record.java

linux下建立JAVA虚拟机的源码KAFFE

// Copyright (c) 1999-2004 Brian Wellington ([e-mail])

package org.xbill.DNS;

import java.io.*;
import java.text.*;
import java.lang.reflect.*;
import java.util.*;
import org.xbill.DNS.utils.*;

/**
 * A generic DNS resource record.  The specific record types extend this class.
 * A record contains a name, type, class, and rdata.
 *
 * @author Brian Wellington
 */

public abstract class Record implements Cloneable, Comparable {

protected Name name;
protected int type, dclass;
protected long ttl;

private static final Record [] knownRecords = new Record[256];
private static final Record unknownRecord = new UNKRecord();
private static final Class [] emptyClassArray = new Class[0];
private static final Object [] emptyObjectArray = new Object[0];

private static final DecimalFormat byteFormat = new DecimalFormat();

static {
	byteFormat.setMinimumIntegerDigits(3);
}

protected
Record() {}

Record(Name name, int type, int dclass, long ttl) {
	if (!name.isAbsolute())
		throw new RelativeNameException(name);
	Type.check(type);
	DClass.check(dclass);
	TTL.check(ttl);
	this.name = name;
	this.type = type;
	this.dclass = dclass;
	this.ttl = ttl;
}

/**
 * Creates an empty record of the correct type; must be overriden
 */
abstract Record
getObject();

private static final Record
getTypedObject(int type) {
	if (type < 0 || type > knownRecords.length)
		return unknownRecord.getObject();
	if (knownRecords[type] != null)
		return knownRecords[type];

	/* Construct the class name by putting the type before "Record". */
	String s = Record.class.getPackage().getName() + "." +
		   Type.string(type).replace('-', '_') + "Record";
	try {
		Class c = Class.forName(s);
		Constructor m = c.getDeclaredConstructor(emptyClassArray);
		knownRecords[type] = (Record) m.newInstance(emptyObjectArray);
	}
	catch (ClassNotFoundException e) {
		/* This is normal; do nothing */
	}
	catch (Exception e) {
		if (Options.check("verbose"))
			System.err.println(e);
	}
	if (knownRecords[type] == null)
		knownRecords[type] = unknownRecord.getObject();
	return knownRecords[type];
}

private static final Record
getEmptyRecord(Name name, int type, int dclass, long ttl, boolean hasData) {
	Record rec;
	if (hasData)
		rec = getTypedObject(type).getObject();
	else
		rec = new EmptyRecord();
	rec.name = name;
	rec.type = type;
	rec.dclass = dclass;
	rec.ttl = ttl;
	return rec;
}

/**
 * Converts the type-specific RR to wire format - must be overriden
 */
abstract void
rrFromWire(DNSInput in) throws IOException;

private static Record
newRecord(Name name, int type, int dclass, long ttl, int length, DNSInput in)
throws IOException
{
	Record rec;
	int recstart;
	rec = getEmptyRecord(name, type, dclass, ttl, in != null);
	if (in != null) {
		if (in.remaining() < length)
			throw new WireParseException("truncated record");
		in.setActive(length);

		rec.rrFromWire(in);

		if (in.remaining() > 0)
			throw new WireParseException("invalid record length");
		in.clearActive();
	}
	return rec;
}

/**
 * Creates a new record, with the given parameters.
 * @param name The owner name of the record.
 * @param type The record's type.
 * @param dclass The record's class.
 * @param ttl The record's time to live.
 * @param length The length of the record's data.
 * @param data The rdata of the record, in uncompressed DNS wire format.  Only
 * the first length bytes are used.
 */
public static Record
newRecord(Name name, int type, int dclass, long ttl, int length, byte [] data) {
	if (!name.isAbsolute())
		throw new RelativeNameException(name);
	Type.check(type);
	DClass.check(dclass);
	TTL.check(ttl);

	DNSInput in;
	if (data != null)
		in = new DNSInput(data);
	else
		in = null;
	try {
		return newRecord(name, type, dclass, ttl, length, in);
	}
	catch (IOException e) {
		return null;
	}
}

/**
 * Creates a new record, with the given parameters.
 * @param name The owner name of the record.
 * @param type The record's type.
 * @param dclass The record's class.
 * @param ttl The record's time to live.
 * @param data The complete rdata of the record, in uncompressed DNS wire
 * format.
 */
public static Record
newRecord(Name name, int type, int dclass, long ttl, byte [] data) {
	return newRecord(name, type, dclass, ttl, data.length, data);
}

/**
 * Creates a new empty record, with the given parameters.
 * @param name The owner name of the record.
 * @param type The record's type.
 * @param dclass The record's class.
 * @param ttl The record's time to live.
 * @return An object of a subclass of Record
 */
public static Record
newRecord(Name name, int type, int dclass, long ttl) {
	if (!name.isAbsolute())
		throw new RelativeNameException(name);
	Type.check(type);
	DClass.check(dclass);
	TTL.check(ttl);

	return getEmptyRecord(name, type, dclass, ttl, false);
}

/**
 * Creates a new empty record, with the given parameters.  This method is
 * designed to create records that will be added to the QUERY section
 * of a message.
 * @param name The owner name of the record.
 * @param type The record's type.
 * @param dclass The record's class.
 * @return An object of a subclass of Record
 */
public static Record
newRecord(Name name, int type, int dclass) {
	return newRecord(name, type, dclass, 0);
}

static Record
fromWire(DNSInput in, int section, boolean isUpdate) throws IOException {
	int type, dclass;
	long ttl;
	int length;
	Name name;
	Record rec;

	name = new Name(in);
	type = in.readU16();
	dclass = in.readU16();

	if (section == Section.QUESTION)
		return newRecord(name, type, dclass);

	ttl = in.readU32();
	length = in.readU16();
	if (length == 0 && isUpdate)
		return newRecord(name, type, dclass, ttl);
	rec = newRecord(name, type, dclass, ttl, length, in);
	return rec;
}

static Record
fromWire(DNSInput in, int section) throws IOException {
	return fromWire(in, section, false);
}

/**
 * Builds a Record from DNS uncompressed wire format.
 */
public static Record
fromWire(byte [] b, int section) throws IOException {
	return fromWire(new DNSInput(b), section, false);
}

void
toWire(DNSOutput out, int section, Compression c) {
	name.toWire(out, c);
	out.writeU16(type);
	out.writeU16(dclass);
	if (section == Section.QUESTION)
		return;
	out.writeU32(ttl);
	int lengthPosition = out.current();
	out.writeU16(0); /* until we know better */
	rrToWire(out, c, false);
	int rrlength = out.current() - lengthPosition - 2;
	out.save();
	out.jump(lengthPosition);
	out.writeU16(rrlength);
	out.restore();
}

/**
 * Converts a Record into DNS uncompressed wire format.
 */
public byte []
toWire(int section) {
	DNSOutput out = new DNSOutput();
	toWire(out, section, null);
	return out.toByteArray();
}

private void
toWireCanonical(DNSOutput out, boolean noTTL) {
	name.toWireCanonical(out);
	out.writeU16(type);
	out.writeU16(dclass);
	if (noTTL) {
		out.writeU32(0);
	} else {
		out.writeU32(ttl);
	}
	int lengthPosition = out.current();
	out.writeU16(0); /* until we know better */
	rrToWire(out, null, true);
	int rrlength = out.current() - lengthPosition - 2;
	out.save();
	out.jump(lengthPosition);
	out.writeU16(rrlength);
	out.restore();
}

/*
 * Converts a Record into canonical DNS uncompressed wire format (all names are
 * converted to lowercase), optionally ignoring the TTL.
 */
private byte []
toWireCanonical(boolean noTTL) {
	DNSOutput out = new DNSOutput();
	toWireCanonical(out, noTTL);
	return out.toByteArray();
}

/**
 * Converts a Record into canonical DNS uncompressed wire format (all names are
 * converted to lowercase).
 */
public byte []
toWireCanonical() {
	return toWireCanonical(false);
}

/**
 * Converts the rdata in a Record into canonical DNS uncompressed wire format
 * (all names are converted to lowercase).
 */
public byte []
rdataToWireCanonical() {
	DNSOutput out = new DNSOutput();
	rrToWire(out, null, true);
	return out.toByteArray();
}

/**
 * Converts the type-specific RR to text format - must be overriden
 */
abstract String rrToString();

/**
 * Converts the rdata portion of a Record into a String representation
 */
public String
rdataToString() {
	return rrToString();
}

/**
 * Converts a Record into a String representation
 */
public String
toString() {
	StringBuffer sb = new StringBuffer();
	sb.append(name);
	if (sb.length() < 8)
		sb.append("\t");
	if (sb.length() < 16)
		sb.append("\t");
	sb.append("\t");
	if (Options.check("BINDTTL"))
		sb.append(TTL.format(ttl));
	else
		sb.append(ttl);
	sb.append("\t");
	if (dclass != DClass.IN || !Options.check("noPrintIN")) {
		sb.append(DClass.string(dclass));
		sb.append("\t");
	}
	sb.append(Type.string(type));
	String rdata = rrToString();
	if (!rdata.equals("")) {
		sb.append("\t");
		sb.append(rdata);
	}
	return sb.toString();
}

/**
 * Converts the text format of an RR to the internal format - must be overriden
 */
abstract void
rdataFromString(Tokenizer st, Name origin) throws IOException;

/**
 * Converts a String into a byte array.
 */
protected static byte []
byteArrayFromString(String s) throws TextParseException {
	byte [] array = s.getBytes();
	boolean escaped = false;
	boolean hasEscapes = false;

	for (int i = 0; i < array.length; i++) {
		if (array[i] == '\\') {
			hasEscapes = true;
			break;
		}