/*

 * usenet.c

 *

 * Copyright (C) 2009-11 - ipoque GmbH

 * Copyright (C) 2011-25 - 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/>.

 * 

 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_USENET

#include "ndpi_api.h"

#include "ndpi_private.h"

static void ndpi_int_usenet_add_connection(struct ndpi_detection_module_struct

             *ndpi_struct, struct ndpi_flow_struct *flow)

{

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

}

static void ndpi_search_usenet_tcp(struct ndpi_detection_module_struct *ndpi_struct,

           struct ndpi_flow_struct *flow)

{

  struct ndpi_packet_struct *packet = &ndpi_struct->packet;

  NDPI_LOG_DBG(ndpi_struct, "search usenet\n");

  NDPI_LOG_DBG2(ndpi_struct, "STAGE IS %u\n", flow->l4.tcp.usenet_stage);

  // check for the first server replay

  /*

     200    Service available, posting allowed

     201    Service available, posting prohibited

   */

  if (flow->l4.tcp.usenet_stage == 0 && packet->payload_packet_len > 10

    && ((memcmp(packet->payload, "200 ", 4) == 0)

      || (memcmp(packet->payload, "201 ", 4) == 0))) {

    NDPI_LOG_DBG2(ndpi_struct, "found 200 or 201\n");

    flow->l4.tcp.usenet_stage = 1 + packet->packet_direction;

    NDPI_LOG_DBG2(ndpi_struct, "maybe hit\n");

    return;

  }

  /*

     [C] AUTHINFO USER fred

     [S] 381 Enter passphrase

     [C] AUTHINFO PASS flintstone

     [S] 281 Authentication accepted

   */

  // check for client username

  if (flow->l4.tcp.usenet_stage == 2 - packet->packet_direction) {

    if (packet->payload_packet_len > 20 && (memcmp(packet->payload, "AUTHINFO USER ", 14) == 0)) {

      NDPI_LOG_DBG2(ndpi_struct, "username found\n");

      flow->l4.tcp.usenet_stage = 3 + packet->packet_direction;

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

      ndpi_int_usenet_add_connection(ndpi_struct, flow);

      return;

    } else if (packet->payload_packet_len == 13 && (memcmp(packet->payload, "MODE READER\r\n", 13) == 0)) {

      NDPI_LOG_DBG2(ndpi_struct,

          "no login necessary but we are a client.\n");

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

      ndpi_int_usenet_add_connection(ndpi_struct, flow);

      return;

    }  else if (packet->payload_packet_len == 6 && (memcmp(packet->payload, "HELP\r\n", 6) == 0)) {

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

      ndpi_int_usenet_add_connection(ndpi_struct, flow);

      return;

    }

  }

  NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);

}

void init_usenet_dissector(struct ndpi_detection_module_struct *ndpi_struct)

{

  register_dissector("Usenet", ndpi_struct,

                     ndpi_search_usenet_tcp,

                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,

                     1, NDPI_PROTOCOL_USENET);

}