2.4.3: Prevent HTTP sockets from using IPv6

DepotDownloader/ContentDownloader.cs

@@ -440,7 +440,7 @@ namespace DepotDownloader
             Directory.CreateDirectory( Path.GetDirectoryName( fileStagingPath ) );
 
             using ( var file = File.OpenWrite( fileStagingPath ) )
-            using ( var client = new HttpClient() )
+            using ( var client = HttpClientFactory.CreateHttpClient() )
             {
                 Console.WriteLine( "Downloading {0}", fileName );
                 var responseStream = await client.GetStreamAsync( url );

DepotDownloader/HttpClientFactory.cs

@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Net.Sockets;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace DepotDownloader
+{
+    // This is based on the dotnet issue #44686 and its workaround at https://github.com/dotnet/runtime/issues/44686#issuecomment-733797994
+    // We don't know if the IPv6 stack is functional.
+    class HttpClientFactory
+    {
+        public static HttpClient CreateHttpClient()
+        {
+            var client = new HttpClient(new SocketsHttpHandler
+            {
+                ConnectCallback = IPv4ConnectAsync
+            });
+
+            var assemblyVersion = typeof(HttpClientFactory).Assembly.GetName().Version.ToString(fieldCount: 3);
+            client.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("DepotDownloader", assemblyVersion));
+
+            return client;
+        }
+
+        static async ValueTask<Stream> IPv4ConnectAsync(SocketsHttpConnectionContext context, CancellationToken cancellationToken)
+        {
+            // By default, we create dual-mode sockets:
+            // Socket socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
+
+            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+            socket.NoDelay = true;
+
+            try
+            {
+                await socket.ConnectAsync(context.DnsEndPoint, cancellationToken).ConfigureAwait(false);
+                return new NetworkStream(socket, ownsSocket: true);
+            }
+            catch
+            {
+                socket.Dispose();
+                throw;
+            }
+        }
+    }
+}

DepotDownloader/Properties/AssemblyInfo.cs

@@ -31,4 +31,4 @@ using System.Runtime.InteropServices;
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("2.4.2.0")]
+[assembly: AssemblyVersion("2.4.3.0")]

DepotDownloader/Steam3Session.cs

@@ -89,7 +89,12 @@ namespace DepotDownloader
             this.PackageInfo = new Dictionary<uint, SteamApps.PICSProductInfoCallback.PICSProductInfo>();
             this.AppBetaPasswords = new Dictionary<string, byte[]>();
 
-            this.steamClient = new SteamClient();
+            var clientConfiguration = SteamConfiguration.Create(config =>
+                config
+                .WithHttpClientFactory(HttpClientFactory.CreateHttpClient)
+            );
+
+            this.steamClient = new SteamClient(clientConfiguration);
 
             this.steamUser = this.steamClient.GetHandler<SteamUser>();
             this.steamApps = this.steamClient.GetHandler<SteamApps>();
@@ -531,6 +536,9 @@ namespace DepotDownloader
             if ( disconnected.UserInitiated || bExpectingDisconnectRemote )
             {
                 Console.WriteLine( "Disconnected from Steam" );
+
+                // Any operations outstanding need to be aborted
+                bAborted = true;
             }
             else if ( connectionBackoff >= 10 )
             {