/*

 * tplink_shp.c

 *

 * TP-LINK Smart Home Protocol

 *

 * 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_TPLINK_SHP

#include "ndpi_api.h"

#include "ndpi_private.h"

#define _TPLSHP_MIN_LEN     2

#define _TPLSHP_TCP_LEN_HDR 4

static void ndpi_int_tplink_shp_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,

                                                  struct ndpi_flow_struct * const flow)

{

  NDPI_LOG_INFO(ndpi_struct, "found TPLINK SHP\n");

  ndpi_set_detected_protocol(ndpi_struct, flow,

                             NDPI_PROTOCOL_TPLINK_SHP,

                             NDPI_PROTOCOL_UNKNOWN,

                             NDPI_CONFIDENCE_DPI);

}

/* ***************************************************** */

static void ndpi_search_tplink_shp(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 TPLINK SHP\n");

  u_int16_t offset = 0;

  /* Skip length header (TCP payloads only) */

  if(packet->tcp != NULL) offset = _TPLSHP_TCP_LEN_HDR;

  if (packet->payload_packet_len - offset < _TPLSHP_MIN_LEN)

  {

    NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

    return;

  }

  u_int16_t i;

  u_int8_t k = 171, b[_TPLSHP_MIN_LEN];

  for (i = 0 ; i < _TPLSHP_MIN_LEN; i++)

  {

    b[i] = packet->payload[i + offset] ^ k;

    k = packet->payload[i + offset];

  }

  if (b[0] != '{' || (b[1] != '}' && b[1] != '"'))

  {

    NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

    return;

  }

  ndpi_int_tplink_shp_add_connection(ndpi_struct, flow);

}

/* ***************************************************** */

void init_tplink_shp_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  register_dissector("TPLINK SHP", ndpi_struct,

                     ndpi_search_tplink_shp,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,

                     1, NDPI_PROTOCOL_TPLINK_SHP);

}