UPnP support

TorrentCore.Cli/Program.cs

@@ -33,11 +33,13 @@ public static void Main(string[] args)
             string input = null;
             string output = null;
             bool verbose = false;
+            bool upnp = false;
             ArgumentSyntax.Parse(args, syntax =>
             {
                 syntax.DefineOption("p|port", ref port, "Port to listen for incoming connections on.");
                 syntax.DefineOption("o|output", ref output, "Path to save downloaded files to.");
                 syntax.DefineOption("v|verbose", ref verbose, "Show detailed logging information.");
+                syntax.DefineOption("u|upnp", ref upnp, "Use UPnP for port forwarding.");
                 var uiPortArgument = syntax.DefineOption("ui", ref uiPort, false, "Run a web UI, optionally specifying the port to listen on (default: 5001).");
                 runWebUi = uiPortArgument.IsSpecified;
 
@@ -53,6 +55,10 @@ public static void Main(string[] args)
             // Listen for incoming connections on the specified port
             builder.UsePort(port);
 
+            // If upnp is selected use it.
+            if (upnp)
+                builder.AddUPnP();
+
             // Add extension protocol
             builder.ConfigureServices(services =>
             {

TorrentCore.Cli/TorrentCore.Cli.csproj

@@ -12,6 +12,10 @@
     <DocumentationFile>bin\Debug\$(AssemblyName).xml</DocumentationFile>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+  </PropertyGroup>
+
   <ItemGroup>
     <AdditionalFiles Include="..\stylecop.json" Visible="false" />
   </ItemGroup>

TorrentCore/TorrentClientBuilder.cs

@@ -88,6 +88,16 @@ public TorrentClientBuilder UsePort(int port)
             return this;
         }
 
+        /// <summary>
+        /// Add UPnP port forwarding feature.
+        /// </summary>
+        /// <returns>TorrentClientBuilder.</returns>
+        public TorrentClientBuilder AddUPnP()
+        {
+            _services.Configure<LocalTcpConnectionOptions>(options => options.UseUPnP = true);
+            return this;
+        }
+
         /// <summary>
         /// Sets up a default Torrent Client using the TCP transport protocol and the BitTorrent application protocol.
         /// </summary>

TorrentCore/TorrentClientSettings.cs

@@ -21,13 +21,19 @@ public TorrentClientSettings()
             PeerId = PeerId.CreateNew();
             ListenPort = 6881;
             AdapterAddress = IPAddress.Any;
+            UseUPnP = false;
         }
 
         /// <summary>
         /// Gets or sets the Peer ID for the local client.
         /// </summary>
         public PeerId PeerId { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether to use UPnP for port forwarding.
+        /// </summary>
+        public bool UseUPnP { get; set; }
+
         /// <summary>
         /// Gets or sets the port to listen for incoming connections on.
         /// </summary>

TorrentCore/TorrentCore.csproj

@@ -25,6 +25,7 @@
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="2.2.0" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="2.2.0" />
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="2.2.0" />
+    <PackageReference Include="Open.NAT.Core" Version="2.1.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.118" PrivateAssets="All" />
     <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
     <PackageReference Include="System.Net.Sockets" Version="4.3.0" />

TorrentCore/Transport/IUPnPClient.cs

@@ -0,0 +1,16 @@
+// This file is part of TorrentCore.
+//   https://torrentcore.org
+// Copyright (c) Samuel Fisher.
+//
+// Licensed under the GNU Lesser General Public License, version 3. See the
+// LICENSE file in the project root for full license information.
+
+using System.Threading.Tasks;
+
+namespace TorrentCore.Transport
+{
+    public interface IUPnPClient
+    {
+        Task TryAddPortMappingAsync(int port);
+    }
+}

TorrentCore/Transport/Tcp/LocalTcpConnectionOptions.cs

@@ -28,5 +28,10 @@ public class LocalTcpConnectionOptions
         /// Gets or sets the address of the local adapter used for connections.
         /// </summary>
         public IPAddress BindAddress { get; set; } = IPAddress.Any;
+
+        /// <summary>
+        /// Gets or sets a value indicating whether to use UPnP for port forwarding.
+        /// </summary>
+        public bool UseUPnP { get; set; }
     }
 }

TorrentCore/Transport/Tcp/TcpTransportProtocol.cs

@@ -27,6 +27,7 @@ class TcpTransportProtocol : ITcpTransportProtocol
     {
         private readonly ILogger<TcpTransportProtocol> _logger;
         private readonly ConcurrentBag<TcpTransportStream> _streams;
+        private readonly IUPnPClient _uPnPClient;
 
         private TcpListener _listener;
 
@@ -40,6 +41,7 @@ public TcpTransportProtocol(ILogger<TcpTransportProtocol> logger, IOptions<Local
             _logger = logger;
             _streams = new ConcurrentBag<TcpTransportStream>();
             Port = options.Value.Port;
+            _uPnPClient = new TcpTransportUPnPClient(options.Value.UseUPnP);
             LocalBindAddress = options.Value.BindAddress ?? IPAddress.Any;
             RateLimiter = new RateLimiter();
         }
@@ -108,6 +110,8 @@ public void Start()
             // If port=0 was supplied, set the actual port we are listening on.
             Port = ((IPEndPoint)_listener.LocalEndpoint).Port;
             ListenForIncomingConnections();
+
+            _uPnPClient.TryAddPortMappingAsync(Port);
         }
 
         /// <summary>

TorrentCore/Transport/Tcp/TcpTransportUPnPClient.cs

@@ -0,0 +1,42 @@
+// This file is part of TorrentCore.
+//   https://torrentcore.org
+// Copyright (c) Samuel Fisher.
+//
+// Licensed under the GNU Lesser General Public License, version 3. See the
+// LICENSE file in the project root for full license information.
+
+using System.Threading;
+using System.Threading.Tasks;
+using Open.Nat;
+
+namespace TorrentCore.Transport.Tcp
+{
+    class TcpTransportUPnPClient : IUPnPClient
+    {
+        private bool _useUPnP;
+
+        public TcpTransportUPnPClient(bool useUPnP)
+        {
+            _useUPnP = useUPnP;
+        }
+
+        public async Task TryAddPortMappingAsync(int port)
+        {
+            if (!_useUPnP)
+                return;
+
+            try
+            {
+                var discoverer = new NatDiscoverer();
+                var cts = new CancellationTokenSource(10000);
+
+                var device = await discoverer.DiscoverDeviceAsync(PortMapper.Upnp, cts);
+                await device.CreatePortMapAsync(new Mapping(Protocol.Tcp, port, port, "TorrentCore"));
+            }
+            catch
+            {
+                // Do nothing
+            }
+        }
+    }
+}