core/src/main/java/org/jclouds/predicates/validators/DnsNameValidator.java

/**
 * Licensed to jclouds, Inc. (jclouds) under one or more
 * contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  jclouds licenses this file
 * to you 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.jclouds.predicates.validators;

import static com.google.common.base.CharMatcher.inRange;
import static com.google.common.base.CharMatcher.is;

import javax.inject.Inject;
import javax.inject.Named;

import org.jclouds.predicates.Validator;

import com.google.common.base.CharMatcher;
import com.google.inject.Singleton;

/**
 * Validates name for dns-style names
 * 
 * @see org.jclouds.rest.InputParamValidator
 * @see org.jclouds.predicates.Validator
 * 
 * @author Adrian Cole
 */
@Singleton
public class DnsNameValidator extends Validator<String> {
   private int min;
   private int max;

   @Inject
   public DnsNameValidator(@Named("jclouds.dns_name_length_min") int min,
            @Named("jclouds.dns_name_length_max") int max) {
      this.min = min;
      this.max = max;
   }

   public void validate(String name) {

      if (name == null || name.length() < min || name.length() > max)
         throw exception(name, "Can't be null or empty. Length must be " + min + " to " + max
                  + " symbols.");
      if (CharMatcher.JAVA_LETTER_OR_DIGIT.indexIn(name) != 0)
         throw exception(name, "Should start with letter/number");
      if (!name.toLowerCase().equals(name))
         throw exception(name, "Should be only lowercase");

      /*
       * The name must be a valid DNS name. From wikipedia: "The characters allowed in a label are a
       * subset of the ASCII character set, a and includes the characters a through z, A through Z,
       * digits 0 through 9". From Azure: Every Dash (-) Must Be Immediately Preceded and Followed
       * by a Letter or Number.
       */
      CharMatcher range = getAcceptableRange();
      if (!range.matchesAllOf(name))
         throw exception(name, "Should have lowercase ASCII letters, " + "numbers, or dashes");
   }

   protected CharMatcher getAcceptableRange() {
      return inRange('a', 'z').or(inRange('0', '9').or(is('-')));
   }

   protected IllegalArgumentException exception(String vAppName, String reason) {
      return new IllegalArgumentException(String.format(
               "Object '%s' doesn't match dns naming constraints. " + "Reason: %s.", vAppName,
               reason));
   }

}