/* -*- 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 UDP_HEADER_H

#define UDP_HEADER_H

#include <stdint.h>

#include <string>

#include "ns3/header.h"

#include "ns3/ipv4-address.h"

#include "ns3/ipv6-address.h"

namespace ns3 {

/**

 * \ingroup udp

 * \brief Packet header for UDP packets

 *

 * This class has fields corresponding to those in a network UDP header

 * (port numbers, payload size, checksum) as well as methods for serialization

 * to and deserialization from a byte buffer.

 */

class UdpHeader : public Header 

{

public:

  /**

   * \brief Constructor

   *

   * Creates a null header

   */

  UdpHeader ();

  ~UdpHeader ();

  /**

   * \brief Enable checksum calculation for UDP 

   */

  void EnableChecksums (void);

  /**

   * \param port the destination port for this UdpHeader

   */

  void SetDestinationPort (uint16_t port);

  /**

   * \param port The source port for this UdpHeader

   */

  void SetSourcePort (uint16_t port);

  /**

   * \return The source port for this UdpHeader

   */

  uint16_t GetSourcePort (void) const;

  /**

   * \return the destination port for this UdpHeader

   */

  uint16_t GetDestinationPort (void) const;

  /**

   * \param source the ip source to use in the underlying

   *        ip packet.

   * \param destination the ip destination to use in the

   *        underlying ip packet.

   * \param protocol the protocol number to use in the underlying

   *        ip packet.

   *

   * If you want to use udp checksums, you should call this

   * method prior to adding the header to a packet.

   */

  void InitializeChecksum (Address source, 

                           Address destination,

                           uint8_t protocol);

  /**

   * \param source the ip source to use in the underlying

   *        ip packet.

   * \param destination the ip destination to use in the

   *        underlying ip packet.

   * \param protocol the protocol number to use in the underlying

   *        ip packet.

   *

   * If you want to use udp checksums, you should call this

   * method prior to adding the header to a packet.

   */

  void InitializeChecksum (Ipv4Address source, 

                           Ipv4Address destination,

                           uint8_t protocol);

  /**

   * \param source the ip source to use in the underlying

   *        ip packet.

   * \param destination the ip destination to use in the

   *        underlying ip packet.

   * \param protocol the protocol number to use in the underlying

   *        ip packet.

   *

   * If you want to use udp checksums, you should call this

   * method prior to adding the header to a packet.

   */

  void InitializeChecksum (Ipv6Address source, 

                           Ipv6Address destination,

                           uint8_t protocol);

  /**

   * \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);

  /**

   * \brief Is the UDP checksum correct ?

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

   */

  bool IsChecksumOk (void) const;

  /**

   * \brief Force the UDP checksum to a given value.

   *

   * This might be useful for test purposes or to

   * restore the UDP checksum when the UDP header

   * has been compressed (e.g., in 6LoWPAN).

   * Note that, normally, the header checksum is

   * calculated on the fly when the packet is

   * serialized.

   *

   * When this option is used, the UDP checksum is written in

   * the header, regardless of the global ChecksumEnabled option.

   *

   * \note The checksum value must be a big endian number.

   *

   * \param checksum the checksum to use (big endian).

   */

  void ForceChecksum (uint16_t checksum);

  /**

   * \brief Force the UDP payload length to a given value.

   *

   * This might be useful when forging a packet for test

   * purposes.

   *

   * \param payloadSize the payload length to use.

   */

  void ForcePayloadSize (uint16_t payloadSize);

  /**

   * \brief Return the checksum (only known after a Deserialize)

   * \return The checksum for this UdpHeader

   */

  uint16_t GetChecksum ();

private:

  /**

   * \brief Calculate the header checksum

   * \param size packet size

   * \returns the checksum

   */

  uint16_t CalculateHeaderChecksum (uint16_t size) const;

  uint16_t m_sourcePort;      //!< Source port

  uint16_t m_destinationPort; //!< Destination port

  uint16_t m_payloadSize;     //!< Payload size

  Address m_source;           //!< Source IP address

  Address m_destination;      //!< Destination IP address

  uint8_t m_protocol;         //!< Protocol number

  uint16_t m_checksum;        //!< Forced Checksum value

  bool m_calcChecksum;        //!< Flag to calculate checksum

  bool m_goodChecksum;        //!< Flag to indicate that checksum is correct

};

} // namespace ns3

#endif /* UDP_HEADER */