Issue #11220 - ContextHandler NPE protections

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ContextHandler.java

@@ -335,9 +335,9 @@ public void setVirtualHosts(List<String> vhosts)
      *
      * @param virtualHosts Array of virtual hosts that this context responds to. A null/empty array means any hostname is acceptable. Host names may be String
      * representation of IP addresses. Host names may start with '*.' to wildcard one level of names. Hosts and wildcard hosts may be followed with
-     * '@connectorname', in which case they will match only if the the {@link Connector#getName()} for the request also matches. If an entry is just
-     * '@connectorname' it will match any host if that connector was used.  Note - In previous versions if one or more connectorname only entries existed
-     * and non of the connectors matched the handler would not match regardless of any hostname entries.  If there is one or more connectorname only
+     * {@code "@connectorname"}, in which case they will match only if the {@link Connector#getName()} for the request also matches. If an entry is just
+     * {@code "@connectorname"} it will match any host if that connector was used.  Note - In previous versions if one or more connectorname only entries existed
+     * and none of the connectors matched the handler would not match regardless of any hostname entries.  If there is one or more connectorname only
      * entries and one or more host only entries but no hostname and connector entries we assume the old behavior and will log a warning.  The warning
      * can be removed by removing the host entries that were previously being ignored, or modifying to include a hostname and connectorname entry.
      */
@@ -356,9 +356,9 @@ public void addVirtualHosts(String... virtualHosts)
      *
      * @param virtualHosts Array of virtual hosts that this context responds to. A null/empty array means any hostname is acceptable. Host names may be String
      * representation of IP addresses. Host names may start with '*.' to wildcard one level of names. Hosts and wildcard hosts may be followed with
-     * '@connectorname', in which case they will match only if the the {@link Connector#getName()} for the request also matches. If an entry is just
-     * '@connectorname' it will match any host if that connector was used.  Note - In previous versions if one or more connectorname only entries existed
-     * and non of the connectors matched the handler would not match regardless of any hostname entries.  If there is one or more connectorname only
+     * {@code "@connectorname"}, in which case they will match only if the {@link Connector#getName()} for the request also matches. If an entry is just
+     * {@code "@connectorname"} it will match any host if that connector was used.  Note - In previous versions if one or more connectorname only entries existed
+     * and none of the connectors matched the handler would not match regardless of any hostname entries.  If there is one or more connectorname only
      * entries and one or more host only entries but no hostname and connector entries we assume the old behavior and will log a warning.  The warning
      * can be removed by removing the host entries that were previously being ignored, or modifying to include a hostname and connectorname entry.
      */
@@ -379,15 +379,17 @@ public void removeVirtualHosts(String... virtualHosts)
      *
      * @return list of virtual hosts that this context responds to. A null/empty array means any hostname is acceptable. Host names may be String
      * representation of IP addresses. Host names may start with '*.' to wildcard one level of names. Hosts and wildcard hosts may be followed with
-     * '@connectorname', in which case they will match only if the the {@link Connector#getName()} for the request also matches. If an entry is just
-     * '@connectorname' it will match any host if that connector was used.  Note - In previous versions if one or more connectorname only entries existed
+     * {@code "@connectorname"}, in which case they will match only if the {@link Connector#getName()} for the request also matches. If an entry is just
+     * {@code "@connectorname"} it will match any host if that connector was used.  Note - In previous versions if one or more connectorname only entries existed
      * and none of the connectors matched the handler would not match regardless of any hostname entries.  If there is one or more connectorname only
      * entries and one or more host only entries but no hostname and connector entries we assume the old behavior and will log a warning.  The warning
      * can be removed by removing the host entries that were previously being ignored, or modifying to include a hostname and connectorname entry.
      */
     @ManagedAttribute(value = "Virtual hosts accepted by the context", readonly = true)
     public List<String> getVirtualHosts()
     {
+        if (_vhosts == null)
+            return null;
         return _vhosts.stream().map(VHost::getName).collect(Collectors.toList());
     }
 
@@ -1038,9 +1040,10 @@ public String toString()
             b.append(getDisplayName()).append(',');
         b.append(getContextPath());
         b.append(",b=").append(getBaseResource());
-        b.append(",a=").append(_availability.get());
+        b.append(",a=");
+        b.append(",a=").append(_availability);
 
-        if (!vhosts.isEmpty())
+        if (vhosts != null && !vhosts.isEmpty())
         {
             b.append(",vh=[");
             b.append(String.join(",", vhosts));

jetty-core/jetty-server/src/test/java/org/eclipse/jetty/server/LoggerDebugTest.java

@@ -0,0 +1,153 @@
+//
+// ========================================================================
+// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+// which is available at https://www.apache.org/licenses/LICENSE-2.0.
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+// ========================================================================
+//
+
+package org.eclipse.jetty.server;
+
+import java.io.PrintStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+import org.eclipse.jetty.logging.JettyLevel;
+import org.eclipse.jetty.logging.JettyLogger;
+import org.eclipse.jetty.logging.JettyLoggerFactory;
+import org.eclipse.jetty.server.handler.ContextHandler;
+import org.eclipse.jetty.util.Callback;
+import org.eclipse.jetty.util.component.ContainerLifeCycle;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assumptions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.ILoggerFactory;
+import org.slf4j.LoggerFactory;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
+
+/**
+ * Logger Debug Testing of Handlers
+ */
+public class LoggerDebugTest
+{
+    private CaptureDebugLogging captureDebugLogging = new CaptureDebugLogging(System.err);
+    private PrintStream old = System.err;
+
+    @BeforeEach
+    public void init()
+    {
+        // Add some classes with Loggers that have triggered logging issues in the past
+        captureDebugLogging.capture(ContainerLifeCycle.class);
+        captureDebugLogging.capture(Handler.Wrapper.class);
+        System.setErr(captureDebugLogging);
+    }
+
+    @AfterEach
+    public void teardown()
+    {
+        System.setErr(old);
+        captureDebugLogging.restore();
+    }
+
+    /**
+     * Test to ensure that "SLF4J: Failed toString() invocation on an object of type" does not happen with Wrappers.
+     * See https://github.com/jetty/jetty.project/issues/11220
+     */
+    @Test
+    public void testWrapperNPE()
+    {
+        ContextHandler simpleContextHandler = new ContextHandler(new Handler.Abstract.NonBlocking()
+        {
+            @Override
+            public boolean handle(Request request, Response response, Callback callback)
+            {
+                callback.succeeded();
+                return true;
+            }
+        });
+
+        // verify that there was no exception in System.err from SLF4J (due to bad "this" handling in Wrapper class)
+        assertThat(captureDebugLogging.capture.toString(), not(containsString("SLF4J: Failed toString()")));
+    }
+
+    record OriginalLogger(JettyLogger logger, JettyLevel level) {}
+
+    public static class CaptureDebugLogging extends PrintStream
+    {
+        private final PrintStream out;
+        StringBuilder capture = new StringBuilder();
+        private final JettyLoggerFactory jettyLoggerFactory;
+        private List<OriginalLogger> originalLoggers = new ArrayList<>();
+
+        public CaptureDebugLogging(PrintStream out)
+        {
+            super(out);
+            this.out = out;
+            ILoggerFactory loggerFactory = LoggerFactory.getILoggerFactory();
+            JettyLoggerFactory jettyFactory = null;
+            if (loggerFactory instanceof JettyLoggerFactory factory)
+            {
+                jettyFactory = factory;
+            }
+            Assumptions.assumeTrue(jettyFactory != null, "Not using jetty-slf4j-impl");
+            this.jettyLoggerFactory = jettyFactory;
+        }
+
+        public void restore()
+        {
+            for (OriginalLogger originalLogger: originalLoggers)
+            {
+                originalLogger.logger.setLevel(originalLogger.level);
+            }
+        }
+
+        public void capture(Class klass)
+        {
+            capture(klass.getName());
+        }
+
+        public void capture(Object obj)
+        {
+            capture(obj.getClass());
+        }
+
+        public void capture(String loggerName)
+        {
+            JettyLogger jettyLogger = jettyLoggerFactory.getJettyLogger(loggerName);
+            JettyLevel originalLevel = jettyLogger.getLevel();
+            originalLoggers.add(new OriginalLogger(jettyLogger, originalLevel));
+            jettyLogger.setLevel(JettyLevel.DEBUG);
+        }
+
+        private void out(String s)
+        {
+            this.out.print(s);
+            capture.append(s);
+        }
+
+        public void print(String s)
+        {
+            out(s);
+        }
+
+        public void println(String s)
+        {
+            out(s + System.lineSeparator());
+        }
+
+        public void println(Object o)
+        {
+            out(Objects.toString(o) + System.lineSeparator());
+        }
+    }
+}