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jsync.io is a non-blocking, event-driven networking framework for Java

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/*
 * 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 DNS query header class which is used to represent the 12 byte header in a
 * {@link DnsQuery}.
 */
public class DnsQueryHeader extends DnsHeader {

    /**
     * Constructor for a DNS packet query header. The id is user generated and
     * will be replicated in the response packet by the server.
     *
     * @param parent the {@link DnsMessage} this header belongs to
     * @param id     a 2 bit unsigned identification number for this query
     */
    public DnsQueryHeader(DnsMessage parent, int id) {
        super(parent);
        setId(id);
        setType(TYPE_QUERY);
        setRecursionDesired(true);
    }

    /**
     * Returns the {@link DnsMessage} type. This will always return
     * {@code TYPE_QUERY}.
     */
    @Override
    public final int getType() {
        return TYPE_QUERY;
    }

    /**
     * Sets the {@link DnsHeader} type. Must be {@code TYPE_RESPONSE}.
     *
     * @param type message type
     * @return the header to allow method chaining
     */
    @Override
    public final DnsQueryHeader setType(int type) {
        if (type != TYPE_QUERY) {
            throw new IllegalArgumentException("type cannot be anything but TYPE_QUERY (0) for a query header.");
        }
        super.setType(type);
        return this;
    }

}