/*
Copyright (C) 2021 Srivats P.

This file is part of "Ostinato"

This is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
*/

#ifndef _GRE_H
#define _GRE_H

#include "abstractprotocol.h"
#include "gre.pb.h"

/*
GRE Protocol Frame Format (RFC2890)-
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |C| |K|S| Reserved0       | Ver |         Protocol Type         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Checksum (optional)      |       Reserved1 (Optional)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Key (optional)                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Sequence Number (Optional)                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figures in brackets represent field width in bits
*/

#define GRE_FLAG_CKSUM 0x8
#define GRE_FLAG_KEY   0x2
#define GRE_FLAG_SEQ   0x1

class GreProtocol : public AbstractProtocol
{
public:
    enum grefield
    {
        // Frame Fields
        gre_flags = 0,
        gre_rsvd0,
        gre_version,
        gre_protocol,
        gre_checksum,
        gre_rsvd1,
        gre_key,
        gre_sequence,

        // Meta Fields
        gre_isOverrideChecksum,

        gre_fieldCount
    };

    GreProtocol(StreamBase *stream, AbstractProtocol *parent = 0);
    virtual ~GreProtocol();

    static AbstractProtocol* createInstance(StreamBase *stream,
        AbstractProtocol *parent = 0);
    virtual quint32 protocolNumber() const;

    virtual void protoDataCopyInto(OstProto::Protocol &protocol) const;
    virtual void protoDataCopyFrom(const OstProto::Protocol &protocol);

    virtual ProtocolIdType protocolIdType() const;
    virtual quint32 protocolId(ProtocolIdType type) const;

    virtual QString name() const;
    virtual QString shortName() const;

    virtual int fieldCount() const;

    virtual AbstractProtocol::FieldFlags fieldFlags(int index) const;
    virtual QVariant fieldData(int index, FieldAttrib attrib,
               int streamIndex = 0) const;
    virtual bool setFieldData(int index, const QVariant &value,
            FieldAttrib attrib = FieldValue);

    virtual int protocolFrameSize(int streamIndex = 0) const;

private:
    OstProto::Gre    data;
};

#endif