/*

 * trdp.c

 *

 * Train Real Time Data Protocol (IEC61375-2-3)

 * 

 * Copyright (C) 2024 - ntop.org

 * Copyright (C) 2024 - 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_TRDP

#include "ndpi_api.h"

#include "ndpi_private.h"

#define TRDP_MD_HDR_LEN 116

#define TRDP_PD_HDR_LEN 40

static void ndpi_int_trdp_add_connection(struct ndpi_detection_module_struct *ndpi_struct,

                                         struct ndpi_flow_struct *flow)

{

  NDPI_LOG_INFO(ndpi_struct, "found TRDP\n");

  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_TRDP, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);

}

static void ndpi_search_trdp(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 TRDP\n");

  if (packet->payload_packet_len >= TRDP_PD_HDR_LEN)

  {

    u_int32_t header_fcs = 0;

    u_int32_t dataset_len = 0;

    if (!packet->tcp && packet->payload[6] == 'P') { /* Process Data */

      dataset_len = ntohl(get_u_int32_t(packet->payload, 20));

      if ((u_int32_t)(packet->payload_packet_len-TRDP_PD_HDR_LEN) == dataset_len &&

          get_u_int32_t(packet->payload, 24) == 0) /* Reserved, must be zero */

      {

        header_fcs = ndpi_crc32(packet->payload, TRDP_PD_HDR_LEN-4, 0);

        if (header_fcs == le32toh(get_u_int32_t(packet->payload, TRDP_PD_HDR_LEN-4))) {

          ndpi_int_trdp_add_connection(ndpi_struct, flow);

          return;

        }

      }

    }

    if (packet->payload_packet_len >= TRDP_MD_HDR_LEN && packet->payload[6] == 'M') { /* Message Data */

      dataset_len = ntohl(get_u_int32_t(packet->payload, 20));

      u_int32_t padding = (4 - (dataset_len % 4)) % 4;

      if ((u_int32_t)(packet->payload_packet_len - TRDP_MD_HDR_LEN - padding) == dataset_len)

      {

        header_fcs = ndpi_crc32(packet->payload, TRDP_MD_HDR_LEN-4, 0);

        if (header_fcs == le32toh(get_u_int32_t(packet->payload, TRDP_MD_HDR_LEN-4))) {

          ndpi_int_trdp_add_connection(ndpi_struct, flow);

          return;

        }

      }

    }

  }

  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

}

void init_trdp_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  register_dissector("TRDP", ndpi_struct,

                     ndpi_search_trdp,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,

                     1, NDPI_PROTOCOL_TRDP);

}