libtins/include/snap.h

/*
 * Copyright (c) 2012, Matias Fontanini
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following disclaimer
 *   in the documentation and/or other materials provided with the
 *   distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef TINS_SNAP_H
#define TINS_SNAP_H


#include <stdint.h>
#include "pdu.h"
#include "macros.h"
#include "endianness.h"
#include "small_uint.h"

namespace Tins {

    /**
     * \brief Class representing a SNAP frame.
     * 
     * Note that this PDU contains the 802.3 LLC structure + SNAP frame.
     * So far only unnumbered information structure is supported.
     */
    class SNAP : public PDU {
    public:
        /**
         * \brief This PDU's flag.
         */
        static const PDU::PDUType pdu_flag = PDU::SNAP;
    
        /**
         * \brief Creates an instance of SNAP
         * This constructor sets the dsap and ssap fields to 0xaa, and
         * the id field to 3.
         */
        SNAP();
        
        /**
         * \brief Constructs a SNAP object from a buffer and adds all 
         * identifiable PDUs found in the buffer as children of this one.
         * 
         * If the next PDU is not recognized, then a RawPDU is used.
         * 
         * If there is not enough size for a SNAP header in the 
         * buffer, a malformed_packet exception is thrown.
         * 
         * \param buffer The buffer from which this PDU will be constructed.
         * \param total_sz The total size of the buffer.
         */
        SNAP(const uint8_t *buffer, uint32_t total_sz);
        
        /* Setters */
        
        /**
         * \brief Setter for the control field.
         * \param new_id The new control to be set.
         */
        void control(uint8_t new_control);
        
        /**
         * \brief Setter for the org code field.
         * \param new_org The new org code to be set.
         */
        void org_code(small_uint<24> new_org);
        
        /**
         * \brief Setter for the eth type field.
         * \param new_eth The new eth type to be set.
         */
        void eth_type(uint16_t new_eth);
        
        /* Getters */
        
        /**
         * \brief Getter for the dsap field.
         * \return The dsap field.
         */
        uint8_t dsap() const { return _snap.dsap; }
        
        /**
         * \brief Getter for the ssap field.
         * \return The ssap field.
         */
        uint8_t ssap() const { return _snap.ssap; }
        
        /**
         * \brief Getter for the control field.
         * \return The control field.
         */
        uint8_t control() const { 
            #if TINS_IS_LITTLE_ENDIAN
            return (_snap.control_org) & 0xff; 
            #else
            return (_snap.control_org >> 24) & 0xff; 
            #endif
        }
        
        /**
         * \brief Getter for the org code field.
         * \return The org code field.
         */        
        small_uint<24> org_code() const { 
            #if TINS_IS_LITTLE_ENDIAN
            return Endian::be_to_host<uint32_t>(_snap.control_org & 0xffffff00);
            #else
            return _snap.control_org & 0xffffff;
            #endif
        }
        
        /**
         * \brief Getter for the eth type field.
         * \return The eth field.
         */
        uint16_t eth_type() const { return Endian::be_to_host(_snap.eth_type); } 
        
        /**
         * \brief Returns the SNAP frame's header length.
         *
         * \return The header's size.
         * \sa PDU::header_size()
         */
        uint32_t header_size() const;
        
        /**
         * \brief Getter for the PDU's type.
         * \sa PDU::pdu_type
         */
        PDUType pdu_type() const { return PDU::SNAP; }
        
        /**
         * \brief Clones this PDU.
         * 
         * \sa PDU::clone
         */
        SNAP *clone() const {
            return new SNAP(*this);
        }    
    private:
        TINS_BEGIN_PACK
        struct snaphdr {
            uint8_t dsap;
            uint8_t ssap;
            uint32_t control_org;
            uint16_t eth_type;
        } TINS_END_PACK;
        
        void write_serialization(uint8_t *buffer, uint32_t total_sz, const PDU *parent);
        
        snaphdr _snap;
    };
}

#endif // TINS_SNAP_H