[HLE] Remove ServerBase 1ms polling (#5855)

Added a KEvent for each ServerBase which signals whenever a session is added to the _sessions list, which allows it to rerun the ReplyAndReceive with the new session handle.

This greatly reduces the presence of ServerBase on profiles, especially of games that aren't particularly busy. It should also increase responsiveness when adding session objects, as it doesn't take at most 1ms for them to start working.

It also reduces the load on KTimeManager, which could allow it to spin less often. I have noticed that a bunch of games still do 1ms waits (they actually request a bit less than 1ms), so they still end up spinning to the next millisecond. Maybe for waits like this, it could attempt to nudge the timepoints to snap to each other when they're close enough, and also snap to whole millisecond waits when close enough.

Directory.Packages.props

@@ -24,6 +24,7 @@
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
     <PackageVersion Include="Microsoft.IO.RecyclableMemoryStream" Version="2.3.2" />
     <PackageVersion Include="MsgPack.Cli" Version="1.0.1" />
+    <PackageVersion Include="NetCoreServer" Version="7.0.0" />
     <PackageVersion Include="NUnit" Version="3.13.3" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.1.0" />
     <PackageVersion Include="OpenTK.Core" Version="4.7.7" />

README.md

@@ -141,4 +141,5 @@ See [LICENSE.txt](LICENSE.txt) and [THIRDPARTY.md](distribution/legal/THIRDPARTY
 
 - [LibHac](https://github.com/Thealexbarney/LibHac) is used for our file-system.
 - [AmiiboAPI](https://www.amiiboapi.com) is used in our Amiibo emulation.
+- [ldn_mitm](https://github.com/spacemeowx2/ldn_mitm) is used for one of our available multiplayer modes.
 - [ShellLink](https://github.com/securifybv/ShellLink) is used for Windows shortcut generation.

src/Ryujinx.Ava/AppHost.cs

@@ -190,6 +190,7 @@ namespace Ryujinx.Ava
             ConfigurationState.Instance.Graphics.ScalingFilterLevel.Event += UpdateScalingFilterLevel;
             ConfigurationState.Instance.Graphics.EnableColorSpacePassthrough.Event += UpdateColorSpacePassthrough;
 
+            ConfigurationState.Instance.System.EnableInternetAccess.Event += UpdateEnableInternetAccessState;
             ConfigurationState.Instance.Multiplayer.LanInterfaceId.Event += UpdateLanInterfaceIdState;
             ConfigurationState.Instance.Multiplayer.Mode.Event += UpdateMultiplayerModeState;
 
@@ -408,6 +409,11 @@ namespace Ryujinx.Ava
             });
         }
 
+        private void UpdateEnableInternetAccessState(object sender, ReactiveEventArgs<bool> e)
+        {
+            Device.Configuration.EnableInternetAccess = e.NewValue;
+        }
+
         private void UpdateLanInterfaceIdState(object sender, ReactiveEventArgs<string> e)
         {
             Device.Configuration.MultiplayerLanInterfaceId = e.NewValue;

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

@@ -650,7 +650,7 @@
   "UserEditorTitle": "Edit User",
   "UserEditorTitleCreate": "Create User",
   "SettingsTabNetworkInterface": "Network Interface:",
-  "NetworkInterfaceTooltip": "The network interface used for LAN features",
+  "NetworkInterfaceTooltip": "The network interface used for LAN/LDN features",
   "NetworkInterfaceDefault": "Default",
   "PackagingShaders": "Packaging Shaders",
   "AboutChangelogButton": "View Changelog on GitHub",

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

@@ -3,5 +3,6 @@
     public enum MultiplayerMode
     {
         Disabled,
+        LdnMitm,
     }
 }

src/Ryujinx.Common/SystemInfo/MacOSSystemInfo.cs

@@ -12,6 +12,13 @@ namespace Ryujinx.Common.SystemInfo
     {
         internal MacOSSystemInfo()
         {
+            if (SysctlByName("kern.osversion", out string buildRevision) != 0)
+            {
+                buildRevision = "Unknown Build";
+            }
+
+            OsDescription = $"macOS {Environment.OSVersion.Version} ({buildRevision}) ({RuntimeInformation.OSArchitecture})";
+
             string cpuName = GetCpuidCpuName();
 
             if (cpuName == null && SysctlByName("machdep.cpu.brand_string", out cpuName) != 0)

src/Ryujinx.Common/Utilities/NetworkHelpers.cs

@@ -74,5 +74,10 @@ namespace Ryujinx.Common.Utilities
         {
             return ConvertIpv4Address(IPAddress.Parse(ipAddress));
         }
+
+        public static IPAddress ConvertUint(uint ipAddress)
+        {
+            return new IPAddress(new byte[] { (byte)((ipAddress >> 24) & 0xFF), (byte)((ipAddress >> 16) & 0xFF), (byte)((ipAddress >> 8) & 0xFF), (byte)(ipAddress & 0xFF) });
+        }
     }
 }

src/Ryujinx.Graphics.Gpu/Image/Texture.cs

@@ -101,6 +101,11 @@ namespace Ryujinx.Graphics.Gpu.Image
         /// </summary>
         public bool AlwaysFlushOnOverlap { get; private set; }
 
+        /// <summary>
+        /// Indicates that the texture was fully unmapped since the modified flag was set, and flushes should be ignored until it is modified again.
+        /// </summary>
+        public bool FlushStale { get; private set; }
+
         /// <summary>
         /// Increments when the host texture is swapped, or when the texture is removed from all pools.
         /// </summary>
@@ -149,6 +154,7 @@ namespace Ryujinx.Graphics.Gpu.Image
         /// </summary>
         public bool HadPoolOwner { get; private set; }
 
+        /// <summary>
         /// Physical memory ranges where the texture data is located.
         /// </summary>
         public MultiRange Range { get; private set; }
@@ -1411,6 +1417,7 @@ namespace Ryujinx.Graphics.Gpu.Image
         /// </summary>
         public void SignalModified()
         {
+            FlushStale = false;
             _scaledSetScore = Math.Max(0, _scaledSetScore - 1);
 
             if (_modifiedStale || Group.HasCopyDependencies)
@@ -1431,6 +1438,7 @@ namespace Ryujinx.Graphics.Gpu.Image
         {
             if (bound)
             {
+                FlushStale = false;
                 _scaledSetScore = Math.Max(0, _scaledSetScore - 1);
             }
 
@@ -1695,12 +1703,17 @@ namespace Ryujinx.Graphics.Gpu.Image
         /// <param name="unmapRange">The range of memory being unmapped</param>
         public void Unmapped(MultiRange unmapRange)
         {
+            if (unmapRange.Contains(Range))
+            {
+                // If this is a full unmap, prevent flushes until the texture is mapped again.
+                FlushStale = true;
+            }
+
             ChangedMapping = true;
 
             if (Group.Storage == this)
             {
                 Group.Unmapped();
-
                 Group.ClearModified(unmapRange);
             }
         }

src/Ryujinx.Graphics.Gpu/Image/TextureCache.cs

@@ -107,8 +107,6 @@ namespace Ryujinx.Graphics.Gpu.Image
                             // Any texture that has been unmapped at any point or is partially unmapped
                             // should update their pool references after the remap completes.
 
-                            MultiRange unmapped = ((MemoryManager)sender).GetPhysicalRegions(e.Address, e.Size);
-
                             foreach (var texture in _partiallyMappedTextures)
                             {
                                 texture.UpdatePoolMappings();

src/Ryujinx.Graphics.Gpu/Image/TextureGroup.cs

@@ -1659,6 +1659,14 @@ namespace Ryujinx.Graphics.Gpu.Image
                 return;
             }
 
+            // If size is zero, we have nothing to flush.
+            // If the flush is stale, we should ignore it because the texture was unmapped since the modified
+            // flag was set, and flushing it is not safe anymore as the GPU might no longer own the memory.
+            if (size == 0 || Storage.FlushStale)
+            {
+                return;
+            }
+
             // There is a small gap here where the action is removed but _actionRegistered is still 1.
             // In this case it will skip registering the action, but here we are already handling it,
             // so there shouldn't be any issue as it's the same handler for all actions.

src/Ryujinx.HLE/HLEConfiguration.cs

@@ -101,7 +101,7 @@ namespace Ryujinx.HLE
         /// <summary>
         /// Control if the guest application should be told that there is a Internet connection available.
         /// </summary>
-        internal readonly bool EnableInternetAccess;
+        public bool EnableInternetAccess { internal get; set; }
 
         /// <summary>
         /// Control LibHac's integrity check level.

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

@@ -0,0 +1,12 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn
+{
+    static class LdnConst
+    {
+        public const int SsidLengthMax = 0x20;
+        public const int AdvertiseDataSizeMax = 0x180;
+        public const int UserNameBytesMax = 0x20;
+        public const int NodeCountMax = 8;
+        public const int StationCountMax = NodeCountMax - 1;
+        public const int PassphraseLengthMax = 0x40;
+    }
+}

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

@@ -1,4 +1,4 @@
-using Ryujinx.Common.Memory;
+using Ryujinx.Common.Memory;
 using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.Types

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

@@ -1,4 +1,4 @@
-using Ryujinx.Common.Memory;
+using Ryujinx.Common.Memory;
 using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.Types

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

@@ -1,4 +1,4 @@
-using Ryujinx.Common.Memory;
+using Ryujinx.Common.Memory;
 using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.Types
@@ -48,7 +48,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.Types
                 {
                     result[i].Reserved = new Array7<byte>();
 
-                    if (i < 8)
+                    if (i < LdnConst.NodeCountMax)
                     {
                         result[i].State = array[i].State;
                         array[i].State = NodeLatestUpdateFlags.None;

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

@@ -1,4 +1,4 @@
-using Ryujinx.Common.Memory;
+using Ryujinx.Common.Memory;
 using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.Types

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

@@ -1,4 +1,4 @@
-using Ryujinx.Common.Memory;
+using Ryujinx.Common.Memory;
 using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.Types

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

@@ -1,4 +1,4 @@
-using Ryujinx.Common.Memory;
+using Ryujinx.Common.Memory;
 using System.Runtime.InteropServices;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.Types

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

@@ -1,7 +1,6 @@
 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.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
 using System;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
@@ -30,7 +29,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
             _parent.NetworkClient.NetworkChange -= NetworkChanged;
         }
 
-        private void NetworkChanged(object sender, RyuLdn.NetworkChangeEventArgs e)
+        private void NetworkChanged(object sender, NetworkChangeEventArgs e)
         {
             LatestUpdates.CalculateLatestUpdate(NetworkInfo.Ldn.Nodes, e.Info.Ldn.Nodes);
 

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

@@ -1,12 +1,13 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
 using System;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
 {
     interface INetworkClient : IDisposable
     {
+        bool NeedsRealId { get; }
+
         event EventHandler<NetworkChangeEventArgs> NetworkChange;
 
         void DisconnectNetwork();

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

@@ -8,7 +8,7 @@ using Ryujinx.Cpu;
 using Ryujinx.HLE.HOS.Ipc;
 using Ryujinx.HLE.HOS.Kernel.Threading;
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm;
 using Ryujinx.Horizon.Common;
 using Ryujinx.Memory;
 using System;
@@ -395,7 +395,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
                             }
                             else
                             {
-                                if (scanFilter.NetworkId.IntentId.LocalCommunicationId == -1)
+                                if (scanFilter.NetworkId.IntentId.LocalCommunicationId == -1 && NetworkClient.NeedsRealId)
                                 {
                                     // TODO: Call nn::arp::GetApplicationControlProperty here when implemented.
                                     ApplicationControlProperty controlProperty = context.Device.Processes.ActiveApplication.ApplicationControlProperties;
@@ -546,7 +546,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
             context.RequestData.BaseStream.Seek(4, SeekOrigin.Current); // Alignment?
             NetworkConfig networkConfig = context.RequestData.ReadStruct<NetworkConfig>();
 
-            if (networkConfig.IntentId.LocalCommunicationId == -1)
+            if (networkConfig.IntentId.LocalCommunicationId == -1 && NetworkClient.NeedsRealId)
             {
                 // TODO: Call nn::arp::GetApplicationControlProperty here when implemented.
                 ApplicationControlProperty controlProperty = context.Device.Processes.ActiveApplication.ApplicationControlProperties;
@@ -555,7 +555,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
             }
 
             bool isLocalCommunicationIdValid = CheckLocalCommunicationIdPermission(context, (ulong)networkConfig.IntentId.LocalCommunicationId);
-            if (!isLocalCommunicationIdValid)
+            if (!isLocalCommunicationIdValid && NetworkClient.NeedsRealId)
             {
                 return ResultCode.InvalidObject;
             }
@@ -568,13 +568,13 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
             networkConfig.Channel = CheckDevelopmentChannel(networkConfig.Channel);
             securityConfig.SecurityMode = CheckDevelopmentSecurityMode(securityConfig.SecurityMode);
 
-            if (networkConfig.NodeCountMax <= 8)
+            if (networkConfig.NodeCountMax <= LdnConst.NodeCountMax)
             {
                 if ((((ulong)networkConfig.LocalCommunicationVersion) & 0x80000000) == 0)
                 {
                     if (securityConfig.SecurityMode <= SecurityMode.Retail)
                     {
-                        if (securityConfig.Passphrase.Length <= 0x40)
+                        if (securityConfig.Passphrase.Length <= LdnConst.PassphraseLengthMax)
                         {
                             if (_state == NetworkState.AccessPoint)
                             {
@@ -678,7 +678,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
                 return _nifmResultCode;
             }
 
-            if (bufferSize == 0 || bufferSize > 0x180)
+            if (bufferSize == 0 || bufferSize > LdnConst.AdvertiseDataSizeMax)
             {
                 return ResultCode.InvalidArgument;
             }
@@ -848,10 +848,10 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
 
                 context.Memory.Read(bufferPosition, networkInfoBytes);
 
-                networkInfo = MemoryMarshal.Cast<byte, NetworkInfo>(networkInfoBytes)[0];
+                networkInfo = MemoryMarshal.Read<NetworkInfo>(networkInfoBytes);
             }
 
-            if (networkInfo.NetworkId.IntentId.LocalCommunicationId == -1)
+            if (networkInfo.NetworkId.IntentId.LocalCommunicationId == -1 && NetworkClient.NeedsRealId)
             {
                 // TODO: Call nn::arp::GetApplicationControlProperty here when implemented.
                 ApplicationControlProperty controlProperty = context.Device.Processes.ActiveApplication.ApplicationControlProperties;
@@ -860,7 +860,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
             }
 
             bool isLocalCommunicationIdValid = CheckLocalCommunicationIdPermission(context, (ulong)networkInfo.NetworkId.IntentId.LocalCommunicationId);
-            if (!isLocalCommunicationIdValid)
+            if (!isLocalCommunicationIdValid && NetworkClient.NeedsRealId)
             {
                 return ResultCode.InvalidObject;
             }
@@ -1061,10 +1061,16 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
                     if (System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable())
                     {
                         MultiplayerMode mode = context.Device.Configuration.MultiplayerMode;
+
+                        Logger.Info?.PrintMsg(LogClass.ServiceLdn, $"Initializing with multiplayer mode: {mode}");
+
                         switch (mode)
                         {
+                            case MultiplayerMode.LdnMitm:
+                                NetworkClient = new LdnMitmClient(context.Device.Configuration);
+                                break;
                             case MultiplayerMode.Disabled:
-                                NetworkClient = new DisabledLdnClient();
+                                NetworkClient = new LdnDisabledClient();
                                 break;
                         }
 

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

@@ -1,12 +1,13 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
 using System;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
 {
-    class DisabledLdnClient : INetworkClient
+    class LdnDisabledClient : INetworkClient
     {
+        public bool NeedsRealId => true;
+
         public event EventHandler<NetworkChangeEventArgs> NetworkChange;
 
         public NetworkError Connect(ConnectRequest request)

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/LanDiscovery.cs

@@ -0,0 +1,611 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
+using Ryujinx.Common.Utilities;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Threading;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm
+{
+    internal class LanDiscovery : IDisposable
+    {
+        private const int DefaultPort = 11452;
+        private const ushort CommonChannel = 6;
+        private const byte CommonLinkLevel = 3;
+        private const byte CommonNetworkType = 2;
+
+        private const int FailureTimeout = 4000;
+
+        private readonly LdnMitmClient _parent;
+        private readonly LanProtocol _protocol;
+        private bool _initialized;
+        private readonly Ssid _fakeSsid;
+        private ILdnTcpSocket _tcp;
+        private LdnProxyUdpServer _udp, _udp2;
+        private readonly List<LdnProxyTcpSession> _stations = new();
+        private readonly object _lock = new();
+
+        private readonly AutoResetEvent _apConnected = new(false);
+
+        internal readonly IPAddress LocalAddr;
+        internal readonly IPAddress LocalBroadcastAddr;
+        internal NetworkInfo NetworkInfo;
+
+        public bool IsHost => _tcp is LdnProxyTcpServer;
+
+        private readonly Random _random = new();
+
+        // NOTE: Credit to https://stackoverflow.com/a/39338188
+        private static IPAddress GetBroadcastAddress(IPAddress address, IPAddress mask)
+        {
+            uint ipAddress = BitConverter.ToUInt32(address.GetAddressBytes(), 0);
+            uint ipMaskV4 = BitConverter.ToUInt32(mask.GetAddressBytes(), 0);
+            uint broadCastIpAddress = ipAddress | ~ipMaskV4;
+
+            return new IPAddress(BitConverter.GetBytes(broadCastIpAddress));
+        }
+
+        private static NetworkInfo GetEmptyNetworkInfo()
+        {
+            NetworkInfo networkInfo = new()
+            {
+                NetworkId = new NetworkId
+                {
+                    SessionId = new Array16<byte>(),
+                },
+                Common = new CommonNetworkInfo
+                {
+                    MacAddress = new Array6<byte>(),
+                    Ssid = new Ssid
+                    {
+                        Name = new Array33<byte>(),
+                    },
+                },
+                Ldn = new LdnNetworkInfo
+                {
+                    NodeCountMax = LdnConst.NodeCountMax,
+                    SecurityParameter = new Array16<byte>(),
+                    Nodes = new Array8<NodeInfo>(),
+                    AdvertiseData = new Array384<byte>(),
+                    Reserved4 = new Array140<byte>(),
+                },
+            };
+
+            for (int i = 0; i < LdnConst.NodeCountMax; i++)
+            {
+                networkInfo.Ldn.Nodes[i] = new NodeInfo
+                {
+                    MacAddress = new Array6<byte>(),
+                    UserName = new Array33<byte>(),
+                    Reserved2 = new Array16<byte>(),
+                };
+            }
+
+            return networkInfo;
+        }
+
+        public LanDiscovery(LdnMitmClient parent, IPAddress ipAddress, IPAddress ipv4Mask)
+        {
+            Logger.Info?.PrintMsg(LogClass.ServiceLdn, $"Initialize LanDiscovery using IP: {ipAddress}");
+
+            _parent = parent;
+            LocalAddr = ipAddress;
+            LocalBroadcastAddr = GetBroadcastAddress(ipAddress, ipv4Mask);
+
+            _fakeSsid = new Ssid
+            {
+                Length = LdnConst.SsidLengthMax,
+            };
+            _random.NextBytes(_fakeSsid.Name.AsSpan()[..32]);
+
+            _protocol = new LanProtocol(this);
+            _protocol.Accept += OnConnect;
+            _protocol.SyncNetwork += OnSyncNetwork;
+            _protocol.DisconnectStation += DisconnectStation;
+
+            NetworkInfo = GetEmptyNetworkInfo();
+
+            ResetStations();
+
+            if (!InitUdp())
+            {
+                Logger.Error?.PrintMsg(LogClass.ServiceLdn, "LanDiscovery Initialize: InitUdp failed.");
+
+                return;
+            }
+
+            _initialized = true;
+        }
+
+        protected void OnSyncNetwork(NetworkInfo info)
+        {
+            bool updated = false;
+
+            lock (_lock)
+            {
+                if (!NetworkInfo.Equals(info))
+                {
+                    NetworkInfo = info;
+                    updated = true;
+
+                    Logger.Debug?.PrintMsg(LogClass.ServiceLdn, $"Host IP: {NetworkHelpers.ConvertUint(info.Ldn.Nodes[0].Ipv4Address)}");
+                }
+            }
+
+            if (updated)
+            {
+                _parent.InvokeNetworkChange(info, true);
+            }
+
+            _apConnected.Set();
+        }
+
+        protected void OnConnect(LdnProxyTcpSession station)
+        {
+            lock (_lock)
+            {
+                station.NodeId = LocateEmptyNode();
+
+                if (_stations.Count > LdnConst.StationCountMax || station.NodeId == -1)
+                {
+                    station.Disconnect();
+                    station.Dispose();
+
+                    return;
+                }
+
+                _stations.Add(station);
+
+                UpdateNodes();
+            }
+        }
+
+        public void DisconnectStation(LdnProxyTcpSession station)
+        {
+            if (!station.IsDisposed)
+            {
+                if (station.IsConnected)
+                {
+                    station.Disconnect();
+                }
+
+                station.Dispose();
+            }
+
+            lock (_lock)
+            {
+                if (_stations.Remove(station))
+                {
+                    NetworkInfo.Ldn.Nodes[station.NodeId] = new NodeInfo()
+                    {
+                        MacAddress = new Array6<byte>(),
+                        UserName = new Array33<byte>(),
+                        Reserved2 = new Array16<byte>(),
+                    };
+
+                    UpdateNodes();
+                }
+            }
+        }
+
+        public bool SetAdvertiseData(byte[] data)
+        {
+            if (data.Length > LdnConst.AdvertiseDataSizeMax)
+            {
+                Logger.Error?.PrintMsg(LogClass.ServiceLdn, "AdvertiseData exceeds size limit.");
+
+                return false;
+            }
+
+            data.CopyTo(NetworkInfo.Ldn.AdvertiseData.AsSpan());
+            NetworkInfo.Ldn.AdvertiseDataSize = (ushort)data.Length;
+
+            // NOTE: Otherwise this results in SessionKeepFailed or MasterDisconnected
+            lock (_lock)
+            {
+                if (NetworkInfo.Ldn.Nodes[0].IsConnected == 1)
+                {
+                    UpdateNodes(true);
+                }
+            }
+
+            return true;
+        }
+
+        public void InitNetworkInfo()
+        {
+            lock (_lock)
+            {
+                NetworkInfo.Common.MacAddress = GetFakeMac();
+                NetworkInfo.Common.Channel = CommonChannel;
+                NetworkInfo.Common.LinkLevel = CommonLinkLevel;
+                NetworkInfo.Common.NetworkType = CommonNetworkType;
+                NetworkInfo.Common.Ssid = _fakeSsid;
+
+                NetworkInfo.Ldn.Nodes = new Array8<NodeInfo>();
+
+                for (int i = 0; i < LdnConst.NodeCountMax; i++)
+                {
+                    NetworkInfo.Ldn.Nodes[i].NodeId = (byte)i;
+                    NetworkInfo.Ldn.Nodes[i].IsConnected = 0;
+                }
+            }
+        }
+
+        protected Array6<byte> GetFakeMac(IPAddress address = null)
+        {
+            address ??= LocalAddr;
+
+            byte[] ip = address.GetAddressBytes();
+
+            var macAddress = new Array6<byte>();
+            new byte[] { 0x02, 0x00, ip[0], ip[1], ip[2], ip[3] }.CopyTo(macAddress.AsSpan());
+
+            return macAddress;
+        }
+
+        public bool InitTcp(bool listening, IPAddress address = null, int port = DefaultPort)
+        {
+            Logger.Debug?.PrintMsg(LogClass.ServiceLdn, $"LanDiscovery InitTcp: IP: {address}, listening: {listening}");
+
+            if (_tcp != null)
+            {
+                _tcp.DisconnectAndStop();
+                _tcp.Dispose();
+                _tcp = null;
+            }
+
+            ILdnTcpSocket tcpSocket;
+
+            if (listening)
+            {
+                try
+                {
+                    address ??= LocalAddr;
+
+                    tcpSocket = new LdnProxyTcpServer(_protocol, address, port);
+                }
+                catch (Exception ex)
+                {
+                    Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Failed to create LdnProxyTcpServer: {ex}");
+
+                    return false;
+                }
+
+                if (!tcpSocket.Start())
+                {
+                    return false;
+                }
+            }
+            else
+            {
+                if (address == null)
+                {
+                    return false;
+                }
+
+                try
+                {
+                    tcpSocket = new LdnProxyTcpClient(_protocol, address, port);
+                }
+                catch (Exception ex)
+                {
+                    Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Failed to create LdnProxyTcpClient: {ex}");
+
+                    return false;
+                }
+            }
+
+            _tcp = tcpSocket;
+
+            return true;
+        }
+
+        public bool InitUdp()
+        {
+            _udp?.Stop();
+            _udp2?.Stop();
+
+            try
+            {
+                // NOTE: Linux won't receive any broadcast packets if the socket is not bound to the broadcast address.
+                //       Windows only works if bound to localhost or the local address.
+                //       See this discussion: https://stackoverflow.com/questions/13666789/receiving-udp-broadcast-packets-on-linux
+                if (OperatingSystem.IsLinux() || OperatingSystem.IsMacOS())
+                {
+                    _udp2 = new LdnProxyUdpServer(_protocol, LocalBroadcastAddr, DefaultPort);
+                }
+
+                _udp = new LdnProxyUdpServer(_protocol, LocalAddr, DefaultPort);
+            }
+            catch (Exception ex)
+            {
+                Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Failed to create LdnProxyUdpServer: {ex}");
+
+                return false;
+            }
+
+            return true;
+        }
+
+        public NetworkInfo[] Scan(ushort channel, ScanFilter filter)
+        {
+            _udp.ClearScanResults();
+
+            if (_protocol.SendBroadcast(_udp, LanPacketType.Scan, DefaultPort) < 0)
+            {
+                return Array.Empty<NetworkInfo>();
+            }
+
+            List<NetworkInfo> outNetworkInfo = new();
+
+            foreach (KeyValuePair<ulong, NetworkInfo> item in _udp.GetScanResults())
+            {
+                bool copy = true;
+
+                if (filter.Flag.HasFlag(ScanFilterFlag.LocalCommunicationId))
+                {
+                    copy &= filter.NetworkId.IntentId.LocalCommunicationId == item.Value.NetworkId.IntentId.LocalCommunicationId;
+                }
+
+                if (filter.Flag.HasFlag(ScanFilterFlag.SessionId))
+                {
+                    copy &= filter.NetworkId.SessionId.AsSpan().SequenceEqual(item.Value.NetworkId.SessionId.AsSpan());
+                }
+
+                if (filter.Flag.HasFlag(ScanFilterFlag.NetworkType))
+                {
+                    copy &= filter.NetworkType == (NetworkType)item.Value.Common.NetworkType;
+                }
+
+                if (filter.Flag.HasFlag(ScanFilterFlag.Ssid))
+                {
+                    Span<byte> gameSsid = item.Value.Common.Ssid.Name.AsSpan()[item.Value.Common.Ssid.Length..];
+                    Span<byte> scanSsid = filter.Ssid.Name.AsSpan()[filter.Ssid.Length..];
+                    copy &= gameSsid.SequenceEqual(scanSsid);
+                }
+
+                if (filter.Flag.HasFlag(ScanFilterFlag.SceneId))
+                {
+                    copy &= filter.NetworkId.IntentId.SceneId == item.Value.NetworkId.IntentId.SceneId;
+                }
+
+                if (copy)
+                {
+                    if (item.Value.Ldn.Nodes[0].UserName[0] != 0)
+                    {
+                        outNetworkInfo.Add(item.Value);
+                    }
+                    else
+                    {
+                        Logger.Warning?.PrintMsg(LogClass.ServiceLdn, "LanDiscovery Scan: Got empty Username. There might be a timing issue somewhere...");
+                    }
+                }
+            }
+
+            return outNetworkInfo.ToArray();
+        }
+
+        protected void ResetStations()
+        {
+            lock (_lock)
+            {
+                foreach (LdnProxyTcpSession station in _stations)
+                {
+                    station.Disconnect();
+                    station.Dispose();
+                }
+
+                _stations.Clear();
+            }
+        }
+
+        private int LocateEmptyNode()
+        {
+            Array8<NodeInfo> nodes = NetworkInfo.Ldn.Nodes;
+
+            for (int i = 1; i < nodes.Length; i++)
+            {
+                if (nodes[i].IsConnected == 0)
+                {
+                    return i;
+                }
+            }
+
+            return -1;
+        }
+
+        protected void UpdateNodes(bool forceUpdate = false)
+        {
+            int countConnected = 1;
+
+            foreach (LdnProxyTcpSession station in _stations.Where(station => station.IsConnected))
+            {
+                countConnected++;
+
+                station.OverrideInfo();
+
+                // NOTE: This is not part of the original implementation.
+                NetworkInfo.Ldn.Nodes[station.NodeId] = station.NodeInfo;
+            }
+
+            byte nodeCount = (byte)countConnected;
+
+            bool networkInfoChanged = forceUpdate || NetworkInfo.Ldn.NodeCount != nodeCount;
+
+            NetworkInfo.Ldn.NodeCount = nodeCount;
+
+            foreach (LdnProxyTcpSession station in _stations)
+            {
+                if (station.IsConnected)
+                {
+                    if (_protocol.SendPacket(station, LanPacketType.SyncNetwork, SpanHelpers.AsSpan<NetworkInfo, byte>(ref NetworkInfo).ToArray()) < 0)
+                    {
+                        Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Failed to send {LanPacketType.SyncNetwork} to station {station.NodeId}");
+                    }
+                }
+            }
+
+            if (networkInfoChanged)
+            {
+                _parent.InvokeNetworkChange(NetworkInfo, true);
+            }
+        }
+
+        protected NodeInfo GetNodeInfo(NodeInfo node, UserConfig userConfig, ushort localCommunicationVersion)
+        {
+            uint ipAddress = NetworkHelpers.ConvertIpv4Address(LocalAddr);
+
+            node.MacAddress = GetFakeMac();
+            node.IsConnected = 1;
+            node.UserName = userConfig.UserName;
+            node.LocalCommunicationVersion = localCommunicationVersion;
+            node.Ipv4Address = ipAddress;
+
+            return node;
+        }
+
+        public bool CreateNetwork(SecurityConfig securityConfig, UserConfig userConfig, NetworkConfig networkConfig)
+        {
+            if (!InitTcp(true))
+            {
+                return false;
+            }
+
+            InitNetworkInfo();
+
+            NetworkInfo.Ldn.NodeCountMax = networkConfig.NodeCountMax;
+            NetworkInfo.Ldn.SecurityMode = (ushort)securityConfig.SecurityMode;
+
+            NetworkInfo.Common.Channel = networkConfig.Channel == 0 ? (ushort)6 : networkConfig.Channel;
+
+            NetworkInfo.NetworkId.SessionId = new Array16<byte>();
+            _random.NextBytes(NetworkInfo.NetworkId.SessionId.AsSpan());
+            NetworkInfo.NetworkId.IntentId = networkConfig.IntentId;
+
+            NetworkInfo.Ldn.Nodes[0] = GetNodeInfo(NetworkInfo.Ldn.Nodes[0], userConfig, networkConfig.LocalCommunicationVersion);
+            NetworkInfo.Ldn.Nodes[0].IsConnected = 1;
+            NetworkInfo.Ldn.NodeCount++;
+
+            _parent.InvokeNetworkChange(NetworkInfo, true);
+
+            return true;
+        }
+
+        public void DestroyNetwork()
+        {
+            if (_tcp != null)
+            {
+                try
+                {
+                    _tcp.DisconnectAndStop();
+                }
+                finally
+                {
+                    _tcp.Dispose();
+                    _tcp = null;
+                }
+            }
+
+            ResetStations();
+        }
+
+        public NetworkError Connect(NetworkInfo networkInfo, UserConfig userConfig, uint localCommunicationVersion)
+        {
+            _apConnected.Reset();
+
+            if (networkInfo.Ldn.NodeCount == 0)
+            {
+                return NetworkError.Unknown;
+            }
+
+            IPAddress address = NetworkHelpers.ConvertUint(networkInfo.Ldn.Nodes[0].Ipv4Address);
+
+            Logger.Info?.PrintMsg(LogClass.ServiceLdn, $"Connecting to host: {address}");
+
+            if (!InitTcp(false, address))
+            {
+                Logger.Error?.PrintMsg(LogClass.ServiceLdn, "Could not initialize TCPClient");
+
+                return NetworkError.ConnectNotFound;
+            }
+
+            if (!_tcp.Connect())
+            {
+                Logger.Error?.PrintMsg(LogClass.ServiceLdn, "Failed to connect.");
+
+                return NetworkError.ConnectFailure;
+            }
+
+            NodeInfo myNode = GetNodeInfo(new NodeInfo(), userConfig, (ushort)localCommunicationVersion);
+            if (_protocol.SendPacket(_tcp, LanPacketType.Connect, SpanHelpers.AsSpan<NodeInfo, byte>(ref myNode).ToArray()) < 0)
+            {
+                return NetworkError.Unknown;
+            }
+
+            return _apConnected.WaitOne(FailureTimeout) ? NetworkError.None : NetworkError.ConnectTimeout;
+        }
+
+        public void Dispose()
+        {
+            if (_initialized)
+            {
+                DisconnectAndStop();
+                ResetStations();
+                _initialized = false;
+            }
+
+            _protocol.Accept -= OnConnect;
+            _protocol.SyncNetwork -= OnSyncNetwork;
+            _protocol.DisconnectStation -= DisconnectStation;
+        }
+
+        public void DisconnectAndStop()
+        {
+            if (_udp != null)
+            {
+                try
+                {
+                    _udp.Stop();
+                }
+                finally
+                {
+                    _udp.Dispose();
+                    _udp = null;
+                }
+            }
+
+            if (_udp2 != null)
+            {
+                try
+                {
+                    _udp2.Stop();
+                }
+                finally
+                {
+                    _udp2.Dispose();
+                    _udp2 = null;
+                }
+            }
+
+            if (_tcp != null)
+            {
+                try
+                {
+                    _tcp.DisconnectAndStop();
+                }
+                finally
+                {
+                    _tcp.Dispose();
+                    _tcp = null;
+                }
+            }
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/LanProtocol.cs

@@ -0,0 +1,314 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
+using Ryujinx.Common.Utilities;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Types;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm
+{
+    internal class LanProtocol
+    {
+        private const uint LanMagic = 0x11451400;
+
+        public const int BufferSize = 2048;
+        public const int TcpTxBufferSize = 0x800;
+        public const int TcpRxBufferSize = 0x1000;
+        public const int TxBufferSizeMax = 0x2000;
+        public const int RxBufferSizeMax = 0x2000;
+
+        private readonly int _headerSize = Marshal.SizeOf<LanPacketHeader>();
+
+        private readonly LanDiscovery _discovery;
+
+        public event Action<LdnProxyTcpSession> Accept;
+        public event Action<EndPoint, LanPacketType, byte[]> Scan;
+        public event Action<NetworkInfo> ScanResponse;
+        public event Action<NetworkInfo> SyncNetwork;
+        public event Action<NodeInfo, EndPoint> Connect;
+        public event Action<LdnProxyTcpSession> DisconnectStation;
+
+        public LanProtocol(LanDiscovery parent)
+        {
+            _discovery = parent;
+        }
+
+        public void InvokeAccept(LdnProxyTcpSession session)
+        {
+            Accept?.Invoke(session);
+        }
+
+        public void InvokeDisconnectStation(LdnProxyTcpSession session)
+        {
+            DisconnectStation?.Invoke(session);
+        }
+
+        private void DecodeAndHandle(LanPacketHeader header, byte[] data, EndPoint endPoint = null)
+        {
+            switch (header.Type)
+            {
+                case LanPacketType.Scan:
+                    // UDP
+                    if (_discovery.IsHost)
+                    {
+                        Scan?.Invoke(endPoint, LanPacketType.ScanResponse, SpanHelpers.AsSpan<NetworkInfo, byte>(ref _discovery.NetworkInfo).ToArray());
+                    }
+                    break;
+                case LanPacketType.ScanResponse:
+                    // UDP
+                    ScanResponse?.Invoke(MemoryMarshal.Cast<byte, NetworkInfo>(data)[0]);
+                    break;
+                case LanPacketType.SyncNetwork:
+                    // TCP
+                    SyncNetwork?.Invoke(MemoryMarshal.Cast<byte, NetworkInfo>(data)[0]);
+                    break;
+                case LanPacketType.Connect:
+                    // TCP Session / Station
+                    Connect?.Invoke(MemoryMarshal.Cast<byte, NodeInfo>(data)[0], endPoint);
+                    break;
+                default:
+                    Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Decode error: Unhandled type {header.Type}");
+                    break;
+            }
+        }
+
+        public void Read(scoped ref byte[] buffer, scoped ref int bufferEnd, byte[] data, int offset, int size, EndPoint endPoint = null)
+        {
+            if (endPoint != null && _discovery.LocalAddr.Equals(((IPEndPoint)endPoint).Address))
+            {
+                return;
+            }
+
+            int index = 0;
+            while (index < size)
+            {
+                if (bufferEnd < _headerSize)
+                {
+                    int copyable2 = Math.Min(size - index, Math.Min(size, _headerSize - bufferEnd));
+
+                    Array.Copy(data, index + offset, buffer, bufferEnd, copyable2);
+
+                    index += copyable2;
+                    bufferEnd += copyable2;
+                }
+
+                if (bufferEnd >= _headerSize)
+                {
+                    LanPacketHeader header = MemoryMarshal.Cast<byte, LanPacketHeader>(buffer)[0];
+                    if (header.Magic != LanMagic)
+                    {
+                        bufferEnd = 0;
+
+                        Logger.Warning?.PrintMsg(LogClass.ServiceLdn, $"Invalid magic number in received packet. [magic: {header.Magic}] [EP: {endPoint}]");
+
+                        return;
+                    }
+
+                    int totalSize = _headerSize + header.Length;
+                    if (totalSize > BufferSize)
+                    {
+                        bufferEnd = 0;
+
+                        Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Max packet size {BufferSize} exceeded.");
+
+                        return;
+                    }
+
+                    int copyable = Math.Min(size - index, Math.Min(size, totalSize - bufferEnd));
+
+                    Array.Copy(data, index + offset, buffer, bufferEnd, copyable);
+
+                    index += copyable;
+                    bufferEnd += copyable;
+
+                    if (totalSize == bufferEnd)
+                    {
+                        byte[] ldnData = new byte[totalSize - _headerSize];
+                        Array.Copy(buffer, _headerSize, ldnData, 0, ldnData.Length);
+
+                        if (header.Compressed == 1)
+                        {
+                            if (Decompress(ldnData, out byte[] decompressedLdnData) != 0)
+                            {
+                                Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Decompress error:\n {header}, {_headerSize}\n {ldnData}, {ldnData.Length}");
+
+                                return;
+                            }
+
+                            if (decompressedLdnData.Length != header.DecompressLength)
+                            {
+                                Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Decompress error: length does not match. ({decompressedLdnData.Length} != {header.DecompressLength})");
+                                Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"Decompress error data: '{string.Join("", decompressedLdnData.Select(x => (int)x).ToArray())}'");
+
+                                return;
+                            }
+
+                            ldnData = decompressedLdnData;
+                        }
+
+                        DecodeAndHandle(header, ldnData, endPoint);
+
+                        bufferEnd = 0;
+                    }
+                }
+            }
+        }
+
+        public int SendBroadcast(ILdnSocket s, LanPacketType type, int port)
+        {
+            return SendPacket(s, type, Array.Empty<byte>(), new IPEndPoint(_discovery.LocalBroadcastAddr, port));
+        }
+
+        public int SendPacket(ILdnSocket s, LanPacketType type, byte[] data, EndPoint endPoint = null)
+        {
+            byte[] buf = PreparePacket(type, data);
+
+            return s.SendPacketAsync(endPoint, buf) ? 0 : -1;
+        }
+
+        public int SendPacket(LdnProxyTcpSession s, LanPacketType type, byte[] data)
+        {
+            byte[] buf = PreparePacket(type, data);
+
+            return s.SendAsync(buf) ? 0 : -1;
+        }
+
+        private LanPacketHeader PrepareHeader(LanPacketHeader header, LanPacketType type)
+        {
+            header.Magic = LanMagic;
+            header.Type = type;
+            header.Compressed = 0;
+            header.Length = 0;
+            header.DecompressLength = 0;
+            header.Reserved = new Array2<byte>();
+
+            return header;
+        }
+
+        private byte[] PreparePacket(LanPacketType type, byte[] data)
+        {
+            LanPacketHeader header = PrepareHeader(new LanPacketHeader(), type);
+            header.Length = (ushort)data.Length;
+
+            byte[] buf;
+            if (data.Length > 0)
+            {
+                if (Compress(data, out byte[] compressed) == 0)
+                {
+                    header.DecompressLength = header.Length;
+                    header.Length = (ushort)compressed.Length;
+                    header.Compressed = 1;
+
+                    buf = new byte[compressed.Length + _headerSize];
+
+                    SpanHelpers.AsSpan<LanPacketHeader, byte>(ref header).ToArray().CopyTo(buf, 0);
+                    compressed.CopyTo(buf, _headerSize);
+                }
+                else
+                {
+                    buf = new byte[data.Length + _headerSize];
+
+                    Logger.Error?.PrintMsg(LogClass.ServiceLdn, "Compressing packet data failed.");
+
+                    SpanHelpers.AsSpan<LanPacketHeader, byte>(ref header).ToArray().CopyTo(buf, 0);
+                    data.CopyTo(buf, _headerSize);
+                }
+            }
+            else
+            {
+                buf = new byte[_headerSize];
+                SpanHelpers.AsSpan<LanPacketHeader, byte>(ref header).ToArray().CopyTo(buf, 0);
+            }
+
+            return buf;
+        }
+
+        private int Compress(byte[] input, out byte[] output)
+        {
+            List<byte> outputList = new();
+            int i = 0;
+            int maxCount = 0xFF;
+
+            while (i < input.Length)
+            {
+                byte inputByte = input[i++];
+                int count = 0;
+
+                if (inputByte == 0)
+                {
+                    while (i < input.Length && input[i] == 0 && count < maxCount)
+                    {
+                        count += 1;
+                        i++;
+                    }
+                }
+
+                if (inputByte == 0)
+                {
+                    outputList.Add(0);
+
+                    if (outputList.Count == BufferSize)
+                    {
+                        output = null;
+
+                        return -1;
+                    }
+
+                    outputList.Add((byte)count);
+                }
+                else
+                {
+                    outputList.Add(inputByte);
+                }
+            }
+
+            output = outputList.ToArray();
+
+            return i == input.Length ? 0 : -1;
+        }
+
+        private int Decompress(byte[] input, out byte[] output)
+        {
+            List<byte> outputList = new();
+            int i = 0;
+
+            while (i < input.Length && outputList.Count < BufferSize)
+            {
+                byte inputByte = input[i++];
+
+                outputList.Add(inputByte);
+
+                if (inputByte == 0)
+                {
+                    if (i == input.Length)
+                    {
+                        output = null;
+
+                        return -1;
+                    }
+
+                    int count = input[i++];
+
+                    for (int j = 0; j < count; j++)
+                    {
+                        if (outputList.Count == BufferSize)
+                        {
+                            break;
+                        }
+
+                        outputList.Add(inputByte);
+                    }
+                }
+            }
+
+            output = outputList.ToArray();
+
+            return i == input.Length ? 0 : -1;
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/LdnMitmClient.cs

@@ -0,0 +1,104 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.Common.Utilities;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types;
+using System;
+using System.Net.NetworkInformation;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm
+{
+    /// <summary>
+    /// Client implementation for <a href="https://github.com/spacemeowx2/ldn_mitm">ldn_mitm</a>
+    /// </summary>
+    internal class LdnMitmClient : INetworkClient
+    {
+        public bool NeedsRealId => false;
+
+        public event EventHandler<NetworkChangeEventArgs> NetworkChange;
+
+        private readonly LanDiscovery _lanDiscovery;
+
+        public LdnMitmClient(HLEConfiguration config)
+        {
+            UnicastIPAddressInformation localIpInterface = NetworkHelpers.GetLocalInterface(config.MultiplayerLanInterfaceId).Item2;
+
+            _lanDiscovery = new LanDiscovery(this, localIpInterface.Address, localIpInterface.IPv4Mask);
+        }
+
+        internal void InvokeNetworkChange(NetworkInfo info, bool connected, DisconnectReason reason = DisconnectReason.None)
+        {
+            NetworkChange?.Invoke(this, new NetworkChangeEventArgs(info, connected: connected, disconnectReason: reason));
+        }
+
+        public NetworkError Connect(ConnectRequest request)
+        {
+            return _lanDiscovery.Connect(request.NetworkInfo, request.UserConfig, request.LocalCommunicationVersion);
+        }
+
+        public NetworkError ConnectPrivate(ConnectPrivateRequest request)
+        {
+            // NOTE: This method is not implemented in ldn_mitm
+            Logger.Stub?.PrintMsg(LogClass.ServiceLdn, "LdnMitmClient ConnectPrivate");
+
+            return NetworkError.None;
+        }
+
+        public bool CreateNetwork(CreateAccessPointRequest request, byte[] advertiseData)
+        {
+            return _lanDiscovery.CreateNetwork(request.SecurityConfig, request.UserConfig, request.NetworkConfig);
+        }
+
+        public bool CreateNetworkPrivate(CreateAccessPointPrivateRequest request, byte[] advertiseData)
+        {
+            // NOTE: This method is not implemented in ldn_mitm
+            Logger.Stub?.PrintMsg(LogClass.ServiceLdn, "LdnMitmClient CreateNetworkPrivate");
+
+            return true;
+        }
+
+        public void DisconnectAndStop()
+        {
+            _lanDiscovery.DisconnectAndStop();
+        }
+
+        public void DisconnectNetwork()
+        {
+            _lanDiscovery.DestroyNetwork();
+        }
+
+        public ResultCode Reject(DisconnectReason disconnectReason, uint nodeId)
+        {
+            // NOTE: This method is not implemented in ldn_mitm
+            Logger.Stub?.PrintMsg(LogClass.ServiceLdn, "LdnMitmClient Reject");
+
+            return ResultCode.Success;
+        }
+
+        public NetworkInfo[] Scan(ushort channel, ScanFilter scanFilter)
+        {
+            return _lanDiscovery.Scan(channel, scanFilter);
+        }
+
+        public void SetAdvertiseData(byte[] data)
+        {
+            _lanDiscovery.SetAdvertiseData(data);
+        }
+
+        public void SetGameVersion(byte[] versionString)
+        {
+            // NOTE: This method is not implemented in ldn_mitm
+            Logger.Stub?.PrintMsg(LogClass.ServiceLdn, "LdnMitmClient SetGameVersion");
+        }
+
+        public void SetStationAcceptPolicy(AcceptPolicy acceptPolicy)
+        {
+            // NOTE: This method is not implemented in ldn_mitm
+            Logger.Stub?.PrintMsg(LogClass.ServiceLdn, "LdnMitmClient SetStationAcceptPolicy");
+        }
+
+        public void Dispose()
+        {
+            _lanDiscovery.Dispose();
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/ILdnSocket.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Net;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy
+{
+    internal interface ILdnSocket : IDisposable
+    {
+        bool SendPacketAsync(EndPoint endpoint, byte[] buffer);
+        bool Start();
+        bool Stop();
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/ILdnTcpSocket.cs

@@ -0,0 +1,8 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy
+{
+    internal interface ILdnTcpSocket : ILdnSocket
+    {
+        bool Connect();
+        void DisconnectAndStop();
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/LdnProxyTcpClient.cs

@@ -0,0 +1,99 @@
+using Ryujinx.Common.Logging;
+using System;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy
+{
+    internal class LdnProxyTcpClient : NetCoreServer.TcpClient, ILdnTcpSocket
+    {
+        private readonly LanProtocol _protocol;
+        private byte[] _buffer;
+        private int _bufferEnd;
+
+        public LdnProxyTcpClient(LanProtocol protocol, IPAddress address, int port) : base(address, port)
+        {
+            _protocol = protocol;
+            _buffer = new byte[LanProtocol.BufferSize];
+            OptionSendBufferSize = LanProtocol.TcpTxBufferSize;
+            OptionReceiveBufferSize = LanProtocol.TcpRxBufferSize;
+            OptionSendBufferLimit = LanProtocol.TxBufferSizeMax;
+            OptionReceiveBufferLimit = LanProtocol.RxBufferSizeMax;
+        }
+
+        protected override void OnConnected()
+        {
+            Logger.Info?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyTCPClient connected!");
+        }
+
+        protected override void OnReceived(byte[] buffer, long offset, long size)
+        {
+            _protocol.Read(ref _buffer, ref _bufferEnd, buffer, (int)offset, (int)size);
+        }
+
+        public void DisconnectAndStop()
+        {
+            DisconnectAsync();
+
+            while (IsConnected)
+            {
+                Thread.Yield();
+            }
+        }
+
+        public bool SendPacketAsync(EndPoint endPoint, byte[] data)
+        {
+            if (endPoint != null)
+            {
+                Logger.Warning?.PrintMsg(LogClass.ServiceLdn, "LdnProxyTcpClient is sending a packet but endpoint is not null.");
+            }
+
+            if (IsConnecting && !IsConnected)
+            {
+                Logger.Info?.PrintMsg(LogClass.ServiceLdn, "LdnProxyTCPClient needs to connect before sending packets. Waiting...");
+
+                while (IsConnecting && !IsConnected)
+                {
+                    Thread.Yield();
+                }
+            }
+
+            return SendAsync(data);
+        }
+
+        protected override void OnError(SocketError error)
+        {
+            Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyTCPClient caught an error with code {error}");
+        }
+
+        protected override void Dispose(bool disposingManagedResources)
+        {
+            DisconnectAndStop();
+            base.Dispose(disposingManagedResources);
+        }
+
+        public override bool Connect()
+        {
+            // TODO: NetCoreServer has a Connect() method, but it currently leads to weird issues.
+            base.ConnectAsync();
+
+            while (IsConnecting)
+            {
+                Thread.Sleep(1);
+            }
+
+            return IsConnected;
+        }
+
+        public bool Start()
+        {
+            throw new InvalidOperationException("Start was called.");
+        }
+
+        public bool Stop()
+        {
+            throw new InvalidOperationException("Stop was called.");
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/LdnProxyTcpServer.cs

@@ -0,0 +1,54 @@
+using NetCoreServer;
+using Ryujinx.Common.Logging;
+using System;
+using System.Net;
+using System.Net.Sockets;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy
+{
+    internal class LdnProxyTcpServer : TcpServer, ILdnTcpSocket
+    {
+        private readonly LanProtocol _protocol;
+
+        public LdnProxyTcpServer(LanProtocol protocol, IPAddress address, int port) : base(address, port)
+        {
+            _protocol = protocol;
+            OptionReuseAddress = true;
+            OptionSendBufferSize = LanProtocol.TcpTxBufferSize;
+            OptionReceiveBufferSize = LanProtocol.TcpRxBufferSize;
+
+            Logger.Info?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyTCPServer created a server for this address: {address}:{port}");
+        }
+
+        protected override TcpSession CreateSession()
+        {
+            return new LdnProxyTcpSession(this, _protocol);
+        }
+
+        protected override void OnError(SocketError error)
+        {
+            Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyTCPServer caught an error with code {error}");
+        }
+
+        protected override void Dispose(bool disposingManagedResources)
+        {
+            Stop();
+            base.Dispose(disposingManagedResources);
+        }
+
+        public bool Connect()
+        {
+            throw new InvalidOperationException("Connect was called.");
+        }
+
+        public void DisconnectAndStop()
+        {
+            Stop();
+        }
+
+        public bool SendPacketAsync(EndPoint endpoint, byte[] buffer)
+        {
+            throw new InvalidOperationException("SendPacketAsync was called.");
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/LdnProxyTcpSession.cs

@@ -0,0 +1,83 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using System.Net;
+using System.Net.Sockets;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy
+{
+    internal class LdnProxyTcpSession : NetCoreServer.TcpSession
+    {
+        private readonly LanProtocol _protocol;
+
+        internal int NodeId;
+        internal NodeInfo NodeInfo;
+
+        private byte[] _buffer;
+        private int _bufferEnd;
+
+        public LdnProxyTcpSession(LdnProxyTcpServer server, LanProtocol protocol) : base(server)
+        {
+            _protocol = protocol;
+            _protocol.Connect += OnConnect;
+            _buffer = new byte[LanProtocol.BufferSize];
+            OptionSendBufferSize = LanProtocol.TcpTxBufferSize;
+            OptionReceiveBufferSize = LanProtocol.TcpRxBufferSize;
+            OptionSendBufferLimit = LanProtocol.TxBufferSizeMax;
+            OptionReceiveBufferLimit = LanProtocol.RxBufferSizeMax;
+        }
+
+        public void OverrideInfo()
+        {
+            NodeInfo.NodeId = (byte)NodeId;
+            NodeInfo.IsConnected = (byte)(IsConnected ? 1 : 0);
+        }
+
+        protected override void OnConnected()
+        {
+            Logger.Info?.PrintMsg(LogClass.ServiceLdn, "LdnProxyTCPSession connected!");
+        }
+
+        protected override void OnDisconnected()
+        {
+            Logger.Info?.PrintMsg(LogClass.ServiceLdn, "LdnProxyTCPSession disconnected!");
+
+            _protocol.InvokeDisconnectStation(this);
+        }
+
+        protected override void OnReceived(byte[] buffer, long offset, long size)
+        {
+            _protocol.Read(ref _buffer, ref _bufferEnd, buffer, (int)offset, (int)size, this.Socket.RemoteEndPoint);
+        }
+
+        protected override void OnError(SocketError error)
+        {
+            Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyTCPSession caught an error with code {error}");
+
+            Dispose();
+        }
+
+        protected override void Dispose(bool disposingManagedResources)
+        {
+            _protocol.Connect -= OnConnect;
+            base.Dispose(disposingManagedResources);
+        }
+
+        private void OnConnect(NodeInfo info, EndPoint endPoint)
+        {
+            try
+            {
+                if (endPoint.Equals(this.Socket.RemoteEndPoint))
+                {
+                    NodeInfo = info;
+                    _protocol.InvokeAccept(this);
+                }
+            }
+            catch (System.ObjectDisposedException)
+            {
+                Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyTCPSession was disposed. [IP: {NodeInfo.Ipv4Address}]");
+
+                _protocol.InvokeDisconnectStation(this);
+            }
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/LdnProxyUdpServer.cs

@@ -0,0 +1,157 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.HLE.HOS.Services.Ldn.Types;
+using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Types;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Proxy
+{
+    internal class LdnProxyUdpServer : NetCoreServer.UdpServer, ILdnSocket
+    {
+        private const long ScanFrequency = 1000;
+
+        private readonly LanProtocol _protocol;
+        private byte[] _buffer;
+        private int _bufferEnd;
+
+        private readonly object _scanLock = new();
+
+        private Dictionary<ulong, NetworkInfo> _scanResultsLast = new();
+        private Dictionary<ulong, NetworkInfo> _scanResults = new();
+        private readonly AutoResetEvent _scanResponse = new(false);
+        private long _lastScanTime;
+
+        public LdnProxyUdpServer(LanProtocol protocol, IPAddress address, int port) : base(address, port)
+        {
+            _protocol = protocol;
+            _protocol.Scan += HandleScan;
+            _protocol.ScanResponse += HandleScanResponse;
+            _buffer = new byte[LanProtocol.BufferSize];
+            OptionReuseAddress = true;
+            OptionReceiveBufferSize = LanProtocol.RxBufferSizeMax;
+            OptionSendBufferSize = LanProtocol.TxBufferSizeMax;
+
+            Start();
+        }
+
+        protected override Socket CreateSocket()
+        {
+            return new Socket(Endpoint.AddressFamily, SocketType.Dgram, ProtocolType.Udp)
+            {
+                EnableBroadcast = true,
+            };
+        }
+
+        protected override void OnStarted()
+        {
+            ReceiveAsync();
+        }
+
+        protected override void OnReceived(EndPoint endpoint, byte[] buffer, long offset, long size)
+        {
+            _protocol.Read(ref _buffer, ref _bufferEnd, buffer, (int)offset, (int)size, endpoint);
+            ReceiveAsync();
+        }
+
+        protected override void OnError(SocketError error)
+        {
+            Logger.Error?.PrintMsg(LogClass.ServiceLdn, $"LdnProxyUdpServer caught an error with code {error}");
+        }
+
+        protected override void Dispose(bool disposingManagedResources)
+        {
+            _protocol.Scan -= HandleScan;
+            _protocol.ScanResponse -= HandleScanResponse;
+
+            _scanResponse.Dispose();
+
+            base.Dispose(disposingManagedResources);
+        }
+
+        public bool SendPacketAsync(EndPoint endpoint, byte[] data)
+        {
+            return SendAsync(endpoint, data);
+        }
+
+        private void HandleScan(EndPoint endpoint, LanPacketType type, byte[] data)
+        {
+            _protocol.SendPacket(this, type, data, endpoint);
+        }
+
+        private void HandleScanResponse(NetworkInfo info)
+        {
+            Span<byte> mac = stackalloc byte[8];
+
+            info.Common.MacAddress.AsSpan().CopyTo(mac);
+
+            lock (_scanLock)
+            {
+                _scanResults[BitConverter.ToUInt64(mac)] = info;
+
+                _scanResponse.Set();
+            }
+        }
+
+        public void ClearScanResults()
+        {
+            // Rate limit scans.
+
+            long timeMs = Stopwatch.GetTimestamp() / (Stopwatch.Frequency / 1000);
+            long delay = ScanFrequency - (timeMs - _lastScanTime);
+
+            if (delay > 0)
+            {
+                Thread.Sleep((int)delay);
+            }
+
+            _lastScanTime = timeMs;
+
+            lock (_scanLock)
+            {
+                var newResults = _scanResultsLast;
+                newResults.Clear();
+
+                _scanResultsLast = _scanResults;
+                _scanResults = newResults;
+
+                _scanResponse.Reset();
+            }
+        }
+
+        public Dictionary<ulong, NetworkInfo> GetScanResults()
+        {
+            // NOTE: Try to minimize waiting time for scan results.
+            // After we receive the first response, wait a short time for follow-ups and return.
+            // Responses that were too late to catch will appear in the next scan.
+
+            // ldn_mitm does not do this, but this improves latency for games that expect it to be low (it is on console).
+
+            if (_scanResponse.WaitOne(1000))
+            {
+                // Wait a short while longer in case there are some other responses.
+                Thread.Sleep(33);
+            }
+
+            lock (_scanLock)
+            {
+                var results = new Dictionary<ulong, NetworkInfo>();
+
+                foreach (KeyValuePair<ulong, NetworkInfo> last in _scanResultsLast)
+                {
+                    results[last.Key] = last.Value;
+                }
+
+                foreach (KeyValuePair<ulong, NetworkInfo> scan in _scanResults)
+                {
+                    results[scan.Key] = scan.Value;
+                }
+
+                return results;
+            }
+        }
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Types/LanPacketHeader.cs

@@ -0,0 +1,16 @@
+using Ryujinx.Common.Memory;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Types
+{
+    [StructLayout(LayoutKind.Sequential, Size = 12)]
+    internal struct LanPacketHeader
+    {
+        public uint Magic;
+        public LanPacketType Type;
+        public byte Compressed;
+        public ushort Length;
+        public ushort DecompressLength;
+        public Array2<byte> Reserved;
+    }
+}

src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Types/LanPacketType.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.LdnMitm.Types
+{
+    internal enum LanPacketType : byte
+    {
+        Scan,
+        ScanResponse,
+        Connect,
+        SyncNetwork,
+    }
+}

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

@@ -1,7 +1,7 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
 using System;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
 {
     class NetworkChangeEventArgs : EventArgs
     {

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

@@ -1,7 +1,6 @@
 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.Types;
-using Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types;
 using System;
 
 namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
@@ -22,7 +21,7 @@ namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator
             _parent.NetworkClient.NetworkChange += NetworkChanged;
         }
 
-        private void NetworkChanged(object sender, RyuLdn.NetworkChangeEventArgs e)
+        private void NetworkChanged(object sender, NetworkChangeEventArgs e)
         {
             LatestUpdates.CalculateLatestUpdate(NetworkInfo.Ldn.Nodes, e.Info.Ldn.Nodes);
 

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

@@ -1,7 +1,7 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
 using System.Runtime.InteropServices;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types
 {
     [StructLayout(LayoutKind.Sequential, Size = 0xBC)]
     struct ConnectPrivateRequest

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

@@ -1,7 +1,7 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
 using System.Runtime.InteropServices;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types
 {
     [StructLayout(LayoutKind.Sequential, Size = 0x4FC)]
     struct ConnectRequest

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

@@ -1,7 +1,7 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
 using System.Runtime.InteropServices;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types
 {
     /// <remarks>
     /// Advertise data is appended separately (remaining data in the buffer).

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

@@ -1,7 +1,7 @@
 using Ryujinx.HLE.HOS.Services.Ldn.Types;
 using System.Runtime.InteropServices;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Network.Types
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types
 {
     /// <remarks>
     /// Advertise data is appended separately (remaining data in the buffer).

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

@@ -1,4 +1,4 @@
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types
 {
     enum NetworkError : int
     {

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

@@ -1,6 +1,6 @@
 using System.Runtime.InteropServices;
 
-namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.RyuLdn.Types
+namespace Ryujinx.HLE.HOS.Services.Ldn.UserServiceCreator.Types
 {
     [StructLayout(LayoutKind.Sequential, Size = 0x4)]
     struct NetworkErrorMessage

src/Ryujinx.HLE/HOS/Services/ServerBase.cs

@@ -39,6 +39,8 @@ namespace Ryujinx.HLE.HOS.Services
         private readonly KernelContext _context;
         private KProcess _selfProcess;
         private KThread _selfThread;
+        private KEvent _wakeEvent;
+        private int _wakeHandle = 0;
 
         private readonly ReaderWriterLockSlim _handleLock = new();
         private readonly Dictionary<int, IpcService> _sessions = new();
@@ -125,6 +127,8 @@ namespace Ryujinx.HLE.HOS.Services
                     _handleLock.ExitWriteLock();
                 }
             }
+
+            _wakeEvent.WritableEvent.Signal();
         }
 
         private IpcService GetSessionObj(int serverSessionHandle)
@@ -195,9 +199,11 @@ namespace Ryujinx.HLE.HOS.Services
             _selfProcess.CpuMemory.Write(messagePtr + 0x0, 0);
             _selfProcess.CpuMemory.Write(messagePtr + 0x4, 2 << 10);
             _selfProcess.CpuMemory.Write(messagePtr + 0x8, heapAddr | ((ulong)PointerBufferSize << 48));
-
             int replyTargetHandle = 0;
 
+            _wakeEvent = new KEvent(_context);
+            Result result = _selfProcess.HandleTable.GenerateHandle(_wakeEvent.ReadableEvent, out _wakeHandle);
+
             while (true)
             {
                 int portHandleCount;
@@ -211,13 +217,15 @@ namespace Ryujinx.HLE.HOS.Services
 
                     portHandleCount = _ports.Count;
 
-                    handleCount = portHandleCount + _sessions.Count;
+                    handleCount = portHandleCount + _sessions.Count + 1;
 
                     handles = ArrayPool<int>.Shared.Rent(handleCount);
 
-                    _ports.Keys.CopyTo(handles, 0);
+                    handles[0] = _wakeHandle;
 
-                    _sessions.Keys.CopyTo(handles, portHandleCount);
+                    _ports.Keys.CopyTo(handles, 1);
+
+                    _sessions.Keys.CopyTo(handles, portHandleCount + 1);
                 }
                 finally
                 {
@@ -227,8 +235,7 @@ namespace Ryujinx.HLE.HOS.Services
                     }
                 }
 
-                // We still need a timeout here to allow the service to pick up and listen new sessions...
+                var rc = _context.Syscall.ReplyAndReceive(out int signaledIndex, handles.AsSpan(0, handleCount), replyTargetHandle, -1);
-                var rc = _context.Syscall.ReplyAndReceive(out int signaledIndex, handles.AsSpan(0, handleCount), replyTargetHandle, 1000000L);
 
                 _selfThread.HandlePostSyscall();
 
@@ -239,7 +246,7 @@ namespace Ryujinx.HLE.HOS.Services
 
                 replyTargetHandle = 0;
 
-                if (rc == Result.Success && signaledIndex >= portHandleCount)
+                if (rc == Result.Success && signaledIndex >= portHandleCount + 1)
                 {
                     // We got a IPC request, process it, pass to the appropriate service if needed.
                     int signaledHandle = handles[signaledIndex];
@@ -252,6 +259,8 @@ namespace Ryujinx.HLE.HOS.Services
                 else
                 {
                     if (rc == Result.Success)
+                    {
+                        if (signaledIndex > 0)
                         {
                             // We got a new connection, accept the session to allow servicing future requests.
                             if (_context.Syscall.AcceptSession(out int serverSessionHandle, handles[signaledIndex]) == Result.Success)
@@ -272,6 +281,12 @@ namespace Ryujinx.HLE.HOS.Services
                                 }
                             }
                         }
+                        else
+                        {
+                            // The _wakeEvent signalled, which means we have a new session.
+                            _wakeEvent.WritableEvent.Clear();
+                        }
+                    }
 
                     _selfProcess.CpuMemory.Write(messagePtr + 0x0, 0);
                     _selfProcess.CpuMemory.Write(messagePtr + 0x4, 2 << 10);
@@ -499,6 +514,8 @@ namespace Ryujinx.HLE.HOS.Services
 
                 if (Interlocked.Exchange(ref _isDisposed, 1) == 0)
                 {
+                    _selfProcess.HandleTable.CloseHandle(_wakeHandle);
+
                     foreach (IpcService service in _sessions.Values)
                     {
                         (service as IDisposable)?.Dispose();

src/Ryujinx.HLE/Ryujinx.HLE.csproj

@@ -27,6 +27,7 @@
     <PackageReference Include="SixLabors.ImageSharp" />
     <PackageReference Include="SixLabors.ImageSharp.Drawing" />
     <PackageReference Include="System.IdentityModel.Tokens.Jwt" />
+    <PackageReference Include="NetCoreServer" />
   </ItemGroup>
 
   <!-- Due to Concentus. -->

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

@@ -571,6 +571,7 @@ namespace Ryujinx.Ui.Common.Configuration
             {
                 LanInterfaceId = new ReactiveObject<string>();
                 Mode = new ReactiveObject<MultiplayerMode>();
+                Mode.Event += static (_, e) => LogValueChange(e, nameof(MultiplayerMode));
             }
         }
 

src/Ryujinx/Ui/MainWindow.cs

@@ -1121,6 +1121,14 @@ namespace Ryujinx.Ui
             Graphics.Gpu.GraphicsConfig.EnableMacroHLE = ConfigurationState.Instance.Graphics.EnableMacroHLE;
         }
 
+        public void UpdateInternetAccess()
+        {
+            if (_gameLoaded)
+            {
+                _emulationContext.Configuration.EnableInternetAccess = ConfigurationState.Instance.System.EnableInternetAccess.Value;
+            }
+        }
+
         public static void SaveConfig()
         {
             ConfigurationState.Instance.ToFileFormat().SaveConfig(Program.ConfigurationPath);

src/Ryujinx/Ui/Windows/SettingsWindow.cs

@@ -671,6 +671,8 @@ namespace Ryujinx.Ui.Windows
             }
 
             ConfigurationState.Instance.ToFileFormat().SaveConfig(Program.ConfigurationPath);
+
+            _parent.UpdateInternetAccess();
             MainWindow.UpdateGraphicsConfig();
             ThemeHelper.ApplyTheme();
         }

src/Ryujinx/Ui/Windows/SettingsWindow.glade

@@ -2993,6 +2993,7 @@
                                         <property name="active-id">Disabled</property>
                                         <items>
                                           <item id="Disabled" translatable="yes">Disabled</item>
+                                          <item id="LdnMitm" translatable="yes">ldn_mitm</item>
                                         </items>
                                       </object>
                                       <packing>
@@ -3064,7 +3065,7 @@
                                       <object class="GtkLabel">
                                         <property name="visible">True</property>
                                         <property name="can-focus">False</property>
-                                        <property name="tooltip-text" translatable="yes">The network interface used for LAN features</property>
+                                        <property name="tooltip-text" translatable="yes">The network interface used for LAN/LDN features</property>
                                         <property name="halign">end</property>
                                         <property name="label" translatable="yes">Network Interface:</property>
                                       </object>
@@ -3079,7 +3080,7 @@
                                       <object class="GtkComboBoxText" id="_multiLanSelect">
                                         <property name="visible">True</property>
                                         <property name="can-focus">False</property>
-                                        <property name="tooltip-text" translatable="yes">The network interface used for LAN features</property>
+                                        <property name="tooltip-text" translatable="yes">The network interface used for LAN/LDN features</property>
                                         <property name="active-id">0</property>
                                         <items>
                                           <item id="0" translatable="yes">Default</item>