jetty-http2/http2-hpack/src/main/java/org/eclipse/jetty/http2/hpack/HpackEncoder.java - gerrit/jetty/org.eclipse.jetty.project - Git at Google

 //
 //  ========================================================================
 //  Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
 //  ------------------------------------------------------------------------
 //  All rights reserved. This program and the accompanying materials
 //  are made available under the terms of the Eclipse Public License v1.0
 //  and Apache License v2.0 which accompanies this distribution.
 //
 //      The Eclipse Public License is available at
 //      http://www.eclipse.org/legal/epl-v10.html
 //
 //      The Apache License v2.0 is available at
 //      http://www.opensource.org/licenses/apache2.0.php
 //
 //  You may elect to redistribute this code under either of these licenses.
 //  ========================================================================
 //


 package org.eclipse.jetty.http2.hpack;

 import java.nio.ByteBuffer;
 import java.util.EnumSet;

 import org.eclipse.jetty.http.HttpField;
 import org.eclipse.jetty.http.HttpHeader;
 import org.eclipse.jetty.http.HttpScheme;
 import org.eclipse.jetty.http.HttpStatus;
 import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.http.MetaData;
 import org.eclipse.jetty.http.PreEncodedHttpField;
 import org.eclipse.jetty.http2.hpack.HpackContext.Entry;
 import org.eclipse.jetty.http2.hpack.HpackContext.StaticEntry;
 import org.eclipse.jetty.util.TypeUtil;
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;

 public class HpackEncoder
 {
     public static final Logger LOG = Log.getLogger(HpackEncoder.class);

     private final static HttpField[] __status= new HttpField[599];


     final static EnumSet<HttpHeader> __DO_NOT_HUFFMAN =
             EnumSet.of(
                     HttpHeader.AUTHORIZATION,
                     HttpHeader.CONTENT_MD5,
                     HttpHeader.PROXY_AUTHENTICATE,
                     HttpHeader.PROXY_AUTHORIZATION);

     final static EnumSet<HttpHeader> __DO_NOT_INDEX =
             EnumSet.of(
                     // HttpHeader.C_PATH,  // TODO more data needed
                     // HttpHeader.DATE,    // TODO more data needed
                     HttpHeader.AUTHORIZATION,
                     HttpHeader.CONTENT_MD5,
                     HttpHeader.CONTENT_RANGE,
                     HttpHeader.ETAG,
                     HttpHeader.IF_MODIFIED_SINCE,
                     HttpHeader.IF_UNMODIFIED_SINCE,
                     HttpHeader.IF_NONE_MATCH,
                     HttpHeader.IF_RANGE,
                     HttpHeader.IF_MATCH,
                     HttpHeader.LOCATION,
                     HttpHeader.RANGE,
                     HttpHeader.RETRY_AFTER,
                     // HttpHeader.EXPIRES,
                     HttpHeader.LAST_MODIFIED,
                     HttpHeader.SET_COOKIE,
                     HttpHeader.SET_COOKIE2);


     final static EnumSet<HttpHeader> __NEVER_INDEX =
             EnumSet.of(
                     HttpHeader.AUTHORIZATION,
                     HttpHeader.SET_COOKIE,
                     HttpHeader.SET_COOKIE2);

     static
     {
         for (HttpStatus.Code code : HttpStatus.Code.values())
             __status[code.getCode()]=new PreEncodedHttpField(HttpHeader.C_STATUS,Integer.toString(code.getCode()));
     }

     private final HpackContext _context;
     private final boolean _debug;
     private int _remoteMaxDynamicTableSize;
     private int _localMaxDynamicTableSize;

     public HpackEncoder()
     {
         this(4096,4096);
     }

     public HpackEncoder(int localMaxDynamicTableSize)
     {
         this(localMaxDynamicTableSize,4096);
     }

     public HpackEncoder(int localMaxDynamicTableSize,int remoteMaxDynamicTableSize)
     {
         _context=new HpackContext(remoteMaxDynamicTableSize);
         _remoteMaxDynamicTableSize=remoteMaxDynamicTableSize;
         _localMaxDynamicTableSize=localMaxDynamicTableSize;
         _debug=LOG.isDebugEnabled();
     }

     public HpackContext getHpackContext()
     {
         return _context;
     }

     public void setRemoteMaxDynamicTableSize(int remoteMaxDynamicTableSize)
     {
         _remoteMaxDynamicTableSize=remoteMaxDynamicTableSize;
     }

     public void setLocalMaxDynamicTableSize(int localMaxDynamicTableSize)
     {
         _localMaxDynamicTableSize=localMaxDynamicTableSize;
     }

     public void encode(ByteBuffer buffer, MetaData metadata)
     {
         if (LOG.isDebugEnabled())
             LOG.debug(String.format("CtxTbl[%x] encoding",_context.hashCode()));

         int pos = buffer.position();

         // Check the dynamic table sizes!
         int maxDynamicTableSize=Math.min(_remoteMaxDynamicTableSize,_localMaxDynamicTableSize);
         if (maxDynamicTableSize!=_context.getMaxDynamicTableSize())
             encodeMaxDynamicTableSize(buffer,maxDynamicTableSize);

         // Add Request/response meta fields
         if (metadata.isRequest())
         {
             MetaData.Request request = (MetaData.Request)metadata;

             // TODO optimise these to avoid HttpField creation
             String scheme=request.getURI().getScheme();
             encode(buffer,new HttpField(HttpHeader.C_SCHEME,scheme==null?HttpScheme.HTTP.asString():scheme));
             encode(buffer,new HttpField(HttpHeader.C_METHOD,request.getMethod()));
             encode(buffer,new HttpField(HttpHeader.C_AUTHORITY,request.getURI().getAuthority()));
             encode(buffer,new HttpField(HttpHeader.C_PATH,request.getURI().getPathQuery()));

         }
         else if (metadata.isResponse())
         {
             MetaData.Response response = (MetaData.Response)metadata;
             int code=response.getStatus();
             HttpField status = code<__status.length?__status[code]:null;
             if (status==null)
                 status=new HttpField.IntValueHttpField(HttpHeader.C_STATUS,code);
             encode(buffer,status);
         }

         // Add all the other fields
         for (HttpField field : metadata)
             encode(buffer,field);

         if (LOG.isDebugEnabled())
             LOG.debug(String.format("CtxTbl[%x] encoded %d octets",_context.hashCode(), buffer.position() - pos));
     }

     public void encodeMaxDynamicTableSize(ByteBuffer buffer, int maxDynamicTableSize)
     {
         if (maxDynamicTableSize>_remoteMaxDynamicTableSize)
             throw new IllegalArgumentException();
         buffer.put((byte)0x20);
         NBitInteger.encode(buffer,5,maxDynamicTableSize);
         _context.resize(maxDynamicTableSize);
     }

     public void encode(ByteBuffer buffer, HttpField field)
     {
         final int p=_debug?buffer.position():-1;

         String encoding=null;

         // Is there an entry for the field?
         Entry entry = _context.get(field);
         if (entry!=null)
         {
             // Known field entry, so encode it as indexed
             if (entry.isStatic())
             {
                 buffer.put(((StaticEntry)entry).getEncodedField());
                 if (_debug)
                     encoding="IdxFieldS1";
             }
             else
             {
                 int index=_context.index(entry);
                 buffer.put((byte)0x80);
                 NBitInteger.encode(buffer,7,index);
                 if (_debug)
                     encoding="IdxField"+(entry.isStatic()?"S":"")+(1+NBitInteger.octectsNeeded(7,index));
             }
         }
         else
         {
             // Unknown field entry, so we will have to send literally.
             final boolean indexed;

             // But do we know it's name?
             HttpHeader header = field.getHeader();

             // Select encoding strategy
             if (header==null)
             {
                 // Select encoding strategy for unknown header names
                 Entry name = _context.get(field.getName());

                 if (field instanceof PreEncodedHttpField)
                 {
                     int i=buffer.position();
                     ((PreEncodedHttpField)field).putTo(buffer,HttpVersion.HTTP_2);
                     byte b=buffer.get(i);
                     indexed=b<0||b>=0x40;
                     if (_debug)
                         encoding=indexed?"PreEncodedIdx":"PreEncoded";
                 }
                 // has the custom header name been seen before?
                 else if (name==null)
                 {
                     // unknown name and value, so let's index this just in case it is
                     // the first time we have seen a custom name or a custom field.
                     // unless the name is changing, this is worthwhile
                     indexed=true;
                     encodeName(buffer,(byte)0x40,6,field.getName(),null);
                     encodeValue(buffer,true,field.getValue());
                     if (_debug)
                         encoding="LitHuffNHuffVIdx";
                 }
                 else
                 {
                     // known custom name, but unknown value.
                     // This is probably a custom field with changing value, so don't index.
                     indexed=false;
                     encodeName(buffer,(byte)0x00,4,field.getName(),null);
                     encodeValue(buffer,true,field.getValue());
                     if (_debug)
                         encoding="LitHuffNHuffV!Idx";
                 }
             }
             else
             {
                 // Select encoding strategy for known header names
                 Entry name = _context.get(header);

                 if (field instanceof PreEncodedHttpField)
                 {
                     // Preencoded field
                     int i=buffer.position();
                     ((PreEncodedHttpField)field).putTo(buffer,HttpVersion.HTTP_2);
                     byte b=buffer.get(i);
                     indexed=b<0||b>=0x40;
                     if (_debug)
                         encoding=indexed?"PreEncodedIdx":"PreEncoded";
                 }
                 else if (__DO_NOT_INDEX.contains(header))
                 {
                     // Non indexed field
                     indexed=false;
                     boolean never_index=__NEVER_INDEX.contains(header);
                     boolean huffman=!__DO_NOT_HUFFMAN.contains(header);
                     encodeName(buffer,never_index?(byte)0x10:(byte)0x00,4,header.asString(),name);
                     encodeValue(buffer,huffman,field.getValue());

                     if (_debug)
                         encoding="Lit"+
                                 ((name==null)?"HuffN":("IdxN"+(name.isStatic()?"S":"")+(1+NBitInteger.octectsNeeded(4,_context.index(name)))))+
                                 (huffman?"HuffV":"LitV")+
                                 (indexed?"Idx":(never_index?"!!Idx":"!Idx"));
                 }
                 else if (header==HttpHeader.CONTENT_LENGTH && field.getValue().length()>1)
                 {
                     // Non indexed content length for 2 digits or more
                     indexed=false;
                     encodeName(buffer,(byte)0x00,4,header.asString(),name);
                     encodeValue(buffer,true,field.getValue());
                     if (_debug)
                         encoding="LitIdxNS"+(1+NBitInteger.octectsNeeded(4,_context.index(name)))+"HuffV!Idx";
                 }
                 else
                 {
                     // indexed
                     indexed=true;
                     boolean huffman=!__DO_NOT_HUFFMAN.contains(header);
                     encodeName(buffer,(byte)0x40,6,header.asString(),name);
                     encodeValue(buffer,huffman,field.getValue());
                     if (_debug)
                         encoding=((name==null)?"LitHuffN":("LitIdxN"+(name.isStatic()?"S":"")+(1+NBitInteger.octectsNeeded(6,_context.index(name)))))+
                                 (huffman?"HuffVIdx":"LitVIdx");
                 }
             }

             // If we want the field referenced, then we add it to our
             // table and reference set.
             if (indexed)
                 _context.add(field);
         }

         if (_debug)
         {
             int e=buffer.position();
             if (LOG.isDebugEnabled())
                 LOG.debug("encode {}:'{}' to '{}'",encoding,field,TypeUtil.toHexString(buffer.array(),buffer.arrayOffset()+p,e-p));
         }
     }

     private void encodeName(ByteBuffer buffer, byte mask, int bits, String name, Entry entry)
     {
         buffer.put(mask);
         if (entry==null)
         {
             // leave name index bits as 0
             // Encode the name always with lowercase huffman
             buffer.put((byte)0x80);
             NBitInteger.encode(buffer,7,Huffman.octetsNeededLC(name));
             Huffman.encodeLC(buffer,name);
         }
         else
         {
             NBitInteger.encode(buffer,bits,_context.index(entry));
         }
     }

     static void encodeValue(ByteBuffer buffer, boolean huffman, String value)
     {
         if (huffman)
         {
             // huffman literal value
             buffer.put((byte)0x80);
             NBitInteger.encode(buffer,7,Huffman.octetsNeeded(value));
             Huffman.encode(buffer,value);
         }
         else
         {
             // add literal assuming iso_8859_1
             buffer.put((byte)0x00);
             NBitInteger.encode(buffer,7,value.length());
             for (int i=0;i<value.length();i++)
             {
                 char c=value.charAt(i);
                 if (c<' '|| c>127)
                     throw new IllegalArgumentException();
                 buffer.put((byte)c);
             }
         }
     }
 }
	//
	// ========================================================================
	// Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
	// ------------------------------------------------------------------------
	// All rights reserved. This program and the accompanying materials
	// are made available under the terms of the Eclipse Public License v1.0
	// and Apache License v2.0 which accompanies this distribution.
	//
	// The Eclipse Public License is available at
	// http://www.eclipse.org/legal/epl-v10.html
	//
	// The Apache License v2.0 is available at
	// http://www.opensource.org/licenses/apache2.0.php
	//
	// You may elect to redistribute this code under either of these licenses.
	// ========================================================================
	//


	package org.eclipse.jetty.http2.hpack;

	import java.nio.ByteBuffer;
	import java.util.EnumSet;

	import org.eclipse.jetty.http.HttpField;
	import org.eclipse.jetty.http.HttpHeader;
	import org.eclipse.jetty.http.HttpScheme;
	import org.eclipse.jetty.http.HttpStatus;
	import org.eclipse.jetty.http.HttpVersion;
	import org.eclipse.jetty.http.MetaData;
	import org.eclipse.jetty.http.PreEncodedHttpField;
	import org.eclipse.jetty.http2.hpack.HpackContext.Entry;
	import org.eclipse.jetty.http2.hpack.HpackContext.StaticEntry;
	import org.eclipse.jetty.util.TypeUtil;
	import org.eclipse.jetty.util.log.Log;
	import org.eclipse.jetty.util.log.Logger;

	public class HpackEncoder
	{
	public static final Logger LOG = Log.getLogger(HpackEncoder.class);

	private final static HttpField[] __status= new HttpField[599];


	final static EnumSet<HttpHeader> __DO_NOT_HUFFMAN =
	EnumSet.of(
	HttpHeader.AUTHORIZATION,
	HttpHeader.CONTENT_MD5,
	HttpHeader.PROXY_AUTHENTICATE,
	HttpHeader.PROXY_AUTHORIZATION);

	final static EnumSet<HttpHeader> __DO_NOT_INDEX =
	EnumSet.of(
	// HttpHeader.C_PATH, // TODO more data needed
	// HttpHeader.DATE, // TODO more data needed
	HttpHeader.AUTHORIZATION,
	HttpHeader.CONTENT_MD5,
	HttpHeader.CONTENT_RANGE,
	HttpHeader.ETAG,
	HttpHeader.IF_MODIFIED_SINCE,
	HttpHeader.IF_UNMODIFIED_SINCE,
	HttpHeader.IF_NONE_MATCH,
	HttpHeader.IF_RANGE,
	HttpHeader.IF_MATCH,
	HttpHeader.LOCATION,
	HttpHeader.RANGE,
	HttpHeader.RETRY_AFTER,
	// HttpHeader.EXPIRES,
	HttpHeader.LAST_MODIFIED,
	HttpHeader.SET_COOKIE,
	HttpHeader.SET_COOKIE2);


	final static EnumSet<HttpHeader> __NEVER_INDEX =
	EnumSet.of(
	HttpHeader.AUTHORIZATION,
	HttpHeader.SET_COOKIE,
	HttpHeader.SET_COOKIE2);

	static
	{
	for (HttpStatus.Code code : HttpStatus.Code.values())
	__status[code.getCode()]=new PreEncodedHttpField(HttpHeader.C_STATUS,Integer.toString(code.getCode()));
	}

	private final HpackContext _context;
	private final boolean _debug;
	private int _remoteMaxDynamicTableSize;
	private int _localMaxDynamicTableSize;

	public HpackEncoder()
	{
	this(4096,4096);
	}

	public HpackEncoder(int localMaxDynamicTableSize)
	{
	this(localMaxDynamicTableSize,4096);
	}

	public HpackEncoder(int localMaxDynamicTableSize,int remoteMaxDynamicTableSize)
	{
	_context=new HpackContext(remoteMaxDynamicTableSize);
	_remoteMaxDynamicTableSize=remoteMaxDynamicTableSize;
	_localMaxDynamicTableSize=localMaxDynamicTableSize;
	_debug=LOG.isDebugEnabled();
	}

	public HpackContext getHpackContext()
	{
	return _context;
	}

	public void setRemoteMaxDynamicTableSize(int remoteMaxDynamicTableSize)
	{
	_remoteMaxDynamicTableSize=remoteMaxDynamicTableSize;
	}

	public void setLocalMaxDynamicTableSize(int localMaxDynamicTableSize)
	{
	_localMaxDynamicTableSize=localMaxDynamicTableSize;
	}

	public void encode(ByteBuffer buffer, MetaData metadata)
	{
	if (LOG.isDebugEnabled())
	LOG.debug(String.format("CtxTbl[%x] encoding",_context.hashCode()));

	int pos = buffer.position();

	// Check the dynamic table sizes!
	int maxDynamicTableSize=Math.min(_remoteMaxDynamicTableSize,_localMaxDynamicTableSize);
	if (maxDynamicTableSize!=_context.getMaxDynamicTableSize())
	encodeMaxDynamicTableSize(buffer,maxDynamicTableSize);

	// Add Request/response meta fields
	if (metadata.isRequest())
	{
	MetaData.Request request = (MetaData.Request)metadata;

	// TODO optimise these to avoid HttpField creation
	String scheme=request.getURI().getScheme();
	encode(buffer,new HttpField(HttpHeader.C_SCHEME,scheme==null?HttpScheme.HTTP.asString():scheme));
	encode(buffer,new HttpField(HttpHeader.C_METHOD,request.getMethod()));
	encode(buffer,new HttpField(HttpHeader.C_AUTHORITY,request.getURI().getAuthority()));
	encode(buffer,new HttpField(HttpHeader.C_PATH,request.getURI().getPathQuery()));

	}
	else if (metadata.isResponse())
	{
	MetaData.Response response = (MetaData.Response)metadata;
	int code=response.getStatus();
	HttpField status = code<__status.length?__status[code]:null;
	if (status==null)
	status=new HttpField.IntValueHttpField(HttpHeader.C_STATUS,code);
	encode(buffer,status);
	}

	// Add all the other fields
	for (HttpField field : metadata)
	encode(buffer,field);

	if (LOG.isDebugEnabled())
	LOG.debug(String.format("CtxTbl[%x] encoded %d octets",_context.hashCode(), buffer.position() - pos));
	}

	public void encodeMaxDynamicTableSize(ByteBuffer buffer, int maxDynamicTableSize)
	{
	if (maxDynamicTableSize>_remoteMaxDynamicTableSize)
	throw new IllegalArgumentException();
	buffer.put((byte)0x20);
	NBitInteger.encode(buffer,5,maxDynamicTableSize);
	_context.resize(maxDynamicTableSize);
	}

	public void encode(ByteBuffer buffer, HttpField field)
	{
	final int p=_debug?buffer.position():-1;

	String encoding=null;

	// Is there an entry for the field?
	Entry entry = _context.get(field);
	if (entry!=null)
	{
	// Known field entry, so encode it as indexed
	if (entry.isStatic())
	{
	buffer.put(((StaticEntry)entry).getEncodedField());
	if (_debug)
	encoding="IdxFieldS1";
	}
	else
	{
	int index=_context.index(entry);
	buffer.put((byte)0x80);
	NBitInteger.encode(buffer,7,index);
	if (_debug)
	encoding="IdxField"+(entry.isStatic()?"S":"")+(1+NBitInteger.octectsNeeded(7,index));
	}
	}
	else
	{
	// Unknown field entry, so we will have to send literally.
	final boolean indexed;

	// But do we know it's name?
	HttpHeader header = field.getHeader();

	// Select encoding strategy
	if (header==null)
	{
	// Select encoding strategy for unknown header names
	Entry name = _context.get(field.getName());

	if (field instanceof PreEncodedHttpField)
	{
	int i=buffer.position();
	((PreEncodedHttpField)field).putTo(buffer,HttpVersion.HTTP_2);
	byte b=buffer.get(i);
	indexed=b<0\|\|b>=0x40;
	if (_debug)
	encoding=indexed?"PreEncodedIdx":"PreEncoded";
	}
	// has the custom header name been seen before?
	else if (name==null)
	{
	// unknown name and value, so let's index this just in case it is
	// the first time we have seen a custom name or a custom field.
	// unless the name is changing, this is worthwhile
	indexed=true;
	encodeName(buffer,(byte)0x40,6,field.getName(),null);
	encodeValue(buffer,true,field.getValue());
	if (_debug)
	encoding="LitHuffNHuffVIdx";
	}
	else
	{
	// known custom name, but unknown value.
	// This is probably a custom field with changing value, so don't index.
	indexed=false;
	encodeName(buffer,(byte)0x00,4,field.getName(),null);
	encodeValue(buffer,true,field.getValue());
	if (_debug)
	encoding="LitHuffNHuffV!Idx";
	}
	}
	else
	{
	// Select encoding strategy for known header names
	Entry name = _context.get(header);

	if (field instanceof PreEncodedHttpField)
	{
	// Preencoded field
	int i=buffer.position();
	((PreEncodedHttpField)field).putTo(buffer,HttpVersion.HTTP_2);
	byte b=buffer.get(i);
	indexed=b<0\|\|b>=0x40;
	if (_debug)
	encoding=indexed?"PreEncodedIdx":"PreEncoded";
	}
	else if (__DO_NOT_INDEX.contains(header))
	{
	// Non indexed field
	indexed=false;
	boolean never_index=__NEVER_INDEX.contains(header);
	boolean huffman=!__DO_NOT_HUFFMAN.contains(header);
	encodeName(buffer,never_index?(byte)0x10:(byte)0x00,4,header.asString(),name);
	encodeValue(buffer,huffman,field.getValue());

	if (_debug)
	encoding="Lit"+
	((name==null)?"HuffN":("IdxN"+(name.isStatic()?"S":"")+(1+NBitInteger.octectsNeeded(4,_context.index(name)))))+
	(huffman?"HuffV":"LitV")+
	(indexed?"Idx":(never_index?"!!Idx":"!Idx"));
	}
	else if (header==HttpHeader.CONTENT_LENGTH && field.getValue().length()>1)
	{
	// Non indexed content length for 2 digits or more
	indexed=false;
	encodeName(buffer,(byte)0x00,4,header.asString(),name);
	encodeValue(buffer,true,field.getValue());
	if (_debug)
	encoding="LitIdxNS"+(1+NBitInteger.octectsNeeded(4,_context.index(name)))+"HuffV!Idx";
	}
	else
	{
	// indexed
	indexed=true;
	boolean huffman=!__DO_NOT_HUFFMAN.contains(header);
	encodeName(buffer,(byte)0x40,6,header.asString(),name);
	encodeValue(buffer,huffman,field.getValue());
	if (_debug)
	encoding=((name==null)?"LitHuffN":("LitIdxN"+(name.isStatic()?"S":"")+(1+NBitInteger.octectsNeeded(6,_context.index(name)))))+
	(huffman?"HuffVIdx":"LitVIdx");
	}
	}

	// If we want the field referenced, then we add it to our
	// table and reference set.
	if (indexed)
	_context.add(field);
	}

	if (_debug)
	{
	int e=buffer.position();
	if (LOG.isDebugEnabled())
	LOG.debug("encode {}:'{}' to '{}'",encoding,field,TypeUtil.toHexString(buffer.array(),buffer.arrayOffset()+p,e-p));
	}
	}

	private void encodeName(ByteBuffer buffer, byte mask, int bits, String name, Entry entry)
	{
	buffer.put(mask);
	if (entry==null)
	{
	// leave name index bits as 0
	// Encode the name always with lowercase huffman
	buffer.put((byte)0x80);
	NBitInteger.encode(buffer,7,Huffman.octetsNeededLC(name));
	Huffman.encodeLC(buffer,name);
	}
	else
	{
	NBitInteger.encode(buffer,bits,_context.index(entry));
	}
	}

	static void encodeValue(ByteBuffer buffer, boolean huffman, String value)
	{
	if (huffman)
	{
	// huffman literal value
	buffer.put((byte)0x80);
	NBitInteger.encode(buffer,7,Huffman.octetsNeeded(value));
	Huffman.encode(buffer,value);
	}
	else
	{
	// add literal assuming iso_8859_1
	buffer.put((byte)0x00);
	NBitInteger.encode(buffer,7,value.length());
	for (int i=0;i<value.length();i++)
	{
	char c=value.charAt(i);
	if (c<' '\|\| c>127)
	throw new IllegalArgumentException();
	buffer.put((byte)c);
	}
	}
	}
	}