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//
// ========================================================================
// Copyright (c) 1995-2013 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.spdy.generator;
import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.Locale;
import org.eclipse.jetty.spdy.CompressionDictionary;
import org.eclipse.jetty.spdy.CompressionFactory;
import org.eclipse.jetty.spdy.api.SPDY;
import org.eclipse.jetty.util.Fields;
public class HeadersBlockGenerator
{
private final CompressionFactory.Compressor compressor;
private boolean needsDictionary = true;
public HeadersBlockGenerator(CompressionFactory.Compressor compressor)
{
this.compressor = compressor;
}
public ByteBuffer generate(short version, Fields headers)
{
// TODO: ByteArrayOutputStream is quite inefficient, but grows on demand; optimize using ByteBuffer ?
ByteArrayOutputStream buffer = new ByteArrayOutputStream(headers.size() * 64);
writeCount(version, buffer, headers.size());
for (Fields.Field header : headers)
{
String name = header.name().toLowerCase(Locale.ENGLISH);
byte[] nameBytes = name.getBytes(StandardCharsets.ISO_8859_1);
writeNameLength(version, buffer, nameBytes.length);
buffer.write(nameBytes, 0, nameBytes.length);
// Most common path first
String value = header.value();
byte[] valueBytes = value.getBytes(StandardCharsets.ISO_8859_1);
if (header.hasMultipleValues())
{
String[] values = header.values();
for (int i = 1; i < values.length; ++i)
{
byte[] moreValueBytes = values[i].getBytes(StandardCharsets.ISO_8859_1);
byte[] newValueBytes = new byte[valueBytes.length + 1 + moreValueBytes.length];
System.arraycopy(valueBytes, 0, newValueBytes, 0, valueBytes.length);
newValueBytes[valueBytes.length] = 0;
System.arraycopy(moreValueBytes, 0, newValueBytes, valueBytes.length + 1, moreValueBytes.length);
valueBytes = newValueBytes;
}
}
writeValueLength(version, buffer, valueBytes.length);
buffer.write(valueBytes, 0, valueBytes.length);
}
return compress(version, buffer.toByteArray());
}
private ByteBuffer compress(short version, byte[] bytes)
{
ByteArrayOutputStream buffer = new ByteArrayOutputStream(bytes.length);
// The headers compression context is per-session, so we need to synchronize
synchronized (compressor)
{
if (needsDictionary)
{
compressor.setDictionary(CompressionDictionary.get(version));
needsDictionary = false;
}
compressor.setInput(bytes);
// Compressed bytes may be bigger than input bytes, so we need to loop and accumulate them
// Beware that the minimum amount of bytes generated by the compressor is few bytes, so we
// need to use an output buffer that is big enough to exit the compress loop
buffer.reset();
int compressed;
byte[] output = new byte[Math.max(256, bytes.length)];
while (true)
{
// SPDY uses the SYNC_FLUSH mode
compressed = compressor.compress(output);
buffer.write(output, 0, compressed);
if (compressed < output.length)
break;
}
}
return ByteBuffer.wrap(buffer.toByteArray());
}
private void writeCount(short version, ByteArrayOutputStream buffer, int value)
{
switch (version)
{
case SPDY.V2:
{
buffer.write((value & 0xFF_00) >>> 8);
buffer.write(value & 0x00_FF);
break;
}
case SPDY.V3:
{
buffer.write((value & 0xFF_00_00_00) >>> 24);
buffer.write((value & 0x00_FF_00_00) >>> 16);
buffer.write((value & 0x00_00_FF_00) >>> 8);
buffer.write(value & 0x00_00_00_FF);
break;
}
default:
{
// Here the version is trusted to be correct; if it's not
// then it's a bug rather than an application error
throw new IllegalStateException();
}
}
}
private void writeNameLength(short version, ByteArrayOutputStream buffer, int length)
{
writeCount(version, buffer, length);
}
private void writeValueLength(short version, ByteArrayOutputStream buffer, int length)
{
writeCount(version, buffer, length);
}
}
