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/*
* telnet.c
*
* Copyright (C) 2009-2011 by ipoque GmbH
* Copyright (C) 2011-15 - 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_protocols.h"
#ifdef NDPI_PROTOCOL_TELNET
static void ndpi_int_telnet_add_connection(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
ndpi_int_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_TELNET/* , NDPI_REAL_PROTOCOL */);
}
#if !defined(WIN32)
static inline
#else
__forceinline static
#endif
u_int8_t search_iac(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
u_int16_t a;
if (packet->payload_packet_len < 3) {
return 0;
}
if (!(packet->payload[0] == 0xff
&& packet->payload[1] > 0xf9 && packet->payload[1] != 0xff && packet->payload[2] < 0x28)) {
return 0;
}
a = 3;
while (a < packet->payload_packet_len - 2) {
// commands start with a 0xff byte followed by a command byte >= 0xf0 and < 0xff
// command bytes 0xfb to 0xfe are followed by an option byte <= 0x28
if (!(packet->payload[a] != 0xff ||
(packet->payload[a] == 0xff && (packet->payload[a + 1] >= 0xf0) && (packet->payload[a + 1] <= 0xfa)) ||
(packet->payload[a] == 0xff && (packet->payload[a + 1] >= 0xfb) && (packet->payload[a + 1] != 0xff)
&& (packet->payload[a + 2] <= 0x28)))) {
return 0;
}
a++;
}
return 1;
}
/* this detection also works asymmetrically */
void ndpi_search_telnet_tcp(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
// struct ndpi_packet_struct *packet = &flow->packet;
// struct ndpi_id_struct *src=ndpi_struct->src;
// struct ndpi_id_struct *dst=ndpi_struct->dst;
NDPI_LOG(NDPI_PROTOCOL_TELNET, ndpi_struct, NDPI_LOG_DEBUG, "search telnet.\n");
if (search_iac(ndpi_struct, flow) == 1) {
if (flow->l4.tcp.telnet_stage == 2) {
NDPI_LOG(NDPI_PROTOCOL_TELNET, ndpi_struct, NDPI_LOG_DEBUG, "telnet identified.\n");
ndpi_int_telnet_add_connection(ndpi_struct, flow);
return;
}
flow->l4.tcp.telnet_stage++;
NDPI_LOG(NDPI_PROTOCOL_TELNET, ndpi_struct, NDPI_LOG_DEBUG, "telnet stage %u.\n", flow->l4.tcp.telnet_stage);
return;
}
if ((flow->packet_counter < 12 && flow->l4.tcp.telnet_stage > 0) || flow->packet_counter < 6) {
return;
} else {
NDPI_LOG(NDPI_PROTOCOL_TELNET, ndpi_struct, NDPI_LOG_DEBUG, "telnet excluded.\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_TELNET);
}
return;
}
#endif
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