feat: adds enableSandboxMode method to enable sandbox mode

src/main/java/com/googlecode/aviator/AviatorEvaluatorInstance.java

@@ -448,6 +448,37 @@ public Map<String, Object> requireScript(final String path) throws IOException {
     }
   }
 
+  /**
+   * Configure the evaluator into sandbox mode for security, it means:
+   * <ul>
+   * <li>Disable syntax feature: Module, NewInstance, StaticMethods and InternalVars,</li>
+   * <li>Disable reflection invocation by function missing,</li>
+   * <li>Set the single maximum loop counter to 65535,</li>
+   * <li>Set ALLOWED_CLASS_SET and ASSIGNABLE_ALLOWED_CLASS_SET to be empty, disable all classes to
+   * be accessed via static fields or methods,</li>
+   * <li>Set the EVAL_TIMEOUT_MS to be 1000 milliseconds(1 second), which means the execution
+   * timeout.
+   * <li>
+   * </ul>
+   * 
+   * For more information on security, please refer to the
+   * <a href="https://www.yuque.com/boyan-avfmj/aviatorscript/ou23gy#elOSu">documentation</a>
+   * 
+   * @since 5.4.3
+   * 
+   */
+  public void enableSandboxMode() {
+    disableFeature(Feature.Module);
+    disableFeature(Feature.NewInstance);
+    disableFeature(Feature.InternalVars);
+    disableFeature(Feature.StaticMethods);
+    setFunctionMissing(null);
+    setOption(Options.MAX_LOOP_COUNT, 65535);
+    setOption(Options.ALLOWED_CLASS_SET, Collections.emptySet());
+    setOption(Options.ASSIGNABLE_ALLOWED_CLASS_SET, Collections.emptySet());
+    setOption(Options.EVAL_TIMEOUT_MS, 1000L);
+  }
+
   /**
    * Adds a module class and import it's public static methods as module's exports into module
    * cache, return the exports map.
@@ -701,8 +732,10 @@ public void setOption(final Options opt, final Object val) {
    * @param feature
    */
   public void enableFeature(final Feature feature) {
-    this.options.get(Options.FEATURE_SET).featureSet.add(feature);
-    this.options.get(Options.FEATURE_SET).featureSet.addAll(feature.getPrequires());
+    Set<Feature> featureSet = new HashSet<>(this.options.get(Options.FEATURE_SET).featureSet);
+    featureSet.add(feature);
+    featureSet.addAll(feature.getPrequires());
+    setOption(Options.FEATURE_SET, featureSet);
     loadFeatureFunctions();
   }
 
@@ -733,10 +766,12 @@ public boolean isFeatureEnabled(final Feature feature) {
    * @param feature
    */
   public void disableFeature(final Feature feature) {
-    this.options.get(Options.FEATURE_SET).featureSet.remove(feature);
+    Set<Feature> featureSet = new HashSet<>(this.options.get(Options.FEATURE_SET).featureSet);
+    featureSet.remove(feature);
     for (AviatorFunction fn : feature.getFunctions()) {
       this.removeFunction(fn);
     }
+    this.setOption(Options.FEATURE_SET, featureSet);
     loadFeatureFunctions();
   }
 

src/main/java/com/googlecode/aviator/runtime/type/AviatorString.java

@@ -26,6 +26,7 @@
 import com.googlecode.aviator.exception.ExpressionRuntimeException;
 import com.googlecode.aviator.runtime.RuntimeUtils;
 import com.googlecode.aviator.utils.Constants;
+import com.googlecode.aviator.utils.Env;
 import com.googlecode.aviator.utils.TypeUtils;
 
 /**
@@ -177,7 +178,8 @@ public String getLexeme(final Map<String, Object> env, final boolean warnOnCompi
       return this.lexeme;
     }
     StringSegments segs = null;
-    BaseExpression exp = (BaseExpression) (env == null ? null : env.get(Constants.EXP_VAR));
+    BaseExpression exp = (BaseExpression) ((env == null || !(env instanceof Env)) ? null
+        : ((Env) env).getExpression());
     if (exp != null) {
       segs = exp.getStringSegements(this.lexeme, this.lineNo);
     } else {

src/test/java/com/googlecode/aviator/AviatorEvaluatorInstanceCompatibleUnitTest.java

@@ -1,10 +1,13 @@
 package com.googlecode.aviator;
 
 import static com.googlecode.aviator.TestUtils.assertEquals;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.fail;
 import java.math.MathContext;
 import org.junit.Before;
 import org.junit.Test;
+import com.googlecode.aviator.exception.ExpressionRuntimeException;
+import com.googlecode.aviator.exception.FunctionNotFoundException;
 import com.googlecode.aviator.exception.UnsupportedFeatureException;
 
 public class AviatorEvaluatorInstanceCompatibleUnitTest extends AviatorEvaluatorInstanceUnitTest {
@@ -22,6 +25,39 @@ public void testIssue549() {
     // ignore
   }
 
+  @Test
+  public void testSandboxMode() {
+    this.instance.enableSandboxMode();
+    try {
+      this.instance.execute("new java.util.Date()");
+    } catch (UnsupportedFeatureException e) {
+      // ignore
+    }
+
+    try {
+      this.instance.execute("Math.abs(-1)");
+    } catch (FunctionNotFoundException e) {
+      // ignore
+    }
+
+    try {
+      this.instance.execute("System.exit(1)");
+    } catch (FunctionNotFoundException e) {
+      // ignore
+    }
+
+    try {
+      this.instance.execute("Math.PI");
+    } catch (ExpressionRuntimeException e) {
+      // ignore
+    }
+    try {
+      assertNull(this.instance.execute("__env__"));
+    } catch (UnsupportedFeatureException e) {
+
+    }
+  }
+
   @Override
   @Test(expected = UnsupportedFeatureException.class)
   public void testMaxLoopCount() {

src/test/java/com/googlecode/aviator/AviatorEvaluatorInstanceUnitTest.java

@@ -38,6 +38,7 @@
 import com.googlecode.aviator.exception.CompileExpressionErrorException;
 import com.googlecode.aviator.exception.ExpressionRuntimeException;
 import com.googlecode.aviator.exception.ExpressionSyntaxErrorException;
+import com.googlecode.aviator.exception.FunctionNotFoundException;
 import com.googlecode.aviator.exception.TimeoutException;
 import com.googlecode.aviator.exception.UnsupportedFeatureException;
 import com.googlecode.aviator.lexer.token.OperatorType;
@@ -61,6 +62,43 @@ public void setup() {
     this.instance.setOption(Options.EVAL_TIMEOUT_MS, 100);
   }
 
+  @Test
+  public void testSandboxMode() {
+    this.instance.enableSandboxMode();
+    try {
+      this.instance.execute("new java.util.Date()");
+    } catch (UnsupportedFeatureException e) {
+      // ignore
+    }
+
+    try {
+      this.instance.execute("Math.abs(-1)");
+    } catch (FunctionNotFoundException e) {
+      // ignore
+    }
+
+    try {
+      this.instance.execute("System.exit(1)");
+    } catch (FunctionNotFoundException e) {
+      // ignore
+    }
+
+    try {
+      this.instance.execute("Math.PI");
+    } catch (ExpressionRuntimeException e) {
+      // ignore
+    }
+    try {
+      this.instance.execute("while(true) {}");
+    } catch (ExpressionRuntimeException e) {
+      // ignore
+    }
+    try {
+      assertNull(this.instance.execute("__env__"));
+    } catch (UnsupportedFeatureException e) {
+
+    }
+  }
 
   @Test
   public void testIssue549() {