text: /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
  /*
   * Copyright (c) 2005 INRIA
   *
   * 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 {
  /**
   * \ingroup ipv4
   *
   * \brief Packet header for IPv4
   */
  class Ipv4Header : public Header 
  {
  public:
    /**
     * \brief Construct a null IPv4 header
     */
    Ipv4Header ();
    /**
     * \brief Enable checksum calculation for this header.
     */
    void EnableChecksum (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);
  public:
    /**
     * \enum DscpType
     * \brief DiffServ codepoints
     *
     * The values correspond to the 6-bit DSCP codepoint within the 8-bit
     * DS field defined in \RFC{2474}.  ECN bits are separately set with the
     * SetEcn() method.  Codepoints are defined in
     * Assured Forwarding (AF) \RFC{2597},
     * Expedited Forwarding (EF) \RFC{2598}, and
     * Default and Class Selector (CS) \RFC{2474}.
     */
    enum DscpType
      {
        DscpDefault = 0x00,
  
        // Prefixed with "DSCP" to avoid name clash (bug 1723)
        DSCP_CS1  = 0x08, // octal 010
        DSCP_AF11 = 0x0A, // octal 012
        DSCP_AF12 = 0x0C, // octal 014
        DSCP_AF13 = 0x0E, // octal 016
  
        DSCP_CS2  = 0x10, // octal 020
        DSCP_AF21 = 0x12, // octal 022
        DSCP_AF22 = 0x14, // octal 024
        DSCP_AF23 = 0x16, // octal 026
  
        DSCP_CS3  = 0x18, // octal 030
        DSCP_AF31 = 0x1A, // octal 032
        DSCP_AF32 = 0x1C, // octal 034
        DSCP_AF33 = 0x1E, // octal 036
  
        DSCP_CS4  = 0x20, // octal 040
        DSCP_AF41 = 0x22, // octal 042
        DSCP_AF42 = 0x24, // octal 044
        DSCP_AF43 = 0x26, // octal 046
  
        DSCP_CS5  = 0x28, // octal 050
        DSCP_EF   = 0x2E, // octal 056
  
        DSCP_CS6  = 0x30, // octal 060
        DSCP_CS7  = 0x38  // octal 070
  
      };
    /**
     * \brief Set DSCP Field
     * \param dscp DSCP value
     */
    void SetDscp (DscpType dscp);
  
    /**
     * \enum EcnType
     * \brief ECN Type defined in \RFC{3168}
     */
    enum EcnType
      {
        // Prefixed with "ECN" to avoid name clash (bug 1723)
        ECN_NotECT = 0x00,
        ECN_ECT1 = 0x01,
        ECN_ECT0 = 0x02,
        ECN_CE = 0x03
      }; 
    /**
     * \brief Set ECN Field
     * \param ecn ECN Type
     */
    void SetEcn (EcnType ecn);
    /**
     * 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);
    /**
     * The offset is measured in bytes for the packet start.
     * Mind that IPv4 "fragment offset" field is 13 bits long and is measured in 8-bytes words.
     * Hence, the function does enforce that the offset is a multiple of 8.
     * \param offsetBytes the ipv4 fragment offset measured in bytes from the start.
     */
    void SetFragmentOffset (uint16_t offsetBytes);
    /**
     * \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 the DSCP field of this packet.
     */
    DscpType GetDscp (void) const;
    /**
     * \param dscp the dscp
     * \returns std::string of DSCPType
     */
    std::string DscpTypeToString (DscpType dscp) const;
    /**
     * \returns the ECN field of this packet.
     */
    EcnType GetEcn (void) const;
    /**
     * \param ecn the ECNType
     * \returns std::string of ECNType
     */
    std::string EcnTypeToString (EcnType ecn) 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 measured in bytes from the start.
     */
    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 ipv4 checksum is correct, false otherwise.
     *
     * If Ipv4Header::EnableChecksums has not been called prior to
     * deserializing this header, this method will always return true.
     */
    bool IsChecksumOk (void) const;
  
    /**
     * \brief Get the type ID.
     * \return the object TypeId
     */
    static TypeId GetTypeId (void);
    virtual TypeId GetInstanceTypeId (void) const;
    virtual void Print (std::ostream &os) const;
    virtual uint32_t GetSerializedSize (void) const;
    virtual void Serialize (Buffer::Iterator start) const;
    virtual uint32_t Deserialize (Buffer::Iterator start);
  private:
  
    /// flags related to IP fragmentation
    enum FlagsE {
      DONT_FRAGMENT = (1<<0),
      MORE_FRAGMENTS = (1<<1)
    };
  
    bool m_calcChecksum; //!< true if the checksum must be calculated
  
    uint16_t m_payloadSize; //!< payload size
    uint16_t m_identification; //!< identification
    uint32_t m_tos : 8; //!< TOS, also used as DSCP + ECN value
    uint32_t m_ttl : 8; //!< TTL
    uint32_t m_protocol : 8;  //!< Protocol
    uint32_t m_flags : 3; //!< flags
    uint16_t m_fragmentOffset;  //!< Fragment offset
    Ipv4Address m_source; //!< source address
    Ipv4Address m_destination; //!< destination address
    uint16_t m_checksum; //!< checksum
    bool m_goodChecksum; //!< true if checksum is correct
    uint16_t m_headerSize; //!< IP header size
  };
  
  } // namespace ns3
  
  
  #endif /* IPV4_HEADER_H */
  