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ActiveMQ example source code file (DNSOutgoing.java)

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

Java - ActiveMQ tags/keywords

dnsoutgoing, dnsoutgoing, dnsrecord, hashtable, illegalstateexception, illegalstateexception, integer, integer, io, ioexception, ioexception, linkedlist, log, logger, logging, questions, stringbuffer, util

The ActiveMQ DNSOutgoing.java source code

/**
 * Copyright 2003-2005 Arthur van Hoff, Rick Blair
 *
 * 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.activemq.jmdns;

import java.io.IOException;
import java.util.Hashtable;
import java.util.LinkedList;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * An outgoing DNS message.
 *
 * @version %I%, %G%
 * @author	Arthur van Hoff, Rick Blair, Werner Randelshofer
 */
final class DNSOutgoing
{
    private static Logger logger = Logger.getLogger(DNSOutgoing.class.toString());
    int id;
    int flags;
    private boolean multicast;
    private int numQuestions;
    private int numAnswers;
    private int numAuthorities;
    private int numAdditionals;
    private Hashtable names;

    byte data[];
    int off;
    int len;

    /**
     * Create an outgoing multicast query or response.
     */
    DNSOutgoing(int flags)
    {
        this(flags, true);
    }

    /**
     * Create an outgoing query or response.
     */
    DNSOutgoing(int flags, boolean multicast)
    {
        this.flags = flags;
        this.multicast = multicast;
        names = new Hashtable();
        data = new byte[DNSConstants.MAX_MSG_TYPICAL];
        off = 12;
    }

    /**
     * Add a question to the message.
     */
    void addQuestion(DNSQuestion rec) throws IOException
    {
        if (numAnswers > 0 || numAuthorities > 0 || numAdditionals > 0)
        {
            throw new IllegalStateException("Questions must be added before answers");
        }
        numQuestions++;
        writeQuestion(rec);
    }

    /**
     * Add an answer if it is not suppressed.
     */
    void addAnswer(DNSIncoming in, DNSRecord rec) throws IOException
    {
        if (numAuthorities > 0 || numAdditionals > 0)
        {
            throw new IllegalStateException("Answers must be added before authorities and additionals");
        }
        if (!rec.suppressedBy(in))
        {
            addAnswer(rec, 0);
        }
    }

    /**
     * Add an additional answer to the record. Omit if there is no room.
     */
    void addAdditionalAnswer(DNSIncoming in, DNSRecord rec) throws IOException
    {
        if ((off < DNSConstants.MAX_MSG_TYPICAL - 200) && !rec.suppressedBy(in))
        {
            writeRecord(rec, 0);
            numAdditionals++;
        }
    }

    /**
     * Add an answer to the message.
     */
    void addAnswer(DNSRecord rec, long now) throws IOException
    {
        if (numAuthorities > 0 || numAdditionals > 0)
        {
            throw new IllegalStateException("Questions must be added before answers");
        }
        if (rec != null)
        {
            if ((now == 0) || !rec.isExpired(now))
            {
                writeRecord(rec, now);
                numAnswers++;
            }
        }
    }

    private LinkedList authorativeAnswers = new LinkedList();

    /**
     * Add an authorative answer to the message.
     */
    void addAuthorativeAnswer(DNSRecord rec) throws IOException
    {
        if (numAdditionals > 0)
        {
            throw new IllegalStateException("Authorative answers must be added before additional answers");
        }
        authorativeAnswers.add(rec);
        writeRecord(rec, 0);
        numAuthorities++;

        // VERIFY:

    }

    void writeByte(int value) throws IOException
    {
        if (off >= data.length)
        {
            throw new IOException("buffer full");
        }
        data[off++] = (byte) value;
    }

    void writeBytes(String str, int off, int len) throws IOException
    {
        for (int i = 0; i < len; i++)
        {
            writeByte(str.charAt(off + i));
        }
    }

    void writeBytes(byte data[]) throws IOException
    {
        if (data != null)
        {
            writeBytes(data, 0, data.length);
        }
    }

    void writeBytes(byte data[], int off, int len) throws IOException
    {
        for (int i = 0; i < len; i++)
        {
            writeByte(data[off + i]);
        }
    }

    void writeShort(int value) throws IOException
    {
        writeByte(value >> 8);
        writeByte(value);
    }

    void writeInt(int value) throws IOException
    {
        writeShort(value >> 16);
        writeShort(value);
    }

    void writeUTF(String str, int off, int len) throws IOException
    {
        // compute utf length
        int utflen = 0;
        for (int i = 0; i < len; i++)
        {
            int ch = str.charAt(off + i);
            if ((ch >= 0x0001) && (ch <= 0x007F))
            {
                utflen += 1;
            }
            else
            {
                if (ch > 0x07FF)
                {
                    utflen += 3;
                }
                else
                {
                    utflen += 2;
                }
            }
        }
        // write utf length
        writeByte(utflen);
        // write utf data
        for (int i = 0; i < len; i++)
        {
            int ch = str.charAt(off + i);
            if ((ch >= 0x0001) && (ch <= 0x007F))
            {
                writeByte(ch);
            }
            else
            {
                if (ch > 0x07FF)
                {
                    writeByte(0xE0 | ((ch >> 12) & 0x0F));
                    writeByte(0x80 | ((ch >> 6) & 0x3F));
                    writeByte(0x80 | ((ch >> 0) & 0x3F));
                }
                else
                {
                    writeByte(0xC0 | ((ch >> 6) & 0x1F));
                    writeByte(0x80 | ((ch >> 0) & 0x3F));
                }
            }
        }
    }

    void writeName(String name) throws IOException
    {
        while (true)
        {
            int n = name.indexOf('.');
            if (n < 0)
            {
                n = name.length();
            }
            if (n <= 0)
            {
                writeByte(0);
                return;
            }
            Integer offset = (Integer) names.get(name);
            if (offset != null)
            {
                int val = offset.intValue();

                if (val > off)
                {
                    logger.log(Level.WARNING, "DNSOutgoing writeName failed val=" + val + " name=" + name);
                }

                writeByte((val >> 8) | 0xC0);
                writeByte(val);
                return;
            }
            names.put(name, new Integer(off));
            writeUTF(name, 0, n);
            name = name.substring(n);
            if (name.startsWith("."))
            {
                name = name.substring(1);
            }
        }
    }

    void writeQuestion(DNSQuestion question) throws IOException
    {
        writeName(question.name);
        writeShort(question.type);
        writeShort(question.clazz);
    }

    void writeRecord(DNSRecord rec, long now) throws IOException
    {
        int save = off;
        try
        {
            writeName(rec.name);
            writeShort(rec.type);
            writeShort(rec.clazz | ((rec.unique && multicast) ? DNSConstants.CLASS_UNIQUE : 0));
            writeInt((now == 0) ? rec.ttl : rec.getRemainingTTL(now));
            writeShort(0);
            int start = off;
            rec.write(this);
            int len = off - start;
            data[start - 2] = (byte) (len >> 8);
            data[start - 1] = (byte) (len & 0xFF);
        }
        catch (IOException e)
        {
            off = save;
            throw e;
        }
    }

    /**
     * Finish the message before sending it off.
     */
    void finish() throws IOException
    {
        int save = off;
        off = 0;

        writeShort(multicast ? 0 : id);
        writeShort(flags);
        writeShort(numQuestions);
        writeShort(numAnswers);
        writeShort(numAuthorities);
        writeShort(numAdditionals);
        off = save;
    }

    boolean isQuery()
    {
        return (flags & DNSConstants.FLAGS_QR_MASK) == DNSConstants.FLAGS_QR_QUERY;
    }

    public boolean isEmpty()
    {
        return numQuestions == 0 && numAuthorities == 0
            && numAdditionals == 0 && numAnswers == 0;
    }


    public String toString()
    {
        StringBuffer buf = new StringBuffer();
        buf.append(isQuery() ? "dns[query," : "dns[response,");
        //buf.append(packet.getAddress().getHostAddress());
        buf.append(':');
        //buf.append(packet.getPort());
        //buf.append(",len=");
        //buf.append(packet.getLength());
        buf.append(",id=0x");
        buf.append(Integer.toHexString(id));
        if (flags != 0)
        {
            buf.append(",flags=0x");
            buf.append(Integer.toHexString(flags));
            if ((flags & DNSConstants.FLAGS_QR_RESPONSE) != 0)
            {
                buf.append(":r");
            }
            if ((flags & DNSConstants.FLAGS_AA) != 0)
            {
                buf.append(":aa");
            }
            if ((flags & DNSConstants.FLAGS_TC) != 0)
            {
                buf.append(":tc");
            }
        }
        if (numQuestions > 0)
        {
            buf.append(",questions=");
            buf.append(numQuestions);
        }
        if (numAnswers > 0)
        {
            buf.append(",answers=");
            buf.append(numAnswers);
        }
        if (numAuthorities > 0)
        {
            buf.append(",authorities=");
            buf.append(numAuthorities);
        }
        if (numAdditionals > 0)
        {
            buf.append(",additionals=");
            buf.append(numAdditionals);
        }
        buf.append(",\nnames=" + names);
        buf.append(",\nauthorativeAnswers=" + authorativeAnswers);

        buf.append("]");
        return buf.toString();
    }

}

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