Stop throwing PortInUseException for unassignable address

Fixes gh-47618

Author: wilkinsona

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/NettyWebServer.java

@@ -64,6 +64,11 @@ public class NettyWebServer implements WebServer {
 	 */
 	private static final int ERROR_NO_EACCES = -13;
 
+	/**
+	 * Address in use error code from {@code errno.h}.
+	 */
+	private static final int ERROR_ADDR_IN_USE = -98;
+
 	private static final Predicate<HttpServerRequest> ALWAYS = (request) -> true;
 
 	private static final Log logger = LogFactory.getLog(NettyWebServer.class);
@@ -115,11 +120,19 @@ public void start() throws WebServerException {
 				this.disposableServer = startHttpServer();
 			}
 			catch (Exception ex) {
-				PortInUseException.ifCausedBy(ex, ChannelBindException.class, (bindException) -> {
-					if (bindException.localPort() > 0 && !isPermissionDenied(bindException.getCause())) {
-						throw new PortInUseException(bindException.localPort(), ex);
+				PortInUseException.ifCausedBy(ex, ChannelBindException.class, (channelBindException) -> {
+					if (channelBindException.localPort() > 0 && !isPermissionDenied(channelBindException.getCause())) {
+						PortInUseException.throwIfPortBindingException(channelBindException,
+								channelBindException::localPort);
 					}
 				});
+				if (ex instanceof ChannelBindException channelBindException) {
+					PortInUseException.ifCausedBy(ex, NativeIoException.class, (nativeIoException) -> {
+						if (nativeIoException.expectedErr() == ERROR_ADDR_IN_USE) {
+							throw new PortInUseException(channelBindException.localPort(), ex);
+						}
+					});
+				}
 				throw new WebServerException("Unable to start Netty", ex);
 			}
 			if (this.disposableServer != null) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactoryTests.java

@@ -17,7 +17,9 @@
 package org.springframework.boot.web.embedded.netty;
 
 import java.net.ConnectException;
+import java.net.InetAddress;
 import java.net.SocketAddress;
+import java.net.UnknownHostException;
 import java.time.Duration;
 import java.util.Arrays;
 
@@ -45,6 +47,7 @@
 import org.springframework.boot.web.server.PortInUseException;
 import org.springframework.boot.web.server.Shutdown;
 import org.springframework.boot.web.server.Ssl;
+import org.springframework.boot.web.server.WebServerException;
 import org.springframework.http.MediaType;
 import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
@@ -70,7 +73,7 @@
 class NettyReactiveWebServerFactoryTests extends AbstractReactiveWebServerFactoryTests {
 
 	@Test
-	void exceptionIsThrownWhenPortIsAlreadyInUse() {
+	void portInUseExceptionIsThrownWhenPortIsAlreadyInUse() {
 		AbstractReactiveWebServerFactory factory = getFactory();
 		factory.setPort(0);
 		this.webServer = factory.getWebServer(new EchoHandler());
@@ -81,6 +84,14 @@ void exceptionIsThrownWhenPortIsAlreadyInUse() {
 			.withCauseInstanceOf(Throwable.class);
 	}
 
+	@Test
+	void webServerExceptionIsThrownWhenAddressCannotBeAssigned() throws UnknownHostException {
+		AbstractReactiveWebServerFactory factory = getFactory();
+		factory.setPort(8080);
+		factory.setAddress(InetAddress.getByName("1.2.3.4"));
+		assertThatExceptionOfType(WebServerException.class).isThrownBy(factory.getWebServer(new EchoHandler())::start);
+	}
+
 	@Test
 	void getPortWhenDisposableServerPortOperationIsUnsupportedReturnsMinusOne() {
 		NettyReactiveWebServerFactory factory = new NoPortNettyReactiveWebServerFactory(0);