Java example source code file (DefaultDnsRecordEncoder.java)

This example Java source code file (DefaultDnsRecordEncoder.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytebuf, defaultdnsrecordencoder, dnsptrrecord, dnsquestion, dnsrawrecord, exception, override, string, unstableapi

The DefaultDnsRecordEncoder.java Java example source code

/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.codec.dns;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.handler.codec.UnsupportedMessageTypeException;
import io.netty.util.internal.StringUtil;
import io.netty.util.internal.UnstableApi;

import static io.netty.handler.codec.dns.DefaultDnsRecordDecoder.ROOT;

/**
 * The default {@link DnsRecordEncoder} implementation.
 *
 * @see DefaultDnsRecordDecoder
 */
@UnstableApi
public class DefaultDnsRecordEncoder implements DnsRecordEncoder {

    /**
     * Creates a new instance.
     */
    protected DefaultDnsRecordEncoder() { }

    @Override
    public final void encodeQuestion(DnsQuestion question, ByteBuf out) throws Exception {
        encodeName(question.name(), out);
        out.writeShort(question.type().intValue());
        out.writeShort(question.dnsClass());
    }

    @Override
    public void encodeRecord(DnsRecord record, ByteBuf out) throws Exception {
        if (record instanceof DnsQuestion) {
            encodeQuestion((DnsQuestion) record, out);
        } else if (record instanceof DnsPtrRecord) {
            encodePtrRecord((DnsPtrRecord) record, out);
        } else if (record instanceof DnsRawRecord) {
            encodeRawRecord((DnsRawRecord) record, out);
        } else {
            throw new UnsupportedMessageTypeException(StringUtil.simpleClassName(record));
        }
    }

    private void encodePtrRecord(DnsPtrRecord record, ByteBuf out) throws Exception {
        encodeName(record.name(), out);

        out.writeShort(record.type().intValue());
        out.writeShort(record.dnsClass());
        out.writeInt((int) record.timeToLive());

        encodeName(record.hostname(), out);
    }

    private void encodeRawRecord(DnsRawRecord record, ByteBuf out) throws Exception {
        encodeName(record.name(), out);

        out.writeShort(record.type().intValue());
        out.writeShort(record.dnsClass());
        out.writeInt((int) record.timeToLive());

        ByteBuf content = record.content();
        int contentLen = content.readableBytes();

        out.writeShort(contentLen);
        out.writeBytes(content, content.readerIndex(), contentLen);
    }

    protected void encodeName(String name, ByteBuf buf) throws Exception {
        if (ROOT.equals(name)) {
            // Root domain
            buf.writeByte(0);
            return;
        }

        final String[] labels = StringUtil.split(name, '.');
        for (String label : labels) {
            final int labelLen = label.length();
            if (labelLen == 0) {
                // zero-length label means the end of the name.
                break;
            }

            buf.writeByte(labelLen);
            ByteBufUtil.writeAscii(buf, label);
        }

        buf.writeByte(0); // marks end of name field
    }
}