java/src/main/com/google/appengine/tools/development/agent/impl/ObjectAccessVisitor.java

   1 // Copyright 2009 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.tools.development.agent.impl;
   4
   5 import org.objectweb.asm.ClassVisitor;
   6 import org.objectweb.asm.MethodVisitor;
   7 import org.objectweb.asm.Opcodes;
   8
   9 import java.net.URL;
  10 import java.util.HashSet;
  11 import java.util.Set;
  12
  13 /**
  14  * Visits method and field instructions, checking for references to
  15  * blacklisted classes.
  16  *
  17  */
  18 public class ObjectAccessVisitor extends ClassVisitor {
  19
  20   private static final String REJECT = "reject";
  21
  22   private static final String REJECT_DESCRIPTOR = "(Ljava/lang/String;)V";
  23
  24   private static final String CHECK_RESTRICTED = "checkRestricted";
  25
  26   private static final String CHECK_RESTRICTED_DESCRIPTOR =
  27       "(ZLjava/lang/String;Ljava/lang/String;Ljava/lang/String;)V";
  28
  29   private final boolean isUserCode;
  30   private final boolean treatRestrictedListViolationsAsErrors;
  31   private final String callingClassName;
  32   private final String callingClassCodeSource;
  33   private final Set<String> referencedClasses = new HashSet<String>();
  34
  35   public ObjectAccessVisitor(
  36       ClassVisitor classVisitor, boolean isUserCode,
  37       boolean treatRestrictedListViolationsAsErrors, String callingClassName, URL callingClassCodeSource) {
  38     super(Opcodes.ASM4, classVisitor);
  39     this.isUserCode = isUserCode;
  40     this.treatRestrictedListViolationsAsErrors = treatRestrictedListViolationsAsErrors;
  41     this.callingClassName = callingClassName;
  42     this.callingClassCodeSource =
  43         callingClassCodeSource == null ? "unknown location" : callingClassCodeSource.toString();
  44   }
  45
  46   @Override
  47   public MethodVisitor visitMethod(int access, String name, String desc, String signature,
  48       String[] exceptions) {
  49     MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
  50     return (mv == null) ? null : new MethodTranslator(mv, access, name, desc);
  51   }
  52
  53   private class MethodTranslator extends NonRecordingGeneratorAdapter {
  54     MethodTranslator(MethodVisitor methodVisitor, int access, String name, String desc) {
  55       super(methodVisitor, access, name, desc);
  56     }
  57
  58     @Override
  59     public void visitFieldInsn(int opcode, String owner, String name, String desc) {
  60       maybeReject(owner);
  61       super.visitFieldInsn(opcode, owner, name, desc);
  62     }
  63
  64     @Override
  65     public void visitMethodInsn(int opcode, String owner, String name, String desc) {
  66       maybeReject(owner);
  67       super.visitMethodInsn(opcode, owner, name, desc);
  68     }
  69
  70     private void maybeReject(String klass) {
  71       if (BlackList.getBlackList().contains(klass)) {
  72         super.push(klass.replace('/', '.'));
  73         super.visitMethodInsn(Opcodes.INVOKESTATIC, AgentImpl.AGENT_RUNTIME,
  74             REJECT, REJECT_DESCRIPTOR);
  75       } else if (isUserCode && !referencedClasses.contains(klass)) {
  76         referencedClasses.add(klass);
  77         super.push(treatRestrictedListViolationsAsErrors);
  78         super.push(klass.replace('/', '.'));
  79         super.push(callingClassName);
  80         super.push(callingClassCodeSource);
  81         super.visitMethodInsn(Opcodes.INVOKESTATIC, AgentImpl.AGENT_RUNTIME,
  82             CHECK_RESTRICTED, CHECK_RESTRICTED_DESCRIPTOR);
  83       }
  84     }
  85   }
  86 }