Merge "Original DnsSd TxtRecord file"

These files are Copyright 1998 - 2009 PacketVideo, but released under

the Apache2 License.

   =========================================================================

   ==  NOTICE file corresponding to the section 4 d of                    ==

   ==  the Apache License, Version 2.0,                                   ==

   ==  in this case for the mDnsResponder code.                           ==

   =========================================================================

mDnsResponder TXTRecord

This file is Copyright 2004 Apple Computer, Inc.  but released under

the Apache2 License.

   =========================================================================

   ==  NOTICE file corresponding to the section 4 d of                    ==

   ==  the Apache License, Version 2.0,                                   ==

/* -*- 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 : "";

	}

}