Check when plugins shade WorldGuard inappropriately.

src/main/java/com/sk89q/worldguard/bukkit/WorldGuardPlugin.java

@@ -19,6 +19,7 @@
 
 package com.sk89q.worldguard.bukkit;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListeningExecutorService;
@@ -37,13 +38,17 @@
 import com.sk89q.worldguard.bukkit.commands.ToggleCommands;
 import com.sk89q.worldguard.bukkit.event.player.ProcessPlayerEvent;
 import com.sk89q.worldguard.bukkit.listener.*;
-import com.sk89q.worldguard.session.SessionManager;
 import com.sk89q.worldguard.bukkit.util.Events;
 import com.sk89q.worldguard.protection.GlobalRegionManager;
+import com.sk89q.worldguard.protection.flags.Flag;
 import com.sk89q.worldguard.protection.managers.RegionManager;
 import com.sk89q.worldguard.protection.managers.storage.StorageException;
+import com.sk89q.worldguard.protection.regions.ProtectedCuboidRegion;
+import com.sk89q.worldguard.protection.regions.ProtectedRegion;
 import com.sk89q.worldguard.protection.util.UnresolvedNamesException;
+import com.sk89q.worldguard.session.SessionManager;
 import com.sk89q.worldguard.util.concurrent.EvenMoreExecutors;
+import com.sk89q.worldguard.util.logging.ClassSourceValidator;
 import com.sk89q.worldguard.util.logging.RecordMessagePrefixer;
 import com.sk89q.worldguard.util.task.SimpleSupervisor;
 import com.sk89q.worldguard.util.task.Supervisor;
@@ -132,6 +137,11 @@ public void onEnable() {
         // Set the proper command injector
         commands.setInjector(new SimpleInjector(this));
 
+        // Catch bad things being done by naughty plugins that include
+        // WorldGuard's classes
+        ClassSourceValidator verifier = new ClassSourceValidator(this);
+        verifier.reportMismatches(ImmutableList.of(WGBukkit.class, ProtectedRegion.class, ProtectedCuboidRegion.class, Flag.class));
+
         // Register command classes
         final CommandsManagerRegistration reg = new CommandsManagerRegistration(this, commands);
         reg.register(ToggleCommands.class);

src/main/java/com/sk89q/worldguard/util/logging/ClassSourceValidator.java

@@ -0,0 +1,124 @@
+/*
+ * WorldGuard, a suite of tools for Minecraft
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldGuard team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldguard.util.logging;
+
+import com.google.common.base.Strings;
+import com.google.common.collect.Maps;
+import org.bukkit.plugin.Plugin;
+
+import javax.annotation.Nullable;
+import java.security.CodeSource;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Validates that certain specified classes came from the same source as
+ * a plugin.
+ */
+public class ClassSourceValidator {
+
+    private static final Logger log = Logger.getLogger(ClassSourceValidator.class.getCanonicalName());
+    private static final String separatorLine = Strings.repeat("*", 46);
+
+    private final Plugin plugin;
+    @Nullable
+    private final CodeSource expectedCodeSource;
+
+    /**
+     * Create a new instance.
+     *
+     * @param plugin The plugin
+     */
+    public ClassSourceValidator(Plugin plugin) {
+        checkNotNull(plugin, "plugin");
+        this.plugin = plugin;
+        this.expectedCodeSource = plugin.getClass().getProtectionDomain().getCodeSource();
+    }
+
+    /**
+     * Return a map of classes that been loaded from a different source.
+     *
+     * @param classes A list of classes to check
+     * @return The results
+     */
+    public Map<Class<?>, CodeSource> findMismatches(List<Class<?>> classes) {
+        checkNotNull(classes, "classes");
+
+        Map<Class<?>, CodeSource> mismatches = Maps.newHashMap();
+
+        if (expectedCodeSource != null) {
+            for (Class<?> testClass : classes) {
+                CodeSource testSource = testClass.getProtectionDomain().getCodeSource();
+                if (!expectedCodeSource.equals(testSource)) {
+                    mismatches.put(testClass, testSource);
+                }
+            }
+        }
+
+        return mismatches;
+    }
+
+    /**
+     * Reports classes that have come from a different source.
+     *
+     * <p>The warning is emitted to the log.</p>
+     *
+     * @param classes The list of classes to check
+     */
+    public void reportMismatches(List<Class<?>> classes) {
+        Map<Class<?>, CodeSource> mismatches = findMismatches(classes);
+
+        if (!mismatches.isEmpty()) {
+            StringBuilder builder = new StringBuilder("\n");
+
+            builder.append(separatorLine).append("\n");
+            builder.append("** /!\\    SEVERE WARNING    /!\\\n");
+            builder.append("** \n");
+            builder.append("** A plugin developer has copied and pasted a portion of \n");
+            builder.append("** ").append(plugin.getName()).append(" into their own plugin, so rather than using\n");
+            builder.append("** the version of ").append(plugin.getName()).append(" that you downloaded, you\n");
+            builder.append("** will be using a broken mix of old ").append(plugin.getName()).append(" (that came\n");
+            builder.append("** with the plugin) and your downloaded version. THIS MAY\n");
+            builder.append("** SEVERELY BREAK ").append(plugin.getName().toUpperCase()).append(" AND ALL OF ITS FEATURES.\n");
+            builder.append("**\n");
+            builder.append("** This may have happened because the developer is using\n");
+            builder.append("** the ").append(plugin.getName()).append(" API and thinks that including\n");
+            builder.append("** ").append(plugin.getName()).append(" is necessary. However, it is not!\n");
+            builder.append("**\n");
+            builder.append("** Here are some of files that have been overridden:\n");
+            builder.append("** \n");
+            for (Map.Entry<Class<?>, CodeSource> entry : mismatches.entrySet()) {
+                CodeSource codeSource = entry.getValue();
+                String url = codeSource != null ? codeSource.getLocation().toExternalForm() : "(unknown)";
+                builder.append("** '").append(entry.getKey().getSimpleName()).append("' came from '").append(url).append("'\n");
+            }
+            builder.append("**\n");
+            builder.append("** Please report this to the plugins' developers.\n");
+            builder.append(separatorLine).append("\n");
+
+            log.log(Level.SEVERE, builder.toString());
+        }
+    }
+
+}