torrentclient.cpp Example File

torrent/torrentclient.cpp

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  #include "connectionmanager.h"
  #include "filemanager.h"
  #include "metainfo.h"
  #include "torrentclient.h"
  #include "torrentserver.h"
  #include "trackerclient.h"
  #include "peerwireclient.h"
  #include "ratecontroller.h"

  #include <QtCore>
  #include <QNetworkInterface>

  #include <algorithm>

  // These constants could also be configurable by the user.
  static const int ServerMinPort = 6881;
  static const int ServerMaxPort = /* 6889 */ 7000;
  static const int BlockSize = 16384;
  static const int MaxBlocksInProgress = 5;
  static const int MaxBlocksInMultiMode = 2;
  static const int MaxConnectionPerPeer = 1;
  static const int RateControlWindowLength = 10;
  static const int RateControlTimerDelay = 1000;
  static const int MinimumTimeBeforeRevisit = 30;
  static const int MaxUploads = 4;
  static const int UploadScheduleInterval = 10000;

  class TorrentPiece {
  public:
      int index;
      int length;
      QBitArray completedBlocks;
      QBitArray requestedBlocks;
      bool inProgress;
  };

  class TorrentClientPrivate
  {
  public:
      TorrentClientPrivate(TorrentClient *qq);

      // State / error
      void setError(TorrentClient::Error error);
      void setState(TorrentClient::State state);
      TorrentClient::Error error;
      TorrentClient::State state;
      QString errorString;
      QString stateString;

      // Where to save data
      QString destinationFolder;
      MetaInfo metaInfo;

      // Announce tracker and file manager
      QByteArray peerId;
      QByteArray infoHash;
      TrackerClient trackerClient;
      FileManager fileManager;

      // Connections
      QList<PeerWireClient *> connections;
      QList<TorrentPeer *> peers;
      bool schedulerCalled;
      void callScheduler();
      bool connectingToClients;
      void callPeerConnector();
      int uploadScheduleTimer;

      // Pieces
      QMap<int, PeerWireClient *> readIds;
      QMultiMap<PeerWireClient *, TorrentPiece *> payloads;
      QMap<int, TorrentPiece *> pendingPieces;
      QBitArray completedPieces;
      QBitArray incompletePieces;
      int pieceCount;

      // Progress
      int lastProgressValue;
      qint64 downloadedBytes;
      qint64 uploadedBytes;
      int downloadRate[RateControlWindowLength];
      int uploadRate[RateControlWindowLength];
      int transferRateTimer;

      TorrentClient *q;
  };

  TorrentClientPrivate::TorrentClientPrivate(TorrentClient *qq)
      : trackerClient(qq), q(qq)
  {
      error = TorrentClient::UnknownError;
      state = TorrentClient::Idle;
      errorString = QT_TRANSLATE_NOOP(TorrentClient, "Unknown error");
      stateString = QT_TRANSLATE_NOOP(TorrentClient, "Idle");
      schedulerCalled = false;
      connectingToClients = false;
      uploadScheduleTimer = 0;
      lastProgressValue = -1;
      pieceCount = 0;
      downloadedBytes = 0;
      uploadedBytes = 0;
      memset(downloadRate, 0, sizeof(downloadRate));
      memset(uploadRate, 0, sizeof(uploadRate));
      transferRateTimer = 0;
  }

  void TorrentClientPrivate::setError(TorrentClient::Error errorCode)
  {
      this->error = errorCode;
      switch (error) {
      case TorrentClient::UnknownError:
          errorString = QT_TRANSLATE_NOOP(TorrentClient, "Unknown error");
          break;
      case TorrentClient::TorrentParseError:
          errorString = QT_TRANSLATE_NOOP(TorrentClient, "Invalid torrent data");
          break;
      case TorrentClient::InvalidTrackerError:
          errorString = QT_TRANSLATE_NOOP(TorrentClient, "Unable to connect to tracker");
          break;
      case TorrentClient::FileError:
          errorString = QT_TRANSLATE_NOOP(TorrentClient, "File error");
          break;
      case TorrentClient::ServerError:
          errorString = QT_TRANSLATE_NOOP(TorrentClient, "Unable to initialize server");
          break;
      }
      emit q->error(errorCode);
  }

  void TorrentClientPrivate::setState(TorrentClient::State state)
  {
      this->state = state;
      switch (state) {
      case TorrentClient::Idle:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Idle");
          break;
      case TorrentClient::Paused:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Paused");
          break;
      case TorrentClient::Stopping:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Stopping");
          break;
      case TorrentClient::Preparing:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Preparing");
          break;
      case TorrentClient::Searching:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Searching");
          break;
      case TorrentClient::Connecting:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Connecting");
          break;
      case TorrentClient::WarmingUp:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Warming up");
          break;
      case TorrentClient::Downloading:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Downloading");
          break;
      case TorrentClient::Endgame:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Finishing");
          break;
      case TorrentClient::Seeding:
          stateString = QT_TRANSLATE_NOOP(TorrentClient, "Seeding");
          break;
      }
      emit q->stateChanged(state);
  }

  void TorrentClientPrivate::callScheduler()
  {
      if (!schedulerCalled) {
          schedulerCalled = true;
          QMetaObject::invokeMethod(q, "scheduleDownloads", Qt::QueuedConnection);
      }
  }

  void TorrentClientPrivate::callPeerConnector()
  {
      if (!connectingToClients) {
          connectingToClients = true;
          QTimer::singleShot(10000, q, SLOT(connectToPeers()));
      }
  }

  TorrentClient::TorrentClient(QObject *parent)
      : QObject(parent), d(new TorrentClientPrivate(this))
  {
      // Connect the file manager
      connect(&d->fileManager, SIGNAL(dataRead(int,int,int,QByteArray)),
              this, SLOT(sendToPeer(int,int,int,QByteArray)));
      connect(&d->fileManager, SIGNAL(verificationProgress(int)),
              this, SLOT(updateProgress(int)));
      connect(&d->fileManager, SIGNAL(verificationDone()),
              this, SLOT(fullVerificationDone()));
      connect(&d->fileManager, SIGNAL(pieceVerified(int,bool)),
              this, SLOT(pieceVerified(int,bool)));
      connect(&d->fileManager, SIGNAL(error()),
              this, SLOT(handleFileError()));

      // Connect the tracker client
      connect(&d->trackerClient, SIGNAL(peerListUpdated(QList<TorrentPeer>)),
              this, SLOT(addToPeerList(QList<TorrentPeer>)));
      connect(&d->trackerClient, SIGNAL(stopped()),
              this, SIGNAL(stopped()));
  }

  TorrentClient::~TorrentClient()
  {
      qDeleteAll(d->peers);
      qDeleteAll(d->pendingPieces);
      delete d;
  }

  bool TorrentClient::setTorrent(const QString &fileName)
  {
      QFile file(fileName);
      if (!file.open(QIODevice::ReadOnly) || !setTorrent(file.readAll())) {
          d->setError(TorrentParseError);
          return false;
      }
      return true;
  }

  bool TorrentClient::setTorrent(const QByteArray &torrentData)
  {
      if (!d->metaInfo.parse(torrentData)) {
          d->setError(TorrentParseError);
          return false;
      }

      // Calculate SHA1 hash of the "info" section in the torrent
      QByteArray infoValue = d->metaInfo.infoValue();
      d->infoHash = QCryptographicHash::hash(infoValue, QCryptographicHash::Sha1);

      return true;
  }

  MetaInfo TorrentClient::metaInfo() const
  {
      return d->metaInfo;
  }

  void TorrentClient::setDestinationFolder(const QString &directory)
  {
      d->destinationFolder = directory;
  }

  QString TorrentClient::destinationFolder() const
  {
      return d->destinationFolder;
  }

  void TorrentClient::setDumpedState(const QByteArray &dumpedState)
  {
      // Recover partially completed pieces
      QDataStream stream(dumpedState);

      quint16 version = 0;
      stream >> version;
      if (version != 2)
          return;

      stream >> d->completedPieces;

      while (!stream.atEnd()) {
          int index;
          int length;
          QBitArray completed;
          stream >> index >> length >> completed;
          if (stream.status() != QDataStream::Ok) {
              d->completedPieces.clear();
              break;
          }

          TorrentPiece *piece = new TorrentPiece;
          piece->index = index;
          piece->length = length;
          piece->completedBlocks = completed;
          piece->requestedBlocks.resize(completed.size());
          piece->inProgress = false;
          d->pendingPieces[index] = piece;
      }
  }

  QByteArray TorrentClient::dumpedState() const
  {
      QByteArray partials;
      QDataStream stream(&partials, QIODevice::WriteOnly);

      stream << quint16(2);
      stream << d->completedPieces;

      // Save the state of all partially downloaded pieces into a format
      // suitable for storing in settings.
      QMap<int, TorrentPiece *>::ConstIterator it = d->pendingPieces.constBegin();
      while (it != d->pendingPieces.constEnd()) {
          TorrentPiece *piece = it.value();
          if (blocksLeftForPiece(piece) > 0 && blocksLeftForPiece(piece) < piece->completedBlocks.size()) {
              stream << piece->index;
              stream << piece->length;
              stream << piece->completedBlocks;
          }
          ++it;
      }

      return partials;
  }

  qint64 TorrentClient::progress() const
  {
      return d->lastProgressValue;
  }

  void TorrentClient::setDownloadedBytes(qint64 bytes)
  {
      d->downloadedBytes = bytes;
  }

  qint64 TorrentClient::downloadedBytes() const
  {
      return d->downloadedBytes;
  }

  void TorrentClient::setUploadedBytes(qint64 bytes)
  {
      d->uploadedBytes = bytes;
  }

  qint64 TorrentClient::uploadedBytes() const
  {
      return d->uploadedBytes;
  }

  int TorrentClient::connectedPeerCount() const
  {
      int tmp = 0;
      foreach (PeerWireClient *client, d->connections) {
          if (client->state() == QAbstractSocket::ConnectedState)
              ++tmp;
      }
      return tmp;
  }

  int TorrentClient::seedCount() const
  {
      int tmp = 0;
      foreach (PeerWireClient *client, d->connections) {
          if (client->availablePieces().count(true) == d->pieceCount)
              ++tmp;
      }
      return tmp;
  }

  TorrentClient::State TorrentClient::state() const
  {
      return d->state;
  }

  QString TorrentClient::stateString() const
  {
      return d->stateString;
  }

  TorrentClient::Error TorrentClient::error() const
  {
      return d->error;
  }

  QString TorrentClient::errorString() const
  {
      return d->errorString;
  }

  QByteArray TorrentClient::peerId() const
  {
      return d->peerId;
  }

  QByteArray TorrentClient::infoHash() const
  {
      return d->infoHash;
  }

  void TorrentClient::start()
  {
      if (d->state != Idle)
          return;

      TorrentServer::instance()->addClient(this);

      // Initialize the file manager
      d->setState(Preparing);
      d->fileManager.setMetaInfo(d->metaInfo);
      d->fileManager.setDestinationFolder(d->destinationFolder);
      d->fileManager.setCompletedPieces(d->completedPieces);
      d->fileManager.start(QThread::LowestPriority);
      d->fileManager.startDataVerification();
  }

  void TorrentClient::stop()
  {
      if (d->state == Stopping)
          return;

      TorrentServer::instance()->removeClient(this);

      // Update the state
      State oldState = d->state;
      d->setState(Stopping);

      // Stop the timer
      if (d->transferRateTimer) {
          killTimer(d->transferRateTimer);
          d->transferRateTimer = 0;
      }

      // Abort all existing connections
      foreach (PeerWireClient *client, d->connections) {
          RateController::instance()->removeSocket(client);
          ConnectionManager::instance()->removeConnection(client);
          client->abort();
      }
      d->connections.clear();

      // Perhaps stop the tracker
      if (oldState > Preparing) {
          d->trackerClient.stop();
      } else {
          d->setState(Idle);
          emit stopped();
      }
  }

  void TorrentClient::setPaused(bool paused)
  {
      if (paused) {
          // Abort all connections, and set the max number of
          // connections to 0. Keep the list of peers, so we can quickly
          // resume later.
          d->setState(Paused);
          foreach (PeerWireClient *client, d->connections)
              client->abort();
          d->connections.clear();
          TorrentServer::instance()->removeClient(this);
      } else {
          // Restore the max number of connections, and start the peer
          // connector. We should also quickly start receiving incoming
          // connections.
          d->setState(d->completedPieces.count(true) == d->fileManager.pieceCount()
                      ? Seeding : Searching);
          connectToPeers();
          TorrentServer::instance()->addClient(this);
      }
  }

  void TorrentClient::timerEvent(QTimerEvent *event)
  {
      if (event->timerId() == d->uploadScheduleTimer) {
          // Update the state of who's choked and who's not
          scheduleUploads();
          return;
      }

      if (event->timerId() != d->transferRateTimer) {
          QObject::timerEvent(event);
          return;
      }

      // Calculate average upload/download rate
      qint64 uploadBytesPerSecond = 0;
      qint64 downloadBytesPerSecond = 0;
      for (int i = 0; i < RateControlWindowLength; ++i) {
          uploadBytesPerSecond += d->uploadRate[i];
          downloadBytesPerSecond += d->downloadRate[i];
      }
      uploadBytesPerSecond /= qint64(RateControlWindowLength);
      downloadBytesPerSecond /= qint64(RateControlWindowLength);
      for (int i = RateControlWindowLength - 2; i >= 0; --i) {
          d->uploadRate[i + 1] = d->uploadRate[i];
          d->downloadRate[i + 1] = d->downloadRate[i];
      }
      d->uploadRate[0] = 0;
      d->downloadRate[0] = 0;
      emit uploadRateUpdated(int(uploadBytesPerSecond));
      emit downloadRateUpdated(int(downloadBytesPerSecond));

      // Stop the timer if there is no activity.
      if (downloadBytesPerSecond == 0 && uploadBytesPerSecond == 0) {
          killTimer(d->transferRateTimer);
          d->transferRateTimer = 0;
      }
  }

  void TorrentClient::sendToPeer(int readId, int pieceIndex, int begin, const QByteArray &data)
  {
      // Send the requested block to the peer if the client connection
      // still exists; otherwise do nothing. This slot is called by the
      // file manager after it has read a block of data.
      PeerWireClient *client = d->readIds.value(readId);
      if (client) {
          if ((client->peerWireState() & PeerWireClient::ChokingPeer) == 0)
              client->sendBlock(pieceIndex, begin, data);
      }
      d->readIds.remove(readId);
  }

  void TorrentClient::fullVerificationDone()
  {
      // Update our list of completed and incomplete pieces.
      d->completedPieces = d->fileManager.completedPieces();
      d->incompletePieces.resize(d->completedPieces.size());
      d->pieceCount = d->completedPieces.size();
      for (int i = 0; i < d->fileManager.pieceCount(); ++i) {
          if (!d->completedPieces.testBit(i))
              d->incompletePieces.setBit(i);
      }

      updateProgress();

      // If the checksums show that what the dumped state thought was
      // partial was in fact complete, then we trust the checksums.
      QMap<int, TorrentPiece *>::Iterator it = d->pendingPieces.begin();
      while (it != d->pendingPieces.end()) {
          if (d->completedPieces.testBit(it.key()))
              it = d->pendingPieces.erase(it);
          else
              ++it;
      }

      d->uploadScheduleTimer = startTimer(UploadScheduleInterval);

      // Start the server
      TorrentServer *server = TorrentServer::instance();
      if (!server->isListening()) {
          // Set up the peer wire server
          for (int i = ServerMinPort; i <= ServerMaxPort; ++i) {
              if (server->listen(QHostAddress::Any, i))
                  break;
          }
          if (!server->isListening()) {
              d->setError(ServerError);
              return;
          }
      }

      d->setState(d->completedPieces.count(true) == d->pieceCount ? Seeding : Searching);

      // Start the tracker client
      d->trackerClient.start(d->metaInfo);
  }

  void TorrentClient::pieceVerified(int pieceIndex, bool ok)
  {
      TorrentPiece *piece = d->pendingPieces.value(pieceIndex);

      // Remove this piece from all payloads
      QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.begin();
      while (it != d->payloads.end()) {
          if (it.value()->index == pieceIndex)
              it = d->payloads.erase(it);
          else
              ++it;
      }

      if (!ok) {
          // If a piece did not pass the SHA1 check, we'll simply clear
          // its state, and the scheduler will re-request it
          piece->inProgress = false;
          piece->completedBlocks.fill(false);
          piece->requestedBlocks.fill(false);
          d->callScheduler();
          return;
      }

      // Update the peer list so we know who's still interesting.
      foreach (TorrentPeer *peer, d->peers) {
          if (!peer->interesting)
              continue;
          bool interesting = false;
          for (int i = 0; i < d->pieceCount; ++i) {
              if (peer->pieces.testBit(i) && d->incompletePieces.testBit(i)) {
                  interesting = true;
                  break;
              }
          }
          peer->interesting = interesting;
      }

      // Delete the piece and update our structures.
      delete piece;
      d->pendingPieces.remove(pieceIndex);
      d->completedPieces.setBit(pieceIndex);
      d->incompletePieces.clearBit(pieceIndex);

      // Notify connected peers.
      foreach (PeerWireClient *client, d->connections) {
          if (client->state() == QAbstractSocket::ConnectedState
              && !client->availablePieces().testBit(pieceIndex)) {
              client->sendPieceNotification(pieceIndex);
          }
      }

      // Notify the tracker if we've entered Seeding status; otherwise
      // call the scheduler.
      int completed = d->completedPieces.count(true);
      if (completed == d->pieceCount) {
          if (d->state != Seeding) {
              d->setState(Seeding);
              d->trackerClient.startSeeding();
          }
      } else {
          if (completed == 1)
              d->setState(Downloading);
          else if (d->incompletePieces.count(true) < 5 && d->pendingPieces.size() > d->incompletePieces.count(true))
              d->setState(Endgame);
          d->callScheduler();
      }

      updateProgress();
  }

  void TorrentClient::handleFileError()
  {
      if (d->state == Paused)
          return;
      setPaused(true);
      emit error(FileError);
  }

  void TorrentClient::connectToPeers()
  {
      d->connectingToClients = false;

      if (d->state == Stopping || d->state == Idle || d->state == Paused)
          return;

      if (d->state == Searching)
          d->setState(Connecting);

      // Find the list of peers we are not currently connected to, where
      // the more interesting peers are listed more than once.
      QList<TorrentPeer *> weighedPeers = weighedFreePeers();

      // Start as many connections as we can
      while (!weighedPeers.isEmpty() && ConnectionManager::instance()->canAddConnection()
             && (qrand() % (ConnectionManager::instance()->maxConnections() / 2))) {
          PeerWireClient *client = new PeerWireClient(ConnectionManager::instance()->clientId(), this);
          RateController::instance()->addSocket(client);
          ConnectionManager::instance()->addConnection(client);

          initializeConnection(client);
          d->connections << client;

          // Pick a random peer from the list of weighed peers.
          TorrentPeer *peer = weighedPeers.takeAt(qrand() % weighedPeers.size());
          weighedPeers.removeAll(peer);
          peer->connectStart = QDateTime::currentDateTime().toTime_t();
          peer->lastVisited = peer->connectStart;

          // Connect to the peer.
          client->setPeer(peer);
          client->connectToHost(peer->address, peer->port);
      }
  }

  QList<TorrentPeer *> TorrentClient::weighedFreePeers() const
  {
      QList<TorrentPeer *> weighedPeers;

      // Generate a list of peers that we want to connect to.
      uint now = QDateTime::currentDateTime().toTime_t();
      QList<TorrentPeer *> freePeers;
      QMap<QString, int> connectionsPerPeer;
      foreach (TorrentPeer *peer, d->peers) {
          bool busy = false;
          foreach (PeerWireClient *client, d->connections) {
              if (client->state() == PeerWireClient::ConnectedState
                  && client->peerAddress() == peer->address
                  && client->peerPort() == peer->port) {
                  if (++connectionsPerPeer[peer->address.toString()] >= MaxConnectionPerPeer) {
                      busy = true;
                      break;
                  }
              }
          }
          if (!busy && (now - peer->lastVisited) > uint(MinimumTimeBeforeRevisit))
              freePeers << peer;
      }

      // Nothing to connect to
      if (freePeers.isEmpty())
          return weighedPeers;

      // Assign points based on connection speed and pieces available.
      QList<QPair<int, TorrentPeer *> > points;
      foreach (TorrentPeer *peer, freePeers) {
          int tmp = 0;
          if (peer->interesting) {
              tmp += peer->numCompletedPieces;
              if (d->state == Seeding)
                  tmp = d->pieceCount - tmp;
              if (!peer->connectStart) // An unknown peer is as interesting as a seed
                  tmp += d->pieceCount;

              // 1/5 of the total score for each second below 5 it takes to
              // connect.
              if (peer->connectTime < 5)
                  tmp += (d->pieceCount / 10) * (5 - peer->connectTime);
          }
          points << QPair<int, TorrentPeer *>(tmp, peer);
      }
      std::sort(points.begin(), points.end());

      // Minimize the list so the point difference is never more than 1.
      typedef QPair<int,TorrentPeer*> PointPair;
      QMultiMap<int, TorrentPeer *> pointMap;
      int lowestScore = 0;
      int lastIndex = 0;
      foreach (PointPair point, points) {
          if (point.first > lowestScore) {
              lowestScore = point.first;
              ++lastIndex;
          }
          pointMap.insert(lastIndex, point.second);
      }

      // Now make up a list of peers where the ones with more points are
      // listed many times.
      QMultiMap<int, TorrentPeer *>::ConstIterator it = pointMap.constBegin();
      while (it != pointMap.constEnd()) {
          for (int i = 0; i < it.key() + 1; ++i)
              weighedPeers << it.value();
          ++it;
      }

      return weighedPeers;
  }

  void TorrentClient::setupIncomingConnection(PeerWireClient *client)
  {
      // Connect signals
      initializeConnection(client);

      // Initialize this client
      RateController::instance()->addSocket(client);
      d->connections << client;

      client->initialize(d->infoHash, d->pieceCount);
      client->sendPieceList(d->completedPieces);

      emit peerInfoUpdated();

      if (d->state == Searching || d->state == Connecting) {
          int completed = d->completedPieces.count(true);
          if (completed == 0)
              d->setState(WarmingUp);
          else if (d->incompletePieces.count(true) < 5 && d->pendingPieces.size() > d->incompletePieces.count(true))
              d->setState(Endgame);
      }

      if (d->connections.isEmpty())
          scheduleUploads();
  }

  void TorrentClient::setupOutgoingConnection()
  {
      PeerWireClient *client = qobject_cast<PeerWireClient *>(sender());

      // Update connection statistics.
      foreach (TorrentPeer *peer, d->peers) {
          if (peer->port == client->peerPort() && peer->address == client->peerAddress()) {
              peer->connectTime = peer->lastVisited - peer->connectStart;
              break;
          }
      }

      // Send handshake and piece list
      client->initialize(d->infoHash, d->pieceCount);
      client->sendPieceList(d->completedPieces);

      emit peerInfoUpdated();

      if (d->state == Searching || d->state == Connecting) {
          int completed = d->completedPieces.count(true);
          if (completed == 0)
              d->setState(WarmingUp);
          else if (d->incompletePieces.count(true) < 5 && d->pendingPieces.size() > d->incompletePieces.count(true))
              d->setState(Endgame);
      }
  }

  void TorrentClient::initializeConnection(PeerWireClient *client)
  {
      connect(client, SIGNAL(connected()),
              this, SLOT(setupOutgoingConnection()));
      connect(client, SIGNAL(disconnected()),
              this, SLOT(removeClient()));
      connect(client, SIGNAL(error(QAbstractSocket::SocketError)),
              this, SLOT(removeClient()));
      connect(client, SIGNAL(piecesAvailable(QBitArray)),
              this, SLOT(peerPiecesAvailable(QBitArray)));
      connect(client, SIGNAL(blockRequested(int,int,int)),
              this, SLOT(peerRequestsBlock(int,int,int)));
      connect(client, SIGNAL(blockReceived(int,int,QByteArray)),
              this, SLOT(blockReceived(int,int,QByteArray)));
      connect(client, SIGNAL(choked()),
              this, SLOT(peerChoked()));
      connect(client, SIGNAL(unchoked()),
              this, SLOT(peerUnchoked()));
      connect(client, SIGNAL(bytesWritten(qint64)),
              this, SLOT(peerWireBytesWritten(qint64)));
      connect(client, SIGNAL(bytesReceived(qint64)),
              this, SLOT(peerWireBytesReceived(qint64)));
  }

  void TorrentClient::removeClient()
  {
      PeerWireClient *client = static_cast<PeerWireClient *>(sender());

      // Remove the host from our list of known peers if the connection
      // failed.
      if (client->peer() && client->error() == QAbstractSocket::ConnectionRefusedError)
          d->peers.removeAll(client->peer());

      // Remove the client from RateController and all structures.
      RateController::instance()->removeSocket(client);
      d->connections.removeAll(client);
      QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.find(client);
      while (it != d->payloads.end() && it.key() == client) {
          TorrentPiece *piece = it.value();
          piece->inProgress = false;
          piece->requestedBlocks.fill(false);
          it = d->payloads.erase(it);
      }

      // Remove pending read requests.
      QMapIterator<int, PeerWireClient *> it2(d->readIds);
      while (it2.findNext(client))
          d->readIds.remove(it2.key());

      // Delete the client later.
      disconnect(client, SIGNAL(disconnected()), this, SLOT(removeClient()));
      client->deleteLater();
      ConnectionManager::instance()->removeConnection(client);

      emit peerInfoUpdated();
      d->callPeerConnector();
  }

  void TorrentClient::peerPiecesAvailable(const QBitArray &pieces)
  {
      PeerWireClient *client = qobject_cast<PeerWireClient *>(sender());

      // Find the peer in our list of announced peers. If it's there,
      // then we can use the piece list into to gather statistics that
      // help us decide what peers to connect to.
      TorrentPeer *peer = 0;
      QList<TorrentPeer *>::Iterator it = d->peers.begin();
      while (it != d->peers.end()) {
          if ((*it)->address == client->peerAddress() && (*it)->port == client->peerPort()) {
              peer = *it;
              break;
          }
          ++it;
      }

      // If the peer is a seed, and we are in seeding mode, then the
      // peer is uninteresting.
      if (pieces.count(true) == d->pieceCount) {
          if (peer)
              peer->seed = true;
          emit peerInfoUpdated();
          if (d->state == Seeding) {
              client->abort();
              return;
          } else {
              if (peer)
                  peer->interesting = true;
              if ((client->peerWireState() & PeerWireClient::InterestedInPeer) == 0)
                  client->sendInterested();
              d->callScheduler();
              return;
          }
      }

      // Update our list of available pieces.
      if (peer) {
          peer->pieces = pieces;
          peer->numCompletedPieces = pieces.count(true);
      }

      // Check for interesting pieces, and tell the peer whether we are
      // interested or not.
      bool interested = false;
      int piecesSize = pieces.size();
      for (int pieceIndex = 0; pieceIndex < piecesSize; ++pieceIndex) {
          if (!pieces.testBit(pieceIndex))
              continue;
          if (!d->completedPieces.testBit(pieceIndex)) {
              interested = true;
              if ((client->peerWireState() & PeerWireClient::InterestedInPeer) == 0) {
                  if (peer)
                      peer->interesting = true;
                  client->sendInterested();
              }

              QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.find(client);
              int inProgress = 0;
              while (it != d->payloads.end() && it.key() == client) {
                  if (it.value()->inProgress)
                      inProgress += it.value()->requestedBlocks.count(true);
                  ++it;
              }
              if (!inProgress)
                  d->callScheduler();
              break;
          }
      }
      if (!interested && (client->peerWireState() & PeerWireClient::InterestedInPeer)) {
          if (peer)
              peer->interesting = false;
          client->sendNotInterested();
      }
  }

  void TorrentClient::peerRequestsBlock(int pieceIndex, int begin, int length)
  {
      PeerWireClient *client = qobject_cast<PeerWireClient *>(sender());

      // Silently ignore requests from choked peers
      if (client->peerWireState() & PeerWireClient::ChokingPeer)
          return;

      // Silently ignore requests for pieces we don't have.
      if (!d->completedPieces.testBit(pieceIndex))
          return;

      // Request the block from the file manager
      d->readIds.insert(d->fileManager.read(pieceIndex, begin, length),
                        qobject_cast<PeerWireClient *>(sender()));
  }

  void TorrentClient::blockReceived(int pieceIndex, int begin, const QByteArray &data)
  {
      PeerWireClient *client = qobject_cast<PeerWireClient *>(sender());
      if (data.size() == 0) {
          client->abort();
          return;
      }

      // Ignore it if we already have this block.
      int blockBit = begin / BlockSize;
      TorrentPiece *piece = d->pendingPieces.value(pieceIndex);
      if (!piece || piece->completedBlocks.testBit(blockBit)) {
          // Discard blocks that we already have, and fill up the pipeline.
          requestMore(client);
          return;
      }

      // If we are in warmup or endgame mode, cancel all duplicate
      // requests for this block.
      if (d->state == WarmingUp || d->state == Endgame) {
          QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.begin();
          while (it != d->payloads.end()) {
              PeerWireClient *otherClient = it.key();
              if (otherClient != client && it.value()->index == pieceIndex) {
                  if (otherClient->incomingBlocks().contains(TorrentBlock(pieceIndex, begin, data.size())))
                      it.key()->cancelRequest(pieceIndex, begin, data.size());
              }
              ++it;
          }
      }

      if (d->state != Downloading && d->state != Endgame && d->completedPieces.count(true) > 0)
          d->setState(Downloading);

      // Store this block
      d->fileManager.write(pieceIndex, begin, data);
      piece->completedBlocks.setBit(blockBit);
      piece->requestedBlocks.clearBit(blockBit);

      if (blocksLeftForPiece(piece) == 0) {
          // Ask the file manager to verify the newly downloaded piece
          d->fileManager.verifyPiece(piece->index);

          // Remove this piece from all payloads
          QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.begin();
          while (it != d->payloads.end()) {
              if (!it.value() || it.value()->index == piece->index)
                  it = d->payloads.erase(it);
              else
                  ++it;
          }
      }

      // Fill up the pipeline.
      requestMore(client);
  }

  void TorrentClient::peerWireBytesWritten(qint64 size)
  {
      if (!d->transferRateTimer)
          d->transferRateTimer = startTimer(RateControlTimerDelay);

      d->uploadRate[0] += size;
      d->uploadedBytes += size;
      emit dataSent(size);
  }

  void TorrentClient::peerWireBytesReceived(qint64 size)
  {
      if (!d->transferRateTimer)
          d->transferRateTimer = startTimer(RateControlTimerDelay);

      d->downloadRate[0] += size;
      d->downloadedBytes += size;
      emit dataSent(size);
  }

  int TorrentClient::blocksLeftForPiece(const TorrentPiece *piece) const
  {
      int blocksLeft = 0;
      int completedBlocksSize = piece->completedBlocks.size();
      for (int i = 0; i < completedBlocksSize; ++i) {
          if (!piece->completedBlocks.testBit(i))
              ++blocksLeft;
      }
      return blocksLeft;
  }

  void TorrentClient::scheduleUploads()
  {
      // Generate a list of clients sorted by their transfer
      // speeds.  When leeching, we sort by download speed, and when
      // seeding, we sort by upload speed. Seeds are left out; there's
      // no use in unchoking them.
      QList<PeerWireClient *> allClients = d->connections;
      QMultiMap<int, PeerWireClient *> transferSpeeds;
      foreach (PeerWireClient *client, allClients) {
          if (client->state() == QAbstractSocket::ConnectedState
              && client->availablePieces().count(true) != d->pieceCount) {
              if (d->state == Seeding) {
                  transferSpeeds.insert(client->uploadSpeed(), client);
              } else {
                  transferSpeeds.insert(client->downloadSpeed(), client);
              }
          }
      }

      // Unchoke the top 'MaxUploads' downloaders (peers that we are
      // uploading to) and choke all others.
      int maxUploaders = MaxUploads;
      QMapIterator<int, PeerWireClient *> it(transferSpeeds);
      it.toBack();
      while (it.hasPrevious()) {
          PeerWireClient *client = it.previous().value();
          bool interested = (client->peerWireState() & PeerWireClient::PeerIsInterested);

          if (maxUploaders) {
              allClients.removeAll(client);
              if (client->peerWireState() & PeerWireClient::ChokingPeer)
                  client->unchokePeer();
              --maxUploaders;
              continue;
          }

          if ((client->peerWireState() & PeerWireClient::ChokingPeer) == 0) {
              if ((qrand() % 10) == 0)
                  client->abort();
              else
                  client->chokePeer();
              allClients.removeAll(client);
          }
          if (!interested)
              allClients.removeAll(client);
      }

      // Only interested peers are left in allClients. Unchoke one
      // random peer to allow it to compete for a position among the
      // downloaders.  (This is known as an "optimistic unchoke".)
      if (!allClients.isEmpty()) {
          PeerWireClient *client = allClients[qrand() % allClients.size()];
          if (client->peerWireState() & PeerWireClient::ChokingPeer)
              client->unchokePeer();
      }
  }

  void TorrentClient::scheduleDownloads()
  {
      d->schedulerCalled = false;

      if (d->state == Stopping || d->state == Paused || d->state == Idle)
          return;

      // Check what each client is doing, and assign payloads to those
      // who are either idle or done.
      foreach (PeerWireClient *client, d->connections)
          schedulePieceForClient(client);
  }

  void TorrentClient::schedulePieceForClient(PeerWireClient *client)
  {
      // Only schedule connected clients.
      if (client->state() != QTcpSocket::ConnectedState)
          return;

      // The peer has choked us; try again later.
      if (client->peerWireState() & PeerWireClient::ChokedByPeer)
          return;

      // Make a list of all the client's pending pieces, and count how
      // many blocks have been requested.
      QList<int> currentPieces;
      bool somePiecesAreNotInProgress = false;
      TorrentPiece *lastPendingPiece = 0;
      QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.find(client);
      while (it != d->payloads.end() && it.key() == client) {
          lastPendingPiece = it.value();
          if (lastPendingPiece->inProgress) {
              currentPieces << lastPendingPiece->index;
          } else {
              somePiecesAreNotInProgress = true;
          }
          ++it;
      }

      // Skip clients that already have too many blocks in progress.
      if (client->incomingBlocks().size() >= ((d->state == Endgame || d->state == WarmingUp)
                                              ? MaxBlocksInMultiMode : MaxBlocksInProgress))
          return;

      // If all pieces are in progress, but we haven't filled up our
      // block requesting quota, then we need to schedule another piece.
      if (!somePiecesAreNotInProgress || client->incomingBlocks().size() > 0)
          lastPendingPiece = 0;
      TorrentPiece *piece = lastPendingPiece;

      // In warmup state, all clients request blocks from the same pieces.
      if (d->state == WarmingUp && d->pendingPieces.size() >= 4) {
          piece = d->payloads.value(client);
          if (!piece) {
              QList<TorrentPiece *> values = d->pendingPieces.values();
              piece = values.value(qrand() % values.size());
              piece->inProgress = true;
              d->payloads.insert(client, piece);
          }
          if (piece->completedBlocks.count(false) == client->incomingBlocks().size())
              return;
      }

      // If no pieces are currently in progress, schedule a new one.
      if (!piece) {
          // Build up a list of what pieces that we have not completed
          // are available to this client.
          QBitArray incompletePiecesAvailableToClient = d->incompletePieces;

          // Remove all pieces that are marked as being in progress
          // already (i.e., pieces that this or other clients are
          // already waiting for). A special rule applies to warmup and
          // endgame mode; there, we allow several clients to request
          // the same piece. In endgame mode, this only applies to
          // clients that are currently uploading (more than 1.0KB/s).
          if ((d->state == Endgame && client->uploadSpeed() < 1024) || d->state != WarmingUp) {
              QMap<int, TorrentPiece *>::ConstIterator it = d->pendingPieces.constBegin();
              while (it != d->pendingPieces.constEnd()) {
                  if (it.value()->inProgress)
                      incompletePiecesAvailableToClient.clearBit(it.key());
                  ++it;
              }
          }

          // Remove all pieces that the client cannot download.
          incompletePiecesAvailableToClient &= client->availablePieces();

          // Remove all pieces that this client has already requested.
          foreach (int i, currentPieces)
              incompletePiecesAvailableToClient.clearBit(i);

          // Only continue if more pieces can be scheduled. If no pieces
          // are available and no blocks are in progress, just leave
          // the connection idle; it might become interesting later.
          if (incompletePiecesAvailableToClient.count(true) == 0)
              return;

          // Check if any of the partially completed pieces can be
          // recovered, and if so, pick a random one of them.
          QList<TorrentPiece *> partialPieces;
          QMap<int, TorrentPiece *>::ConstIterator it = d->pendingPieces.constBegin();
          while (it != d->pendingPieces.constEnd()) {
              TorrentPiece *tmp = it.value();
              if (incompletePiecesAvailableToClient.testBit(it.key())) {
                  if (!tmp->inProgress || d->state == WarmingUp || d->state == Endgame) {
                      partialPieces << tmp;
                      break;
                  }
              }
              ++it;
          }
          if (!partialPieces.isEmpty())
              piece = partialPieces.value(qrand() % partialPieces.size());

          if (!piece) {
              // Pick a random piece 3 out of 4 times; otherwise, pick either
              // one of the most common or the least common pieces available,
              // depending on the state we're in.
              int pieceIndex = 0;
              if (d->state == WarmingUp || (qrand() & 4) == 0) {
                  int *occurrences = new int[d->pieceCount];
                  memset(occurrences, 0, d->pieceCount * sizeof(int));

                  // Count how many of each piece are available.
                  foreach (PeerWireClient *peer, d->connections) {
                      QBitArray peerPieces = peer->availablePieces();
                      int peerPiecesSize = peerPieces.size();
                      for (int i = 0; i < peerPiecesSize; ++i) {
                          if (peerPieces.testBit(i))
                              ++occurrences[i];
                      }
                  }

                  // Find the rarest or most common pieces.
                  int numOccurrences = d->state == WarmingUp ? 0 : 99999;
                  QList<int> piecesReadyForDownload;
                  for (int i = 0; i < d->pieceCount; ++i) {
                      if (d->state == WarmingUp) {
                          // Add common pieces
                          if (occurrences[i] >= numOccurrences
                              && incompletePiecesAvailableToClient.testBit(i)) {
                              if (occurrences[i] > numOccurrences)
                                  piecesReadyForDownload.clear();
                              piecesReadyForDownload.append(i);
                              numOccurrences = occurrences[i];
                          }
                      } else {
                          // Add rare pieces
                          if (occurrences[i] <= numOccurrences
                              && incompletePiecesAvailableToClient.testBit(i)) {
                              if (occurrences[i] < numOccurrences)
                                  piecesReadyForDownload.clear();
                              piecesReadyForDownload.append(i);
                              numOccurrences = occurrences[i];
                          }
                      }
                  }

                  // Select one piece randomly
                  pieceIndex = piecesReadyForDownload.at(qrand() % piecesReadyForDownload.size());
                  delete [] occurrences;
              } else {
                  // Make up a list of available piece indices, and pick
                  // a random one.
                  QList<int> values;
                  int incompletePiecesAvailableToClientSize = incompletePiecesAvailableToClient.size();
                  for (int i = 0; i < incompletePiecesAvailableToClientSize; ++i) {
                      if (incompletePiecesAvailableToClient.testBit(i))
                          values << i;
                  }
                  pieceIndex = values.at(qrand() % values.size());
              }

              // Create a new TorrentPiece and fill in all initial
              // properties.
              piece = new TorrentPiece;
              piece->index = pieceIndex;
              piece->length = d->fileManager.pieceLengthAt(pieceIndex);
              int numBlocks = piece->length / BlockSize;
              if (piece->length % BlockSize)
                  ++numBlocks;
              piece->completedBlocks.resize(numBlocks);
              piece->requestedBlocks.resize(numBlocks);
              d->pendingPieces.insert(pieceIndex, piece);
          }

          piece->inProgress = true;
          d->payloads.insert(client, piece);
      }

      // Request more blocks from all pending pieces.
      requestMore(client);
  }

  void TorrentClient::requestMore(PeerWireClient *client)
  {
      // Make a list of all pieces this client is currently waiting for,
      // and count the number of blocks in progress.
      QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.find(client);
      int numBlocksInProgress = client->incomingBlocks().size();
      QList<TorrentPiece *> piecesInProgress;
      while (it != d->payloads.end() && it.key() == client) {
          TorrentPiece *piece = it.value();
          if (piece->inProgress || (d->state == WarmingUp || d->state == Endgame))
              piecesInProgress << piece;
          ++it;
      }

      // If no pieces are in progress, call the scheduler.
      if (piecesInProgress.isEmpty() && d->incompletePieces.count(true)) {
          d->callScheduler();
          return;
      }

      // If too many pieces are in progress, there's nothing to do.
      int maxInProgress = ((d->state == Endgame || d->state == WarmingUp)
                           ? MaxBlocksInMultiMode : MaxBlocksInProgress);
      if (numBlocksInProgress == maxInProgress)
          return;

      // Starting with the first piece that we're waiting for, request
      // blocks until the quota is filled up.
      foreach (TorrentPiece *piece, piecesInProgress) {
          numBlocksInProgress += requestBlocks(client, piece, maxInProgress - numBlocksInProgress);
          if (numBlocksInProgress == maxInProgress)
              break;
      }

      // If we still didn't fill up the quota, we need to schedule more
      // pieces.
      if (numBlocksInProgress < maxInProgress && d->state != WarmingUp)
          d->callScheduler();
  }

  int TorrentClient::requestBlocks(PeerWireClient *client, TorrentPiece *piece, int maxBlocks)
  {
      // Generate the list of incomplete blocks for this piece.
      QVector<int> bits;
      int completedBlocksSize = piece->completedBlocks.size();
      for (int i = 0; i < completedBlocksSize; ++i) {
          if (!piece->completedBlocks.testBit(i) && !piece->requestedBlocks.testBit(i))
              bits << i;
      }

      // Nothing more to request.
      if (bits.size() == 0) {
          if (d->state != WarmingUp && d->state != Endgame)
              return 0;
          bits.clear();
          for (int i = 0; i < completedBlocksSize; ++i) {
              if (!piece->completedBlocks.testBit(i))
                  bits << i;
          }
      }

      if (d->state == WarmingUp || d->state == Endgame) {
          // By randomizing the list of blocks to request, we
          // significantly speed up the warmup and endgame modes, where
          // the same blocks are requested from multiple peers. The
          // speedup comes from an increased chance of receiving
          // different blocks from the different peers.
          for (int i = 0; i < bits.size(); ++i) {
              int a = qrand() % bits.size();
              int b = qrand() % bits.size();
              int tmp = bits[a];
              bits[a] = bits[b];
              bits[b] = tmp;
          }
      }

      // Request no more blocks than we've been asked to.
      int blocksToRequest = qMin(maxBlocks, bits.size());

      // Calculate the offset and size of each block, and send requests.
      for (int i = 0; i < blocksToRequest; ++i) {
          int blockSize = BlockSize;
          if ((piece->length % BlockSize) && bits.at(i) == completedBlocksSize - 1)
              blockSize = piece->length % BlockSize;
          client->requestBlock(piece->index, bits.at(i) * BlockSize, blockSize);
          piece->requestedBlocks.setBit(bits.at(i));
      }

      return blocksToRequest;
  }

  void TorrentClient::peerChoked()
  {
      PeerWireClient *client = qobject_cast<PeerWireClient *>(sender());
      if (!client)
          return;

      // When the peer chokes us, we immediately forget about all blocks
      // we've requested from it. We also remove the piece from out
      // payload, making it available to other clients.
      QMultiMap<PeerWireClient *, TorrentPiece *>::Iterator it = d->payloads.find(client);
      while (it != d->payloads.end() && it.key() == client) {
          it.value()->inProgress = false;
          it.value()->requestedBlocks.fill(false);
          it = d->payloads.erase(it);
      }
  }

  void TorrentClient::peerUnchoked()
  {
      PeerWireClient *client = qobject_cast<PeerWireClient *>(sender());
      if (!client)
          return;

      // We got unchoked, which means we can request more blocks.
      if (d->state != Seeding)
          d->callScheduler();
  }

  void TorrentClient::addToPeerList(const QList<TorrentPeer> &peerList)
  {
      // Add peers we don't already know of to our list of peers.
      QList<QHostAddress> addresses =  QNetworkInterface::allAddresses();
      foreach (TorrentPeer peer, peerList) {
          if (addresses.contains(peer.address)
              && peer.port == TorrentServer::instance()->serverPort()) {
              // Skip our own server.
              continue;
          }

          bool known = false;
          foreach (TorrentPeer *knownPeer, d->peers) {
              if (knownPeer->port == peer.port
                  && knownPeer->address == peer.address) {
                  known = true;
                  break;
              }
          }
          if (!known) {
              TorrentPeer *newPeer = new TorrentPeer;
              *newPeer = peer;
              newPeer->interesting = true;
              newPeer->seed = false;
              newPeer->lastVisited = 0;
              newPeer->connectStart = 0;
              newPeer->connectTime = 999999;
              newPeer->pieces.resize(d->pieceCount);
              newPeer->numCompletedPieces = 0;
              d->peers << newPeer;
          }
      }

      // If we've got more peers than we can connect to, we remove some
      // of the peers that have no (or low) activity.
      int maxPeers = ConnectionManager::instance()->maxConnections() * 3;
      if (d->peers.size() > maxPeers) {
          // Find what peers are currently connected & active
          QSet<TorrentPeer *> activePeers;
          foreach (TorrentPeer *peer, d->peers) {
              foreach (PeerWireClient *client, d->connections) {
                  if (client->peer() == peer && (client->downloadSpeed() + client->uploadSpeed()) > 1024)
                      activePeers << peer;
              }
          }

          // Remove inactive peers from the peer list until we're below
          // the max connections count.
          QList<int> toRemove;
          for (int i = 0; i < d->peers.size() && (d->peers.size() - toRemove.size()) > maxPeers; ++i) {
              if (!activePeers.contains(d->peers.at(i)))
                  toRemove << i;
          }
          QListIterator<int> toRemoveIterator(toRemove);
          toRemoveIterator.toBack();
          while (toRemoveIterator.hasPrevious())
              d->peers.removeAt(toRemoveIterator.previous());

          // If we still have too many peers, remove the oldest ones.
          while (d->peers.size() > maxPeers)
              d->peers.takeFirst();
      }

      if (d->state != Paused && d->state != Stopping && d->state != Idle) {
          if (d->state == Searching || d->state == WarmingUp)
              connectToPeers();
          else
              d->callPeerConnector();
      }
  }

  void TorrentClient::trackerStopped()
  {
      d->setState(Idle);
      emit stopped();
  }

  void TorrentClient::updateProgress(int progress)
  {
      if (progress == -1 && d->pieceCount > 0) {
          int newProgress = (d->completedPieces.count(true) * 100) / d->pieceCount;
          if (d->lastProgressValue != newProgress) {
              d->lastProgressValue = newProgress;
              emit progressUpdated(newProgress);
          }
      } else if (d->lastProgressValue != progress) {
          d->lastProgressValue = progress;
          emit progressUpdated(progress);
      }
  }