| /* |
| * 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.directory.server.dns.io.encoder; |
| |
| |
| /** |
| * 4. NAPTR RR Format |
| * |
| * 4.1 Packet Format |
| * |
| * The packet format of the NAPTR RR is given below. The DNS type code |
| * for NAPTR is 35. |
| * |
| * The packet format for the NAPTR record is as follows |
| * 1 1 1 1 1 1 |
| * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * | ORDER | |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * | PREFERENCE | |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * / FLAGS / |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * / SERVICES / |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * / REGEXP / |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * / REPLACEMENT / |
| * / / |
| * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| * |
| * <character-string> and <domain-name> as used here are defined in RFC |
| * 1035 [7]. |
| * |
| * ORDER |
| * A 16-bit unsigned integer specifying the order in which the NAPTR |
| * records MUST be processed in order to accurately represent the |
| * ordered list of Rules. The ordering is from lowest to highest. |
| * If two records have the same order value then they are considered |
| * to be the same rule and should be selected based on the |
| * combination of the Preference values and Services offered. |
| * |
| * PREFERENCE |
| * Although it is called "preference" in deference to DNS |
| * terminology, this field is equivalent to the Priority value in the |
| * DDDS Algorithm. It is a 16-bit unsigned integer that specifies |
| * the order in which NAPTR records with equal Order values SHOULD be |
| * processed, low numbers being processed before high numbers. This |
| * is similar to the preference field in an MX record, and is used so |
| * domain administrators can direct clients towards more capable |
| * hosts or lighter weight protocols. A client MAY look at records |
| * with higher preference values if it has a good reason to do so |
| * such as not supporting some protocol or service very well. |
| * |
| * The important difference between Order and Preference is that once |
| * a match is found the client MUST NOT consider records with a |
| * different Order but they MAY process records with the same Order |
| * but different Preferences. The only exception to this is noted in |
| * the second important Note in the DDDS algorithm specification |
| * concerning allowing clients to use more complex Service |
| * determination between steps 3 and 4 in the algorithm. Preference |
| * is used to give communicate a higher quality of service to rules |
| * that are considered the same from an authority standpoint but not |
| * from a simple load balancing standpoint. |
| * |
| * It is important to note that DNS contains several load balancing |
| * mechanisms and if load balancing among otherwise equal services |
| * should be needed then methods such as SRV records or multiple A |
| * records should be utilized to accomplish load balancing. |
| * |
| * FLAGS |
| * A <character-string> containing flags to control aspects of the |
| * rewriting and interpretation of the fields in the record. Flags |
| * are single characters from the set A-Z and 0-9. The case of the |
| * alphabetic characters is not significant. The field can be empty. |
| * |
| * It is up to the Application specifying how it is using this |
| * Database to define the Flags in this field. It must define which |
| * ones are terminal and which ones are not. |
| * |
| * SERVICES |
| * A <character-string> that specifies the Service Parameters |
| * applicable to this this delegation path. It is up to the |
| * Application Specification to specify the values found in this |
| * field. |
| * |
| * REGEXP |
| * A <character-string> containing a substitution expression that is |
| * applied to the original string held by the client in order to |
| * construct the next domain name to lookup. See the DDDS Algorithm |
| * specification for the syntax of this field. |
| * |
| * As stated in the DDDS algorithm, The regular expressions MUST NOT |
| * be used in a cumulative fashion, that is, they should only be |
| * applied to the original string held by the client, never to the |
| * domain name produced by a previous NAPTR rewrite. The latter is |
| * tempting in some applications but experience has shown such use to |
| * be extremely fault sensitive, very error prone, and extremely |
| * difficult to debug. |
| * |
| * REPLACEMENT |
| * A <domain-name> which is the next domain-name to query for |
| * depending on the potential values found in the flags field. This |
| * field is used when the regular expression is a simple replacement |
| * operation. Any value in this field MUST be a fully qualified |
| * domain-name. Name compression is not to be used for this field. |
| * |
| * This field and the REGEXP field together make up the Substitution |
| * Expression in the DDDS Algorithm. It is simply a historical |
| * optimization specifically for DNS compression that this field |
| * exists. The fields are also mutually exclusive. If a record is |
| * returned that has values for both fields then it is considered to |
| * be in error and SHOULD be either ignored or an error returned. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| * @version $Rev$, $Date$ |
| */ |
| public class NameAuthorityPointerEncoder |
| { |
| } |
