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Original DnsSd TxtRecord file
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Change-Id: I4aa308a3b417d6bdce50567fb66c7119b048140a
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@isheriff
isheriff committed Apr 4, 2012
1 parent 6756f74 commit 26d4452
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11 changes: 11 additions & 0 deletions NOTICE
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Expand Up @@ -53,6 +53,17 @@ Media Codecs
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, ==
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289 changes: 289 additions & 0 deletions core/java/android/net/nsd/DnsSdTxtRecord.java
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@@ -0,0 +1,289 @@
/* -*- 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 : "";
}
}

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