packet-metadata.h

Go to the documentation of this file.

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2006,2007 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 PACKET_METADATA_H
#define PACKET_METADATA_H

#include <stdint.h>
#include <vector>
#include <limits>
#include "ns3/callback.h"
#include "ns3/assert.h"
#include "ns3/type-id.h"
#include "buffer.h"

namespace ns3 {

class Chunk;
class Buffer;
class Header;
class Trailer;

class PacketMetadata 
{
public:

  struct Item 
  {
    enum {
      PAYLOAD,
      HEADER,
      TRAILER
    } type; 

    bool isFragment;
    TypeId tid;
    uint32_t currentSize;
    uint32_t currentTrimedFromStart;
    uint32_t currentTrimedFromEnd;
    Buffer::Iterator current;
  };

  class ItemIterator 
  {
public:
    ItemIterator (const PacketMetadata *metadata, Buffer buffer);
    bool HasNext (void) const;
    Item Next (void);
private:
    const PacketMetadata *m_metadata; 
    Buffer m_buffer; 
    uint16_t m_current; 
    uint32_t m_offset; 
    bool m_hasReadTail; 
  };

  static void Enable (void);
  static void EnableChecking (void);

  inline PacketMetadata (uint64_t uid, uint32_t size);
  inline PacketMetadata (PacketMetadata const &o);
  inline PacketMetadata &operator = (PacketMetadata const& o);
  inline ~PacketMetadata ();

  void AddHeader (Header const &header, uint32_t size);
  void RemoveHeader (Header const &header, uint32_t size);

  void AddTrailer (Trailer const &trailer, uint32_t size);
  void RemoveTrailer (Trailer const &trailer, uint32_t size);

  PacketMetadata CreateFragment (uint32_t start, uint32_t end) const;

  void AddAtEnd (PacketMetadata const&o);
  void AddPaddingAtEnd (uint32_t end);
  void RemoveAtStart (uint32_t start);
  void RemoveAtEnd (uint32_t end);

  uint64_t GetUid (void) const;

  uint32_t GetSerializedSize (void) const;

  ItemIterator BeginItem (Buffer buffer) const;

  uint32_t Serialize   (uint8_t* buffer, uint32_t maxSize) const;
  uint32_t Deserialize (const uint8_t* buffer, uint32_t size);

private:
  static uint8_t* AddToRawU8 (const uint8_t& data,
                              uint8_t* start,
                              uint8_t* current,
                              uint32_t maxSize);

  static uint8_t* AddToRawU16 (const uint16_t& data,
                               uint8_t* start,
                               uint8_t* current,
                               uint32_t maxSize);

  static uint8_t* AddToRawU32 (const uint32_t& data,
                               uint8_t* start,
                               uint8_t* current,
                               uint32_t maxSize);

  static uint8_t* AddToRawU64 (const uint64_t& data,
                               uint8_t* start,
                               uint8_t* current,
                               uint32_t maxSize);

  static uint8_t* AddToRaw (const uint8_t* data,
                            uint32_t dataSize,
                            uint8_t* start,
                            uint8_t* current,
                            uint32_t maxSize);

  static uint8_t* ReadFromRawU8 (uint8_t& data,
                                 const uint8_t* start,
                                 const uint8_t* current,
                                 uint32_t maxSize);

  static uint8_t* ReadFromRawU16 (uint16_t& data,
                                  const uint8_t* start,
                                  const uint8_t* current,
                                  uint32_t maxSize);

  static uint8_t* ReadFromRawU32 (uint32_t& data,
                                  const uint8_t* start,
                                  const uint8_t* current,
                                  uint32_t maxSize);

  static uint8_t* ReadFromRawU64 (uint64_t& data,
                                  const uint8_t* start,
                                  const uint8_t* current,
                                  uint32_t maxSize);

#define PACKET_METADATA_DATA_M_DATA_SIZE 8
  
  struct Data {
    uint32_t m_count;
    uint16_t m_size;
    uint16_t m_dirtyEnd;
    uint8_t m_data[PACKET_METADATA_DATA_M_DATA_SIZE]; 
  };
  /* Note that since the next and prev fields are 16 bit integers
     and since the value 0xffff is reserved to identify the 
     fact that the end or the start of the list is reached,
     only a limited number of elements can be stored in 
     a m_data byte buffer.
   */
  struct SmallItem {
    uint16_t next;
    uint16_t prev;
    uint32_t typeUid;
    uint32_t size;
    uint16_t chunkUid;
  };

  struct ExtraItem {
    uint32_t fragmentStart;
    uint32_t fragmentEnd;
    uint64_t packetUid;
  };

  class DataFreeList : public std::vector<struct Data *>
  {
public:
    ~DataFreeList ();
  };

  friend DataFreeList::~DataFreeList ();
  friend class ItemIterator;

  PacketMetadata ();

  inline uint16_t AddSmall (const PacketMetadata::SmallItem *item);
  uint16_t AddBig (uint32_t head, uint32_t tail,
                   const PacketMetadata::SmallItem *item, 
                   const PacketMetadata::ExtraItem *extraItem);
  void ReplaceTail (PacketMetadata::SmallItem *item, 
                    PacketMetadata::ExtraItem *extraItem,
                    uint32_t available);
  inline void UpdateHead (uint16_t written);
  inline void UpdateTail (uint16_t written);

  inline uint32_t GetUleb128Size (uint32_t value) const;
  uint32_t ReadUleb128 (const uint8_t **pBuffer) const;
  inline void Append16 (uint16_t value, uint8_t *buffer);
  inline void Append32 (uint32_t value, uint8_t *buffer);
  inline void AppendValue (uint32_t value, uint8_t *buffer);
  void AppendValueExtra (uint32_t value, uint8_t *buffer);

  inline void Reserve (uint32_t n);
  void ReserveCopy (uint32_t n);

  uint32_t GetTotalSize (void) const;

  uint32_t ReadItems (uint16_t current, 
                      struct PacketMetadata::SmallItem *item,
                      struct PacketMetadata::ExtraItem *extraItem) const;
  void DoAddHeader (uint32_t uid, uint32_t size);
  bool IsStateOk (void) const;
  bool IsPointerOk (uint16_t pointer) const;
  bool IsSharedPointerOk (uint16_t pointer) const;

  static void Recycle (struct PacketMetadata::Data *data);
  static struct PacketMetadata::Data *Create (uint32_t size);
  static struct PacketMetadata::Data *Allocate (uint32_t n);
  static void Deallocate (struct PacketMetadata::Data *data);

  static DataFreeList m_freeList; 
  static bool m_enable; 
  static bool m_enableChecking; 

  static bool m_metadataSkipped;

  static uint32_t m_maxSize; 
  static uint16_t m_chunkUid; 

  struct Data *m_data; 
  /*
     head -(next)-> tail
       ^             |
        \---(prev)---|
   */
  uint16_t m_head; 
  uint16_t m_tail; 
  uint16_t m_used; 
  uint64_t m_packetUid; 
};

} // namespace ns3

namespace ns3 {

PacketMetadata::PacketMetadata (uint64_t uid, uint32_t size)
  : m_data (PacketMetadata::Create (10)),
    m_head (0xffff),
    m_tail (0xffff),
    m_used (0),
    m_packetUid (uid)
{
  memset (m_data->m_data, 0xff, 4);
  if (size > 0)
    {
      DoAddHeader (0, size);
    }
}
PacketMetadata::PacketMetadata (PacketMetadata const &o)
  : m_data (o.m_data),
    m_head (o.m_head),
    m_tail (o.m_tail),
    m_used (o.m_used),
    m_packetUid (o.m_packetUid)
{
  NS_ASSERT (m_data != 0);
  NS_ASSERT (m_data->m_count < std::numeric_limits<uint32_t>::max());
  m_data->m_count++;
}
PacketMetadata &
PacketMetadata::operator = (PacketMetadata const& o)
{
  if (m_data != o.m_data) 
    {
      // not self assignment
      NS_ASSERT (m_data != 0);
      m_data->m_count--;
      if (m_data->m_count == 0) 
        {
          PacketMetadata::Recycle (m_data);
        }
      m_data = o.m_data;
      NS_ASSERT (m_data != 0);
      m_data->m_count++;
    }
  m_head = o.m_head;
  m_tail = o.m_tail;
  m_used = o.m_used;
  m_packetUid = o.m_packetUid;
  return *this;
}
PacketMetadata::~PacketMetadata ()
{
  NS_ASSERT (m_data != 0);
  m_data->m_count--;
  if (m_data->m_count == 0) 
    {
      PacketMetadata::Recycle (m_data);
    }
}

} // namespace ns3


#endif /* PACKET_METADATA_H */