Protect TcpNetConnectionSupport calls

5.0 introduced the `TcpNetConnectionSupport` user hook to create connection objects.

If a user-supplied instance threw an exception, the server socket would remain open
but the server `accept()` thread is gone.

- wrap the connection initialization code in try/catch
- close the server socket if necessary on an exception

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -140,22 +140,31 @@ public class TcpNetServerConnectionFactory extends AbstractServerConnectionFacto
 				if (isShuttingDown()) {
 					if (logger.isInfoEnabled()) {
 						logger.info("New connection from " + socket.getInetAddress().getHostAddress()
+								+ ":" + socket.getPort()
 								+ " rejected; the server is in the process of shutting down.");
 					}
 					socket.close();
 				}
 				else {
 					if (logger.isDebugEnabled()) {
-						logger.debug("Accepted connection from " + socket.getInetAddress().getHostAddress());
+						logger.debug("Accepted connection from " + socket.getInetAddress().getHostAddress()
+								+ ":" + socket.getPort());
+					}
+					try {
+						setSocketAttributes(socket);
+						TcpConnectionSupport connection = this.tcpNetConnectionSupport.createNewConnection(socket, true,
+								isLookupHost(), getApplicationEventPublisher(), getComponentName());
+						connection = wrapConnection(connection);
+						initializeConnection(connection, socket);
+						getTaskExecutor().execute(connection);
+						harvestClosedConnections();
+						connection.publishConnectionOpenEvent();
+					}
+					catch (Exception e) {
+						this.logger.error("Failed to create and configure a TcpConnection for the new socket: "
+								+ socket.getInetAddress().getHostAddress() + ":" + socket.getPort(), e);
+						socket.close();
 					}
-					setSocketAttributes(socket);
-					TcpConnectionSupport connection = this.tcpNetConnectionSupport.createNewConnection(socket, true,
-							isLookupHost(), getApplicationEventPublisher(), getComponentName());
-					connection = wrapConnection(connection);
-					initializeConnection(connection, socket);
-					getTaskExecutor().execute(connection);
-					harvestClosedConnections();
-					connection.publishConnectionOpenEvent();
 				}
 			}
 		}
@@ -167,6 +176,12 @@ public class TcpNetServerConnectionFactory extends AbstractServerConnectionFacto
 			else if (isActive()) {
 				logger.error("Error on ServerSocket; port = " + getPort(), e);
 				publishServerExceptionEvent(e);
+				try {
+					this.serverSocket.close();
+				}
+				catch (IOException e1) {
+					// empty
+				}
 			}
 		}
 		finally {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -203,6 +203,7 @@ public class TcpNioServerConnectionFactory extends AbstractServerConnectionFacto
 		if (isShuttingDown()) {
 			if (logger.isInfoEnabled()) {
 				logger.info("New connection from " + channel.socket().getInetAddress().getHostAddress()
+						+ ":" + channel.socket().getPort()
 						+ " rejected; the server is in the process of shutting down.");
 			}
 			channel.close();
@@ -226,7 +227,9 @@ public class TcpNioServerConnectionFactory extends AbstractServerConnectionFacto
 				connection.publishConnectionOpenEvent();
 			}
 			catch (Exception e) {
-				logger.error("Exception accepting new connection", e);
+				logger.error("Exception accepting new connection from "
+						+ channel.socket().getInetAddress().getHostAddress()
+						+ ":" + channel.socket().getPort(), e);
 				channel.close();
 			}
 		}

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

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2018 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 static org.assertj.core.api.Assertions.assertThat;
+
+import java.net.Socket;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+import javax.net.SocketFactory;
+
+import org.junit.Test;
+
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.messaging.Message;
+
+/**
+ * @author Gary Russell
+ * @since 5.0.3
+ *
+ */
+public class TcpNetConnectionSupportTests {
+
+	@Test
+	public void testBadCode() throws Exception {
+		TcpNetServerConnectionFactory server = new TcpNetServerConnectionFactory(0);
+		AtomicReference<Message<?>> message = new AtomicReference<>();
+		CountDownLatch latch1 = new CountDownLatch(1);
+		server.registerListener(m -> {
+			message.set(m);
+			latch1.countDown();
+			return false;
+		});
+		AtomicBoolean firstTime = new AtomicBoolean(true);
+		server.setTcpNetConnectionSupport(new DefaultTcpNetConnectionSupport() {
+
+			@Override
+			public TcpNetConnection createNewConnection(Socket socket, boolean server, boolean lookupHost,
+					ApplicationEventPublisher applicationEventPublisher, String connectionFactoryName)
+					throws Exception {
+				if (firstTime.getAndSet(false)) {
+					throw new RuntimeException("intended");
+				}
+				return super.createNewConnection(socket, server, lookupHost, applicationEventPublisher, connectionFactoryName);
+			}
+
+		});
+		CountDownLatch latch2 = new CountDownLatch(1);
+		server.setApplicationEventPublisher(e -> {
+			if (e instanceof TcpConnectionServerListeningEvent) {
+			latch2.countDown();
+		}
+		});
+		server.afterPropertiesSet();
+		server.start();
+		assertThat(latch2.await(10, TimeUnit.SECONDS)).isTrue();
+		Socket socket = SocketFactory.getDefault().createSocket("localhost", server.getPort());
+		socket.close();
+		socket = SocketFactory.getDefault().createSocket("localhost", server.getPort());
+		socket.getOutputStream().write("foo\r\n".getBytes());
+		socket.close();
+		assertThat(latch1.await(10, TimeUnit.SECONDS)).isTrue();
+		assertThat(message.get()).isNotNull();
+		server.stop();
+	}
+
+}