Extract connection methods, generalise for different address families

Author: michaelklishin

projects/client/RabbitMQ.Client/src/client/impl/SocketFrameHandler.cs

@@ -84,29 +84,15 @@ public SocketFrameHandler(AmqpTcpEndpoint endpoint,
             int connectionTimeout, int readTimeout, int writeTimeout)
         {
             Endpoint = endpoint;
-            m_socket = null;
+
             if (Socket.OSSupportsIPv6 && endpoint.AddressFamily != AddressFamily.InterNetwork)
             {
-                try
-                {
-                    m_socket = socketFactory(AddressFamily.InterNetworkV6);
-                    Connect(m_socket, endpoint, connectionTimeout);
-                }
-                catch (ConnectFailureException) // could not connect using IPv6
-                {
-                    m_socket = null;
-                }
-                // Mono might raise a SocketException when using IPv4 addresses on
-                // an OS that supports IPv6
-                catch (SocketException)
-                {
-                    m_socket = null;
-                }
+                m_socket = ConnectUsingIPv6(endpoint, socketFactory, connectionTimeout);
             }
+
             if (m_socket == null && endpoint.AddressFamily != AddressFamily.InterNetworkV6)
             {
-                m_socket = socketFactory(AddressFamily.InterNetwork);
-                Connect(m_socket, endpoint, connectionTimeout);
+                m_socket = ConnectUsingIPv4(endpoint, socketFactory, connectionTimeout);
             }
 
             Stream netstream = m_socket.GetStream();
@@ -273,14 +259,52 @@ public void Flush()
             }
         }
 
-        private void Connect(ITcpClient socket, AmqpTcpEndpoint endpoint, int timeout)
+        private ITcpClient ConnectUsingIPv6(AmqpTcpEndpoint endpoint,
+                                            Func<AddressFamily, ITcpClient> socketFactory,
+                                            int timeout)
+        {
+            return ConnectUsingAddressFamily(endpoint, socketFactory, timeout, AddressFamily.InterNetworkV6);
+        }
+
+        private ITcpClient ConnectUsingIPv4(AmqpTcpEndpoint endpoint,
+                                            Func<AddressFamily, ITcpClient> socketFactory,
+                                            int timeout)
+        {
+            return ConnectUsingAddressFamily(endpoint, socketFactory, timeout, AddressFamily.InterNetwork);
+        }
+
+        private ITcpClient ConnectUsingAddressFamily(AmqpTcpEndpoint endpoint,
+                                                    Func<AddressFamily, ITcpClient> socketFactory,
+                                                    int timeout, AddressFamily family)
+        {
+            ITcpClient socket;
+            try
+            {
+                socket = socketFactory(family);
+                ConnectOrFail(socket, endpoint, timeout);
+                return socket;
+            }
+            catch (ConnectFailureException) // could not connect using IPv6
+            {
+                return null;
+            }
+            // Mono might raise a SocketException when using IPv4 addresses on
+            // an OS that supports IPv6
+            catch (SocketException)
+            {
+                return null;
+            }
+        }
+
+        private void ConnectOrFail(ITcpClient socket, AmqpTcpEndpoint endpoint, int timeout)
         {
             try
             {
                 socket.ConnectAsync(endpoint.HostName, endpoint.Port)
                             .TimeoutAfter(timeout)
                             .ConfigureAwait(false)
-                            .GetAwaiter()//this ensures exceptions aren't wrapped in an AggregateException
+                            // this ensures exceptions aren't wrapped in an AggregateException
+                            .GetAwaiter()
                             .GetResult();
             }
             catch (ArgumentException e)