peer_connection_leech.cc

LibTorrent is a BitTorrent library written in C++ for *nix, with a focus on high performance and goo

// libTorrent - BitTorrent library
// Copyright (C) 2005-2006, Jari Sundell
//
// 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
//
// In addition, as a special exception, the copyright holders give
// permission to link the code of portions of this program with the
// OpenSSL library under certain conditions as described in each
// individual source file, and distribute linked combinations
// including the two.
//
// You must obey the GNU General Public License in all respects for
// all of the code used other than OpenSSL.  If you modify file(s)
// with this exception, you may extend this exception to your version
// of the file(s), but you are not obligated to do so.  If you do not
// wish to do so, delete this exception statement from your version.
// If you delete this exception statement from all source files in the
// program, then also delete it here.
//
// Contact:  Jari Sundell <[e-mail]>
//
//           Skomakerveien 33
//           3185 Skoppum, NORWAY

#include "config.h"

#include <cstring>
#include <sstream>

#include "data/content.h"
#include "data/chunk_list_node.h"
#include "download/chunk_selector.h"
#include "download/chunk_statistics.h"
#include "download/download_info.h"
#include "download/download_main.h"

#include "peer_connection_leech.h"

namespace torrent {

PeerConnectionLeech::~PeerConnectionLeech() {
//   if (m_download != NULL && m_down->get_state() != ProtocolRead::READ_BITFIELD)
//     m_download->bitfield_counter().dec(m_peerChunks.bitfield()->bitfield());

//   priority_queue_erase(&taskScheduler, &m_taskSendChoke);
}

void
PeerConnectionLeech::initialize_custom() {
//   if (m_download->content()->chunks_completed() != 0) {
//     m_up->write_bitfield(m_download->content()->bitfield()->size_bytes());

//     m_up->buffer()->prepare_end();
//     m_up->set_position(0);
//     m_up->set_state(ProtocolWrite::WRITE_BITFIELD_HEADER);
//   }
}

void
PeerConnectionLeech::update_interested() {
// FIXME:   if (m_download->delegator()->get_select().interested(m_peerChunks.bitfield()->bitfield())) {

  // Consider just setting to interested without checking the
  // bitfield. The status might change by the time we get unchoked
  // anyway.

  if (true) {
    m_sendInterested = !m_up->interested();
    m_up->set_interested(true);
  } else {
    m_sendInterested = m_up->interested();
    m_up->set_interested(false);
  }

  m_peerChunks.download_cache()->clear();
}

// Disconnecting connections where both are seeders should be done by
// DownloadMain when it finishes the last chunk.
void
PeerConnectionLeech::receive_finished_chunk(int32_t index) {
  m_peerChunks.have_queue()->push_back(index);

  if (download_queue()->has_index(index))
    throw internal_error("PeerConnection::sendHave(...) found a request with the same index");
}

bool
PeerConnectionLeech::receive_keepalive() {
  if (cachedTime - m_timeLastRead > rak::timer::from_seconds(240))
    return false;

  // There's no point in adding ourselves to the write poll if the
  // buffer is full, as that will already have been taken care of.
  if (m_up->get_state() == ProtocolWrite::IDLE &&
      m_up->can_write_keepalive()) {

    write_insert_poll_safe();
    m_up->write_keepalive();
  }

  m_tryRequest = true;

  // Stall pieces when more than one receive_keepalive() has been
  // called while a single piece is downloading.
  //
  // m_downStall is decremented for every successfull download, so it
  // should stay at zero or one when downloading at an acceptable
  // speed. Thus only when m_downStall >= 2 is the download actually
  // stalling.
  if (!download_queue()->empty() && m_downStall++ != 0)
    download_queue()->stall();

  return true;
}

// We keep the message in the buffer if it is incomplete instead of
// keeping the state and remembering the read information. This
// shouldn't happen very often compared to full reads.
inline bool
PeerConnectionLeech::read_message() {
  ProtocolBuffer<512>* buf = m_down->buffer();

  if (buf->remaining() < 4)
    return false;

  // Remember the start of the message so we may reset it if we don't
  // have the whole message.
  ProtocolBuffer<512>::iterator beginning = buf->position();

  uint32_t length = buf->read_32();

  if (length == 0) {
    // Keepalive message.
    m_down->set_last_command(ProtocolBase::KEEP_ALIVE);

    return true;

  } else if (buf->remaining() < 1) {
    buf->set_position_itr(beginning);
    return false;

  } else if (length > (1 << 20)) {
    throw network_error("PeerConnectionLeech::read_message() got an invalid message length.");
  }
    
  // We do not verify the message length of those with static
  // length. A bug in the remote client causing the message start to
  // be unsyncronized would in practically all cases be caught with
  // the above test.
  //
  // Those that do in some weird way manage to produce a valid
  // command, will not be able to do any damage as malicious
  // peer. Those cases should be caught elsewhere in the code.

  // Temporary.
  m_down->set_last_command((ProtocolBase::Protocol)buf->peek_8());

  switch (buf->read_8()) {
  case ProtocolBase::CHOKE:
    m_down->set_choked(true);

    m_peerChunks.download_cache()->disable();

    download_queue()->cancel();
    m_download->download_throttle()->erase(m_peerChunks.download_throttle());

    return true;

  case ProtocolBase::UNCHOKE:
    if (is_down_choked()) {
      write_insert_poll_safe();

      m_down->set_choked(false);
      m_tryRequest = true;
    }

    return true;

  case ProtocolBase::INTERESTED:
    set_remote_interested();
    return true;

  case ProtocolBase::NOT_INTERESTED:
    set_remote_not_interested();
    return true;

  case ProtocolBase::HAVE:
    if (!m_down->can_read_have_body())
      break;

    read_have_chunk(buf->read_32());
    return true;

  case ProtocolBase::REQUEST:
    if (!m_down->can_read_request_body())
      break;

    if (!m_up->choked()) {
      write_insert_poll_safe();
      read_request_piece(m_down->read_request());

    } else {
      m_down->read_request();
    }

    return true;

  case ProtocolBase::PIECE:
    if (!m_down->can_read_piece_body())
      break;

    if (!down_chunk_start(m_down->read_piece(length - 9))) {

      // We don't want this chunk.
      if (down_chunk_skip_from_buffer()) {
        m_tryRequest = true;
        down_chunk_finished();
        return true;

      } else {
        m_down->set_state(ProtocolRead::READ_SKIP_PIECE);
        return false;
      }
      
    } else {

      if (down_chunk_from_buffer()) {
        m_tryRequest = true;
        down_chunk_finished();
        return true;

      } else {
        m_down->set_state(ProtocolRead::READ_PIECE);
        m_download->download_throttle()->insert(m_peerChunks.download_throttle());
        return false;
      }
    }

  case ProtocolBase::CANCEL:
    if (!m_down->can_read_cancel_body())
      break;

    read_cancel_piece(m_down->read_request());
    return true;

  default:
    throw network_error("Received unsupported message type.");
  }

  // We were unsuccessfull in reading the message, need more data.
  buf->set_position_itr(beginning);
  return false;
}

void
PeerConnectionLeech::event_read() {
  m_timeLastRead = cachedTime;

  // Need to make sure ProtocolBuffer::end() is pointing to the end of
  // the unread data, and that the unread data starts from the