asn1.h

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#ifndef EVE_ASN1_H_INCLUDED
#define EVE_ASN1_H_INCLUDED

/**********************************************************************/
/*
 * Copyright (c) 2014-2015, Jetro AS
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONRIBUTORS ``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 AUTHOR 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.
 *
 * This file is part of the EVE platform.
 */

 /**
 * \file
 * \brief Header file for the EVE ASN.1 decoder
 *
 * \author DT, Jetro AS
 */ /******************************************************************/

/**
 * \defgroup asn1 ASN.1 decoder
 * \ingroup security
 * \{
 *
 * EVE ASN.1 decoder
 */

/**********************************************************************/
/** Search for a SEQUENCE in ASN.1 data */
#define ASN1_SEQUENCE  (0x30)

/**********************************************************************/
/** Search for a INTEGER in the ASN.1 data */
#define ASN1_INTEGER   (0x02)

/**********************************************************************/
/** Encodes length of the integer */
#define ASN1_LENGTH(x) ((uint8_t)((x) >> 0)), ((uint8_t)((x) >> 8)), ((uint8_t)((x) >> 16)), ((uint8_t)((x) >> 24))

/**********************************************************************/
/** ASN.1 decoder return codes */
enum asn1_rc_t {
  ASN1_STATE_IDLE,                      /**< Processing of the ASN.1 data was not finished yet */
  ASN1_STATE_RDY,                       /**< Processing of the ASN.1 data was finished according to template */
  ASN1_STATE_ERROR,                     /**< The ASN.1 data or template is not valid */
};

/**********************************************************************/
/** ASN.1 decoder state type, used internally by the decoder */
enum asn1_state_t {
  ASN1_DECODER_STATE_TYPE,
  ASN1_DECODER_STATE_LENGTH,
  ASN1_DECODER_STATE_VALUE,
  ASN1_DECODER_STATE_TOTAL_LENGTH,
};

/**********************************************************************/
/** ASN.1 decoder state */
struct asn1_dec_state_t {
  enum asn1_state_t state;              /**< Internal decoder state */
  uint32_t tpl_off;                     /**< Current offset in the template */
  uint32_t tot_size;                    /**< Total size of the ASN.1 data block */
  uint32_t size;                        /**< Size of the current field of the ASN.1 data block */
  uint32_t acc;                         /**< Internal decoder variable */
  uint32_t result_idx;                  /**< Current offset in the result array */
  uint32_t offset;                      /**< Offset in the ASN.1 data block */
};

/**********************************************************************/
/** ASN.1 result descriptor */
struct asn1_result_t {
  void *value;                          /**< Pointer to the buffer for the variable */
  uint32_t size;                        /**< Size of the variable as obtained from the ASN.1 data block */
};

/**********************************************************************/
/**
 * Initializes the ASN.1 decoder structure.
 *
 * \param s pointer to the ASN.1 decoder structure
 */
void asn1_dec_init(struct asn1_dec_state_t *s);

/**********************************************************************/
/**
 * Feeds the encoder with a single character.
 *
 * \param s pointer to the base64 encoder structure
 * \param tplt parsing template, zero-terminated string of ASN1_XXX macroes
 * \param result parsing result desctiptors, an array of asn1_result_t elements
 * \param ch the character to be fed to the encoder
 * \return ASN1_STATE_ERROR when the character was not accepted
 * \return ASN1_STATE_IDLE whan the character was accepted, but the processing was not finished
 * \return ASN1_STATE_RDY whan the character was accepted and result is available in the result array
 */
enum asn1_rc_t asn1_dec(
    struct asn1_dec_state_t *s,
    const uint8_t *tplt,
    struct asn1_result_t *result,
    uint8_t ch);

/** @} */ /* asn1 */

#endif /* EVE_ASN1_H_INCLUDED */