org.eclipse.jetty.spdy.parser.DataFrameParser Maven / Gradle / Ivy
//
// ========================================================================
// 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.parser;
import java.nio.ByteBuffer;
import org.eclipse.jetty.spdy.api.DataInfo;
import org.eclipse.jetty.spdy.frames.DataFrame;
public abstract class DataFrameParser
{
private State state = State.STREAM_ID;
private int cursor;
private int streamId;
private byte flags;
private int length;
/**
* Parses the given {@link ByteBuffer} for a data frame.
*
* @param buffer the {@link ByteBuffer} to parse
* @return true if the data frame has been fully parsed, false otherwise
*/
public boolean parse(ByteBuffer buffer)
{
while (buffer.hasRemaining())
{
switch (state)
{
case STREAM_ID:
{
if (buffer.remaining() >= 4)
{
streamId = buffer.getInt() & 0x7F_FF_FF_FF;
state = State.FLAGS;
}
else
{
state = State.STREAM_ID_BYTES;
cursor = 4;
}
break;
}
case STREAM_ID_BYTES:
{
byte currByte = buffer.get();
--cursor;
streamId += (currByte & 0xFF) << 8 * cursor;
if (cursor == 0)
state = State.FLAGS;
break;
}
case FLAGS:
{
flags = buffer.get();
cursor = 3;
state = State.LENGTH;
break;
}
case LENGTH:
{
byte currByte = buffer.get();
--cursor;
length += (currByte & 0xFF) << 8 * cursor;
if (cursor > 0)
break;
state = State.DATA;
// Fall down if length == 0: we can't loop because the buffer
// may be empty but we need to invoke the application anyway
if (length > 0)
break;
}
case DATA:
{
// Length can only be at most 3 bytes, which is 16_777_215 i.e. 16 MiB.
// However, compliant clients should implement flow control, so it's
// unlikely that we will get that 16 MiB chunk.
// However, TCP may further split the flow control window, so we may
// only have part of the data at this point.
int size = Math.min(length, buffer.remaining());
int limit = buffer.limit();
buffer.limit(buffer.position() + size);
ByteBuffer bytes = buffer.slice();
buffer.limit(limit);
buffer.position(buffer.position() + size);
length -= size;
if (length == 0)
{
onDataFrame(bytes);
return true;
}
else
{
// We got only part of the frame data bytes,
// so we generate a synthetic data frame
onDataFragment(bytes);
}
break;
}
default:
{
throw new IllegalStateException();
}
}
}
return false;
}
private void onDataFrame(ByteBuffer bytes)
{
DataFrame frame = new DataFrame(streamId, flags, bytes.remaining());
onDataFrame(frame, bytes);
reset();
}
private void onDataFragment(ByteBuffer bytes)
{
DataFrame frame = new DataFrame(streamId, (byte)(flags & ~DataInfo.FLAG_CLOSE), bytes.remaining());
onDataFrame(frame, bytes);
// Do not reset, we're expecting more data
}
protected abstract void onDataFrame(DataFrame frame, ByteBuffer data);
private void reset()
{
state = State.STREAM_ID;
cursor = 0;
streamId = 0;
flags = 0;
length = 0;
}
private enum State
{
STREAM_ID, STREAM_ID_BYTES, FLAGS, LENGTH, DATA
}
}