/* -*-  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_TAHOE_H

#define TCP_TAHOE_H

#include "tcp-socket-base.h"

namespace ns3 {

/**

 * \ingroup socket

 * \ingroup tcp

 *

 * \brief An implementation of a stream socket using TCP.

 *

 * This class contains the Tahoe implementation of TCP. Tahoe is not officially

 * published in RFC. The reference for implementing this is based on

 * Kevin Fall and Sally Floyd, "Simulation-based Comparisons of Tahoe, Reno, and SACK TCP", CCR, 1996

 * http://inst.eecs.berkeley.edu/~ee122/fa05/projects/Project2/proj2_spec_files/sacks.pdf

 * In summary, we have slow start, congestion avoidance, and fast retransmit.

 * The implementation of these algorithms are based on W. R. Stevens's book and

 * also RFC2001.

 */

class TcpTahoe : public TcpSocketBase

{

public:

  static TypeId GetTypeId (void);

  /**

   * Create an unbound tcp socket.

   */

  TcpTahoe (void);

  TcpTahoe (const TcpTahoe& sock);

  virtual ~TcpTahoe (void);

  // From TcpSocketBase

  virtual int Connect (const Address &address);      

  virtual int Listen (void);  

protected:

  virtual uint32_t Window (void); // Return the max possible number of unacked bytes

  virtual Ptr<TcpSocketBase> Fork (void); // Call CopyObject<TcpTahoe> to clone me

  virtual void NewAck (SequenceNumber32 const& seq); // Inc cwnd and call NewAck() of parent

  virtual void DupAck (const TcpHeader& t, uint32_t count);  // Treat 3 dupack as timeout

  virtual void Retransmit (void); // Retransmit time out

  // Implementing ns3::TcpSocket -- Attribute get/set

  virtual void     SetSegSize (uint32_t size);

  virtual void     SetSSThresh (uint32_t threshold);

  virtual uint32_t GetSSThresh (void) const;

  virtual void     SetInitialCwnd (uint32_t cwnd);

  virtual uint32_t GetInitialCwnd (void) const;

private:

  void InitializeCwnd (void);            // set m_cWnd when connection starts

protected:

  TracedValue<uint32_t>  m_cWnd;         //< Congestion window

  uint32_t               m_ssThresh;     //< Slow Start Threshold

  uint32_t               m_initialCWnd;  //< Initial cWnd value

};

} // namespace ns3

#endif /* TCP_TAHOE_H */