Support loading plugins from classpath

build.gradle.kts

@@ -2,13 +2,15 @@ plugins {
     `java-library`
     id("velocity-checkstyle") apply false
     id("velocity-spotless") apply false
+    alias(libs.plugins.ideaExt)
 }
 
 subprojects {
     apply<JavaLibraryPlugin>()
 
     apply(plugin = "velocity-checkstyle")
     apply(plugin = "velocity-spotless")
+    apply(plugin = "org.jetbrains.gradle.plugin.idea-ext")
 
     java {
         toolchain {
@@ -28,4 +30,20 @@ subprojects {
             }
         }
     }
+
+    idea {
+        if (project != null) {
+            (project as ExtensionAware).extensions["settings"].run {
+                (this as ExtensionAware).extensions.getByType(org.jetbrains.gradle.ext.ActionDelegationConfig::class).run {
+                    delegateBuildRunToGradle = false
+                    testRunner = org.jetbrains.gradle.ext.ActionDelegationConfig.TestRunner.PLATFORM
+                }
+                extensions.getByType(org.jetbrains.gradle.ext.IdeaCompilerConfiguration::class).run {
+                    addNotNullAssertions = false
+                    useReleaseOption = JavaVersion.current().isJava10Compatible
+                    parallelCompilation = true
+                }
+            }
+        }
+    }
 }

gradle/libs.versions.toml

@@ -4,11 +4,13 @@ configurate4 = "4.1.2"
 flare = "2.0.1"
 log4j = "2.22.1"
 netty = "4.1.106.Final"
+ideaExt = "1.1.8"
 
 [plugins]
 indra-publishing = "net.kyori.indra.publishing:2.0.6"
 shadow = "io.github.goooler.shadow:8.1.5"
 spotless = "com.diffplug.spotless:6.25.0"
+ideaExt = { id = "org.jetbrains.gradle.plugin.idea-ext", version.ref = "ideaExt" }
 
 [libraries]
 adventure-bom = "net.kyori:adventure-bom:4.16.0"

proxy/src/main/java/com/velocitypowered/proxy/plugin/VelocityPluginManager.java

@@ -37,12 +37,16 @@
 import com.velocitypowered.proxy.plugin.util.PluginDependencyUtils;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
 import java.nio.file.DirectoryStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.IdentityHashMap;
 import java.util.LinkedHashMap;
@@ -89,6 +93,26 @@ public void loadPlugins(Path directory) throws IOException {
     List<PluginDescription> found = new ArrayList<>();
     JavaPluginLoader loader = new JavaPluginLoader(server, directory);
 
+    Enumeration<URL> resources = ClassLoader.getSystemClassLoader().getResources("velocity-plugin.json");
+    while (resources.hasMoreElements()) {
+      URL url = resources.nextElement();
+
+      URI uri;
+      try {
+        uri = url.toURI();
+      } catch (URISyntaxException e) {
+        logger.error("Malformed URI {}", url, e);
+        continue;
+      }
+
+      Path path = Path.of(uri);
+      try {
+        found.add(loader.loadCandidate(path.getParent()));
+      } catch (Throwable e) {
+        logger.error("Unable to load plugin {}", path, e);
+      }
+    }
+
     try (DirectoryStream<Path> stream = Files.newDirectoryStream(directory,
         p -> p.toFile().isFile() && p.toString().endsWith(".jar"))) {
       for (Path path : stream) {

proxy/src/main/java/com/velocitypowered/proxy/plugin/loader/java/JavaPluginLoader.java

@@ -32,6 +32,8 @@
 import com.velocitypowered.proxy.plugin.loader.VelocityPluginContainer;
 import com.velocitypowered.proxy.plugin.loader.VelocityPluginDescription;
 import java.io.BufferedInputStream;
+import java.io.IOException;
+import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.net.URL;
@@ -141,32 +143,47 @@ public void createPlugin(PluginContainer container, Module... modules) {
   private Optional<SerializedPluginDescription> getSerializedPluginInfo(Path source)
       throws Exception {
     boolean foundBungeeBukkitPluginFile = false;
-    try (JarInputStream in = new JarInputStream(
-        new BufferedInputStream(Files.newInputStream(source)))) {
-      JarEntry entry;
-      while ((entry = in.getNextJarEntry()) != null) {
-        if (entry.getName().equals("velocity-plugin.json")) {
-          try (Reader pluginInfoReader = new InputStreamReader(in, StandardCharsets.UTF_8)) {
-            return Optional.of(VelocityServer.GENERAL_GSON.fromJson(pluginInfoReader,
-                SerializedPluginDescription.class));
+    if (source.getFileName().endsWith(".jar")) {
+      try (JarInputStream in = new JarInputStream(
+              new BufferedInputStream(Files.newInputStream(source)))) {
+        JarEntry entry;
+        while ((entry = in.getNextJarEntry()) != null) {
+          if (entry.getName().equals("velocity-plugin.json")) {
+            return Optional.of(readPluginInfo(in));
+          }
+
+          if (entry.getName().equals("plugin.yml") || entry.getName().equals("bungee.yml")) {
+            foundBungeeBukkitPluginFile = true;
           }
         }
 
-        if (entry.getName().equals("plugin.yml") || entry.getName().equals("bungee.yml")) {
-          foundBungeeBukkitPluginFile = true;
+        if (foundBungeeBukkitPluginFile) {
+          throw new InvalidPluginException("The plugin file " + source.getFileName() + " appears to "
+                  + "be a Bukkit or BungeeCord plugin. Velocity does not support Bukkit or BungeeCord "
+                  + "plugins.");
         }
-      }
 
-      if (foundBungeeBukkitPluginFile) {
-        throw new InvalidPluginException("The plugin file " + source.getFileName() + " appears to "
-            + "be a Bukkit or BungeeCord plugin. Velocity does not support Bukkit or BungeeCord "
-            + "plugins.");
+        return Optional.empty();
+      }
+    } else {
+      Path velocityPluginPath = source.resolve("velocity-plugin.json");
+      if (Files.exists(velocityPluginPath)) {
+        try (BufferedInputStream in = new BufferedInputStream(Files.newInputStream(velocityPluginPath))) {
+          return Optional.of(readPluginInfo(in));
+        }
       }
 
       return Optional.empty();
     }
   }
 
+  private SerializedPluginDescription readPluginInfo(InputStream in) throws IOException {
+    try (Reader pluginInfoReader = new InputStreamReader(in, StandardCharsets.UTF_8)) {
+      return VelocityServer.GENERAL_GSON.fromJson(pluginInfoReader,
+              SerializedPluginDescription.class);
+    }
+  }
+
   private VelocityPluginDescription createCandidateDescription(
       SerializedPluginDescription description,
       Path source) {