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/*
* dcerpc.c
*
* Copyright (C) 2011-18 by 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_DCERPC
#include "ndpi_api.h"
#include "ndpi_private.h"
#include <stdbool.h>
static void ndpi_int_dcerpc_add_connection(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_DCERPC, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
static bool is_connection_oriented_dcerpc(struct ndpi_packet_struct *packet)
{
if((packet->tcp != NULL)
&& (packet->payload_packet_len >= 64)
&& (packet->payload[0] == 0x05) /* version 5 */
&& (packet->payload[2] < 16) /* Packet type */
&& (((packet->payload[9]<<8) | packet->payload[8]) == packet->payload_packet_len) /* Packet Length */
) {
return true;
}
return false;
}
static bool is_connectionless_dcerpc(struct ndpi_packet_struct *packet)
{
u_int16_t fragment_len;
if (packet->udp == NULL)
return false;
if (packet->payload_packet_len < 80)
return false;
if (packet->payload[0] != 0x04) /* type must be equal to 4 */
return false;
if (packet->payload[1] > 10) /* must be <= CANCEL ACK or it's not connectionless DCE/RPC */
return false;
if (packet->payload[3] & 0xFC) /* flags2: bit 3:8 are reserved for future use and must be set to 0 */
return false;
if (packet->payload[4] & 0xEE) /* neither big endian nor little endian */
return false;
if (packet->payload[5] > 3) /* invalid floating point type */
return false;
if(packet->payload[4] == 0x10)
fragment_len = (packet->payload[75] << 8) + packet->payload[74]; /* Big endian */
else
fragment_len = (packet->payload[74] << 8) + packet->payload[75]; /* Little endian */
if(packet->payload_packet_len != (fragment_len+76 /* offset */ + 4 /* rest of the packet */))
return false; /* Too short or too long, bot RPC */
return true;
}
static void ndpi_search_dcerpc(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 DCERPC\n");
if (is_connection_oriented_dcerpc(packet) || is_connectionless_dcerpc(packet)) {
NDPI_LOG_INFO(ndpi_struct, "found DCERPC\n");
ndpi_int_dcerpc_add_connection(ndpi_struct, flow);
return;
}
if(packet->payload_packet_len>1)
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
void init_dcerpc_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id)
{
ndpi_set_bitmask_protocol_detection("DCERPC", ndpi_struct, *id,
NDPI_PROTOCOL_DCERPC,
ndpi_search_dcerpc,
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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