add plugin system

Signed-off-by: pengzhile <pengzhile@gmail.com>

README.md

@@ -1,4 +1,4 @@
-# ja-netfilter
+# ja-netfilter v1.1.0
 
 ### A javaagent lib for network filter
 
@@ -6,25 +6,19 @@
 
 * download from the [releases page](https://github.com/pengzhile/ja-netfilter/releases)
 * add `-javaagent:/absolute/path/to/ja-netfilter.jar` argument (**Change to your actual path**)
-    * add as an argument of the `java` command.
-      eg: `java -javaagent:/absolute/path/to/ja-netfilter.jar -jar executable_jar_file.jar`
+    * add as an argument of the `java` command. eg: `java -javaagent:/absolute/path/to/ja-netfilter.jar -jar executable_jar_file.jar`
     * some apps support the `JVM Options file`, you can add as a line of the `JVM Options file`.
     * **WARNING: DO NOT put some unnecessary whitespace characters!**
 
-* edit your own rule list config file. The `ja-netfilter` will look for it in the following order(find one and stop
-  searching):
-    * passed as args of `-javaagent`.
-      eg: `-javaagent:/absolute/path/to/ja-netfilter.jar=/home/neo/downloads/janf_config.txt`
+* edit your own rule list config file. The `ja-netfilter` will look for it in the following order(find one and stop searching):
+    * passed as args of `-javaagent`. eg: `-javaagent:/absolute/path/to/ja-netfilter.jar=/home/neo/downloads/janf_config.txt`
     * file path in environment variable: `JANF_CONFIG`
-    * file path in `java` startup property: `janf.config`
-      . `eg: java -Djanf.config="/home/neo/downloads/janf_config.txt"`
-    * some apps support the `JVM Options file`, you can add as a line of the `JVM Options file`
-      . `eg: -Djanf.config="/home/neo/downloads/janf_config.txt"`
-    * file path in the same dir as the `ja-netfilter.jar` (**PREFERRED!**)
+    * file path in `java` startup property: `janf.config`. `eg: java -Djanf.config="/home/neo/downloads/janf_config.txt"`
+    * some apps support the `JVM Options file`, you can add as a line of the `JVM Options file`. `eg: -Djanf.config="/home/neo/downloads/janf_config.txt"`
+    * file path in the same dir as the `ja-netfilter.jar`, no need for additional configuration (<font color=green>**PREFERRED!**</font>)
     * file path in your home directory, named: `.janf_config.txt`. `eg: /home/neo/.janf_config.txt`
     * file path in the subdirectory named `.config` in your home directory. `eg: /home/neo/.config/janf_config.txt`
-    * file path in the subdirectory named `.local/etc` in your home
-      directory. `eg: /home/neo/.local/ect/janf_config.txt`
+    * file path in the subdirectory named `.local/etc` in your home directory. `eg: /home/neo/.local/ect/janf_config.txt`
     * file path in the directory named `/usr/local/etc`. `eg: /usr/local/etc/janf_config.txt`
     * file path in the directory named `/etc`. eg: `/etc/janf_config.txt`
 
@@ -33,6 +27,9 @@
 ## Config file format
 
 ```
+[ABC]
+# for the specified plugin called "ABC"
+
 [URL]
 EQUAL,https://someurl
 
@@ -50,4 +47,17 @@ EQUAL,somedomain
 
 * the `ja-netfilter` will **NOT** output debugging information by default
 * add environment variable `JANF_DEBUG=1` and start to enable it
-* or add system property `-Djanf.debug=1` to enable it
+* or add system property `-Djanf.debug=1` to enable it
+
+## Plugin system
+
+* for developer:
+    * view the [scaffold project](!https://github.com/pengzhile/ja-netfilter-sample-plugin) written for the plug-in system
+    * compile your plugin and publish it
+    * just use your imagination~
+
+* for user:
+    * download the jar file of the plugin
+    * put it in the subdirectory called `plugins` where the ja-netfilter.jar file is located
+    * enjoy the new capabilities brought by the plugin
+   

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>io.zhile.research</groupId>
     <artifactId>ja-netfilter</artifactId>
-    <version>1.0.0</version>
+    <version>1.1.0</version>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

src/main/java/io/zhile/research/ja/netfilter/Dispatcher.java

@@ -0,0 +1,64 @@
+package io.zhile.research.ja.netfilter;
+
+import io.zhile.research.ja.netfilter.commons.DebugInfo;
+import io.zhile.research.ja.netfilter.transformers.MyTransformer;
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.security.ProtectionDomain;
+import java.util.*;
+
+public class Dispatcher implements ClassFileTransformer {
+    private static Dispatcher INSTANCE;
+
+    private final Map<String, List<MyTransformer>> transformerMap = new HashMap<>();
+
+    public static synchronized Dispatcher getInstance() {
+        if (null == INSTANCE) {
+            INSTANCE = new Dispatcher();
+        }
+
+        return INSTANCE;
+    }
+
+    public void addTransformer(MyTransformer transformer) {
+        List<MyTransformer> transformers = transformerMap.computeIfAbsent(transformer.getHookClassName(), k -> new ArrayList<>());
+
+        transformers.add(transformer);
+    }
+
+    public void addTransformers(List<MyTransformer> transformers) {
+        for (MyTransformer transformer : transformers) {
+            addTransformer(transformer);
+        }
+    }
+
+    public void addTransformers(MyTransformer[] transformers) {
+        addTransformers(Arrays.asList(transformers));
+    }
+
+    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classFileBuffer) throws IllegalClassFormatException {
+        do {
+            if (null == className) {
+                break;
+            }
+
+            List<MyTransformer> transformers = transformerMap.get(className);
+            if (null == transformers) {
+                break;
+            }
+
+            int order = 0;
+
+            try {
+                for (MyTransformer transformer : transformers) {
+                    classFileBuffer = transformer.transform(className, classFileBuffer, order++);
+                }
+            } catch (Exception e) {
+                DebugInfo.output("Transform class failed: " + e.getMessage());
+            }
+        } while (false);
+
+        return classFileBuffer;
+    }
+}

src/main/java/io/zhile/research/ja/netfilter/Initializer.java

@@ -0,0 +1,40 @@
+package io.zhile.research.ja.netfilter;
+
+import io.zhile.research.ja.netfilter.commons.ConfigDetector;
+import io.zhile.research.ja.netfilter.commons.ConfigParser;
+import io.zhile.research.ja.netfilter.commons.DebugInfo;
+import io.zhile.research.ja.netfilter.models.FilterConfig;
+import io.zhile.research.ja.netfilter.plugin.PluginManager;
+
+import java.io.File;
+import java.lang.instrument.Instrumentation;
+import java.lang.instrument.UnmodifiableClassException;
+
+public class Initializer {
+    public static void init(String args, Instrumentation inst, File currentDirectory) {
+        File configFile = ConfigDetector.detect(currentDirectory, args);
+        if (null == configFile) {
+            DebugInfo.output("Could not find any configuration files.");
+        } else {
+            DebugInfo.output("Current config file: " + configFile.getPath());
+        }
+
+        try {
+            FilterConfig.setCurrent(new FilterConfig(ConfigParser.parse(configFile)));
+        } catch (Exception e) {
+            DebugInfo.output(e.getMessage());
+        }
+
+        PluginManager.getInstance().loadPlugins(inst, currentDirectory);
+
+        for (Class<?> c : inst.getAllLoadedClasses()) {
+            try {
+                inst.retransformClasses(c);
+            } catch (UnmodifiableClassException e) {
+                // ok, ok. just ignore
+            }
+        }
+
+        inst.addTransformer(Dispatcher.getInstance(), true);
+    }
+}

src/main/java/io/zhile/research/ja/netfilter/Launcher.java

@@ -1,13 +1,9 @@
 package io.zhile.research.ja.netfilter;
 
-import io.zhile.research.ja.netfilter.commons.ConfigDetector;
-import io.zhile.research.ja.netfilter.commons.ConfigParser;
 import io.zhile.research.ja.netfilter.commons.DebugInfo;
-import io.zhile.research.ja.netfilter.models.FilterConfig;
 
 import java.io.File;
 import java.lang.instrument.Instrumentation;
-import java.lang.instrument.UnmodifiableClassException;
 import java.net.URI;
 import java.net.URL;
 import java.util.jar.JarFile;
@@ -28,35 +24,16 @@ public class Launcher {
             return;
         }
 
+        File currentFile = new File(jarURI.getPath());
+        File currentDirectory = currentFile.getParentFile();
         try {
-            inst.appendToBootstrapClassLoaderSearch(new JarFile(jarURI.getPath()));
+            inst.appendToBootstrapClassLoaderSearch(new JarFile(currentFile));
         } catch (Throwable e) {
             DebugInfo.output("ERROR: Can not access ja-netfilter jar file.");
             return;
         }
 
-        File configFile = ConfigDetector.detect(new File(jarURI.getPath()).getParentFile().getPath(), args);
-        if (null == configFile) {
-            DebugInfo.output("Could not find any configuration files.");
-        } else {
-            DebugInfo.output("Current config file: " + configFile.getPath());
-        }
-
-        try {
-            FilterConfig.setCurrent(new FilterConfig(ConfigParser.parse(configFile)));
-        } catch (Exception e) {
-            DebugInfo.output(e.getMessage());
-        }
-
-        for (Class<?> c : inst.getAllLoadedClasses()) {
-            try {
-                inst.retransformClasses(c);
-            } catch (UnmodifiableClassException e) {
-                // ok, ok. just ignore
-            }
-        }
-
-        inst.addTransformer(new TransformDispatcher(), true);
+        Initializer.init(args, inst, currentDirectory); // for some custom UrlLoaders
     }
 
     private static void printUsage() {

src/main/java/io/zhile/research/ja/netfilter/TransformDispatcher.java

@@ -1,43 +0,0 @@
-package io.zhile.research.ja.netfilter;
-
-import io.zhile.research.ja.netfilter.commons.DebugInfo;
-import io.zhile.research.ja.netfilter.transformers.HttpClientTransformer;
-import io.zhile.research.ja.netfilter.transformers.InetAddressTransformer;
-import io.zhile.research.ja.netfilter.transformers.MyTransformer;
-
-import java.lang.instrument.ClassFileTransformer;
-import java.lang.instrument.IllegalClassFormatException;
-import java.security.ProtectionDomain;
-import java.util.HashMap;
-import java.util.Map;
-
-public class TransformDispatcher implements ClassFileTransformer {
-    public static final Map<String, MyTransformer> TRANSFORMER_MAP;
-
-    static {
-        TRANSFORMER_MAP = new HashMap<>();
-        TRANSFORMER_MAP.put("sun/net/www/http/HttpClient", new HttpClientTransformer());
-        TRANSFORMER_MAP.put("java/net/InetAddress", new InetAddressTransformer());
-    }
-
-    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classFileBuffer) throws IllegalClassFormatException {
-        do {
-            if (null == className) {
-                break;
-            }
-
-            MyTransformer transformer = TRANSFORMER_MAP.get(className);
-            if (null == transformer) {
-                break;
-            }
-
-            try {
-                return transformer.transform(className, classFileBuffer);
-            } catch (Exception e) {
-                DebugInfo.output("Transform class failed: " + e.getMessage());
-            }
-        } while (false);
-
-        return classFileBuffer;
-    }
-}

src/main/java/io/zhile/research/ja/netfilter/commons/ConfigDetector.java

@@ -7,6 +7,10 @@ import java.io.File;
 public class ConfigDetector {
     private static final String CONFIG_FILENAME = "janf_config.txt";
 
+    public static File detect(File currentDirectory, String args) {
+        return detect(currentDirectory.getPath(), args);
+    }
+
     public static File detect(String currentDirectory, String args) {
         File configFile = tryFile(args);        // by javaagent argument
 

src/main/java/io/zhile/research/ja/netfilter/filters/URLFilter.java

@@ -9,7 +9,7 @@ import java.net.SocketTimeoutException;
 import java.net.URL;
 
 public class URLFilter {
-    public static final String SECTION_NAME = "URL";
+    private static final String SECTION_NAME = "URL";
 
     public static URL testURL(URL url) throws IOException {
         if (null == url) {

src/main/java/io/zhile/research/ja/netfilter/models/FilterRule.java

@@ -60,4 +60,4 @@ public class FilterRule {
                 ", rule='" + rule + '\'' +
                 '}';
     }
-}
+}

src/main/java/io/zhile/research/ja/netfilter/plugin/PluginClassLoader.java

@@ -0,0 +1,44 @@
+package io.zhile.research.ja.netfilter.plugin;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.jar.JarFile;
+import java.util.zip.ZipEntry;
+
+public class PluginClassLoader extends ClassLoader {
+    private final JarFile jarFile;
+
+    public PluginClassLoader(JarFile jarFile) {
+        this.jarFile = jarFile;
+    }
+
+    @Override
+    public Class<?> findClass(String name) throws ClassNotFoundException {
+        byte[] bytes = loadClassFromFile(name);
+
+        return defineClass(name, bytes, 0, bytes.length);
+    }
+
+    private byte[] loadClassFromFile(String fileName) throws ClassNotFoundException {
+        String classFile = fileName.replace('.', '/') + ".class";
+        ZipEntry entry = jarFile.getEntry(classFile);
+        if (null == entry) {
+            throw new ClassNotFoundException("Class not found: " + fileName);
+        }
+
+        int length;
+        byte[] buffer = new byte[1024];
+        ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
+
+        try (InputStream is = jarFile.getInputStream(entry)) {
+            while (-1 != (length = is.read(buffer))) {
+                byteStream.write(buffer, 0, length);
+            }
+        } catch (IOException e) {
+            throw new ClassNotFoundException("Can't access class: " + fileName, e);
+        }
+
+        return byteStream.toByteArray();
+    }
+}

src/main/java/io/zhile/research/ja/netfilter/plugin/PluginEntry.java

@@ -0,0 +1,24 @@
+package io.zhile.research.ja.netfilter.plugin;
+
+import io.zhile.research.ja.netfilter.models.FilterRule;
+import io.zhile.research.ja.netfilter.transformers.MyTransformer;
+
+import java.util.List;
+
+public interface PluginEntry {
+    default void init(List<FilterRule> filterRules) {
+        // get plugin config
+    }
+
+    String getName();
+
+    default String getVersion() {
+        return "v1.0.0";
+    }
+
+    default String getDescription() {
+        return "A ja-netfilter plugin.";
+    }
+
+    List<MyTransformer> getTransformers();
+}

src/main/java/io/zhile/research/ja/netfilter/plugin/PluginManager.java

@@ -0,0 +1,74 @@
+package io.zhile.research.ja.netfilter.plugin;
+
+import io.zhile.research.ja.netfilter.Dispatcher;
+import io.zhile.research.ja.netfilter.commons.DebugInfo;
+import io.zhile.research.ja.netfilter.models.FilterConfig;
+import io.zhile.research.ja.netfilter.transformers.HttpClientTransformer;
+import io.zhile.research.ja.netfilter.transformers.InetAddressTransformer;
+import io.zhile.research.ja.netfilter.transformers.MyTransformer;
+import io.zhile.research.ja.netfilter.utils.StringUtils;
+
+import java.io.File;
+import java.lang.instrument.Instrumentation;
+import java.util.Arrays;
+import java.util.jar.JarFile;
+import java.util.jar.Manifest;
+
+public class PluginManager {
+    private static final String PLUGINS_DIR = "plugins";
+    private static final String ENTRY_NAME = "JANF-Plugin-Entry";
+
+    private static PluginManager INSTANCE;
+
+    public static synchronized PluginManager getInstance() {
+        if (null == INSTANCE) {
+            INSTANCE = new PluginManager();
+        }
+
+        return INSTANCE;
+    }
+
+    public void loadPlugins(Instrumentation inst, File currentDirectory) {
+        File pluginsDirectory = new File(currentDirectory, PLUGINS_DIR);
+        if (!pluginsDirectory.exists() || !pluginsDirectory.isDirectory()) {
+            return;
+        }
+
+        File[] pluginFiles = pluginsDirectory.listFiles((d, n) -> n.endsWith(".jar"));
+        if (null == pluginFiles) {
+            return;
+        }
+
+        Dispatcher.getInstance().addTransformers(new MyTransformer[]{   // built-in transformers
+                new HttpClientTransformer(),
+                new InetAddressTransformer()
+        });
+
+        for (File pluginFile : pluginFiles) {
+            try {
+                JarFile jarFile = new JarFile(pluginFile);
+                Manifest manifest = jarFile.getManifest();
+                String entryClass = manifest.getMainAttributes().getValue(ENTRY_NAME);
+                if (StringUtils.isEmpty(entryClass)) {
+                    continue;
+                }
+
+                PluginClassLoader classLoader = new PluginClassLoader(jarFile);
+                Class<?> klass = Class.forName(entryClass, false, classLoader);
+                if (!Arrays.asList(klass.getInterfaces()).contains(PluginEntry.class)) {
+                    continue;
+                }
+
+                inst.appendToBootstrapClassLoaderSearch(jarFile);
+
+                PluginEntry pluginEntry = (PluginEntry) Class.forName(entryClass).newInstance();
+                pluginEntry.init(FilterConfig.getBySection(pluginEntry.getName()));
+                Dispatcher.getInstance().addTransformers(pluginEntry.getTransformers());
+
+                DebugInfo.output("Plugin loaded: {name=" + pluginEntry.getName() + ", version=" + pluginEntry.getVersion() + "}");
+            } catch (Exception e) {
+                DebugInfo.output("Load plugin failed: " + e.getMessage());
+            }
+        }
+    }
+}

src/main/java/io/zhile/research/ja/netfilter/transformers/HttpClientTransformer.java

@@ -8,7 +8,12 @@ import static jdk.internal.org.objectweb.asm.Opcodes.*;
 
 public class HttpClientTransformer implements MyTransformer {
     @Override
-    public byte[] transform(String className, byte[] classBytes) throws Exception {
+    public String getHookClassName() {
+        return "sun/net/www/http/HttpClient";
+    }
+
+    @Override
+    public byte[] transform(String className, byte[] classBytes, int order) throws Exception {
         ClassReader reader = new ClassReader(classBytes);
         ClassNode node = new ClassNode(ASM5);
         reader.accept(node, 0);

src/main/java/io/zhile/research/ja/netfilter/transformers/InetAddressTransformer.java

@@ -8,7 +8,12 @@ import static jdk.internal.org.objectweb.asm.Opcodes.*;
 
 public class InetAddressTransformer implements MyTransformer {
     @Override
-    public byte[] transform(String className, byte[] classBytes) throws Exception {
+    public String getHookClassName() {
+        return "java/net/InetAddress";
+    }
+
+    @Override
+    public byte[] transform(String className, byte[] classBytes, int order) throws Exception {
         ClassReader reader = new ClassReader(classBytes);
         ClassNode node = new ClassNode(ASM5);
         reader.accept(node, 0);

src/main/java/io/zhile/research/ja/netfilter/transformers/MyTransformer.java

@@ -1,5 +1,9 @@
 package io.zhile.research.ja.netfilter.transformers;
 
 public interface MyTransformer {
-    byte[] transform(String className, byte[] classBytes) throws Exception;
+    String getHookClassName();
+
+    default byte[] transform(String className, byte[] classBytes, int order) throws Exception {
+        return classBytes;
+    }
 }