SecurityMode;
+        public ushort PassphraseSize;
+        public Array64<byte> Passphrase;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/SecurityMode.cs

@@ -0,0 +1,9 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    enum SecurityMode : ushort
+    {
+        All,
+        Retail,
+        Debug,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/SecurityParameter.cs

@@ -0,0 +1,12 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x20)]
+    struct SecurityParameter
+    {
+        public Array16<byte> Data;
+        public Array16<byte> SessionId;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/Ssid.cs

@@ -0,0 +1,12 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x22)]
+    struct Ssid
+    {
+        public byte Length;
+        public Array33<byte> Name;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/Types/UserConfig.cs

@@ -0,0 +1,12 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x30)]
+    struct UserConfig
+    {
+        public Array33<byte> UserName;
+        public Array15<byte> Unknown1;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/AccessPoint.cs

@@ -0,0 +1,104 @@
+using Ryujinx.Common.Memory;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
+{
+    class AccessPoint : IDisposable
+    {
+        private byte[] _advertiseData;
+
+        private readonly IUserLocalCommunicationService _parent;
+
+        public NetworkInfo NetworkInfo;
+        public Array8<NodeLatestUpdate> LatestUpdates = new();
+        public bool Connected { get; private set; }
+
+        public AccessPoint(IUserLocalCommunicationService parent)
+        {
+            _parent = parent;
+
+            _parent.NetworkClient.NetworkChange += NetworkChanged;
+        }
+
+        public void Dispose()
+        {
+            _parent.NetworkClient.DisconnectNetwork();
+
+            _parent.NetworkClient.NetworkChange -= NetworkChanged;
+        }
+
+        private void NetworkChanged(object sender, RyuLdn.NetworkChangeEventArgs e)
+        {
+            LatestUpdates.CalculateLatestUpdate(NetworkInfo.Ldn.Nodes, e.Info.Ldn.Nodes);
+
+            NetworkInfo = e.Info;
+
+            if (Connected != e.Connected)
+            {
+                Connected = e.Connected;
+
+                if (Connected)
+                {
+                    _parent.SetState(NetworkState.AccessPointCreated);
+                }
+                else
+                {
+                    _parent.SetDisconnectReason(e.DisconnectReasonOrDefault(DisconnectReason.DestroyedBySystem));
+                }
+            }
+            else
+            {
+                _parent.SetState();
+            }
+        }
+
+        public ResultCode SetAdvertiseData(byte[] advertiseData)
+        {
+            _advertiseData = advertiseData;
+
+            _parent.NetworkClient.SetAdvertiseData(_advertiseData);
+
+            return ResultCode.Success;
+        }
+
+        public ResultCode SetStationAcceptPolicy(AcceptPolicy acceptPolicy)
+        {
+            _parent.NetworkClient.SetStationAcceptPolicy(acceptPolicy);
+
+            return ResultCode.Success;
+        }
+
+        public ResultCode CreateNetwork(SecurityConfig securityConfig, UserConfig userConfig, NetworkConfig networkConfig)
+        {
+            CreateAccessPointRequest request = new()
+            {
+                SecurityConfig = securityConfig,
+                UserConfig = userConfig,
+                NetworkConfig = networkConfig,
+            };
+
+            bool success = _parent.NetworkClient.CreateNetwork(request, _advertiseData ?? Array.Empty<byte>());
+
+            return success ? ResultCode.Success : ResultCode.InvalidState;
+        }
+
+        public ResultCode CreateNetworkPrivate(SecurityConfig securityConfig, SecurityParameter securityParameter, UserConfig userConfig, NetworkConfig networkConfig, AddressList addressList)
+        {
+            CreateAccessPointPrivateRequest request = new()
+            {
+                SecurityConfig = securityConfig,
+                SecurityParameter = securityParameter,
+                UserConfig = userConfig,
+                NetworkConfig = networkConfig,
+                AddressList = addressList,
+            };
+
+            bool success = _parent.NetworkClient.CreateNetworkPrivate(request, _advertiseData);
+
+            return success ? ResultCode.Success : ResultCode.InvalidState;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/Network/Types/ConnectRequest.cs

@@ -0,0 +1,15 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x4FC)]
+    struct ConnectRequest
+    {
+        public SecurityConfig SecurityConfig;
+        public UserConfig UserConfig;
+        public uint LocalCommunicationVersion;
+        public uint OptionUnknown;
+        public NetworkInfo NetworkInfo;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/Network/Types/CreateAccessPointRequest.cs

@@ -0,0 +1,16 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types
+{
+    /// <remarks>
+    /// Advertise data is appended separately (remaining data in the buffer).
+    /// </remarks>
+    [StructLayout(LayoutKind.Sequential, Size = 0x94, CharSet = CharSet.Ansi)]
+    struct CreateAccessPointRequest
+    {
+        public SecurityConfig SecurityConfig;
+        public UserConfig UserConfig;
+        public NetworkConfig NetworkConfig;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/DisabledLdnClient.cs

@@ -0,0 +1,62 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn
+{
+    class DisabledLdnClient : INetworkClient
+    {
+        public event EventHandler<NetworkChangeEventArgs> NetworkChange;
+
+        public NetworkError Connect(ConnectRequest request)
+        {
+            NetworkChange?.Invoke(this, new NetworkChangeEventArgs(new NetworkInfo(), false));
+
+            return NetworkError.None;
+        }
+
+        public NetworkError ConnectPrivate(ConnectPrivateRequest request)
+        {
+            NetworkChange?.Invoke(this, new NetworkChangeEventArgs(new NetworkInfo(), false));
+
+            return NetworkError.None;
+        }
+
+        public bool CreateNetwork(CreateAccessPointRequest request, byte[] advertiseData)
+        {
+            NetworkChange?.Invoke(this, new NetworkChangeEventArgs(new NetworkInfo(), false));
+
+            return true;
+        }
+
+        public bool CreateNetworkPrivate(CreateAccessPointPrivateRequest request, byte[] advertiseData)
+        {
+            NetworkChange?.Invoke(this, new NetworkChangeEventArgs(new NetworkInfo(), false));
+
+            return true;
+        }
+
+        public void DisconnectAndStop() { }
+
+        public void DisconnectNetwork() { }
+
+        public ResultCode Reject(DisconnectReason disconnectReason, uint nodeId)
+        {
+            return ResultCode.Success;
+        }
+
+        public NetworkInfo[] Scan(ushort channel, ScanFilter scanFilter)
+        {
+            return Array.Empty<NetworkInfo>();
+        }
+
+        public void SetAdvertiseData(byte[] data) { }
+
+        public void SetGameVersion(byte[] versionString) { }
+
+        public void SetStationAcceptPolicy(AcceptPolicy acceptPolicy) { }
+
+        public void Dispose() { }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/INetworkClient.cs

@@ -0,0 +1,24 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn
+{
+    interface INetworkClient : IDisposable
+    {
+        event EventHandler<NetworkChangeEventArgs> NetworkChange;
+
+        void DisconnectNetwork();
+        void DisconnectAndStop();
+        NetworkError Connect(ConnectRequest request);
+        NetworkError ConnectPrivate(ConnectPrivateRequest request);
+        ResultCode Reject(DisconnectReason disconnectReason, uint nodeId);
+        NetworkInfo[] Scan(ushort channel, ScanFilter scanFilter);
+        void SetGameVersion(byte[] versionString);
+        void SetStationAcceptPolicy(AcceptPolicy acceptPolicy);
+        void SetAdvertiseData(byte[] data);
+        bool CreateNetwork(CreateAccessPointRequest request, byte[] advertiseData);
+        bool CreateNetworkPrivate(CreateAccessPointPrivateRequest request, byte[] advertiseData);
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/NetworkChangeEventArgs.cs

@@ -0,0 +1,24 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn
+{
+    class NetworkChangeEventArgs : EventArgs
+    {
+        public NetworkInfo Info;
+        public bool Connected;
+        public DisconnectReason DisconnectReason;
+
+        public NetworkChangeEventArgs(NetworkInfo info, bool connected, DisconnectReason disconnectReason = DisconnectReason.None)
+        {
+            Info = info;
+            Connected = connected;
+            DisconnectReason = disconnectReason;
+        }
+
+        public DisconnectReason DisconnectReasonOrDefault(DisconnectReason defaultReason)
+        {
+            return DisconnectReason == DisconnectReason.None ? defaultReason : DisconnectReason;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/Types/ConnectPrivateRequest.cs

@@ -0,0 +1,16 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0xBC)]
+    struct ConnectPrivateRequest
+    {
+        public SecurityConfig SecurityConfig;
+        public SecurityParameter SecurityParameter;
+        public UserConfig UserConfig;
+        public uint LocalCommunicationVersion;
+        public uint OptionUnknown;
+        public NetworkConfig NetworkConfig;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/Types/CreateAccessPointPrivateRequest.cs

@@ -0,0 +1,18 @@
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+{
+    /// <remarks>
+    /// Advertise data is appended separately (remaining data in the buffer).
+    /// </remarks>
+    [StructLayout(LayoutKind.Sequential, Size = 0x13C, Pack = 1)]
+    struct CreateAccessPointPrivateRequest
+    {
+        public SecurityConfig SecurityConfig;
+        public SecurityParameter SecurityParameter;
+        public UserConfig UserConfig;
+        public NetworkConfig NetworkConfig;
+        public AddressList AddressList;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/Types/NetworkError.cs

@@ -0,0 +1,22 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+{
+    enum NetworkError : int
+    {
+        None,
+
+        PortUnreachable,
+
+        TooManyPlayers,
+        VersionTooLow,
+        VersionTooHigh,
+
+        ConnectFailure,
+        ConnectNotFound,
+        ConnectTimeout,
+        ConnectRejected,
+
+        RejectFailed,
+
+        Unknown = -1,
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/RyuLdn/Types/NetworkErrorMessage.cs

@@ -0,0 +1,10 @@
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 0x4)]
+    struct NetworkErrorMessage
+    {
+        public NetworkError Error;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/Station.cs

@@ -0,0 +1,115 @@
+using Ryujinx.Common.Memory;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
+using System;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
+{
+    class Station : IDisposable
+    {
+        public NetworkInfo NetworkInfo;
+        public Array8<NodeLatestUpdate> LatestUpdates = new();
+
+        private readonly IUserLocalCommunicationService _parent;
+
+        public bool Connected { get; private set; }
+
+        public Station(IUserLocalCommunicationService parent)
+        {
+            _parent = parent;
+
+            _parent.NetworkClient.NetworkChange += NetworkChanged;
+        }
+
+        private void NetworkChanged(object sender, RyuLdn.NetworkChangeEventArgs e)
+        {
+            LatestUpdates.CalculateLatestUpdate(NetworkInfo.Ldn.Nodes, e.Info.Ldn.Nodes);
+
+            NetworkInfo = e.Info;
+
+            if (Connected != e.Connected)
+            {
+                Connected = e.Connected;
+
+                if (Connected)
+                {
+                    _parent.SetState(NetworkState.StationConnected);
+                }
+                else
+                {
+                    _parent.SetDisconnectReason(e.DisconnectReasonOrDefault(DisconnectReason.DestroyedByUser));
+                }
+            }
+            else
+            {
+                _parent.SetState();
+            }
+        }
+
+        public void Dispose()
+        {
+            _parent.NetworkClient.DisconnectNetwork();
+
+            _parent.NetworkClient.NetworkChange -= NetworkChanged;
+        }
+
+        private ResultCode NetworkErrorToResult(NetworkError error)
+        {
+            return error switch
+            {
+                NetworkError.None => ResultCode.Success,
+                NetworkError.VersionTooLow => ResultCode.VersionTooLow,
+                NetworkError.VersionTooHigh => ResultCode.VersionTooHigh,
+                NetworkError.TooManyPlayers => ResultCode.TooManyPlayers,
+
+                NetworkError.ConnectFailure => ResultCode.ConnectFailure,
+                NetworkError.ConnectNotFound => ResultCode.ConnectNotFound,
+                NetworkError.ConnectTimeout => ResultCode.ConnectTimeout,
+                NetworkError.ConnectRejected => ResultCode.ConnectRejected,
+
+                _ => ResultCode.DeviceNotAvailable,
+            };
+        }
+
+        public ResultCode Connect(
+            SecurityConfig securityConfig,
+            UserConfig userConfig,
+            uint localCommunicationVersion,
+            uint optionUnknown,
+            NetworkInfo networkInfo)
+        {
+            ConnectRequest request = new()
+            {
+                SecurityConfig = securityConfig,
+                UserConfig = userConfig,
+                LocalCommunicationVersion = localCommunicationVersion,
+                OptionUnknown = optionUnknown,
+                NetworkInfo = networkInfo,
+            };
+
+            return NetworkErrorToResult(_parent.NetworkClient.Connect(request));
+        }
+
+        public ResultCode ConnectPrivate(
+            SecurityConfig securityConfig,
+            SecurityParameter securityParameter,
+            UserConfig userConfig,
+            uint localCommunicationVersion,
+            uint optionUnknown,
+            NetworkConfig networkConfig)
+        {
+            ConnectPrivateRequest request = new()
+            {
+                SecurityConfig = securityConfig,
+                SecurityParameter = securityParameter,
+                UserConfig = userConfig,
+                LocalCommunicationVersion = localCommunicationVersion,
+                OptionUnknown = optionUnknown,
+                NetworkConfig = networkConfig,
+            };
+
+            return NetworkErrorToResult(_parent.NetworkClient.ConnectPrivate(request));
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Mii/Types/RandomMiiConstants.cs

@@ -320,7 +320,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         };
 
         private static ReadOnlySpan<byte> RandomMiiFacelineColorRawArray => new byte[]
@@ -399,8 +399,8 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-   ,     };
+        };
 
         private static ReadOnlySpan<byte> RandomMiiFacelineWrinkleRawArray => new byte[]
         {
@@ -633,8 +633,8 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    ,    };
+        };
 
         private static ReadOnlySpan<byte> RandomMiiFacelineMakeRawArray => new byte[]
         {
@@ -867,8 +867,8 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-     ,   };
+        };
 
         private static ReadOnlySpan<byte> RandomMiiHairTypeRawArray => new byte[]
         {
@@ -1101,8 +1101,8 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-      ,  };
+        };
 
         private static ReadOnlySpan<byte> RandomMiiHairColorRawArray => new byte[]
         {
@@ -1218,8 +1218,8 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-       , };
+        };
 
         private static ReadOnlySpan<byte> RandomMiiEyeTypeRawArray => new byte[]
         {
@@ -1452,8 +1452,8 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x2e, 0x00, 0x00, 0x00, 0x2f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-        ,};
+        };
 
         private static ReadOnlySpan<byte> RandomMiiEyeColorRawArray => new byte[]
         {
@@ -1493,7 +1493,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         };
 
         private static ReadOnlySpan<byte> RandomMiiEyebrowTypeRawArray => new byte[]
@@ -1727,7 +1727,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         };
 
         private static ReadOnlySpan<byte> RandomMiiNoseTypeRawArray => new byte[]
@@ -1961,7 +1961,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         };
 
         private static ReadOnlySpan<byte> RandomMiiMouthTypeRawArray => new byte[]
@@ -2195,7 +2195,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         };
 
         private static ReadOnlySpan<byte> RandomMiiGlassTypeRawArray => new byte[]
@@ -2236,7 +2236,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii.Types
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         };
         #endregion
     }

src/Ryujinx.Headless.SDL2/Program.cs

@@ -556,7 +556,8 @@ namespace Ryujinx.Headless.SDL2
                 options.AspectRatio,
                 options.AudioVolume,
                 options.UseHypervisor ?? true,
-                options.MultiplayerLanInterfaceId);
+                options.MultiplayerLanInterfaceId,
+                Common.Configuration.Multiplayer.MultiplayerMode.Disabled);
 
             return new Switch(configuration);
         }

src/Ryujinx.Ui.Common/Configuration/ConfigurationFileFormat.cs

@@ -1,5 +1,6 @@
 using Ryujinx.Common.Configuration;
 using Ryujinx.Common.Configuration.Hid;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Common.Logging;
 using Ryujinx.Common.Utilities;
 using Ryujinx.Ui.Common.Configuration.System;
@@ -360,6 +361,11 @@ namespace Ryujinx.Ui.Common.Configuration
         /// </summary>
         public string PreferredGpu { get; set; }
 
+        /// <summary>
+        /// Multiplayer Mode
+        /// </summary>
+        public MultiplayerMode MultiplayerMode { get; set; }
+
         /// <summary>
         /// GUID for the network interface used by LAN (or 0 for default)
         /// </summary>

src/Ryujinx.Ui.Common/Configuration/ConfigurationState.cs

@@ -3,6 +3,7 @@ using Ryujinx.Common.Configuration;
 using Ryujinx.Common.Configuration.Hid;
 using Ryujinx.Common.Configuration.Hid.Controller;
 using Ryujinx.Common.Configuration.Hid.Keyboard;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Common.Logging;
 using Ryujinx.Ui.Common.Configuration.System;
 using Ryujinx.Ui.Common.Configuration.Ui;
@@ -561,9 +562,15 @@ namespace Ryujinx.Ui.Common.Configuration
             /// </summary>
             public ReactiveObject<string> LanInterfaceId { get; private set; }
 
+            /// <summary>
+            /// Multiplayer Mode
+            /// </summary>
+            public ReactiveObject<MultiplayerMode> Mode { get; private set; }
+
             public MultiplayerSection()
             {
                 LanInterfaceId = new ReactiveObject<string>();
+                Mode = new ReactiveObject<MultiplayerMode>();
             }
         }
 
@@ -741,6 +748,7 @@ namespace Ryujinx.Ui.Common.Configuration
                 GraphicsBackend = Graphics.GraphicsBackend,
                 PreferredGpu = Graphics.PreferredGpu,
                 MultiplayerLanInterfaceId = Multiplayer.LanInterfaceId,
+                MultiplayerMode = Multiplayer.Mode,
             };
 
             return configurationFile;
@@ -795,6 +803,7 @@ namespace Ryujinx.Ui.Common.Configuration
             System.IgnoreMissingServices.Value = false;
             System.UseHypervisor.Value = true;
             Multiplayer.LanInterfaceId.Value = "0";
+            Multiplayer.Mode.Value = MultiplayerMode.Disabled;
             Ui.GuiColumns.FavColumn.Value = true;
             Ui.GuiColumns.IconColumn.Value = true;
             Ui.GuiColumns.AppColumn.Value = true;
@@ -1003,6 +1012,8 @@ namespace Ryujinx.Ui.Common.Configuration
                 configurationFileUpdated = true;
             }
 
+            // configurationFileFormat.Version == 13 -> LDN1
+
             if (configurationFileFormat.Version < 14)
             {
                 Ryujinx.Common.Logging.Logger.Warning?.Print(LogClass.Application, $"Outdated configuration version {configurationFileFormat.Version}, migrating to version 14.");
@@ -1039,6 +1050,8 @@ namespace Ryujinx.Ui.Common.Configuration
                 configurationFileUpdated = true;
             }
 
+            // configurationFileFormat.Version == 19 -> LDN2
+
             if (configurationFileFormat.Version < 20)
             {
                 Ryujinx.Common.Logging.Logger.Warning?.Print(LogClass.Application, $"Outdated configuration version {configurationFileFormat.Version}, migrating to version 20.");
@@ -1048,6 +1061,18 @@ namespace Ryujinx.Ui.Common.Configuration
                 configurationFileUpdated = true;
             }
 
+            if (configurationFileFormat.Version < 21)
+            {
+                Ryujinx.Common.Logging.Logger.Warning?.Print(LogClass.Application, $"Outdated configuration version {configurationFileFormat.Version}, migrating to version 21.");
+
+                // Initialize network config.
+
+                configurationFileFormat.MultiplayerMode = MultiplayerMode.Disabled;
+                configurationFileFormat.MultiplayerLanInterfaceId = "0";
+
+                configurationFileUpdated = true;
+            }
+
             if (configurationFileFormat.Version < 22)
             {
                 Ryujinx.Common.Logging.Logger.Warning?.Print(LogClass.Application, $"Outdated configuration version {configurationFileFormat.Version}, migrating to version 22.");
@@ -1501,6 +1526,7 @@ namespace Ryujinx.Ui.Common.Configuration
             }
 
             Multiplayer.LanInterfaceId.Value = configurationFileFormat.MultiplayerLanInterfaceId;
+            Multiplayer.Mode.Value = configurationFileFormat.MultiplayerMode;
 
             if (configurationFileUpdated)
             {

src/Ryujinx/Ui/MainWindow.cs

@@ -13,6 +13,7 @@ using Ryujinx.Audio.Backends.SoundIo;
 using Ryujinx.Audio.Integration;
 using Ryujinx.Common;
 using Ryujinx.Common.Configuration;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Common.Logging;
 using Ryujinx.Common.SystemInterop;
 using Ryujinx.Cpu;
@@ -207,6 +208,9 @@ namespace Ryujinx.Ui
             ConfigurationState.Instance.System.EnableDockedMode.Event += UpdateDockedModeState;
             ConfigurationState.Instance.System.AudioVolume.Event += UpdateAudioVolumeState;
 
+            ConfigurationState.Instance.Multiplayer.Mode.Event += UpdateMultiplayerMode;
+            ConfigurationState.Instance.Multiplayer.LanInterfaceId.Event += UpdateMultiplayerLanInterfaceId;
+
             if (ConfigurationState.Instance.Ui.StartFullscreen)
             {
                 _startFullScreen.Active = true;
@@ -331,6 +335,22 @@ namespace Ryujinx.Ui
             InputManager = new InputManager(new GTK3KeyboardDriver(this), new SDL2GamepadDriver());
         }
 
+        private void UpdateMultiplayerLanInterfaceId(object sender, ReactiveEventArgs<string> args)
+        {
+            if (_emulationContext != null)
+            {
+                _emulationContext.Configuration.MultiplayerLanInterfaceId = args.NewValue;
+            }
+        }
+
+        private void UpdateMultiplayerMode(object sender, ReactiveEventArgs<MultiplayerMode> args)
+        {
+            if (_emulationContext != null)
+            {
+                _emulationContext.Configuration.MultiplayerMode = args.NewValue;
+            }
+        }
+
         private void UpdateIgnoreMissingServicesState(object sender, ReactiveEventArgs<bool> args)
         {
             if (_emulationContext != null)
@@ -649,7 +669,8 @@ namespace Ryujinx.Ui
                 ConfigurationState.Instance.Graphics.AspectRatio,
                 ConfigurationState.Instance.System.AudioVolume,
                 ConfigurationState.Instance.System.UseHypervisor,
-                ConfigurationState.Instance.Multiplayer.LanInterfaceId.Value);
+                ConfigurationState.Instance.Multiplayer.LanInterfaceId.Value,
+                ConfigurationState.Instance.Multiplayer.Mode);
 
             _emulationContext = new HLE.Switch(configuration);
         }

src/Ryujinx/Ui/Windows/SettingsWindow.cs

@@ -5,6 +5,7 @@ using Ryujinx.Audio.Backends.SDL2;
 using Ryujinx.Audio.Backends.SoundIo;
 using Ryujinx.Common.Configuration;
 using Ryujinx.Common.Configuration.Hid;
+using Ryujinx.Common.Configuration.Multiplayer;
 using Ryujinx.Common.GraphicsDriver;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS.Services.Time.TimeZone;
@@ -18,6 +19,7 @@ using System.Globalization;
 using System.IO;
 using System.Net.NetworkInformation;
 using System.Reflection;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using GUI = Gtk.Builder.ObjectAttribute;
 
@@ -87,6 +89,7 @@ namespace Ryujinx.Ui.Windows
         [GUI] Adjustment _systemTimeHourSpinAdjustment;
         [GUI] Adjustment _systemTimeMinuteSpinAdjustment;
         [GUI] ComboBoxText _multiLanSelect;
+        [GUI] ComboBoxText _multiModeSelect;
         [GUI] CheckButton _custThemeToggle;
         [GUI] Entry _custThemePath;
         [GUI] ToggleButton _browseThemePath;
@@ -361,6 +364,7 @@ namespace Ryujinx.Ui.Windows
             _graphicsBackend.Changed += (sender, e) => UpdatePreferredGpuComboBox();
             PopulateNetworkInterfaces();
             _multiLanSelect.SetActiveId(ConfigurationState.Instance.Multiplayer.LanInterfaceId.Value);
+            _multiModeSelect.SetActiveId(ConfigurationState.Instance.Multiplayer.Mode.Value.ToString());
 
             _custThemePath.Buffer.Text = ConfigurationState.Instance.Ui.CustomThemePath;
             _resScaleText.Buffer.Text = ConfigurationState.Instance.Graphics.ResScaleCustom.Value.ToString();
@@ -658,6 +662,9 @@ namespace Ryujinx.Ui.Windows
 
             _previousVolumeLevel = ConfigurationState.Instance.System.AudioVolume.Value;
 
+            ConfigurationState.Instance.Multiplayer.Mode.Value = Enum.Parse<MultiplayerMode>(_multiModeSelect.ActiveId);
+            ConfigurationState.Instance.Multiplayer.LanInterfaceId.Value = _multiLanSelect.ActiveId;
+
             if (_audioBackendSelect.GetActiveIter(out TreeIter activeIter))
             {
                 ConfigurationState.Instance.System.AudioBackend.Value = (AudioBackend)_audioBackendStore.GetValue(activeIter, 1);

src/Ryujinx/Ui/Windows/SettingsWindow.glade

@@ -2933,6 +2933,96 @@
                         <property name="margin-right">10</property>
                         <property name="margin-top">5</property>
                         <property name="orientation">vertical</property>
+                        <child>
+                          <object class="GtkBox" id="CatMultiplayer">
+                            <property name="visible">True</property>
+                            <property name="can-focus">False</property>
+                            <property name="valign">start</property>
+                            <property name="margin-left">5</property>
+                            <property name="margin-right">5</property>
+                            <property name="orientation">vertical</property>
+                            <child>
+                              <object class="GtkLabel">
+                                <property name="visible">True</property>
+                                <property name="can-focus">False</property>
+                                <property name="halign">start</property>
+                                <property name="margin-bottom">5</property>
+                                <property name="label" translatable="yes">Multiplayer</property>
+                                <attributes>
+                                  <attribute name="weight" value="bold"/>
+                                </attributes>
+                              </object>
+                              <packing>
+                                <property name="expand">False</property>
+                                <property name="fill">True</property>
+                                <property name="position">0</property>
+                              </packing>
+                            </child>
+                            <child>
+                              <object class="GtkBox" id="MultiplayerOptions">
+                                <property name="visible">True</property>
+                                <property name="can-focus">False</property>
+                                <property name="valign">start</property>
+                                <property name="margin-left">10</property>
+                                <property name="margin-right">10</property>
+                                <property name="orientation">vertical</property>
+                                <child>
+                                  <object class="GtkBox" id="ModeBox">
+                                    <property name="visible">True</property>
+                                    <property name="can-focus">False</property>
+                                    <child>
+                                      <object class="GtkLabel">
+                                        <property name="visible">True</property>
+                                        <property name="can-focus">False</property>
+                                        <property name="tooltip-text" translatable="yes">Change Multiplayer Mode</property>
+                                        <property name="halign">end</property>
+                                        <property name="label" translatable="yes">Mode:</property>
+                                      </object>
+                                      <packing>
+                                        <property name="expand">False</property>
+                                        <property name="fill">True</property>
+                                        <property name="padding">5</property>
+                                        <property name="position">0</property>
+                                      </packing>
+                                    </child>
+                                    <child>
+                                      <object class="GtkComboBoxText" id="_multiModeSelect">
+                                        <property name="visible">True</property>
+                                        <property name="can-focus">False</property>
+                                        <property name="tooltip-text" translatable="yes">Change Multiplayer Mode</property>
+                                        <property name="active-id">Disabled</property>
+                                        <items>
+                                          <item id="Disabled" translatable="yes">Disabled</item>
+                                        </items>
+                                      </object>
+                                      <packing>
+                                        <property name="expand">False</property>
+                                        <property name="fill">True</property>
+                                        <property name="position">1</property>
+                                      </packing>
+                                    </child>
+                                  </object>
+                                  <packing>
+                                    <property name="expand">False</property>
+                                    <property name="fill">True</property>
+                                    <property name="position">3</property>
+                                  </packing>
+                                </child>
+                              </object>
+                              <packing>
+                                <property name="expand">True</property>
+                                <property name="fill">True</property>
+                                <property name="position">2</property>
+                              </packing>
+                            </child>
+                          </object>
+                          <packing>
+                            <property name="expand">False</property>
+                            <property name="fill">True</property>
+                            <property name="padding">5</property>
+                            <property name="position">0</property>
+                          </packing>
+                        </child>
                         <child>
                           <object class="GtkBox" id="CatLAN">
                             <property name="visible">True</property>