/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2010 Adrian Sai-wah Tam

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * 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

 *

 * Author: Adrian Sai-wah Tam <adrian.sw.tam@gmail.com>

 */

#ifndef TCP_RX_BUFFER_H

#define TCP_RX_BUFFER_H

#include <map>

#include "ns3/traced-value.h"

#include "ns3/trace-source-accessor.h"

#include "ns3/sequence-number.h"

#include "ns3/ptr.h"

#include "ns3/tcp-header.h"

namespace ns3 {

class Packet;

/**

 * \ingroup tcp

 *

 * \brief class for the reordering buffer that keeps the data from lower layer, i.e.

 *        TcpL4Protocol, sent to the application

 */

class TcpRxBuffer : public Object

{

public:

  /**

   * \brief Get the type ID.

   * \return the object TypeId

   */

  static TypeId GetTypeId (void);

  /**

   * \brief Constructor

   * \param n initial Sequence number to be received

   */

  TcpRxBuffer (uint32_t n = 0);

  virtual ~TcpRxBuffer ();

  // Accessors

  /**

   * \brief Get Next Rx Sequence number

   * \returns Next Rx Sequence number

   */

  SequenceNumber32 NextRxSequence (void) const;

  /**

   * \brief Get the lowest sequence number that this TcpRxBuffer cannot accept

   * \returns the lowest sequence number that this TcpRxBuffer cannot accept

   */

  SequenceNumber32 MaxRxSequence (void) const;

  /**

   * \brief Increment the Next Sequence number

   */

  void IncNextRxSequence (void);

  /**

   * \brief Set the Next Sequence number

   * \param s the Sequence number

   */

  void SetNextRxSequence (const SequenceNumber32& s);

  /**

   * \brief Set the FIN Sequence number (i.e., the one closing the connection)

   * \param s the Sequence number

   */

  void SetFinSequence (const SequenceNumber32& s);

  /**

   * \brief Get the Maximum buffer size

   * \returns the Maximum buffer size

   */

  uint32_t MaxBufferSize (void) const;

  /**

   * \brief Set the Maximum buffer size

   * \param s the Maximum buffer size

   */

  void SetMaxBufferSize (uint32_t s);

  /**

   * \brief Get the actual buffer occupancy

   * \returns buffer occupancy (in bytes)

   */

  uint32_t Size (void) const;

  /**

   * \brief Get the actual number of bytes available to be read

   * \returns size of available data (in bytes)

   */

  uint32_t Available () const;

  /**

   * \brief Check if the buffer did receive all the data (and the connection is closed)

   * \returns true if all data have been received

   */

  bool Finished (void);

  /**

   * Insert a packet into the buffer and update the availBytes counter to

   * reflect the number of bytes ready to send to the application. This

   * function handles overlap by triming the head of the inputted packet and

   * removing data from the buffer that overlaps the tail of the inputted

   * packet

   *

   * \param p packet

   * \param tcph packet's TCP header

   * \return True when success, false otherwise.

   */

  bool Add (Ptr<Packet> p, TcpHeader const& tcph);

  /**

   * Extract data from the head of the buffer as indicated by nextRxSeq.

   * The extracted data is going to be forwarded to the application.

   *

   * \param maxSize maximum number of bytes to extract

   * \returns a packet

   */

  Ptr<Packet> Extract (uint32_t maxSize);

public:

  /// container for data stored in the buffer

  typedef std::map<SequenceNumber32, Ptr<Packet> >::iterator BufIterator;

  TracedValue<SequenceNumber32> m_nextRxSeq; //!< Seqnum of the first missing byte in data (RCV.NXT)

  SequenceNumber32 m_finSeq;                 //!< Seqnum of the FIN packet

  bool m_gotFin;                             //!< Did I received FIN packet?

  uint32_t m_size;                           //!< Number of total data bytes in the buffer, not necessarily contiguous

  uint32_t m_maxBuffer;                      //!< Upper bound of the number of data bytes in buffer (RCV.WND)

  uint32_t m_availBytes;                     //!< Number of bytes available to read, i.e. contiguous block at head

  std::map<SequenceNumber32, Ptr<Packet> > m_data; //!< Corresponding data (may be null)

};

} //namepsace ns3

#endif /* TCP_RX_BUFFER_H */