//Copyright 2003-2005 Arthur van Hoff, Rick Blair
//Licensed under Apache License version 2.0
//Original license LGPL
package javax.jmdns.impl;
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
*/
public final class DNSOutgoing
{
/**
* This can be used to turn off domain name compression. This was helpful for
* tracking problems interacting with other mdns implementations.
*/
public static boolean USE_DOMAIN_NAME_COMPRESSION = true;
// private static Logger logger = Logger.getLogger(DNSOutgoing.class.getName());
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.
*/
public DNSOutgoing(int flags)
{
this(flags, true);
}
/**
* Create an outgoing query or response.
*/
public 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.
*/
public 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.
*/
public 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.
*/
public 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
{
writeName(name, true);
}
void writeName(String name, boolean useCompression) throws IOException
{
while (true)
{
int n = name.indexOf('.');
if (n < 0)
{
n = name.length();
}
if (n <= 0)
{
writeByte(0);
return;
}
if(useCompression && USE_DOMAIN_NAME_COMPRESSION){
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 & 0xFF);
return;
}
names.put(name, Integer.valueOf(""+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.getTtl() : 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();
}
}