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

/*

 * Copyright (c) 2013 Universita' di Firenze

 *

 * 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: Tommaso Pecorella <tommaso.pecorella@unifi.it>

 */

#ifndef IPV6_PMTU_CACHE_H

#define IPV6_PMTU_CACHE_H

#include <map>

#include "ns3/core-module.h"

#include "ns3/ipv6-address.h"

namespace ns3 {

/**

 * \ingroup ipv6

 * \brief This class implements the Path MTU cache, as defined by RFC 1981.

 *

 * The Path MTU is stored according to the destination address, and it is

 * cleared upon expiration (default validity time is 10 minutes).

 *

 * The "infinite lifetime" PMTU entry type is not implemented, since it is

 * useful only in an very limited number of cases. See the RFC for further

 * details.

 */

class Ipv6PmtuCache : public Object

{

public:

  class Entry;

  /**

   * \brief Get the type ID

   * \return type ID

   */

  static TypeId GetTypeId ();

  /**

   * \brief Constructor.

   */

  Ipv6PmtuCache ();

  /**

   * \brief Destructor.

   */

  ~Ipv6PmtuCache ();

  /**

   * \brief Dispose object.

   */

  virtual void DoDispose ();

  /**

   * \brief Gets the known Path MTU for the specific destination

   * \param dst the destination

   * \return the Path MTU (zero if unknown)

   */

  uint32_t GetPmtu (Ipv6Address dst);

  /**

   * \brief Sets the Path MTU for the specific destination

   * \param dst the destination

   * \param pmtu the Path MTU

   */

  void SetPmtu (Ipv6Address dst, uint32_t pmtu);

  /**

   * \brief Gets the Path MTU validity time

   * \return the Path MTU validity time

   */

  Time GetPmtuValidityTime () const;

  /**

   * \brief Sets the Path MTU validity time (minimum is 5 minutes)

   * \param validity the Path MTU validity time

   * \return true if the change was successful

   */

  bool SetPmtuValidityTime (Time validity);

private:

  /**

   * \brief Clears the Path MTU for the specific destination

   * \param dst the destination

   */

  void ClearPmtu (Ipv6Address dst);

  /**

   * \brief Path MTU table

   */

  std::map<Ipv6Address, uint32_t> m_pathMtu;

  typedef std::map<Ipv6Address, EventId> ::iterator pathMtuTimerIter;

  /**

   * \brief Path MTU Expiration table

   */

  std::map<Ipv6Address, EventId> m_pathMtuTimer;

  /**

   * \brief Path MTU entry validity time

   */

  Time m_validityTime;

};

}

#endif /* IPV6_PMTU_CACHE_H */