Tolerate multiple calls to UndertowWebServer.destroy()

Undertow's DeploymentManagerImpl is not idempotent. Calling undeploy()
multiple times will result in an NPE. Similarly, calling start() or
stop() after undeploy() will also result in an NPE.

This commit protects against this by checking that the deployment
manager's state is not UNDEPLOYED before calling stop() and
undeploy().

Fixes gh-48446

Author: wilkinsona

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/DeploymentManagerHttpHandlerFactory.java

@@ -22,6 +22,7 @@
 import io.undertow.server.HttpHandler;
 import io.undertow.server.HttpServerExchange;
 import io.undertow.servlet.api.DeploymentManager;
+import io.undertow.servlet.api.DeploymentManager.State;
 import jakarta.servlet.ServletException;
 
 import org.springframework.util.Assert;
@@ -76,12 +77,14 @@ public void handleRequest(HttpServerExchange exchange) throws Exception {
 
 		@Override
 		public void close() throws IOException {
-			try {
-				this.deploymentManager.stop();
-				this.deploymentManager.undeploy();
-			}
-			catch (ServletException ex) {
-				throw new RuntimeException(ex);
+			if (this.deploymentManager.getState() != State.UNDEPLOYED) {
+				try {
+					this.deploymentManager.stop();
+					this.deploymentManager.undeploy();
+				}
+				catch (ServletException ex) {
+					throw new RuntimeException(ex);
+				}
 			}
 		}
 

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactoryTests.java

@@ -54,6 +54,7 @@
 import org.springframework.boot.web.server.GracefulShutdownResult;
 import org.springframework.boot.web.server.PortInUseException;
 import org.springframework.boot.web.server.Shutdown;
+import org.springframework.boot.web.server.WebServer;
 import org.springframework.boot.web.servlet.ServletRegistrationBean;
 import org.springframework.boot.web.servlet.server.AbstractServletWebServerFactory;
 import org.springframework.boot.web.servlet.server.AbstractServletWebServerFactoryTests;
@@ -64,6 +65,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIOException;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.assertj.core.api.Assertions.assertThatNoException;
 import static org.hamcrest.Matchers.is;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.inOrder;
@@ -320,6 +322,16 @@ void sslRestrictedProtocolsRSATLS11Failure() {
 			.isInstanceOfAny(SSLException.class, SocketException.class);
 	}
 
+	@Test
+	void multipleCallsToDestroyAreTolerated() {
+		AbstractServletWebServerFactory factory = getFactory();
+		factory.setPort(0);
+		WebServer webServer = factory.getWebServer();
+		webServer.start();
+		webServer.destroy();
+		assertThatNoException().isThrownBy(webServer::destroy);
+	}
+
 	@Override
 	protected JspServlet getJspServlet() {
 		return null; // Undertow does not support JSPs