io.jsync.dns.impl.netty.DnsHeader Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jsync.io Show documentation
jsync.io is a non-blocking, event-driven networking framework for Java
There is a newer version: 1.10.13
/*
 * Copyright (c) 2013 The Netty Project
 * ------------------------------------
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Apache License v2.0 which accompanies this distribution.
 *
 *     The Eclipse Public License is available at
 *     http://www.eclipse.org/legal/epl-v10.html
 *
 *     The Apache License v2.0 is available at
 *     http://www.opensource.org/licenses/apache2.0.php
 *
 * You may elect to redistribute this code under either of these licenses.
 */
package io.jsync.dns.impl.netty;

/**
 * The header super-class which includes information shared by DNS query and
 * response packet headers such as the ID, opcode, and type. The only flag
 * shared by both classes is the flag for desiring recursion.
 */
public class DnsHeader {

    /**
     * Message type is query.
     */
    public static final int TYPE_QUERY = 0;

    /**
     * Message type is response.
     */
    public static final int TYPE_RESPONSE = 1;

    /**
     * Message is for a standard query.
     */
    public static final int OPCODE_QUERY = 0;

    /**
     * Message is for an inverse query. Note: inverse queries have been
     * obsoleted since RFC 3425, and are not necessarily supported.
     */
    @Deprecated
    public static final int OPCODE_IQUERY = 1;

    private final DnsMessage parent;

    private boolean recursionDesired;
    private int opcode;
    private int id;
    private int type;

    public DnsHeader(DnsMessage parent) {
        if (parent == null) {
            throw new NullPointerException("the parent field cannot be null and must point to a valid DnsMessage.");
        }
        this.parent = parent;
    }

    /**
     * Returns the number of questions in the {@link DnsMessage}.
     */
    public int questionCount() {
        return parent.getQuestions().size();
    }

    /**
     * Returns the number of answer resource records in the {@link DnsMessage}.
     */
    public int answerCount() {
        return parent.getAnswers().size();
    }

    /**
     * Returns the number of authority resource records in the
     * {@link DnsMessage}.
     */
    public int authorityResourceCount() {
        return parent.getAuthorityResources().size();
    }

    /**
     * Returns the number of additional resource records in the
     * {@link DnsMessage}.
     */
    public int additionalResourceCount() {
        return parent.getAdditionalResources().size();
    }

    /**
     * Returns {@code true} if a query is to be pursued recursively.
     */
    public boolean isRecursionDesired() {
        return recursionDesired;
    }

    /**
     * Sets whether a name server is directed to pursue a query recursively or
     * not.
     *
     * @param recursionDesired if set to {@code true}, pursues query recursively
     * @return the header to allow method chaining
     */
    public DnsHeader setRecursionDesired(boolean recursionDesired) {
        this.recursionDesired = recursionDesired;
        return this;
    }

    /**
     * Returns the 4 bit opcode used for the {@link DnsMessage}.
     *
     * @see #OPCODE_QUERY
     * @see #OPCODE_IQUERY
     */
    public int getOpcode() {
        return opcode;
    }

    /**
     * Sets the opcode for this {@link DnsMessage}.
     *
     * @param opcode opcode to set
     * @return the header to allow method chaining
     */
    public DnsHeader setOpcode(int opcode) {
        this.opcode = opcode;
        return this;
    }

    /**
     * Returns the type of {@link DnsMessage}.
     *
     * @see #TYPE_QUERY
     */
    public int getType() {
        return type;
    }

    /**
     * Sets the {@link DnsMessage} type.
     *
     * @param type message type
     * @return the header to allow method chaining
     */
    public DnsHeader setType(int type) {
        this.type = type;
        return this;
    }

    /**
     * Returns the 2 byte unsigned identifier number used for the
     * {@link DnsMessage}.
     */
    public int getId() {
        return id;
    }

    /**
     * Sets the id for this {@link DnsMessage}.
     *
     * @param id a unique 2 byte unsigned identifier
     * @return the header to allow method chaining
     */
    public DnsHeader setId(int id) {
        this.id = id;
        return this;
    }

}