/*

 * natpmp.c

 *

 * Copyright (C) 2022-23 - ntop.org

 *

 * 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_NATPMP

#include "ndpi_api.h"

#include "ndpi_private.h"

#define NATPMP_PORT 5351

enum natpmp_type {

  NATPMP_REQUEST_ADDRESS      = 0x00,

  NATPMP_REQUEST_UDP_MAPPING  = 0x01,

  NATPMP_REQUEST_TCP_MAPPING  = 0x02,

  NATPMP_RESPONSE_ADDRESS     = 0x80,

  NATPMP_RESPONSE_UDP_MAPPING = 0x81,

  NATPMP_RESPONSE_TCP_MAPPING = 0x82

};

static int ndpi_search_natpmp_extra(struct ndpi_detection_module_struct *ndpi_struct,

                                    struct ndpi_flow_struct *flow);

static void ndpi_int_natpmp_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,

                                           struct ndpi_flow_struct * const flow)

{

  NDPI_LOG_INFO(ndpi_struct, "found nat-pmp\n");

  ndpi_set_detected_protocol(ndpi_struct, flow,

                             NDPI_PROTOCOL_NATPMP,

                             NDPI_PROTOCOL_UNKNOWN,

                             NDPI_CONFIDENCE_DPI);

  if (flow->extra_packets_func == NULL)

  {

    flow->max_extra_packets_to_check = 5;

    flow->extra_packets_func = ndpi_search_natpmp_extra;

  }

}

static void natpmp_disable_extra_dissection(struct ndpi_flow_struct * const flow)

{

  flow->max_extra_packets_to_check = 0;

  flow->extra_packets_func = NULL;

}

static int natpmp_is_common_header(struct ndpi_packet_struct const * const packet)

{

  return packet->payload_packet_len >= 2 && packet->payload[0] == 0x00 /* Protocol version: 0x00 */;

}

static int natpmp_is_valid(struct ndpi_packet_struct const * const packet, enum natpmp_type * const natpmp_type)

{

  if (natpmp_is_common_header(packet) == 0)

  {

    return 0;

  }

  *natpmp_type = packet->payload[1];

  switch (*natpmp_type)

  {

    case NATPMP_REQUEST_ADDRESS:

      if (packet->payload_packet_len != 2)

      {

        return 0;

      }

      break;

    case NATPMP_REQUEST_UDP_MAPPING:

    case NATPMP_REQUEST_TCP_MAPPING:

      if (packet->payload_packet_len != 12 || get_u_int16_t(packet->payload, 2) != 0x0000)

      {

        return 0;

      }

      break;

    case NATPMP_RESPONSE_ADDRESS:

    case NATPMP_RESPONSE_UDP_MAPPING:

    case NATPMP_RESPONSE_TCP_MAPPING:

      if ((*natpmp_type == NATPMP_RESPONSE_ADDRESS && packet->payload_packet_len != 12) ||

          (*natpmp_type != NATPMP_RESPONSE_ADDRESS && packet->payload_packet_len != 16))

      {

        return 0;

      }

      {

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

        if (result_code > 5)

        {

          return 0;

        }

      }

      break;

    default:

      return 0;

  }

  return 1;

}

static int ndpi_search_natpmp_extra(struct ndpi_detection_module_struct *ndpi_struct,

                                    struct ndpi_flow_struct *flow)

{

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

  enum natpmp_type natpmp_type;

  if (natpmp_is_valid(packet, &natpmp_type) == 0)

  {

    ndpi_set_risk(ndpi_struct, flow, NDPI_MALFORMED_PACKET, "Invalid NATPMP Header");

    return 0;

  }

  switch (natpmp_type)

  {

    case NATPMP_REQUEST_ADDRESS:

      return 1; // Nothing to do here.

    case NATPMP_REQUEST_UDP_MAPPING:

    case NATPMP_REQUEST_TCP_MAPPING:

      flow->protos.natpmp.internal_port = ntohs(get_u_int16_t(packet->payload, 4));

      flow->protos.natpmp.external_port = ntohs(get_u_int16_t(packet->payload, 6));

      if (flow->protos.natpmp.internal_port == 0)

      {

        ndpi_set_risk(ndpi_struct, flow, NDPI_MALFORMED_PACKET, "Request Port Mapping: Internal port must not 0");

      }

      break;

    case NATPMP_RESPONSE_ADDRESS:

      flow->protos.natpmp.result_code = ntohs(get_u_int16_t(packet->payload, 2));

      flow->protos.natpmp.external_address.ipv4 = get_u_int32_t(packet->payload, 8);

      if (flow->protos.natpmp.result_code != 0 && flow->protos.natpmp.external_address.ipv4 != 0)

      {

        ndpi_set_risk(ndpi_struct, flow, NDPI_MALFORMED_PACKET, "Address Response: Result code indicates an error, but External IPv4 Address is set");

      }

      break;

    case NATPMP_RESPONSE_UDP_MAPPING:

    case NATPMP_RESPONSE_TCP_MAPPING:

    {

      flow->protos.natpmp.internal_port = ntohs(get_u_int16_t(packet->payload, 8));

      flow->protos.natpmp.external_port = ntohs(get_u_int16_t(packet->payload, 10));

      if (flow->protos.natpmp.internal_port == 0 || flow->protos.natpmp.external_port == 0)

      {

        ndpi_set_risk(ndpi_struct, flow, NDPI_MALFORMED_PACKET, "Port Mapping Response: Internal/External port must not 0");

      }

      break;

    }

  }

  return 1;

}

static void ndpi_search_natpmp(struct ndpi_detection_module_struct *ndpi_struct,

                               struct ndpi_flow_struct *flow)

{

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

  enum natpmp_type natpmp_type;

  NDPI_LOG_DBG(ndpi_struct, "search nat-pmp\n");

  if (natpmp_is_valid(packet, &natpmp_type) == 0)

  {

    NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

    return;

  }

  if ((flow->packet_counter > 2 && natpmp_type != NATPMP_REQUEST_ADDRESS) ||

      ntohs(packet->udp->source) == NATPMP_PORT || ntohs(packet->udp->dest) == NATPMP_PORT)

  {

    ndpi_int_natpmp_add_connection(ndpi_struct, flow);

    if (ndpi_search_natpmp_extra(ndpi_struct, flow) == 0)

    {

      natpmp_disable_extra_dissection(flow);

    }

  }

}

void init_natpmp_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  register_dissector("NAT-PMP", ndpi_struct,

                     ndpi_search_natpmp,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,

                     1, NDPI_PROTOCOL_NATPMP);

}