mDNSShared/Java/TXTRecord.java - third_party/mdnsresponder - Git at Google

 /* -*- Mode: Java; tab-width: 4 -*-
  *
  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
  *
  * Licensed 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.

 	To do:
 	- implement remove()
 	- fix set() to replace existing values
  */


 package	com.apple.dnssd;


 /**
 	Object used to construct and parse DNS-SD format TXT records.
 	For more info see <a href="http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt">DNS-Based Service Discovery</a>, section 6.
 */

 public class	TXTRecord
 {
 	/*
 	DNS-SD specifies that a TXT record corresponding to an SRV record consist of
 	a packed array of bytes, each preceded by a length byte. Each string
 	is an attribute-value pair.

 	The TXTRecord object stores the entire TXT data as a single byte array, traversing it
 	as need be to implement its various methods.
 	*/

 	static final protected byte		kAttrSep = '=';

 	protected byte[]		fBytes;

 	/** Constructs a new, empty TXT record. */
 	public		TXTRecord()
 	{ fBytes = new byte[0]; }

 	/** Constructs a new TXT record from a byte array in the standard format. */
 	public		TXTRecord( byte[] initBytes)
 	{ fBytes = (byte[]) initBytes.clone(); }

 	/** Set a key/value pair in the TXT record. Setting an existing key will replace its value.<P>
 		@param	key
 					The key name. Must be ASCII, with no '=' characters.
 		<P>
 		@param	value
 					Value to be encoded into bytes using the default platform character set.
 	*/
 	public void	set( String key, String value)
 	{
 		byte[]	valBytes = (value != null) ? value.getBytes() : null;
 		this.set( key, valBytes);
 	}

 	/** Set a key/value pair in the TXT record. Setting an existing key will replace its value.<P>
 		@param	key
 					The key name. Must be ASCII, with no '=' characters.
 		<P>
 		@param	value
 					Binary representation of the value.
 	*/
 	public void	set( String key, byte[] value)
 	{
 		byte[]	keyBytes;
 		int		valLen = (value != null) ? value.length : 0;

 		try {
 			keyBytes = key.getBytes( "US-ASCII");
 		}
 		catch ( java.io.UnsupportedEncodingException uee) {
 			throw new IllegalArgumentException();
 		}

 		for ( int i=0; i < keyBytes.length; i++)
 			if ( keyBytes[i] == '=')
 				throw new IllegalArgumentException();

 		if ( keyBytes.length + valLen >= 255)
 			throw new ArrayIndexOutOfBoundsException();

 		int		prevLoc = this.remove( key);
 		if ( prevLoc == -1)
 			prevLoc = this.size();

 		this.insert( keyBytes, value, prevLoc);
 	}

 	protected void	insert( byte[] keyBytes, byte[] value, int index)
 	// Insert a key-value pair at index
 	{
 		byte[]	oldBytes = fBytes;
 		int		valLen = (value != null) ? value.length : 0;
 		int		insertion = 0;
 		int		newLen, avLen;

 		// locate the insertion point
 		for ( int i=0; i < index && insertion < fBytes.length; i++)
 			insertion += (0xFF & (fBytes[ insertion] + 1));

 		avLen = keyBytes.length + valLen + (value != null ? 1 : 0);
 		newLen = avLen + oldBytes.length + 1;

 		fBytes = new byte[ newLen];
 		System.arraycopy( oldBytes, 0, fBytes, 0, insertion);
 		int secondHalfLen = oldBytes.length - insertion;
 		System.arraycopy( oldBytes, insertion, fBytes, newLen - secondHalfLen, secondHalfLen);
 		fBytes[ insertion] = ( byte) avLen;
 		System.arraycopy( keyBytes, 0, fBytes, insertion + 1, keyBytes.length);
 		if ( value != null)
 		{
 			fBytes[ insertion + 1 + keyBytes.length] = kAttrSep;
 			System.arraycopy( value, 0, fBytes, insertion + keyBytes.length + 2, valLen);
 		}
 	}

 	/** Remove a key/value pair from the TXT record. Returns index it was at, or -1 if not found. */
 	public int	remove( String key)
 	{
 		int		avStart = 0;

 		for ( int i=0; avStart < fBytes.length; i++)
 		{
 			int		avLen = fBytes[ avStart];
 			if ( key.length() <= avLen &&
 				 ( key.length() == avLen || fBytes[ avStart + key.length() + 1] == kAttrSep))
 			{
 				String	s = new String( fBytes, avStart + 1, key.length());
 				if ( 0 == key.compareToIgnoreCase( s))
 				{
 					byte[]	oldBytes = fBytes;
 					fBytes = new byte[ oldBytes.length - avLen - 1];
 					System.arraycopy( oldBytes, 0, fBytes, 0, avStart);
 					System.arraycopy( oldBytes, avStart + avLen + 1, fBytes, avStart, oldBytes.length - avStart - avLen - 1);
 					return i;
 				}
 			}
 			avStart += (0xFF & (avLen + 1));
 		}
 		return -1;
 	}

 	/**	Return the number of keys in the TXT record. */
 	public int	size()
 	{
 		int		i, avStart;

 		for ( i=0, avStart=0; avStart < fBytes.length; i++)
 			avStart += (0xFF & (fBytes[ avStart] + 1));
 		return i;
 	}

 	/** Return true if key is present in the TXT record, false if not. */
 	public boolean	contains( String key)
 	{
 		String	s = null;

 		for ( int i=0; null != ( s = this.getKey( i)); i++)
 			if ( 0 == key.compareToIgnoreCase( s))
 				return true;
 		return false;
 	}

 	/**	Return a key in the TXT record by zero-based index. Returns null if index exceeds the total number of keys. */
 	public String	getKey( int index)
 	{
 		int		avStart = 0;

 		for ( int i=0; i < index && avStart < fBytes.length; i++)
 			avStart += fBytes[ avStart] + 1;

 		if ( avStart < fBytes.length)
 		{
 			int	avLen = fBytes[ avStart];
 			int	aLen = 0;

 			for ( aLen=0; aLen < avLen; aLen++)
 				if ( fBytes[ avStart + aLen + 1] == kAttrSep)
 					break;
 			return new String( fBytes, avStart + 1, aLen);
 		}
 		return null;
 	}

 	/**
 		Look up a key in the TXT record by zero-based index and return its value. <P>
 		Returns null if index exceeds the total number of keys.
 		Returns null if the key is present with no value.
 	*/
 	public byte[]	getValue( int index)
 	{
 		int		avStart = 0;
 		byte[]	value = null;

 		for ( int i=0; i < index && avStart < fBytes.length; i++)
 			avStart += fBytes[ avStart] + 1;

 		if ( avStart < fBytes.length)
 		{
 			int	avLen = fBytes[ avStart];
 			int	aLen = 0;

 			for ( aLen=0; aLen < avLen; aLen++)
 			{
 				if ( fBytes[ avStart + aLen + 1] == kAttrSep)
 				{
 					value = new byte[ avLen - aLen - 1];
 					System.arraycopy( fBytes, avStart + aLen + 2, value, 0, avLen - aLen - 1);
 					break;
 				}
 			}
 		}
 		return value;
 	}

 	/** Converts the result of getValue() to a string in the platform default character set. */
 	public String	getValueAsString( int index)
 	{
 		byte[]	value = this.getValue( index);
 		return value != null ? new String( value) : null;
 	}

 	/**	Get the value associated with a key. Will be null if the key is not defined.
 		Array will have length 0 if the key is defined with an = but no value.<P>

 		@param	forKey
 					The left-hand side of the key-value pair.
 		<P>
 		@return		The binary representation of the value.
 	*/
 	public byte[]	getValue( String forKey)
 	{
 		String	s = null;
 		int		i;

 		for ( i=0; null != ( s = this.getKey( i)); i++)
 			if ( 0 == forKey.compareToIgnoreCase( s))
 				return this.getValue( i);
 		return null;
 	}

 	/**	Converts the result of getValue() to a string in the platform default character set.<P>

 		@param	forKey
 					The left-hand side of the key-value pair.
 		<P>
 		@return		The value represented in the default platform character set.
 	*/
 	public String	getValueAsString( String forKey)
 	{
 		byte[]	val = this.getValue( forKey);
 		return val != null ? new String( val) : null;
 	}

 	/** Return the contents of the TXT record as raw bytes. */
 	public byte[]	getRawBytes() { return (byte[]) fBytes.clone(); }

 	/** Return a string representation of the object. */
 	public String	toString()
 	{
 		String		a, result = null;

 		for ( int i=0; null != ( a = this.getKey( i)); i++)
 		{
 			String av = String.valueOf( i) + "={" + a;
 			String val = this.getValueAsString( i);
 			if ( val != null)
 				av += "=" + val + "}";
 			else
 				av += "}";
 			if ( result == null)
 				result = av;
 			else
 				result = result + ", " + av;
 		}
 		return result != null ? result : "";
 	}
 }
	/* -- Mode: Java; tab-width: 4 --
	*
	* Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
	*
	* Licensed 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.

	To do:
	- implement remove()
	- fix set() to replace existing values
	*/


	package com.apple.dnssd;


	/**
	Object used to construct and parse DNS-SD format TXT records.
	For more info see <a href="http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt">DNS-Based Service Discovery</a>, section 6.
	*/

	public class TXTRecord
	{
	/*
	DNS-SD specifies that a TXT record corresponding to an SRV record consist of
	a packed array of bytes, each preceded by a length byte. Each string
	is an attribute-value pair.

	The TXTRecord object stores the entire TXT data as a single byte array, traversing it
	as need be to implement its various methods.
	*/

	static final protected byte kAttrSep = '=';

	protected byte[] fBytes;

	/** Constructs a new, empty TXT record. */
	public TXTRecord()
	{ fBytes = new byte[0]; }

	/** Constructs a new TXT record from a byte array in the standard format. */
	public TXTRecord( byte[] initBytes)
	{ fBytes = (byte[]) initBytes.clone(); }

	/** Set a key/value pair in the TXT record. Setting an existing key will replace its value.<P>
	@param key
	The key name. Must be ASCII, with no '=' characters.
	<P>
	@param value
	Value to be encoded into bytes using the default platform character set.
	*/
	public void set( String key, String value)
	{
	byte[] valBytes = (value != null) ? value.getBytes() : null;
	this.set( key, valBytes);
	}

	/** Set a key/value pair in the TXT record. Setting an existing key will replace its value.<P>
	@param key
	The key name. Must be ASCII, with no '=' characters.
	<P>
	@param value
	Binary representation of the value.
	*/
	public void set( String key, byte[] value)
	{
	byte[] keyBytes;
	int valLen = (value != null) ? value.length : 0;

	try {
	keyBytes = key.getBytes( "US-ASCII");
	}
	catch ( java.io.UnsupportedEncodingException uee) {
	throw new IllegalArgumentException();
	}

	for ( int i=0; i < keyBytes.length; i++)
	if ( keyBytes[i] == '=')
	throw new IllegalArgumentException();

	if ( keyBytes.length + valLen >= 255)
	throw new ArrayIndexOutOfBoundsException();

	int prevLoc = this.remove( key);
	if ( prevLoc == -1)
	prevLoc = this.size();

	this.insert( keyBytes, value, prevLoc);
	}

	protected void insert( byte[] keyBytes, byte[] value, int index)
	// Insert a key-value pair at index
	{
	byte[] oldBytes = fBytes;
	int valLen = (value != null) ? value.length : 0;
	int insertion = 0;
	int newLen, avLen;

	// locate the insertion point
	for ( int i=0; i < index && insertion < fBytes.length; i++)
	insertion += (0xFF & (fBytes[ insertion] + 1));

	avLen = keyBytes.length + valLen + (value != null ? 1 : 0);
	newLen = avLen + oldBytes.length + 1;

	fBytes = new byte[ newLen];
	System.arraycopy( oldBytes, 0, fBytes, 0, insertion);
	int secondHalfLen = oldBytes.length - insertion;
	System.arraycopy( oldBytes, insertion, fBytes, newLen - secondHalfLen, secondHalfLen);
	fBytes[ insertion] = ( byte) avLen;
	System.arraycopy( keyBytes, 0, fBytes, insertion + 1, keyBytes.length);
	if ( value != null)
	{
	fBytes[ insertion + 1 + keyBytes.length] = kAttrSep;
	System.arraycopy( value, 0, fBytes, insertion + keyBytes.length + 2, valLen);
	}
	}

	/** Remove a key/value pair from the TXT record. Returns index it was at, or -1 if not found. */
	public int remove( String key)
	{
	int avStart = 0;

	for ( int i=0; avStart < fBytes.length; i++)
	{
	int avLen = fBytes[ avStart];
	if ( key.length() <= avLen &&
	( key.length() == avLen \|\| fBytes[ avStart + key.length() + 1] == kAttrSep))
	{
	String s = new String( fBytes, avStart + 1, key.length());
	if ( 0 == key.compareToIgnoreCase( s))
	{
	byte[] oldBytes = fBytes;
	fBytes = new byte[ oldBytes.length - avLen - 1];
	System.arraycopy( oldBytes, 0, fBytes, 0, avStart);
	System.arraycopy( oldBytes, avStart + avLen + 1, fBytes, avStart, oldBytes.length - avStart - avLen - 1);
	return i;
	}
	}
	avStart += (0xFF & (avLen + 1));
	}
	return -1;
	}

	/** Return the number of keys in the TXT record. */
	public int size()
	{
	int i, avStart;

	for ( i=0, avStart=0; avStart < fBytes.length; i++)
	avStart += (0xFF & (fBytes[ avStart] + 1));
	return i;
	}

	/** Return true if key is present in the TXT record, false if not. */
	public boolean contains( String key)
	{
	String s = null;

	for ( int i=0; null != ( s = this.getKey( i)); i++)
	if ( 0 == key.compareToIgnoreCase( s))
	return true;
	return false;
	}

	/** Return a key in the TXT record by zero-based index. Returns null if index exceeds the total number of keys. */
	public String getKey( int index)
	{
	int avStart = 0;

	for ( int i=0; i < index && avStart < fBytes.length; i++)
	avStart += fBytes[ avStart] + 1;

	if ( avStart < fBytes.length)
	{
	int avLen = fBytes[ avStart];
	int aLen = 0;

	for ( aLen=0; aLen < avLen; aLen++)
	if ( fBytes[ avStart + aLen + 1] == kAttrSep)
	break;
	return new String( fBytes, avStart + 1, aLen);
	}
	return null;
	}

	/**
	Look up a key in the TXT record by zero-based index and return its value. <P>
	Returns null if index exceeds the total number of keys.
	Returns null if the key is present with no value.
	*/
	public byte[] getValue( int index)
	{
	int avStart = 0;
	byte[] value = null;

	for ( int i=0; i < index && avStart < fBytes.length; i++)
	avStart += fBytes[ avStart] + 1;

	if ( avStart < fBytes.length)
	{
	int avLen = fBytes[ avStart];
	int aLen = 0;

	for ( aLen=0; aLen < avLen; aLen++)
	{
	if ( fBytes[ avStart + aLen + 1] == kAttrSep)
	{
	value = new byte[ avLen - aLen - 1];
	System.arraycopy( fBytes, avStart + aLen + 2, value, 0, avLen - aLen - 1);
	break;
	}
	}
	}
	return value;
	}

	/** Converts the result of getValue() to a string in the platform default character set. */
	public String getValueAsString( int index)
	{
	byte[] value = this.getValue( index);
	return value != null ? new String( value) : null;
	}

	/** Get the value associated with a key. Will be null if the key is not defined.
	Array will have length 0 if the key is defined with an = but no value.<P>

	@param forKey
	The left-hand side of the key-value pair.
	<P>
	@return The binary representation of the value.
	*/
	public byte[] getValue( String forKey)
	{
	String s = null;
	int i;

	for ( i=0; null != ( s = this.getKey( i)); i++)
	if ( 0 == forKey.compareToIgnoreCase( s))
	return this.getValue( i);
	return null;
	}

	/** Converts the result of getValue() to a string in the platform default character set.<P>

	@param forKey
	The left-hand side of the key-value pair.
	<P>
	@return The value represented in the default platform character set.
	*/
	public String getValueAsString( String forKey)
	{
	byte[] val = this.getValue( forKey);
	return val != null ? new String( val) : null;
	}

	/** Return the contents of the TXT record as raw bytes. */
	public byte[] getRawBytes() { return (byte[]) fBytes.clone(); }

	/** Return a string representation of the object. */
	public String toString()
	{
	String a, result = null;

	for ( int i=0; null != ( a = this.getKey( i)); i++)
	{
	String av = String.valueOf( i) + "={" + a;
	String val = this.getValueAsString( i);
	if ( val != null)
	av += "=" + val + "}";
	else
	av += "}";
	if ( result == null)
	result = av;
	else
	result = result + ", " + av;
	}
	return result != null ? result : "";
	}
	}