INT-3800: Expose Actual Port Chosen When Random

JIRA: https://jira.spring.io/browse/INT-3800

If the server port is 0, return the actual port after the factory is started.

Also add more TCP Test Diagnostics.

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/AbstractServerConnectionFactory.java

@@ -18,6 +18,7 @@ package org.springframework.integration.ip.tcp.connection;
 
 import java.net.ServerSocket;
 import java.net.Socket;
+import java.net.SocketAddress;
 import java.net.SocketException;
 
 import org.springframework.integration.context.OrderlyShutdownCapable;
@@ -32,8 +33,8 @@ import org.springframework.util.Assert;
  * @author Gary Russell
  * @since 2.0
  */
-public abstract class AbstractServerConnectionFactory
-		extends AbstractConnectionFactory implements SchedulingAwareRunnable, OrderlyShutdownCapable {
+public abstract class AbstractServerConnectionFactory extends AbstractConnectionFactory
+		implements TcpServerConnectionFactory, SchedulingAwareRunnable, OrderlyShutdownCapable {
 
 	private static final int DEFAULT_BACKLOG = 5;
 
@@ -60,6 +61,11 @@ public abstract class AbstractServerConnectionFactory
 		return true;
 	}
 
+	@Override
+	public SocketAddress getServerSocketAddress() {
+		return null;
+	}
+
 	@Override
 	public void start() {
 		synchronized (this.lifecycleMonitor) {

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNetServerConnectionFactory.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
+import java.net.SocketAddress;
 import java.net.SocketException;
 import java.net.SocketTimeoutException;
 
@@ -54,6 +55,25 @@ public class TcpNetServerConnectionFactory extends AbstractServerConnectionFacto
 		return "tcp-net-server-connection-factory";
 	}
 
+	@Override
+	public int getPort() {
+		int port = super.getPort();
+		if (port == 0 && this.serverSocket != null) {
+			return this.serverSocket.getLocalPort();
+		}
+		return port;
+	}
+
+	@Override
+	public SocketAddress getServerSocketAddress() {
+		if (this.serverSocket != null) {
+			return this.serverSocket.getLocalSocketAddress();
+		}
+		else {
+			return null;
+		}
+	}
+
 	/**
 	 * If no listener registers, exits.
 	 * Accepts incoming connections and creates TcpConnections for each new connection.
@@ -70,11 +90,11 @@ public class TcpNetServerConnectionFactory extends AbstractServerConnectionFacto
 		}
 		try {
 			if (getLocalAddress() == null) {
-				theServerSocket = createServerSocket(getPort(), getBacklog(), null);
+				theServerSocket = createServerSocket(super.getPort(), getBacklog(), null);
 			}
 			else {
 				InetAddress whichNic = InetAddress.getByName(getLocalAddress());
-				theServerSocket = createServerSocket(getPort(), getBacklog(), whichNic);
+				theServerSocket = createServerSocket(super.getPort(), getBacklog(), whichNic);
 			}
 			getTcpSocketSupport().postProcessServerSocket(theServerSocket);
 			this.serverSocket = theServerSocket;

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpNioServerConnectionFactory.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.net.SocketAddress;
 import java.nio.channels.CancelledKeyException;
 import java.nio.channels.ClosedSelectorException;
 import java.nio.channels.SelectionKey;
@@ -66,6 +67,34 @@ public class TcpNioServerConnectionFactory extends AbstractServerConnectionFacto
 		return "tcp-nio-server-connection-factory";
 	}
 
+	@Override
+	public int getPort() {
+		int port = super.getPort();
+		if (port == 0 && this.serverChannel != null) {
+			try {
+				SocketAddress address = this.serverChannel.getLocalAddress();
+				if (address instanceof InetSocketAddress) {
+					port = ((InetSocketAddress) address).getPort();
+				}
+			}
+			catch (IOException e) {
+			}
+		}
+		return port;
+	}
+
+	@Override
+	public SocketAddress getServerSocketAddress() {
+		if (this.serverChannel != null) {
+			try {
+				return this.serverChannel.getLocalAddress();
+			}
+			catch (IOException e) {
+			}
+		}
+		return null;
+	}
+
 	/**
 	 * If no listener registers, exits.
 	 * Accepts incoming connections and creates TcpConnections for each new connection.
@@ -81,11 +110,8 @@ public class TcpNioServerConnectionFactory extends AbstractServerConnectionFacto
 		}
 		try {
 			this.serverChannel = ServerSocketChannel.open();
-			int port = getPort();
+			int port = super.getPort();
 			getTcpSocketSupport().postProcessServerSocket(this.serverChannel.socket());
-			if (logger.isInfoEnabled()) {
-				logger.info("Listening on port " + port);
-			}
 			this.serverChannel.configureBlocking(false);
 			if (getLocalAddress() == null) {
 				this.serverChannel.socket().bind(new InetSocketAddress(port), Math.abs(getBacklog()));
@@ -94,6 +120,9 @@ public class TcpNioServerConnectionFactory extends AbstractServerConnectionFacto
 				InetAddress whichNic = InetAddress.getByName(getLocalAddress());
 				this.serverChannel.socket().bind(new InetSocketAddress(whichNic, port), Math.abs(getBacklog()));
 			}
+			if (logger.isInfoEnabled()) {
+				logger.info("Listening on port " + getPort());
+			}
 			final Selector selector = Selector.open();
 			this.serverChannel.register(selector, SelectionKey.OP_ACCEPT);
 			setListening(true);

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpServerConnectionFactory.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.integration.ip.tcp.connection;
+
+import java.net.SocketAddress;
+
+/**
+ * Connection factories that act as TCP servers, listening for incoming connections.
+ * @author Gary Russell
+ * @since 4.2
+ *
+ */
+public interface TcpServerConnectionFactory {
+
+	/**
+	 * Return the port this server is listening on.
+	 * If the factory is configured to listen on a random port (0), this
+	 * will return the actual port after the factory is started. It may
+	 * return the previous value if the factory is stopped.
+	 * @return the port.
+	 */
+	int getPort();
+
+	/**
+	 * Return the {@link SocketAddress} that the underlying {@code ServerSocket}
+	 * is bound to.
+	 * @return the socket address.
+	 */
+	SocketAddress getServerSocketAddress();
+
+}

spring-integration-ip/src/test/java/org/springframework/integration/ip/tcp/TcpOutboundGatewayTests.java

@@ -52,7 +52,9 @@ import javax.net.ServerSocketFactory;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.log4j.Level;
 import org.hamcrest.Matchers;
+import org.junit.Rule;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -69,6 +71,7 @@ import org.springframework.integration.ip.tcp.connection.TcpConnectionSupport;
 import org.springframework.integration.ip.tcp.connection.TcpNetClientConnectionFactory;
 import org.springframework.integration.ip.tcp.connection.TcpNioClientConnectionFactory;
 import org.springframework.integration.support.MessageBuilder;
+import org.springframework.integration.test.rule.Log4jLevelAdjuster;
 import org.springframework.integration.test.util.SocketUtils;
 import org.springframework.integration.test.util.TestUtils;
 import org.springframework.messaging.Message;
@@ -81,6 +84,10 @@ import org.springframework.messaging.support.GenericMessage;
  */
 public class TcpOutboundGatewayTests {
 
+	@Rule
+	public Log4jLevelAdjuster adjuster = new Log4jLevelAdjuster(Level.TRACE,
+			"org.springframework.integration.ip.tcp");
+
 	private final Log logger = LogFactory.getLog(this.getClass());
 
 	@Test

spring-integration-ip/src/test/java/org/springframework/integration/ip/tcp/connection/ConnectionFactoryTests.java

@@ -24,6 +24,8 @@ import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.spy;
 
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -36,10 +38,9 @@ import org.mockito.stubbing.Answer;
 
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationEventPublisher;
-import org.springframework.messaging.Message;
 import org.springframework.integration.ip.tcp.TcpReceivingChannelAdapter;
 import org.springframework.integration.ip.util.TestingUtilities;
-import org.springframework.integration.test.util.SocketUtils;
+import org.springframework.messaging.Message;
 
 /**
  * @author Gary Russell
@@ -50,7 +51,18 @@ import org.springframework.integration.test.util.SocketUtils;
 public class ConnectionFactoryTests {
 
 	@Test
-	public void testObtainConnectionIds() throws Exception {
+	public void testObtainConnectionIdsNet() throws Exception {
+		TcpNetServerConnectionFactory serverFactory = new TcpNetServerConnectionFactory(0);
+		testObtainConnectionIds(serverFactory);
+	}
+
+	@Test
+	public void testObtainConnectionIdsNio() throws Exception {
+		TcpNioServerConnectionFactory serverFactory = new TcpNioServerConnectionFactory(0);
+		testObtainConnectionIds(serverFactory);
+	}
+
+	public void testObtainConnectionIds(AbstractServerConnectionFactory serverFactory) throws Exception {
 		final List<TcpConnectionEvent> events =
 				Collections.synchronizedList(new ArrayList<TcpConnectionEvent>());
 		ApplicationEventPublisher publisher = new ApplicationEventPublisher() {
@@ -62,17 +74,16 @@ public class ConnectionFactoryTests {
 
 			@Override
 			public void publishEvent(Object event) {
-				
+
 			}
-			
+
 		};
-		int port = SocketUtils.findAvailableServerSocket();
-		TcpNetServerConnectionFactory serverFactory = new TcpNetServerConnectionFactory(port);
 		serverFactory.setBeanName("serverFactory");
 		serverFactory.setApplicationEventPublisher(publisher);
 		serverFactory = spy(serverFactory);
 		final CountDownLatch serverConnectionInitLatch = new CountDownLatch(1);
 		doAnswer(new Answer<Object>() {
+			@Override
 			public Object answer(InvocationOnMock invocation) throws Throwable {
 				Object result = invocation.callRealMethod();
 				serverConnectionInitLatch.countDown();
@@ -83,8 +94,10 @@ public class ConnectionFactoryTests {
 		adapter.setConnectionFactory(serverFactory);
 		adapter.start();
 		TestingUtilities.waitListening(serverFactory, null);
+		int port = serverFactory.getPort();
 		TcpNetClientConnectionFactory clientFactory = new TcpNetClientConnectionFactory("localhost", port);
 		clientFactory.registerListener(new TcpListener() {
+			@Override
 			public boolean onMessage(Message<?> message) {
 				return false;
 			}
@@ -105,11 +118,13 @@ public class ConnectionFactoryTests {
 		Thread.sleep(1000);
 		clients = clientFactory.getOpenConnectionIds();
 		assertEquals(0, clients.size());
-		assertEquals(6, events.size()); // OPEN, CLOSE, EXCEPTION for each side
+		int expected = serverFactory instanceof TcpNetServerConnectionFactory ? 6// OPEN, CLOSE, EXCEPTION for each side
+				: 4; //OPEN, CLOSE
+		assertEquals(expected, events.size());
 
 		FooEvent event = new FooEvent(client, "foo");
 		client.publishEvent(event);
-		assertEquals(7, events.size());
+		assertEquals(expected + 1, events.size());
 
 		try {
 			event = new FooEvent(mock(TcpConnectionSupport.class), "foo");
@@ -119,6 +134,13 @@ public class ConnectionFactoryTests {
 		catch (IllegalArgumentException e) {
 			assertTrue("Can only publish events with this as the source".equals(e.getMessage()));
 		}
+
+		SocketAddress address = serverFactory.getServerSocketAddress();
+		if (address instanceof InetSocketAddress) {
+			InetSocketAddress inetAddress = (InetSocketAddress) address;
+			assertEquals(port, inetAddress.getPort());
+		}
+		serverFactory.stop();
 	}
 
 	@SuppressWarnings("serial")

src/reference/asciidoc/ip.adoc

@@ -166,6 +166,11 @@ A simple server connection factory that uses `java.net.Socket` connections.
 
 A simple server connection factory that uses `java.nio.channel.SocketChannel` connections.
 
+NOTE: Starting with Spring Integration _version 4.2_, if the server is configured to listen on a random port (0),
+the actual port chosen by the OS can be obtained using `getPort()`.
+Also, `getServerSocketAddress()` is available to get the complete `SocketAddress`.
+See the javadocs for the `TcpServerConnectionFactory` interface for more information.
+
 [source,xml]
 ----
 <int-ip:tcp-connection-factory id="client"

src/reference/asciidoc/whats-new.adoc

@@ -145,6 +145,15 @@ If you are using the serializers directly within user code, you may have to `flu
 `TcpConnectionServerExceptionEvent` s are now published whenever an unexpected exception occurs on a TCP server socket (also added to 4.1.3, 4.0.7).
 See <<tcp-events>> for more information.
 
+[[x4.2-tcp-server-port]]
+===== TCP Server Port
+
+If a TCP server socket factory is configured to listen on a random port, the actual port chosen by the OS can now
+be obtained using `getPort()`.
+`getServerSocketAddress()` is also available.
+
+See <<connection-factories>> for more information.
+
 [[x4.2-tcp-gw-rto]]
 ===== TCP Gateway Remote Timeout