ReassemblyBuffer.h

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//
// Copyright (C) 2004-2005 Andras Varga
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program; if not, see <http://www.gnu.org/licenses/>.
//

#ifndef __INET_REASSEMBLYBUFFER_H
#define __INET_REASSEMBLYBUFFER_H

#include <map>
#include <vector>
#include "INETDefs.h"


class INET_API ReassemblyBuffer
{
  protected:
    // stores an offset range
    struct Region
    {
        ushort beg;   // first offset stored
        ushort end;   // last+1 offset stored
        bool islast;  // if this region represents the last bytes of the datagram
    };

    typedef std::vector<Region> RegionVector;

    //
    // Thinking of IP/IPv6 fragmentation, 99% of the time fragments
    // will arrive in order and none gets lost, so we have to
    // handle this case very efficiently. For this purpose
    // we'll store the offset of the first and last+1 byte we have
    // (main.beg, main.end variables), and keep extending this range
    // as new fragments arrive. If we receive non-connecting fragments,
    // put them aside into buf until new fragments come and fill the gap.
    //
    Region main;   // offset range we already have
    RegionVector *fragments;  // only used if we receive disjoint fragments

  protected:
    void merge(ushort beg, ushort end, bool islast);
    void mergeFragments();

  public:
    ReassemblyBuffer();

    ~ReassemblyBuffer();

    bool addFragment(ushort beg, ushort end, bool islast);

    ushort getTotalLength() const {return main.end;}
};

#endif