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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 response header class which is used when receiving data from a DNS
 * server. Contains information contained in a DNS response header, such as
 * recursion availability, and response codes.
 */
public class DnsResponseHeader extends DnsHeader {

    private int readQuestions;
    private int readAnswers;
    private int readAuthorityResources;
    private int readAdditionalResources;

    private boolean authoritativeAnswer;
    private boolean truncated;
    private boolean recursionAvailable;

    private int z;
    private int responseCode;

    /**
     * Constructor for a DNS packet response header. The id is received by
     * reading a {@link DnsQuery} and is sent back to the client.
     *
     * @param parent the {@link DnsMessage} this header belongs to
     * @param id     a 2 bit unsigned identification number received from client
     */
    public DnsResponseHeader(DnsMessage parent, int id) {
        super(parent);
        setId(id);
        setType(TYPE_RESPONSE);
    }

    /**
     * Returns {@code true} if responding server is authoritative for the domain
     * name in the query message.
     */
    public boolean isAuthoritativeAnswer() {
        return authoritativeAnswer;
    }

    /**
     * Set to {@code true} if responding server is authoritative for the domain
     * name in the query message.
     *
     * @param authoritativeAnswer flag for authoritative answer
     */
    public void setAuthoritativeAnswer(boolean authoritativeAnswer) {
        this.authoritativeAnswer = authoritativeAnswer;
    }

    /**
     * Returns {@code true} if response has been truncated, usually if it is
     * over 512 bytes.
     */
    public boolean isTruncated() {
        return truncated;
    }

    /**
     * Set to {@code true} if response has been truncated (usually happens for
     * responses over 512 bytes).
     *
     * @param truncated flag for truncation
     */
    public void setTruncated(boolean truncated) {
        this.truncated = truncated;
    }

    /**
     * Returns {@code true} if DNS server can handle recursive queries.
     */
    public boolean isRecursionAvailable() {
        return recursionAvailable;
    }

    /**
     * Set to {@code true} if DNS server can handle recursive queries.
     *
     * @param recursionAvailable flag for recursion availability
     */
    public void setRecursionAvailable(boolean recursionAvailable) {
        this.recursionAvailable = recursionAvailable;
    }

    /**
     * Returns the 3 bit reserved field 'Z'.
     */
    public int getZ() {
        return z;
    }

    /**
     * Sets the field Z. This field is reserved and should remain as 0 if the
     * DNS server does not make usage of this field.
     *
     * @param z the value for the reserved field Z
     */
    public void setZ(int z) {
        this.z = z;
    }

    /**
     * Returns the 4 bit return code.
     */
    public int getResponseCode() {
        return responseCode;
    }

    /**
     * Sets the response code for this message.
     *
     * @param responseCode the response code
     */
    public void setResponseCode(int responseCode) {
        this.responseCode = responseCode;
    }

    /**
     * Returns the number of questions to read for this DNS response packet.
     */
    public int getReadQuestions() {
        return readQuestions;
    }

    /**
     * Sets the number of questions that should be read after this header has
     * been decoded.
     *
     * @param readQuestions the number of questions to read
     */
    public void setReadQuestions(int readQuestions) {
        this.readQuestions = readQuestions;
    }

    /**
     * Returns the number of answers to read for this DNS response packet.
     */
    public int getReadAnswers() {
        return readAnswers;
    }

    /**
     * Sets the number of answers that should be read after this header has been
     * decoded.
     *
     * @param readAnswers the number of answers to read
     */
    public void setReadAnswers(int readAnswers) {
        this.readAnswers = readAnswers;
    }

    /**
     * Returns the number of authority resource records to read for this DNS
     * response packet.
     */
    public int getReadAuthorityResources() {
        return readAuthorityResources;
    }

    /**
     * Sets the number of authority resources to be read after this header has
     * been decoded.
     *
     * @param readAuthorityResources the number of authority resources to read
     */
    public void setReadAuthorityResources(int readAuthorityResources) {
        this.readAuthorityResources = readAuthorityResources;
    }

    /**
     * Returns the number of additional resource records to read for this DNS
     * response packet.
     */
    public int getReadAdditionalResources() {
        return readAdditionalResources;
    }

    /**
     * Sets the number of additional resources to be read after this header has
     * been decoded.
     *
     * @param readAdditionalResources the number of additional resources to read
     */
    public void setReadAdditionalResources(int readAdditionalResources) {
        this.readAdditionalResources = readAdditionalResources;
    }

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

    /**
     * Sets the {@link DnsHeader} type. Must be {@code TYPE_RESPONSE}.
     *
     * @param type message type
     * @return the header to allow method chaining
     */
    @Override
    public final DnsResponseHeader setType(int type) {
        if (type != TYPE_RESPONSE) {
            throw new IllegalArgumentException("type cannot be anything but TYPE_RESPONSE (1) for a response header.");
        }
        super.setType(type);
        return this;
    }

}