peerwireclient.h Example File

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  #ifndef PEERWIRECLIENT_H
  #define PEERWIRECLIENT_H

  #include <QBitArray>
  #include <QList>
  #include <QTcpSocket>

  class QHostAddress;
  class QTimerEvent;

  class TorrentPeer;

  struct TorrentBlock
  {
      inline TorrentBlock(int p, int o, int l)
          : pieceIndex(p), offset(o), length(l)
      {
      }
      inline bool operator==(const TorrentBlock &other) const
      {
          return pieceIndex == other.pieceIndex
                  && offset == other.offset
                  && length == other.length;
      }

      int pieceIndex;
      int offset;
      int length;
  };

  class PeerWireClient : public QTcpSocket
  {
      Q_OBJECT

  public:
      enum PeerWireStateFlag {
          ChokingPeer = 0x1,
          InterestedInPeer = 0x2,
          ChokedByPeer = 0x4,
          PeerIsInterested = 0x8
      };
      Q_DECLARE_FLAGS(PeerWireState, PeerWireStateFlag)

      explicit PeerWireClient(const QByteArray &peerId, QObject *parent = 0);
      void initialize(const QByteArray &infoHash, int pieceCount);

      void setPeer(TorrentPeer *peer);
      TorrentPeer *peer() const;

      // State
      inline PeerWireState peerWireState() const { return pwState; }
      QBitArray availablePieces() const;
      QList<TorrentBlock> incomingBlocks() const;

      // Protocol
      void chokePeer();
      void unchokePeer();
      void sendInterested();
      void sendKeepAlive();
      void sendNotInterested();
      void sendPieceNotification(int piece);
      void sendPieceList(const QBitArray &bitField);
      void requestBlock(int piece, int offset, int length);
      void cancelRequest(int piece, int offset, int length);
      void sendBlock(int piece, int offset, const QByteArray &data);

      // Rate control
      qint64 writeToSocket(qint64 bytes);
      qint64 readFromSocket(qint64 bytes);
      qint64 downloadSpeed() const;
      qint64 uploadSpeed() const;

      bool canTransferMore() const;
      qint64 bytesAvailable() const Q_DECL_OVERRIDE { return incomingBuffer.size() + QTcpSocket::bytesAvailable(); }
      qint64 socketBytesAvailable() const { return socket.bytesAvailable(); }
      qint64 socketBytesToWrite() const { return socket.bytesToWrite(); }

      void setReadBufferSize(qint64 size) Q_DECL_OVERRIDE;

      void connectToHost(const QHostAddress &address,
                         quint16 port, OpenMode openMode = ReadWrite) Q_DECL_OVERRIDE;
      void diconnectFromHost();

  signals:
      void infoHashReceived(const QByteArray &infoHash);
      void readyToTransfer();

      void choked();
      void unchoked();
      void interested();
      void notInterested();

      void piecesAvailable(const QBitArray &pieces);
      void blockRequested(int pieceIndex, int begin, int length);
      void blockReceived(int pieceIndex, int begin, const QByteArray &data);

      void bytesReceived(qint64 size);

  protected:
      void timerEvent(QTimerEvent *event) Q_DECL_OVERRIDE;

      qint64 readData(char *data, qint64 maxlen) Q_DECL_OVERRIDE;
      qint64 readLineData(char *data, qint64 maxlen) Q_DECL_OVERRIDE;
      qint64 writeData(const char *data, qint64 len) Q_DECL_OVERRIDE;

  private slots:
      void sendHandShake();
      void processIncomingData();
      void socketStateChanged(QAbstractSocket::SocketState state);

  private:
      // Data waiting to be read/written
      QByteArray incomingBuffer;
      QByteArray outgoingBuffer;

      struct BlockInfo {
          int pieceIndex;
          int offset;
          int length;
          QByteArray block;
      };
      QList<BlockInfo> pendingBlocks;
      int pendingBlockSizes;
      QList<TorrentBlock> incoming;

      enum PacketType {
          ChokePacket = 0,
          UnchokePacket = 1,
          InterestedPacket = 2,
          NotInterestedPacket = 3,
          HavePacket = 4,
          BitFieldPacket = 5,
          RequestPacket = 6,
          PiecePacket = 7,
          CancelPacket = 8
      };

      // State
      PeerWireState pwState;
      bool receivedHandShake;
      bool gotPeerId;
      bool sentHandShake;
      int nextPacketLength;

      // Upload/download speed records
      qint64 uploadSpeedData[8];
      qint64 downloadSpeedData[8];
      int transferSpeedTimer;

      // Timeout handling
      int timeoutTimer;
      int pendingRequestTimer;
      bool invalidateTimeout;
      int keepAliveTimer;

      // Checksum, peer ID and set of available pieces
      QByteArray infoHash;
      QByteArray peerIdString;
      QBitArray peerPieces;
      TorrentPeer *torrentPeer;

      QTcpSocket socket;
  };

  Q_DECLARE_OPERATORS_FOR_FLAGS(PeerWireClient::PeerWireState)

  #endif