nDPI/src/lib/protocols/tinc.c

/*
 * tinc.c
 *
 * Copyright (C) 2017 - William Guglielmo <william@deselmo.com>
 * Copyright (C) 2017 - 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_api.h"

#ifdef NDPI_PROTOCOL_TINC

static void ndpi_check_tinc(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
  struct ndpi_packet_struct *packet = &flow->packet;
  const u_int8_t *packet_payload = packet->payload;
  u_int32_t payload_len = packet->payload_packet_len;
  struct ndpi_id_struct *src = flow->src;
  struct ndpi_id_struct *dst = flow->dst;
  
  if(packet->udp != NULL) {
    if(ndpi_struct->tinc_cache != NULL) {
      tinc_cache_entry_t tinc_cache_entry1 = {
        .src_address = packet->iph->saddr,
        .dst_address = packet->iph->daddr,
        .dst_port = packet->udp->dest
      };

      tinc_cache_entry_t tinc_cache_entry2 = {
        .src_address = packet->iph->daddr,
        .dst_address = packet->iph->saddr,
        .dst_port = packet->udp->source
      };

      if( cache_remove(ndpi_struct->tinc_cache, &tinc_cache_entry1, sizeof(tinc_cache_entry1)) == CACHE_NO_ERROR ||
          cache_remove(ndpi_struct->tinc_cache, &tinc_cache_entry2, sizeof(tinc_cache_entry2)) == CACHE_NO_ERROR)
      {
        cache_remove(ndpi_struct->tinc_cache, &tinc_cache_entry1, sizeof(tinc_cache_entry1));
        cache_remove(ndpi_struct->tinc_cache, &tinc_cache_entry2, sizeof(tinc_cache_entry2));

        // cache_free(ndpi_struct->tinc_cache);

        NDPI_LOG(NDPI_PROTOCOL_TINC, ndpi_struct, NDPI_LOG_DEBUG, "Found tinc udp connection\n");
        ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_TINC, NDPI_PROTOCOL_UNKNOWN);
      }
    }

    return;

  } 
  else if(packet->tcp != NULL) {

    if(payload_len == 0) {
      if(packet->tcp->syn == 1 && packet->tcp->ack == 0) {
        flow->tinc_cache_entry.src_address = packet->iph->saddr;
        flow->tinc_cache_entry.dst_address = packet->iph->daddr;
        flow->tinc_cache_entry.dst_port = packet->tcp->dest;
      }
      return;
    }

    switch(flow->tinc_state) {
      case 0:
      case 1:
        if(payload_len > 6 && memcmp(packet_payload, "0 ", 2) == 0 && packet_payload[2] != ' ') {
          u_int16_t i = 3;
          while(i < payload_len && packet_payload[i++] != ' ');
          if(i+3 == payload_len && memcmp((packet_payload+i), "17\n", 3) == 0) {
            flow->tinc_state++;
            return;
          }
        }
        break;

      case 2:
      case 3:
        if(payload_len > 11 && memcmp(packet_payload, "1 ", 2) == 0 && packet_payload[2] != ' ') {
          u_int16_t i = 3;
          u_int8_t numbers_left = 4;
          while(numbers_left) {
            while(packet_payload[i] >= '0' && packet_payload[i] <= '9') {
              i++;
            }

            if(packet_payload[i++] == ' ') {
              numbers_left--;
            }
            else break;
          }
          
          if(numbers_left) break;
          
          while((packet_payload[i] >= '0' && packet_payload[i] <= '9') ||
                (packet_payload[i] >= 'A' && packet_payload[i] <= 'Z')) {
            i++;
          }
          
          if(packet_payload[i] == '\n') {
            if(++flow->tinc_state > 3) {
              if(ndpi_struct->tinc_cache == NULL) {
                ndpi_struct->tinc_cache = cache_new(TINC_CACHE_MAX_SIZE);
              }

              cache_add(ndpi_struct->tinc_cache, &(flow->tinc_cache_entry), sizeof(flow->tinc_cache_entry));

              NDPI_LOG(NDPI_PROTOCOL_TINC, ndpi_struct, NDPI_LOG_DEBUG, "Found tinc tcp connection\n");
              ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_TINC, NDPI_PROTOCOL_UNKNOWN);
            }
            return;
          }
        }
        break;
      
      default: break;
    }
  }

  NDPI_LOG(NDPI_PROTOCOL_TINC, ndpi_struct, NDPI_LOG_DEBUG, "exclude tinc.\n");
  NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_TINC);
}

void ndpi_search_tinc(struct ndpi_detection_module_struct* ndpi_struct, struct ndpi_flow_struct* flow) {
  struct ndpi_packet_struct* packet = &flow->packet;

  NDPI_LOG(NDPI_PROTOCOL_TINC, ndpi_struct, NDPI_LOG_DEBUG, "tinc detection...\n");

  if (packet->detected_protocol_stack[0] != NDPI_PROTOCOL_TINC) {
    if (packet->tcp_retransmission == 0) {
      ndpi_check_tinc(ndpi_struct, flow);
    }
  }
}

void init_tinc_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
  ndpi_set_bitmask_protocol_detection("TINC", ndpi_struct, detection_bitmask, *id,
              NDPI_PROTOCOL_TINC,
              ndpi_search_tinc,
              NDPI_SELECTION_BITMASK_PROTOCOL_TCP_OR_UDP,
              SAVE_DETECTION_BITMASK_AS_UNKNOWN,
              ADD_TO_DETECTION_BITMASK);

  *id += 1;
}

#endif