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/*
* rsh.c
*
* Copyright (C) 2022-23 - 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_RSH
#include "ndpi_api.h"
#include "ndpi_private.h"
#define RSH_DEFAULT_PORT 514
static void ndpi_int_rsh_add_connection(struct ndpi_detection_module_struct * ndpi_struct,
struct ndpi_flow_struct * flow)
{
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_UNKNOWN, NDPI_PROTOCOL_RSH,
NDPI_CONFIDENCE_DPI);
}
static void ndpi_search_rsh(struct ndpi_detection_module_struct * ndpi_struct,
struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
/* Use a port based approach for midstream detection. */
if (packet->tcp->dest == RSH_DEFAULT_PORT ||
packet->tcp->source == RSH_DEFAULT_PORT)
{
if (packet->payload[packet->payload_packet_len - 1] == '\n')
{
if (flow->packet_counter > 5)
{
ndpi_int_rsh_add_connection(ndpi_struct, flow);
flow->protos.rsh.client_username[0] = '\0';
flow->protos.rsh.server_username[0] = '\0';
flow->protos.rsh.command[0] = '\0';
}
return;
}
}
switch (flow->packet_counter)
{
case 1:
if (packet->payload_packet_len >= 2 &&
packet->payload_packet_len <= 6)
{
int i;
for (i = 0; i < packet->payload_packet_len - 1; ++i)
{
if (ndpi_isdigit(packet->payload[i]) == 0)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
}
} else {
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
return;
case 2:
if (packet->payload_packet_len < 3 ||
packet->payload[packet->payload_packet_len - 1] != '\0')
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
{
char str[64];
char const * dissected_info[] = { (char const *)packet->payload,
NULL, NULL };
size_t i;
for (i = 1; i < NDPI_ARRAY_LENGTH(dissected_info); ++i) {
dissected_info[i] = memchr(dissected_info[i - 1], '\0',
packet->payload_packet_len -
(dissected_info[i - 1] - dissected_info[0]));
if (dissected_info[i] == NULL ||
ndpi_is_printable_buffer((uint8_t const *)dissected_info[i - 1],
(dissected_info[i] - dissected_info[i - 1])) == 0)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
if (dissected_info[i] - dissected_info[0] >= packet->payload_packet_len - 1)
{
if (dissected_info[NDPI_ARRAY_LENGTH(dissected_info) - 1] == NULL)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
break;
}
dissected_info[i]++;
}
ndpi_int_rsh_add_connection(ndpi_struct, flow);
strncpy(flow->protos.rsh.client_username, dissected_info[0],
ndpi_min(NDPI_ARRAY_LENGTH(flow->protos.rsh.client_username),
(unsigned long)(dissected_info[1] - dissected_info[0])));
strncpy(flow->protos.rsh.server_username, dissected_info[1],
ndpi_min(NDPI_ARRAY_LENGTH(flow->protos.rsh.server_username),
(unsigned long)(dissected_info[2] - dissected_info[1])));
strncpy(flow->protos.rsh.command, dissected_info[2],
ndpi_min(NDPI_ARRAY_LENGTH(flow->protos.rsh.command),
(unsigned long)packet->payload_packet_len -
(unsigned long)(dissected_info[2] - dissected_info[0])));
if (snprintf(str, NDPI_ARRAY_LENGTH(str), "User '%s' executing '%s'",
flow->protos.rsh.server_username,
flow->protos.rsh.command) < 0)
str[0] = '\0';
ndpi_set_risk(flow, NDPI_CLEAR_TEXT_CREDENTIALS, str);
}
return;
default:
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
}
void init_rsh_dissector(struct ndpi_detection_module_struct * ndpi_struct,
u_int32_t * id)
{
ndpi_set_bitmask_protocol_detection("RSH", ndpi_struct, *id,
NDPI_PROTOCOL_RSH, ndpi_search_rsh,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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