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/*
* rdp.c
*
* Copyright (C) 2009-11 - ipoque GmbH
* Copyright (C) 2011-24 - 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_RDP
#define RDP_PORT 3389
#include "ndpi_api.h"
#include "ndpi_private.h"
extern int ndpi_tls_obfuscated_heur_search_again(struct ndpi_detection_module_struct* ndpi_struct,
struct ndpi_flow_struct* flow);
/* **************************************** */
static void ndpi_int_rdp_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
NDPI_LOG_INFO(ndpi_struct, "found RDP\n");
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_RDP, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
ndpi_set_risk(ndpi_struct, flow, NDPI_DESKTOP_OR_FILE_SHARING_SESSION, "Found RDP"); /* Remote assistance */
}
/* **************************************** */
/* tls.c */
extern int ndpi_search_tls_tcp(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow);
int ndpi_search_tls_over_rdp(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
const struct ndpi_packet_struct * const packet = &ndpi_struct->packet;
if((packet->payload_packet_len > 1)
&& (packet->payload[0] == 0x16 /* This might be a TLS block */)) {
int rc = ndpi_search_tls_tcp(ndpi_struct, flow);
return(rc);
} else
return 1; /* Keep searching */
}
/* **************************************** */
static void ndpi_search_rdp(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
const struct ndpi_packet_struct * const packet = &ndpi_struct->packet;
NDPI_LOG_DBG(ndpi_struct, "search RDP\n");
if (packet->tcp != NULL) {
if(packet->payload_packet_len > 13 &&
tpkt_verify_hdr(packet) &&
/* COTP */
packet->payload[4] == packet->payload_packet_len - 5) {
if(current_pkt_from_client_to_server(ndpi_struct, flow)) {
if(packet->payload[5] == 0xE0 && /* COTP CR */
((packet->payload[11] == 0x01 && /* RDP Negotiation Request */
packet->payload[13] == 0x08 /* RDP Length */) ||
(packet->payload_packet_len > 17 &&
memcmp(&packet->payload[11], "Cookie:", 7) == 0))) /* RDP Cookie */ {
if(packet->payload_packet_len > 43) {
u_int8_t rdp_requested_proto = packet->payload[43];
/* Check if TLS support has been requested in RDP */
if((rdp_requested_proto & 0x1) == 0x1) {
/* RDP Response + Client Hello + Server hello */
flow->max_extra_packets_to_check = 5;
flow->extra_packets_func = ndpi_search_tls_over_rdp;
}
}
ndpi_int_rdp_add_connection(ndpi_struct, flow);
return;
}
} else {
/* Asymmetric detection via RDP Negotiation Response */
if(packet->payload[5] == 0xD0 && /* COTP CC */
packet->payload[11] == 0x02 && /* RDP Negotiation Response */
packet->payload[13] == 0x08 /* RDP Length */) {
ndpi_int_rdp_add_connection(ndpi_struct, flow);
return;
}
}
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
} else if(packet->udp != NULL) {
u_int16_t s_port = ntohs(packet->udp->source);
u_int16_t d_port = ntohs(packet->udp->dest);
/* Detection:
* initial syn/syn-ack pair for RDPUDP v1 & v2
* mid-flow (only v1) */
if((packet->payload_packet_len >= 10) && ((s_port == RDP_PORT) || (d_port == RDP_PORT))) {
if(s_port == RDP_PORT) {
/* Server -> Client */
if(flow->l4.udp.rdp_from_srv_pkts == 0) {
if(memcmp(packet->payload, flow->l4.udp.rdp_from_srv, 3) == 0 &&
packet->payload_packet_len >= 16 &&
(ntohs(get_u_int16_t(packet->payload, 6)) & 0x0003) && /* Flags: syn-ack */
ntohs(get_u_int16_t(packet->payload, 12)) <= 1600 && /* Sensible values for upstream MTU */
ntohs(get_u_int16_t(packet->payload, 14)) <= 1600) { /* Sensible values for downstream MTU */
/* Initial "syn-ack" */
ndpi_int_rdp_add_connection(ndpi_struct, flow);
return;
} else {
/* Mid-flow session? */
memcpy(flow->l4.udp.rdp_from_srv, packet->payload, 3), flow->l4.udp.rdp_from_srv_pkts = 1;
}
} else {
if(memcmp(flow->l4.udp.rdp_from_srv, packet->payload, 3) != 0)
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
else {
flow->l4.udp.rdp_from_srv_pkts = 2 /* stage 2 */;
if(flow->l4.udp.rdp_to_srv_pkts == 2) {
ndpi_int_rdp_add_connection(ndpi_struct, flow);
return;
}
}
}
} else {
/* Client -> Server */
if(flow->l4.udp.rdp_to_srv_pkts == 0) {
if(get_u_int32_t(packet->payload, 0) == 0xFFFFFFFF &&
packet->payload_packet_len >= 16 &&
(ntohs(get_u_int16_t(packet->payload, 6)) & 0x0001) && /* Flags: syn */
ntohs(get_u_int16_t(packet->payload, 12)) <= 1600 && /* Sensible values for upstream MTU */
ntohs(get_u_int16_t(packet->payload, 14)) <= 1600) { /* Sensible values for downstream MTU */
/* Initial "syn" */
memcpy(flow->l4.udp.rdp_from_srv, packet->payload + 8, 3);
} else {
/* Mid-flow session? */
memcpy(flow->l4.udp.rdp_to_srv, packet->payload, 3), flow->l4.udp.rdp_to_srv_pkts = 1;
}
} else {
if(memcmp(flow->l4.udp.rdp_to_srv, packet->payload, 3) != 0)
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
else {
flow->l4.udp.rdp_to_srv_pkts = 2 /* stage 2 */;
if(flow->l4.udp.rdp_from_srv_pkts == 2) {
ndpi_int_rdp_add_connection(ndpi_struct, flow);
return;
}
}
}
}
} else
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
}
/* **************************************** */
void init_rdp_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id)
{
ndpi_set_bitmask_protocol_detection("RDP", ndpi_struct, *id,
NDPI_PROTOCOL_RDP,
ndpi_search_rdp,
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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