ISSUE#416 Fixed Socket.ConnectAsync timeout issue

src/Docker.DotNet/Microsoft.Net.Http.Client/ManagedHandler.cs

@@ -332,7 +332,19 @@ private static async Task<Socket> TCPSocketOpenerAsync(string host, int port, Ca
                 var s = new Socket(address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
                 try
                 {
-                    await s.ConnectAsync(address, port).ConfigureAwait(false);
+#if (NETSTANDARD1_3 || NETSTANDARD1_6 || NETSTANDARD2_0)
+                    // TODO: This method can be replaced by native ConnectAsync when this functionality is available:
+                    // https://github.com/dotnet/runtime/pull/40750
+                    await s.ConnectAsync(address, port, cancellationToken).ConfigureAwait(false);
+#else
+                    await Task.Factory.FromAsync(
+                        s.BeginConnect,
+                        s.EndConnect,
+                        new IPEndPoint(address, port),
+                        null
+                    ).ConfigureAwait(false);
+#endif
+
                     connectedSocket = s;
                     break;
                 }

src/Docker.DotNet/Microsoft.Net.Http.Client/SocketExtensionMethods.cs

@@ -0,0 +1,18 @@
+using System.Net;
+using System.Net.Sockets;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.Net.Http.Client
+{
+    public static class SocketExtensionMethods
+    {
+        public static async Task ConnectAsync(this Socket socket, IPAddress address, int port, CancellationToken cancellationToken)
+        {
+            Task socketConnectTask = socket.ConnectAsync(address, port);
+            Task delayTask = Task.Delay(int.MaxValue, cancellationToken);
+
+            await await Task.WhenAny(socketConnectTask, delayTask);
+        }
+    }
+}