Manually download netty-codec-http when missing (fixes #29)

build.gradle

@@ -1,6 +1,6 @@
 allprojects {
     group 'com.azuriom'
-    version '1.3.1'
+    version '1.3.2'
 }
 
 subprojects {

bukkit/src/main/java/com/azuriom/azlink/bukkit/AzLinkBukkitPlugin.java

@@ -3,6 +3,7 @@
 import com.azuriom.azlink.bukkit.command.BukkitCommandExecutor;
 import com.azuriom.azlink.bukkit.command.BukkitCommandSender;
 import com.azuriom.azlink.bukkit.injector.InjectedHttpServer;
+import com.azuriom.azlink.bukkit.injector.NettyLibraryLoader;
 import com.azuriom.azlink.bukkit.integrations.AuthMeIntegration;
 import com.azuriom.azlink.bukkit.integrations.FoliaSchedulerAdapter;
 import com.azuriom.azlink.bukkit.integrations.MoneyPlaceholderExpansion;
@@ -55,6 +56,15 @@ public void onEnable() {
         this.plugin = new AzLinkPlugin(this) {
             @Override
             protected HttpServer createHttpServer() {
+                NettyLibraryLoader libraryLoader = new NettyLibraryLoader(this);
+
+                try {
+                    libraryLoader.loadRequiredLibraries();
+                } catch (Exception e) {
+                    getLogger().error("Unable to load required libraries for instant commands", e);
+                    return null;
+                }
+
                 if (plugin.getConfig().getHttpPort() == getServer().getPort()) {
                     return new InjectedHttpServer(AzLinkBukkitPlugin.this);
                 }

bukkit/src/main/java/com/azuriom/azlink/bukkit/injector/HttpDecoder.java

@@ -20,10 +20,6 @@
  */
 public class HttpDecoder extends ByteToMessageDecoder {
 
-    // Since Spigot 1.19, netty-codec-http is no longer included in SpigotMC.
-    // PaperMC must be used instead to have instant commands.
-    private final boolean supported = isSupported();
-
     private final AzLinkPlugin plugin;
 
     public HttpDecoder(AzLinkPlugin plugin) {
@@ -68,11 +64,6 @@ protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
             // ignore
         }
 
-        if (!supported) {
-            logUnsupported();
-            return;
-        }
-
         pipeline.addLast("codec-http", new HttpServerCodec());
         pipeline.addLast("aggregator", new HttpObjectAggregator(65536));
         pipeline.addLast("handler", new HttpHandler(this.plugin));
@@ -82,26 +73,8 @@ protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
         in.release();
     }
 
-    private void logUnsupported() {
-        this.plugin.getLogger().error("AzLink is not compatible with your server software, please use Paper instead!");
-        this.plugin.getLogger().error("Paper offers significant performance improvements, bug fixes, security");
-        this.plugin.getLogger().error("enhancements and optional features for server owners to enhance their server.");
-        this.plugin.getLogger().error("");
-        this.plugin.getLogger().error("Download: https://papermc.io/downloads");
-    }
-
     private boolean isHttp(int magic1, int magic2, int magic3, int magic4) {
         return magic1 == 'G' && magic2 == 'E' && magic3 == 'T' && magic4 == ' ' || // GET
                 magic1 == 'P' && magic2 == 'O' && magic3 == 'S' && magic4 == 'T'; // POST
     }
-
-    private boolean isSupported() {
-        try {
-            Class.forName("io.netty.handler.codec.http.HttpServerCodec");
-
-            return true;
-        } catch (ClassNotFoundException e) {
-            return false;
-        }
-    }
 }

bukkit/src/main/java/com/azuriom/azlink/bukkit/injector/NettyLibraryLoader.java

@@ -0,0 +1,78 @@
+package com.azuriom.azlink.bukkit.injector;
+
+import com.azuriom.azlink.common.AzLinkPlugin;
+import io.netty.util.Version;
+
+import java.io.InputStream;
+import java.lang.reflect.Field;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+/**
+ * Since Spigot 1.19, netty-codec-http is no longer included, so we need to manually load it.
+ * <p>
+ * We are not including it in the plugin.yml 'libraries' list, because it's not needed for all Minecraft versions,
+ * and the Netty version changes between Minecraft versions.
+ */
+public class NettyLibraryLoader {
+
+    private static final String MAVEN_CENTRAL = "https://repo1.maven.org/maven2/%s/%s/%s/%s-%s.jar";
+
+    private final AzLinkPlugin plugin;
+    private final Path libsFolder;
+
+    public NettyLibraryLoader(AzLinkPlugin plugin) {
+        this.plugin = plugin;
+        this.libsFolder = plugin.getPlatform().getDataDirectory().resolve("libs");
+    }
+
+    public void loadRequiredLibraries() throws Exception {
+        try {
+            Class.forName("io.netty.handler.codec.http.HttpServerCodec");
+            // netty-codec-http is already loaded, all good
+            return;
+        } catch (ClassNotFoundException e) {
+            // manually load netty-codec-http below
+        }
+
+        this.plugin.getLogger().info("Loading netty-codec-http...");
+
+        loadLibrary("io.netty", "netty-codec-http", identifyNettyVersion());
+
+        this.plugin.getLogger().info("Loaded netty-codec-http successfully.");
+    }
+
+    private void loadLibrary(String groupId, String artifactId, String version) throws Exception {
+        Path jar = this.libsFolder.resolve(artifactId + "-" + version + ".jar");
+
+        if (!Files.exists(jar)) {
+            Files.createDirectory(jar.getParent());
+
+            this.plugin.getLogger().warn("Downloading " + artifactId + " v" + version + "...");
+
+            URL url = new URL(String.format(MAVEN_CENTRAL, groupId.replace('.', '/'), artifactId, version, artifactId, version));
+
+            try (InputStream in = url.openStream()) {
+                Files.copy(in, jar);
+            }
+
+            this.plugin.getLogger().info("Successfully downloaded " + artifactId + ".");
+        }
+
+        URL[] urls = {jar.toUri().toURL()};
+        ClassLoader pluginClassLoader = plugin.getClass().getClassLoader();
+        Field classLoaderField = pluginClassLoader.getClass().getDeclaredField("libraryLoader");
+        ClassLoader libraryLoader = new URLClassLoader(urls, pluginClassLoader.getParent());
+
+        classLoaderField.setAccessible(true);
+        classLoaderField.set(pluginClassLoader, libraryLoader);
+    }
+
+    private String identifyNettyVersion() {
+        Version version = Version.identify().get("netty-codec");
+
+        return version != null ? version.artifactVersion() : "4.1.97.Final";
+    }
+}

common/src/main/java/com/azuriom/azlink/common/AzLinkPlugin.java

@@ -88,7 +88,7 @@ public void init() {
             return;
         }
 
-        if (this.config.hasInstantCommands()) {
+        if (this.config.hasInstantCommands() && this.httpServer != null) {
             this.httpServer.start();
         }
 
@@ -186,10 +186,6 @@ public HttpClient getHttpClient() {
         return this.httpClient;
     }
 
-    public HttpServer getHttpServer() {
-        return this.httpServer;
-    }
-
     public UserManager getUserManager() {
         return this.userManager;
     }

universal-legacy/build.gradle

@@ -12,8 +12,8 @@ dependencies {
     implementation project(':azlink-nukkit')
 
     implementation 'com.google.code.gson:gson:2.8.9'
-    implementation 'io.netty:netty-handler:4.1.86.Final'
-    implementation 'io.netty:netty-codec-http:4.1.72.Final'
+    implementation 'io.netty:netty-handler:4.1.100.Final'
+    implementation 'io.netty:netty-codec-http:4.1.100.Final'
 }
 
 shadowJar {