/*
 * bfcp.c
 *
 * Binary Floor Control Protocol
 * 
 * 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_BFCP

#include "ndpi_api.h"
#include "ndpi_private.h"

static void ndpi_search_bfcp(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 BFCP\n");

  if (packet->payload_packet_len < 12) {
    goto not_bfcp;
  }

  u_int8_t version = (packet->payload[0] >> 5) & 0x07;
  u_int8_t reserved = (packet->payload[0] & 0x03);

  /* RFC4582: 1
     RFC8855: 1 on TCP, 2 on UDP */
  if (!(version == 1 ||
        (version == 2 && flow->l4_proto == IPPROTO_UDP))) {
    goto not_bfcp;
  }
  if (reserved != 0) {
    goto not_bfcp;
  }

  u_int8_t primitive = packet->payload[1];
  if (primitive < 1 || primitive > 18) {
    goto not_bfcp;
  }

  u_int16_t length = ntohs(get_u_int16_t(packet->payload, 2));
  if (12 + length * 4 != packet->payload_packet_len) {
    goto not_bfcp;
  }

  NDPI_LOG_INFO(ndpi_struct, "found BFCP\n");
  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_BFCP,
                                               NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);

  flow->protos.bfcp.conference_id = ntohl(get_u_int32_t(packet->payload, 4));
  flow->protos.bfcp.user_id = ntohs(get_u_int16_t(packet->payload, 10));
  return;

not_bfcp:
  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
}

void init_bfcp_dissector(struct ndpi_detection_module_struct *ndpi_struct)
{
  register_dissector("BFCP", ndpi_struct,
                     ndpi_search_bfcp,
                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
                     1, NDPI_PROTOCOL_BFCP);
}