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/*
* telegram.c
*
* Copyright (C) 2012-22 - ntop.org
* Copyright (C) 2014 by Gianluca Costa xplico.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_TELEGRAM
#include "ndpi_api.h"
#include "ndpi_private.h"
static void ndpi_int_telegram_add_connection(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow,
ndpi_confidence_t confidence) {
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_TELEGRAM, NDPI_PROTOCOL_UNKNOWN, confidence);
NDPI_LOG_INFO(ndpi_struct, "found telegram\n");
}
static u_int8_t is_telegram_port_range(u_int16_t port) {
if((port >= 500) && (port <= 600))
return(1);
return(0);
}
static void ndpi_search_telegram(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 telegram\n");
if(packet->tcp != NULL) {
/* With MTProto 2.0 telegram via app is no longer TLS-based (althought based on TCP/443) so
we need to detect it with Telegram IPs.
Basically, we want a fast classification by ip. Note that, real Telegram traffic over
TLS (i.e. Telegram Web) is correctly classified as TLS/Telegram because TLS dissector
already kicked in.
Let's check every port for the time being */
if(flow->guessed_protocol_id_by_ip == NDPI_PROTOCOL_TELEGRAM) {
ndpi_int_telegram_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_MATCH_BY_IP);
return;
}
} else if(packet->udp != NULL) {
/*
The latest telegram protocol
- contains a sequence of 12 consecutive 0xFF packets
- it uses low UDP ports in the 500 range
*/
if(packet->payload_packet_len >= 40) {
u_int16_t sport = ntohs(packet->udp->source), dport = ntohs(packet->udp->dest);
if(is_telegram_port_range(sport) || is_telegram_port_range(dport)) {
u_int i, found = 0;
for(i=0; i<packet->payload_packet_len; i++) {
if(packet->payload[i] == 0xFF) {
found = 1;
break;
}
}
if(!found) return;
for(i += 1; i<packet->payload_packet_len; i++) {
if(packet->payload[i] == 0xFF)
found++;
else
break;
}
if(found == 12) {
ndpi_int_telegram_add_connection(ndpi_struct, flow, NDPI_CONFIDENCE_DPI);
/* It seems this kind of traffic is used:
* for "normal" stuff (at least years ago... and now? TODO)
* for calls, as a custom encapsulation of STUN/DTLS/RTP packets
Since we are not able to tell the former from the latter, always
switch to STUN dissection. If we find STUN/DTLS/RTP stuff we will
update the classification to something like STUN/Telegram_voip,
otherwise it will remain Telegram */
switch_extra_dissection_to_stun(ndpi_struct, flow, 0);
return;
}
}
}
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
void init_telegram_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id)
{
ndpi_set_bitmask_protocol_detection("Telegram", ndpi_struct, *id,
NDPI_PROTOCOL_TELEGRAM,
ndpi_search_telegram,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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