/*

 * vnc.c

 *

 * Copyright (C) 2016-22 - 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_VNC

#include "ndpi_api.h"

#include "ndpi_private.h"

static void ndpi_search_vnc_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 vnc\n");

  /* search over TCP */

  if(packet->tcp) {

    if(flow->l4.tcp.vnc_stage == 0) {

      if((packet->payload_packet_len == 12) &&

   (((memcmp(packet->payload, "RFB 003.", 7) == 0) && (packet->payload[11] == 0x0a))

    ||

    ((memcmp(packet->payload, "RFB 004.", 7) == 0) && (packet->payload[11] == 0x0a)))) {

  NDPI_LOG_DBG2(ndpi_struct, "reached vnc stage one\n");

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

  return;

      }

    } else if(flow->l4.tcp.vnc_stage == 2 - packet->packet_direction) {

      if((packet->payload_packet_len == 12) &&

   (((memcmp(packet->payload, "RFB 003.", 7) == 0) && (packet->payload[11] == 0x0a))

    ||

    ((memcmp(packet->payload, "RFB 004.", 7) == 0) && (packet->payload[11] == 0x0a)))) {    

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

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

  ndpi_set_risk(ndpi_struct, flow, NDPI_DESKTOP_OR_FILE_SHARING_SESSION, "Found VNC"); /* Remote assistance */

  return;

      }

    }

  }

  NDPI_EXCLUDE_PROTO(ndpi_struct, flow);

}

void init_vnc_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id)

{

  ndpi_set_bitmask_protocol_detection("VNC", ndpi_struct, *id,

              NDPI_PROTOCOL_VNC,

              ndpi_search_vnc_tcp,

              NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,

              SAVE_DETECTION_BITMASK_AS_UNKNOWN,

              ADD_TO_DETECTION_BITMASK);

  *id += 1;

}