bacnet_stack/src/bacnet/bacerror.c

/**
 * @file
 * @brief BACnet error encode and decode helper functions
 * @author Steve Karg <skarg@users.sourceforge.net>
 * @date 2005
 * @copyright SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0
 */
#include <stdint.h>
/* BACnet Stack defines - first */
#include "bacnet/bacdef.h"
/* BACnet Stack API */
#include "bacnet/bacdcode.h"
#include "bacnet/bacerror.h"

/** @file bacerror.c  Encode/Decode BACnet Errors */

/**
 * @brief Encodes BACnet Error class and code values into a PDU
 *  From clause 21. FORMAL DESCRIPTION OF APPLICATION PROTOCOL DATA UNITS
 *
 *      Error ::= SEQUENCE {
 *          -- NOTE: The valid combinations of error-class and error-code
 *          -- are defined in Clause 18.
 *          error-class ENUMERATED,
 *          error-code ENUMERATED
 *      }
 *
 * @param apdu - buffer for the data to be encoded, or NULL for length
 * @param invoke_id - invokeID to be encoded
 * @param service - BACnet service to be encoded
 * @param error_class - #BACNET_ERROR_CLASS value to be encoded
 * @param error_code - #BACNET_ERROR_CODE value to be encoded
 * @return number of bytes encoded
 */
int bacerror_encode_apdu(
    uint8_t *apdu,
    uint8_t invoke_id,
    BACNET_CONFIRMED_SERVICE service,
    BACNET_ERROR_CLASS error_class,
    BACNET_ERROR_CODE error_code)
{
    /* length of the specific element of the PDU */
    int len = 0;
    /* total length of the apdu, return value */
    int apdu_len = 0;

    if (apdu) {
        apdu[0] = PDU_TYPE_ERROR;
        apdu[1] = invoke_id;
        apdu[2] = service;
    }
    len = 3;
    apdu_len = len;
    if (apdu) {
        apdu += len;
    }
    /* service parameters */
    len = encode_application_enumerated(apdu, error_class);
    apdu_len += len;
    if (apdu) {
        apdu += len;
    }
    len = encode_application_enumerated(apdu, error_code);
    apdu_len += len;

    return apdu_len;
}

#if !BACNET_SVC_SERVER
/**
 * @brief Decodes from bytes a BACnet Error service APDU
 *  From clause 21. FORMAL DESCRIPTION OF APPLICATION PROTOCOL DATA UNITS
 *
 *  Error ::= SEQUENCE {
 *      -- NOTE: The valid combinations of error-class and error-code
 *      -- are defined in Clause 18.
 *      error-class ENUMERATED,
 *      error-code ENUMERATED
 *  }
 *
 * @param apdu - buffer of data to be decoded
 * @param apdu_size - number of bytes in the buffer
 * @param error_class - decoded #BACNET_ERROR_CLASS value
 * @param error_code - decoded #BACNET_ERROR_CODE value
 *
 * @return number of bytes decoded, or #BACNET_STATUS_ERROR (-1) if malformed
 */
int bacerror_decode_error_class_and_code(
    const uint8_t *apdu,
    unsigned apdu_size,
    BACNET_ERROR_CLASS *error_class,
    BACNET_ERROR_CODE *error_code)
{
    int apdu_len = 0;
    int tag_len = 0;
    uint32_t decoded_value = 0;

    if (apdu) {
        /* error class */
        tag_len = bacnet_enumerated_application_decode(
            &apdu[apdu_len], apdu_size - apdu_len, &decoded_value);
        if (tag_len <= 0) {
            return BACNET_STATUS_ERROR;
        }
        if (error_class) {
            *error_class = (BACNET_ERROR_CLASS)decoded_value;
        }
        apdu_len += tag_len;
        /* error code */
        tag_len = bacnet_enumerated_application_decode(
            &apdu[apdu_len], apdu_size - apdu_len, &decoded_value);
        if (tag_len <= 0) {
            return BACNET_STATUS_ERROR;
        }
        if (error_code) {
            *error_code = (BACNET_ERROR_CODE)decoded_value;
        }
        apdu_len += tag_len;
    }

    return apdu_len;
}

/**
 * @brief Decodes from bytes a BACnet Error service
 * @param apdu - buffer of data to be decoded
 * @param apdu_size - number of bytes in the buffer
 * @param invoke_id - decoded invokeID
 * @param service - decoded BACnet service
 * @param error_class - decoded #BACNET_ERROR_CLASS value
 * @param error_code - decoded #BACNET_ERROR_CODE value
 *
 * @return number of bytes decoded, or #BACNET_STATUS_ERROR (-1) if malformed
 */
int bacerror_decode_service_request(
    const uint8_t *apdu,
    unsigned apdu_size,
    uint8_t *invoke_id,
    BACNET_CONFIRMED_SERVICE *service,
    BACNET_ERROR_CLASS *error_class,
    BACNET_ERROR_CODE *error_code)
{
    int apdu_len = BACNET_STATUS_ERROR;
    int len = 0;

    if (apdu && (apdu_size > 2)) {
        if (invoke_id) {
            *invoke_id = apdu[0];
        }
        if (service) {
            *service = (BACNET_CONFIRMED_SERVICE)apdu[1];
        }
        len = 2;
        apdu_len = len;
        /* decode the application class and code */
        len = bacerror_decode_error_class_and_code(
            &apdu[apdu_len], apdu_size - apdu_len, error_class, error_code);
        if (len > 0) {
            apdu_len += len;
        } else {
            apdu_len = BACNET_STATUS_ERROR;
        }
    }

    return apdu_len;
}
#endif