/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.apache.ambari.server.utils;
import java.util.regex.Pattern;
/**
* HostUtils provides utilities related to processing and validating hosts and host names.
*/
public class HostUtils {
/**
* A regular expression to validate that a hostname meets the specifications described in RFC 1123.
* <p>
* Various sources on the Internet specific this regular expression for hostname validation.
*/
private static final Pattern REGEX_VALID_HOSTNAME = Pattern.compile("^(?:(?:[a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*(?:[A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\\-]*[A-Za-z0-9])$");
/**
* Validates a hostname to ensure it meets the specifications described in RFC 1123.
* <p>
* Note: this does not validate whether the host exists or if the name is a valid DNS name.
* For example, host.example.anything is a valid host name however may be an invalid DNS name
* since "anything" may not be a valid top-level domain.
*
* @param hostname a hostname
* @return true if the hostname is valid; false otherwise
*/
public static boolean isValidHostname(String hostname) {
return (hostname != null) && REGEX_VALID_HOSTNAME.matcher(hostname).matches();
}
}