BaseInflator.h

/*
 * This program 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 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 Library 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * BaseInflator.h
 * Provides the base class for inflating PDU blocks.
 * Copyright (C) 2007 Simon Newton
 *
 * The BaseInflator takes care of most of the heavy lifting when inflating PDU
 * blocks. To create a specific Inflator, subclass BaseInflator and implement
 * the Id() and DecodeHeader() methods.
 */

#ifndef LIBS_ACN_BASEINFLATOR_H_
#define LIBS_ACN_BASEINFLATOR_H_

#include <stdint.h>
#include <map>
#include "libs/acn/HeaderSet.h"
#include "libs/acn/PDU.h"

namespace ola {
namespace acn {

class BaseInflatorTest;


class InflatorInterface {
 public:
    virtual ~InflatorInterface() {}

    /*
     * Return the id for this inflator
     */
    virtual uint32_t Id() const = 0;

    /*
     * Parse a block of PDU data
     */
    virtual unsigned int InflatePDUBlock(HeaderSet *headers,
                                         const uint8_t *data,
                                         unsigned int len) = 0;
};


/*
 * An abstract PDU inflator
 */
class BaseInflator : public InflatorInterface {
  friend class BaseInflatorTest;

 public:
    explicit BaseInflator(PDU::vector_size v_size = PDU::FOUR_BYTES);
    virtual ~BaseInflator() {}

    /*
     * Add another inflator as a handler. Ownership is not transferred.
     */
    bool AddInflator(InflatorInterface *inflator);

    /*
     * Return the inflator used for a particular vector.
     */
    class InflatorInterface *GetInflator(uint32_t vector) const;

    /*
     * Parse a block of PDU data
     */
    virtual unsigned int InflatePDUBlock(HeaderSet *headers,
                                         const uint8_t *data,
                                         unsigned int len);

    // masks for the flag fields
    // This indicates a 20 bit length field (default is 12 bits)
    static const uint8_t LFLAG_MASK = 0x80;
    // This masks the first 4 bits of the length field
    static const uint8_t LENGTH_MASK = 0x0F;

 protected:
    uint32_t m_last_vector;
    bool m_vector_set;
    PDU::vector_size m_vector_size;  // size of the vector field
    // map protos to inflators
    std::map<uint32_t, InflatorInterface*> m_proto_map;

    // Reset repeated pdu fields
    virtual void ResetPDUFields();
    virtual void ResetHeaderField() = 0;

    // determine the length of a pdu
    bool DecodeLength(const uint8_t *data,
                      unsigned int data_length,
                      unsigned int *pdu_length,
                      unsigned int *bytes_used) const;

    // determine the vector of a pdu
    bool DecodeVector(uint8_t flags,
                      const uint8_t *data,
                      unsigned int length,
                      uint32_t *vector,
                      unsigned int *bytes_used);

    // Decode a header block and adds any PduHeaders to the HeaderSet object
    virtual bool DecodeHeader(HeaderSet *headers,
                              const uint8_t *data,
                              unsigned int len,
                              unsigned int *bytes_used) = 0;

    // parse the body of a pdu
    bool InflatePDU(HeaderSet *headers,
                    uint8_t flags,
                    const uint8_t *data,
                    unsigned int pdu_len);

    // called after the header is parsed
    virtual bool PostHeader(uint32_t vector, const HeaderSet &headers);

    // called in the absence of an inflator to handle the pdu data
    virtual bool HandlePDUData(uint32_t vector,
                               const HeaderSet &headers,
                               const uint8_t *data,
                               unsigned int pdu_len);
};
}  // namespace acn
}  // namespace ola
#endif  // LIBS_ACN_BASEINFLATOR_H_