/*
 * ciscovpn.c
 *
 * Copyright (C) 2013-22 - 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/>.
 *
 * Dissector developed by Remy Mudingay <mudingay@ill.fr>
 *
 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_CISCOVPN

#include "ndpi_api.h"

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

static void ndpi_int_ciscovpn_add_connection(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
  ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_CISCOVPN, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}

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

void ndpi_search_ciscovpn(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
  struct ndpi_packet_struct *packet = &ndpi_struct->packet;
  u_int16_t udport = 0, usport = 0;
  u_int16_t tdport = 0, tsport = 0;


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

  if(packet->tcp != NULL) {
    tsport = ntohs(packet->tcp->source), tdport = ntohs(packet->tcp->dest);
    NDPI_LOG_DBG2(ndpi_struct, "calculated CISCOVPN over tcp ports\n");
  }

  if(packet->udp != NULL) {
    usport = ntohs(packet->udp->source), udport = ntohs(packet->udp->dest);
    NDPI_LOG_DBG2(ndpi_struct, "calculated CISCOVPN over udp ports\n");
  }

  if((tdport == 10000 && tsport == 10000) ||
     ((tsport == 443 || tdport == 443) &&
      (packet->payload_packet_len >= 4) &&
      (packet->payload[0] == 0x17 /* TLS Application Data */ &&
       packet->payload[1] == 0x01 &&
       packet->payload[2] == 0x00 &&
       packet->payload[3] == 0x00)
      )
     ) {
    /* This is a good query  17010000*/
    NDPI_LOG_INFO(ndpi_struct, "found CISCOVPN\n");
    ndpi_int_ciscovpn_add_connection(ndpi_struct, flow);
    return;
  }
#if 0
  /* Code disabled as it is too generic and it can lead to false positives */
  else if(((tsport == 443 || tdport == 443) ||
	   (tsport == 80 || tdport == 80)) &&
          (packet->payload_packet_len >= 5) &&
          ((packet->payload[0] == 0x17 /* TLS Application Data */ &&
	    packet->payload[1] == 0x03 && packet->payload[2] == 0x03 && /* TLS 1.2 */
	    packet->payload[3] == 0x00 && packet->payload[4] == 0x3A /* Length */)))
    {
      /* TLS signature of Cisco AnyConnect 0X170303003A */
      NDPI_LOG_INFO(ndpi_struct, "found CISCO Anyconnect VPN\n");
      ndpi_int_ciscovpn_add_connection(ndpi_struct, flow);
      return;
    }
#endif
  else if(((tsport == 8009 || tdport == 8009) ||
	   (tsport == 8008 || tdport == 8008)) &&
          (packet->payload_packet_len >= 5) &&
          ((packet->payload[0] == 0x17 /* TLS Application Data */ &&
	    packet->payload[1] == 0x03 && packet->payload[2] == 0x03 && /* TLS 1.2 */
	    packet->payload[3] == 0x00 && packet->payload[4] == 0x69 /* Length */)))
    {
      /* TCP signature of Cisco AnyConnect 0X1703030069 */
      NDPI_LOG_INFO(ndpi_struct, "found CISCO Anyconnect VPN\n");
      ndpi_int_ciscovpn_add_connection(ndpi_struct, flow);
      return;
    }
  else if(
	  (
	   (usport == 10000 && udport == 10000)
	   &&
	   (packet->payload_packet_len >= 4) &&
	   (packet->payload[0] == 0xfe &&
	    packet->payload[1] == 0x57 &&
	    packet->payload[2] == 0x7e &&
	    packet->payload[3] == 0x2b)
	   )
	  )
    {
      /* This is a good query  fe577e2b */
      NDPI_LOG_INFO(ndpi_struct, "found CISCOVPN\n");
      ndpi_int_ciscovpn_add_connection(ndpi_struct, flow);
    } else if(
	      (
	       (usport == 443 || udport == 443)
	       &&
	       (packet->payload_packet_len >= 5) &&
	       (packet->payload[0] == 0x17 /* TLS Application Data */ &&
		packet->payload[1] == 0x01 &&
		packet->payload[2] == 0x00 &&
		packet->payload[3] == 0x00 &&
		packet->payload[4] == 0x01)
	       )
	      )
    {
      NDPI_LOG_INFO(ndpi_struct, "found CISCOVPN\n");
      ndpi_int_ciscovpn_add_connection(ndpi_struct, flow);
      return;
    } 

  if(flow->num_processed_pkts > 5)
    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}


void init_ciscovpn_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
  ndpi_set_bitmask_protocol_detection("CiscoVPN", ndpi_struct, detection_bitmask, *id,
				      NDPI_PROTOCOL_CISCOVPN,
				      ndpi_search_ciscovpn,
				      NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD,
				      SAVE_DETECTION_BITMASK_AS_UNKNOWN,
				      ADD_TO_DETECTION_BITMASK);
  *id += 1;
}
