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

/*

 * Copyright (c) 2005 INRIA

 * All rights reserved.

 *

 * 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: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef IPV4_HEADER_H

#define IPV4_HEADER_H

#include "ns3/header.h"

#include "ns3/ipv4-address.h"

namespace ns3 {

/**

 * \brief Packet header for IPv4

 */

class Ipv4Header : public Header 

{

public:

  /**

   * \brief Construct a null IPv4 header

   */

  Ipv4Header ();

  /**

   * \brief Enable checksum calculation for IP (XXX currently has no effect)

   */

  static void EnableChecksums (void);

  /**

   * \param size the size of the payload in bytes

   */

  void SetPayloadSize (uint16_t size);

  /**

   * \param identification the Identification field of IPv4 packets.

   *

   * By default, set to zero.

   */

  void SetIdentification (uint16_t identification);

  /**

   * \param tos the 8 bits of Ipv4 TOS.

   */

  void SetTos (uint8_t tos);

  /**

   * This packet is not the last packet of a fragmented ipv4 packet.

   */

  void SetMoreFragments (void);

  /**

   * This packet is the last packet of a fragmented ipv4 packet.

   */

  void SetLastFragment (void);

  /**

   * Don't fragment this packet: if you need to anyway, drop it.

   */

  void SetDontFragment (void);

  /**

   * If you need to fragment this packet, you can do it.

   */

  void SetMayFragment (void);

  /**

   * \param offset the ipv4 fragment offset

   */

  void SetFragmentOffset (uint16_t offset);

  /**

   * \param ttl the ipv4 TTL

   */

  void SetTtl (uint8_t ttl);

  /**

   * \param num the ipv4 protocol field

   */

  void SetProtocol (uint8_t num);

  /**

   * \param source the source of this packet

   */

  void SetSource (Ipv4Address source);

  /**

   * \param destination the destination of this packet.

   */

  void SetDestination (Ipv4Address destination);

  /**

   * \returns the size of the payload in bytes

   */

  uint16_t GetPayloadSize (void) const;

  /**

   * \returns the identification field of this packet.

   */

  uint16_t GetIdentification (void) const;

  /**

   * \returns the TOS field of this packet.

   */

  uint8_t GetTos (void) const;

  /**

   * \returns true if this is the last fragment of a packet, false otherwise.

   */

  bool IsLastFragment (void) const;

  /**

   * \returns true if this is this packet can be fragmented.

   */  

  bool IsDontFragment (void) const;

  /**

   * \returns the offset of this fragment.

   */

  uint16_t GetFragmentOffset (void) const;

  /**

   * \returns the TTL field of this packet

   */

  uint8_t GetTtl (void) const;

  /**

   * \returns the protocol field of this packet

   */

  uint8_t GetProtocol (void) const;

  /**

   * \returns the source address of this packet

   */

  Ipv4Address GetSource (void) const;

  /**

   * \returns the destination address of this packet

   */

  Ipv4Address GetDestination (void) const;

  /**

   * \returns true if the upv4 checksum is correct, false otherwise.

   *

   * If Ipv4Header::EnableChecksums has not been called prior to

   * creating this packet, this method will always return true.

   */

  bool IsChecksumOk (void) const;

  virtual uint32_t GetSerializedSize (void) const;

  virtual void Serialize (Buffer::Iterator start) const;

  virtual uint32_t Deserialize (Buffer::Iterator start);

private:

  enum FlagsE {

    DONT_FRAGMENT = (1<<0),

    MORE_FRAGMENTS = (1<<1)

  };

  static bool m_calcChecksum;

  uint16_t m_payloadSize;

  uint16_t m_identification;

  uint32_t m_tos : 8;

  uint32_t m_ttl : 8;

  uint32_t m_protocol : 8;

  uint32_t m_flags : 3;

  uint16_t m_fragmentOffset : 13;

  Ipv4Address m_source;

  Ipv4Address m_destination;

  bool m_goodChecksum;

};

} // namespace ns3

#endif /* IPV4_HEADER_H */