/*

 * ieee-c37118.c

 *

 * IEEE C37.118 Synchrophasor Protocol

 * 

 * Copyright (C) 2023 - ntop.org

 * Copyright (C) 2023 - V.G <v.gavrilov@securitycode.ru>

 *

 * This file is part of nDPI, an open source deep packet inspection

 * library based on the OpenDPI and PACE technology by ipoque GmbH

 *

 * nDPI is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * nDPI 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with nDPI.  If not, see <http://www.gnu.org/licenses/>.

 * 

 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_IEEE_C37118

#include "ndpi_api.h"

#include "ndpi_private.h"

static void ndpi_int_ieee_c37118_add_connection(struct ndpi_detection_module_struct *ndpi_struct,

                                            struct ndpi_flow_struct *flow)

{

  NDPI_LOG_INFO(ndpi_struct, "found IEEE C37.118\n");

  ndpi_set_detected_protocol(ndpi_struct, flow,

                             NDPI_PROTOCOL_IEEE_C37118, NDPI_PROTOCOL_UNKNOWN,

                             NDPI_CONFIDENCE_DPI);

}

static void ndpi_search_ieee_c37118(struct ndpi_detection_module_struct *ndpi_struct,

                                    struct ndpi_flow_struct *flow)

{

  struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;

  NDPI_LOG_DBG(ndpi_struct, "search IEEE C37.118\n");

  /* A little bit of heuristics. Check the minimum length, 

   * version (0xAA) and frame type (0 to 5) */

  if ((packet->payload_packet_len >= 17) && (packet->payload[0] == 0xAA) &&

      ((packet->payload[1] >> 4) < 6))

  {

    u_int16_t frame_size = ntohs(get_u_int16_t(packet->payload, 2));

    u_int16_t crc = ntohs(get_u_int16_t(packet->payload, packet->payload_packet_len-2));

    if ((frame_size == packet->payload_packet_len) &&

        (crc == ndpi_crc16_ccit_false(packet->payload, packet->payload_packet_len-2)))

    {

      ndpi_int_ieee_c37118_add_connection(ndpi_struct, flow);

      return;

    }

  }

  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

}

void init_ieee_c37118_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  ndpi_register_dissector("IEEE-C37118", ndpi_struct,

                     ndpi_search_ieee_c37118,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,

                     1, NDPI_PROTOCOL_IEEE_C37118);

}