/*
* Created on Jan 24, 2005
* Created by Alon Rohter
* Copyright (C) 2004-2005 Aelitis, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*
*/
package com.aelitis.azureus.core.peermanager.messaging.bittorrent;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.*;
import org.gudy.azureus2.core3.util.*;
import com.aelitis.azureus.core.networkmanager.Transport;
import com.aelitis.azureus.core.peermanager.messaging.*;
/**
*
*/
public class BTMessageDecoder implements MessageStreamDecoder {
private static final int MIN_MESSAGE_LENGTH = 1; //for type id
private static final int MAX_MESSAGE_LENGTH = 16393; //should never be > 16KB+9B, as we never request chunks > 16KB
private static final int HANDSHAKE_FAKE_LENGTH = 323119476; //(byte)19 + "Bit" readInt() value of header
private static final byte SS = DirectByteBuffer.SS_MSG;
private DirectByteBuffer payload_buffer = null;
private final DirectByteBuffer length_buffer = DirectByteBufferPool.getBuffer( DirectByteBuffer.AL_MSG, 4 );
private final ByteBuffer[] decode_array = new ByteBuffer[] { null, length_buffer.getBuffer( SS ) };
private boolean reading_length_mode = true;
private boolean reading_handshake_message = false;
private int message_length;
private int pre_read_start_buffer;
private int pre_read_start_position;
private boolean last_received_was_keepalive = false;
private volatile boolean destroyed = false;
private volatile boolean is_paused = false;
private ArrayList messages_last_read = new ArrayList();
private int protocol_bytes_last_read = 0;
private int data_bytes_last_read = 0;
private int percent_complete = -1;
public BTMessageDecoder() {
/* nothing */
}
public int performStreamDecode( Transport transport, int max_bytes ) throws IOException {
protocol_bytes_last_read = 0;
data_bytes_last_read = 0;
int bytes_remaining = max_bytes;
while( bytes_remaining > 0 ) {
if( destroyed ) {
// destruction currently isn't thread safe so one thread can destroy the decoder (e.g. when closing a connection)
// while the read-controller is still actively processing the us
//throw( new IOException( "BTMessageDecoder already destroyed" ));
break;
}
if( is_paused ) {
break;
}
int bytes_possible = preReadProcess( bytes_remaining );
if( bytes_possible < 1 ) {
Debug.out( "ERROR BT: bytes_possible < 1" );
break;
}
if( reading_length_mode ) {
transport.read( decode_array, 1, 1 ); //only read into length buffer
}
else {
transport.read( decode_array, 0, 2 ); //read into payload buffer, and possibly next message length
}
int bytes_read = postReadProcess();
bytes_remaining -= bytes_read;
if( bytes_read < bytes_possible ) {
break;
}
if( reading_length_mode && last_received_was_keepalive ) {
//hack to stop a 0-byte-read after receiving a keep-alive message
//otherwise we won't realize there's nothing left on the line until trying to read again
last_received_was_keepalive = false;
break;
}
}
return max_bytes - bytes_remaining;
}
public int getPercentDoneOfCurrentMessage() {
return percent_complete;
}
public Message[] removeDecodedMessages() {
if( messages_last_read.isEmpty() ) return null;
Message[] msgs = (Message[])messages_last_read.toArray( new Message[messages_last_read.size()] );
messages_last_read.clear();
return msgs;
}
public int getProtocolBytesDecoded() { return protocol_bytes_last_read; }
public int getDataBytesDecoded() { return data_bytes_last_read; }
public ByteBuffer destroy() {
is_paused = true;
destroyed = true;
int lbuff_read = 0;
int pbuff_read = 0;
length_buffer.limit( SS, 4 );
if( reading_length_mode ) {
lbuff_read = length_buffer.position( SS );
}
else { //reading payload
length_buffer.position( SS, 4 );
lbuff_read = 4;
pbuff_read = payload_buffer == null ? 0 : payload_buffer.position( SS );
}
ByteBuffer unused = ByteBuffer.allocate( lbuff_read + pbuff_read ); //TODO convert to direct?
length_buffer.flip( SS );
unused.put( length_buffer.getBuffer( SS ) );
if ( payload_buffer != null ) {
payload_buffer.flip( SS );
unused.put( payload_buffer.getBuffer( SS ) );
}
unused.flip();
length_buffer.returnToPool();
if( payload_buffer != null ) {
payload_buffer.returnToPool();
payload_buffer = null;
}
for( int i=0; i < messages_last_read.size(); i++ ) {
Message msg = (Message)messages_last_read.get( i );
msg.destroy();
}
messages_last_read.clear();
return unused;
}
private int preReadProcess( int allowed ) {
if( allowed < 1 ) {
Debug.out( "allowed < 1" );
}
decode_array[ 0 ] = payload_buffer == null ? null : payload_buffer.getBuffer( SS ); //ensure the decode array has the latest payload pointer
int bytes_available = 0;
boolean shrink_remaining_buffers = false;
int start_buff = reading_length_mode ? 1 : 0;
boolean marked = false;
for( int i = start_buff; i < 2; i++ ) { //set buffer limits according to bytes allowed
ByteBuffer bb = decode_array[ i ];
if( bb == null ) {
Debug.out( "preReadProcess:: bb["+i+"] == null, decoder destroyed=" +destroyed );
}
if( shrink_remaining_buffers ) {
bb.limit( 0 ); //ensure no read into this next buffer is possible
}
else {
int remaining = bb.remaining();
if( remaining < 1 ) continue; //skip full buffer
if( !marked ) {
pre_read_start_buffer = i;
pre_read_start_position = bb.position();
marked = true;
}
if( remaining > allowed ) { //read only part of this buffer
bb.limit( bb.position() + allowed ); //limit current buffer
bytes_available += bb.remaining();
shrink_remaining_buffers = true; //shrink any tail buffers
}
else { //full buffer is allowed to be read
bytes_available += remaining;
allowed -= remaining; //count this buffer toward allowed and move on to the next
}
}
}
return bytes_available;
}
private int postReadProcess() throws IOException {
int prot_bytes_read = 0;
int data_bytes_read = 0;
if( !reading_length_mode && !destroyed ) { //reading payload data mode
//ensure-restore proper buffer limits
payload_buffer.limit( SS, message_length );
length_buffer.limit( SS, 4 );
int read = payload_buffer.position( SS ) - pre_read_start_position;
if( payload_buffer.position( SS ) > 0 ) { //need to have read the message id first byte
if( BTMessageFactory.getMessageType( payload_buffer) == Message.TYPE_DATA_PAYLOAD ) {
data_bytes_read += read;
}
else {
prot_bytes_read += read;
}
}
if( !payload_buffer.hasRemaining( SS ) && !is_paused ) { //full message received!
payload_buffer.position( SS, 0 );
DirectByteBuffer ref_buff = payload_buffer;
payload_buffer = null;
if( reading_handshake_message ) { //decode handshake
reading_handshake_message = false;
DirectByteBuffer handshake_data = DirectByteBufferPool.getBuffer( DirectByteBuffer.AL_MSG_BT_HAND, 68 );
handshake_data.putInt( SS, HANDSHAKE_FAKE_LENGTH );
handshake_data.put( SS, ref_buff );
handshake_data.flip( SS );
ref_buff.returnToPool();
try {
Message handshake = MessageManager.getSingleton().createMessage( BTMessage.ID_BT_HANDSHAKE_BYTES, handshake_data, (byte)1 );
messages_last_read.add( handshake );
}
catch( MessageException me ) {
handshake_data.returnToPool();
throw new IOException( "BT message decode failed: " + me.getMessage() );
}
//we need to auto-pause decoding until we're told to start again externally,
//as we don't want to accidentally read the next message on the stream if it's an AZ-format handshake
pauseDecoding();
}
else { //decode normal message
try {
Message msg = BTMessageFactory.createBTMessage( ref_buff );
messages_last_read.add( msg );
}
catch( Throwable e ) {
ref_buff.returnToPoolIfNotFree();
// maintain unexpected erorrs as such so they get logged later
if ( e instanceof RuntimeException ){
throw((RuntimeException)e );
}
throw new IOException( "BT message decode failed: " +e.getMessage() );
}
}
reading_length_mode = true; //see if we've already read the next message's length
percent_complete = -1; //reset receive percentage
}
else { //only partial received so far
percent_complete = (payload_buffer.position( SS ) * 100) / message_length; //compute receive percentage
}
}
if( reading_length_mode && !destroyed ) {
length_buffer.limit( SS, 4 ); //ensure proper buffer limit
prot_bytes_read += (pre_read_start_buffer == 1) ? length_buffer.position( SS ) - pre_read_start_position : length_buffer.position( SS );
if( !length_buffer.hasRemaining( SS ) ) { //done reading the length
reading_length_mode = false;
length_buffer.position( SS, 0 );
message_length = length_buffer.getInt( SS );
length_buffer.position( SS, 0 ); //reset it for next length read
if( message_length == HANDSHAKE_FAKE_LENGTH ) { //handshake message
reading_handshake_message = true;
message_length = 64; //restore 'real' length
payload_buffer = DirectByteBufferPool.getBuffer( DirectByteBuffer.AL_MSG_BT_HAND, message_length );
}
else if( message_length == 0 ) { //keep-alive message
reading_length_mode = true;
last_received_was_keepalive = true;
try{
Message keep_alive = MessageManager.getSingleton().createMessage( BTMessage.ID_BT_KEEP_ALIVE_BYTES, null, (byte)1 );
messages_last_read.add( keep_alive );
}
catch( MessageException me ) {
throw new IOException( "BT message decode failed: " + me.getMessage() );
}
}
else if( message_length < MIN_MESSAGE_LENGTH || message_length > MAX_MESSAGE_LENGTH ) {
throw new IOException( "Invalid message length given for BT message decode: " + message_length );
}
else { //normal message
payload_buffer = DirectByteBufferPool.getBuffer( DirectByteBuffer.AL_MSG_BT_PAYLOAD, message_length );
}
}
}
protocol_bytes_last_read += prot_bytes_read;
data_bytes_last_read += data_bytes_read;
return prot_bytes_read + data_bytes_read;
}
public void pauseDecoding() {
is_paused = true;
}
public void resumeDecoding() {
is_paused = false;
}
}
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