/src/ndpi/src/lib/protocols/rdp.c

Source
/*
 * rdp.c
 *
 * Copyright (C) 2009-11 - ipoque GmbH
 * Copyright (C) 2011-25 - 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->tls_quic.from_rdp = 1;
        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_DISSECTOR(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_DISSECTOR(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_DISSECTOR(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_DISSECTOR(ndpi_struct, flow);
  }
}

/* **************************************** */

void init_rdp_dissector(struct ndpi_detection_module_struct *ndpi_struct)
{
  register_dissector("RDP", ndpi_struct,
                     ndpi_search_rdp,
                     NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
                     1, NDPI_PROTOCOL_RDP);
}

Line	Count	Source
1		/*
2		* rdp.c
3		*
4		* Copyright (C) 2009-11 - ipoque GmbH
5		* Copyright (C) 2011-25 - ntop.org
6		*
7		* This file is part of nDPI, an open source deep packet inspection
8		* library based on the OpenDPI and PACE technology by ipoque GmbH
9		*
10		* nDPI is free software: you can redistribute it and/or modify
11		* it under the terms of the GNU Lesser General Public License as published by
12		* the Free Software Foundation, either version 3 of the License, or
13		* (at your option) any later version.
14		*
15		* nDPI is distributed in the hope that it will be useful,
16		* but WITHOUT ANY WARRANTY; without even the implied warranty of
17		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18		* GNU Lesser General Public License for more details.
19		*
20		* You should have received a copy of the GNU Lesser General Public License
21		* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
22		*
23		*/
24
25
26		#include "ndpi_protocol_ids.h"
27
28		#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_RDP
29
30	0	#define RDP_PORT 3389
31
32		#include "ndpi_api.h"
33		#include "ndpi_private.h"
34
35		extern int ndpi_tls_obfuscated_heur_search_again(struct ndpi_detection_module_struct* ndpi_struct,
36		struct ndpi_flow_struct* flow);
37
38		/* **************************************** */
39
40		static void ndpi_int_rdp_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
41	0	struct ndpi_flow_struct *flow) {
42	0	NDPI_LOG_INFO(ndpi_struct, "found RDP\n");
43	0	ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_RDP, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
44	0	ndpi_set_risk(ndpi_struct, flow, NDPI_DESKTOP_OR_FILE_SHARING_SESSION, "Found RDP"); /* Remote assistance */
45	0	}
46
47		/* **************************************** */
48
49		/* tls.c */
50		extern int ndpi_search_tls_tcp(struct ndpi_detection_module_struct *ndpi_struct,
51		struct ndpi_flow_struct *flow);
52
53		int ndpi_search_tls_over_rdp(struct ndpi_detection_module_struct *ndpi_struct,
54	0	struct ndpi_flow_struct *flow) {
55	0	const struct ndpi_packet_struct * const packet = &ndpi_struct->packet;
56
57	0	if((packet->payload_packet_len > 1)
58	0	&& (packet->payload[0] == 0x16 /* This might be a TLS block */)) {
59	0	int rc = ndpi_search_tls_tcp(ndpi_struct, flow);
60
61	0	return(rc);
62	0	} else
63	0	return 1; /* Keep searching */
64	0	}
65
66		/* **************************************** */
67
68		static void ndpi_search_rdp(struct ndpi_detection_module_struct *ndpi_struct,
69	0	struct ndpi_flow_struct *flow) {
70	0	const struct ndpi_packet_struct * const packet = &ndpi_struct->packet;
71
72	0	NDPI_LOG_DBG(ndpi_struct, "search RDP\n");
73
74	0	if (packet->tcp != NULL) {
75	0	if(packet->payload_packet_len > 13 &&
76	0	tpkt_verify_hdr(packet) &&
77		/* COTP */
78	0	packet->payload[4] == packet->payload_packet_len - 5) {
79
80	0	if(current_pkt_from_client_to_server(ndpi_struct, flow)) {
81	0	if(packet->payload[5] == 0xE0 && /* COTP CR */
82	0	((packet->payload[11] == 0x01 && /* RDP Negotiation Request */
83	0	packet->payload[13] == 0x08 /* RDP Length */) \|\|
84	0	(packet->payload_packet_len > 17 &&
85	0	memcmp(&packet->payload[11], "Cookie:", 7) == 0))) /* RDP Cookie */ {
86
87	0	if(packet->payload_packet_len > 43) {
88	0	u_int8_t rdp_requested_proto = packet->payload[43];
89
90		/* Check if TLS support has been requested in RDP */
91	0	if((rdp_requested_proto & 0x1) == 0x1) {
92		/* RDP Response + Client Hello + Server hello */
93	0	flow->max_extra_packets_to_check = 5;
94	0	flow->tls_quic.from_rdp = 1;
95	0	flow->extra_packets_func = ndpi_search_tls_over_rdp;
96	0	}
97	0	}
98
99	0	ndpi_int_rdp_add_connection(ndpi_struct, flow);
100
101	0	return;
102	0	}
103	0	} else {
104		/* Asymmetric detection via RDP Negotiation Response */
105	0	if(packet->payload[5] == 0xD0 && /* COTP CC */
106	0	packet->payload[11] == 0x02 && /* RDP Negotiation Response */
107	0	packet->payload[13] == 0x08 /* RDP Length */) {
108	0	ndpi_int_rdp_add_connection(ndpi_struct, flow);
109	0	return;
110	0	}
111	0	}
112	0	}
113	0	NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
114	0	} else if(packet->udp != NULL) {
115	0	u_int16_t s_port = ntohs(packet->udp->source);
116	0	u_int16_t d_port = ntohs(packet->udp->dest);
117
118		/* Detection:
119		* initial syn/syn-ack pair for RDPUDP v1 & v2
120		* mid-flow (only v1) */
121
122	0	if((packet->payload_packet_len >= 10) && ((s_port == RDP_PORT) \|\| (d_port == RDP_PORT))) {
123	0	if(s_port == RDP_PORT) {
124		/* Server -> Client */
125	0	if(flow->l4.udp.rdp_from_srv_pkts == 0) {
126	0	if(memcmp(packet->payload, flow->l4.udp.rdp_from_srv, 3) == 0 &&
127	0	packet->payload_packet_len >= 16 &&
128	0	(ntohs(get_u_int16_t(packet->payload, 6)) & 0x0003) && /* Flags: syn-ack */
129	0	ntohs(get_u_int16_t(packet->payload, 12)) <= 1600 && /* Sensible values for upstream MTU */
130	0	ntohs(get_u_int16_t(packet->payload, 14)) <= 1600) { /* Sensible values for downstream MTU */
131		/* Initial "syn-ack" */
132	0	ndpi_int_rdp_add_connection(ndpi_struct, flow);
133	0	return;
134	0	} else {
135		/* Mid-flow session? */
136	0	memcpy(flow->l4.udp.rdp_from_srv, packet->payload, 3), flow->l4.udp.rdp_from_srv_pkts = 1;
137	0	}
138	0	} else {
139	0	if(memcmp(flow->l4.udp.rdp_from_srv, packet->payload, 3) != 0)
140	0	NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
141	0	else {
142	0	flow->l4.udp.rdp_from_srv_pkts = 2 /* stage 2 */;
143
144	0	if(flow->l4.udp.rdp_to_srv_pkts == 2) {
145	0	ndpi_int_rdp_add_connection(ndpi_struct, flow);
146	0	return;
147	0	}
148	0	}
149	0	}
150	0	} else {
151		/* Client -> Server */
152	0	if(flow->l4.udp.rdp_to_srv_pkts == 0) {
153	0	if(get_u_int32_t(packet->payload, 0) == 0xFFFFFFFF &&
154	0	packet->payload_packet_len >= 16 &&
155	0	(ntohs(get_u_int16_t(packet->payload, 6)) & 0x0001) && /* Flags: syn */
156	0	ntohs(get_u_int16_t(packet->payload, 12)) <= 1600 && /* Sensible values for upstream MTU */
157	0	ntohs(get_u_int16_t(packet->payload, 14)) <= 1600) { /* Sensible values for downstream MTU */
158		/* Initial "syn" */
159	0	memcpy(flow->l4.udp.rdp_from_srv, packet->payload + 8, 3);
160	0	} else {
161		/* Mid-flow session? */
162	0	memcpy(flow->l4.udp.rdp_to_srv, packet->payload, 3), flow->l4.udp.rdp_to_srv_pkts = 1;
163	0	}
164	0	} else {
165	0	if(memcmp(flow->l4.udp.rdp_to_srv, packet->payload, 3) != 0)
166	0	NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
167	0	else {
168	0	flow->l4.udp.rdp_to_srv_pkts = 2 /* stage 2 */;
169
170	0	if(flow->l4.udp.rdp_from_srv_pkts == 2) {
171	0	ndpi_int_rdp_add_connection(ndpi_struct, flow);
172	0	return;
173	0	}
174	0	}
175	0	}
176	0	}
177	0	} else
178	0	NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
179	0	}
180	0	}
181
182		/* **************************************** */
183
184		void init_rdp_dissector(struct ndpi_detection_module_struct *ndpi_struct)
185	1	{
186	1	register_dissector("RDP", ndpi_struct,
187	1	ndpi_search_rdp,
188	1	NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
189	1	1, NDPI_PROTOCOL_RDP);
190	1	}

Coverage Report

Created: 2025-11-02 06:33