1 files changed, 157 insertions, 0 deletions
diff --git a/src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/LdnProxyUdpServer.cs b/src/Ryujinx.HLE/HOS/Services/Ldn/UserServiceCreator/LdnMitm/Proxy/LdnProxyUdpServer.cs
new file mode 100644
index 00000000..b1519d1f
--- /dev/null
+++ b/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;
+            }
+        }
+    }
+}