/*

 * diameter.c

 *

 * Copyright (C) 2018 - ntop.org

 *

 * 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/>.

 *

 * Based on code of:

 * Michele Campus - <campus@ntop.org>

 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_DIAMETER

#include "ndpi_api.h"

#include "ndpi_private.h"

// Header Flags possibile values

#define DIAMETER_REQUEST   0X80

#define DIAMETER_PROXYABLE 0X40

#define DIAMETER_ERROR     0X20

#define DIAMETER_RETRASM   0X10

typedef enum {

    AC = 271,

    AS = 274,

    CC = 272,

    CE = 257,

    DW = 280,

    DP = 282,

    RA = 258,

    ST = 275

} com_type_t;

#define DIAM_HEADER_LEN 20

// DIAMETER header

struct diameter_header_t

{

  u_int8_t  version;

  u_int8_t  length[3];

  u_int8_t  flags;

  u_int8_t  com_code[3];

  u_int32_t app_id;

  u_int32_t hop_id;

  u_int32_t end_id;

};

// Check packet

static int is_diameter(struct ndpi_packet_struct *packet)

{

  struct diameter_header_t *diameter = (struct diameter_header_t *)packet->payload;

  if(packet->payload_packet_len >= sizeof(struct diameter_header_t) &&

     diameter->version == 0x01 &&

     (diameter->flags == DIAMETER_REQUEST ||

      diameter->flags == DIAMETER_PROXYABLE ||

      diameter->flags == DIAMETER_ERROR ||

      diameter->flags == DIAMETER_RETRASM)) {

    u_int32_t com_code = diameter->com_code[2] + (diameter->com_code[1] << 8) + (diameter->com_code[0] << 8);

     if(com_code == AC || com_code == AS ||

  com_code == CC || com_code == CE ||

  com_code == DW || com_code == DP ||

  com_code == RA || com_code == ST)

       return 0;

  }

  return -1;

}

static void ndpi_search_diameter(struct ndpi_detection_module_struct *ndpi_struct,

         struct ndpi_flow_struct *flow)

{

  struct ndpi_packet_struct *packet = &ndpi_struct->packet;

  if(packet->tcp) {

    int ret = is_diameter(packet);

    if(ret == 0) {

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

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

      return;

    }

  }

  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

}

void init_diameter_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  ndpi_register_dissector("Diameter", ndpi_struct,

                     ndpi_search_diameter,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,

                     1, NDPI_PROTOCOL_DIAMETER);

}