org.sonar.plugins.web.checks.scripting.OGNLExpressionCheck Maven / Gradle / Ivy

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/*
 * Sonar Web Plugin
 * Copyright (C) 2010 Matthijs Galesloot
 * [email protected]
 *
 * Licensed under the Apache License, Version 2.0 (the "License")
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.sonar.plugins.web.checks.scripting;

import ognl.Ognl;
import ognl.OgnlException;
import org.apache.commons.lang.StringUtils;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.plugins.web.checks.AbstractPageCheck;
import org.sonar.plugins.web.node.Attribute;
import org.sonar.plugins.web.node.TagNode;

/**
 * Checker to validate OGNL Expressions.
 *
 * @author Matthijs Galesloot
 * @since 1.1
 */
@Rule(key = "OGNLExpressionCheck", priority = Priority.BLOCKER)
public class OGNLExpressionCheck extends AbstractPageCheck {

  @Override
  public void startElement(TagNode element) {

    for (Attribute attribute : element.getAttributes()) {
      String value = attribute.getValue();
      if (value != null) {
        parseAndValidate(element, value);
      }
    }
  }

  private void parseAndValidate(TagNode element, String text) {
    for (int i = 0; i + 1 < text.length(); i++) {
      if ((text.charAt(i) == '%' || text.charAt(i) == '#') && text.charAt(i + 1) == '{') {
        String expression = extractExpression(text, i);
        validateExpression(element, expression);
      }
    }
  }

  /**
   * Method needed in order to be able to parse strings like "%{foo.message}" but also "%{'${foo.message}'}" which is valid as well.
   */
  private String extractExpression(String text, int startIndex) {
    StringBuilder expression = new StringBuilder();

    String remainingText = StringUtils.substring(text, startIndex + 2);
    int insideCurlyBraceCounter = 0;
    for (char c : remainingText.toCharArray()) {
      if (c == '}' && insideCurlyBraceCounter == 0) {
        break;
      }
      if (c == '{') {
        insideCurlyBraceCounter++;
      } else if (c == '}') {
        insideCurlyBraceCounter--;
      }
      expression.append(c);
    }

    return expression.toString();
  }

  private void validateExpression(TagNode element, String value) {
    try {
      Ognl.parseExpression(value);
    } catch (OgnlException e) {
      createViolation(element.getStartLinePosition(), "This OGNL expression is not valid. " + (e.getMessage() == null ? "" : e.getMessage()));
    }
  }
}