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/*
* line.c
*
* Copyright (C) 2022 - ntop.org
*
* 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_LINE_CALL
#include "ndpi_api.h"
extern int is_valid_rtp_payload_type(uint8_t type);
static void ndpi_int_line_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,
struct ndpi_flow_struct * const flow)
{
NDPI_LOG_INFO(ndpi_struct, "found LineCall\n");
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_UNKNOWN,
NDPI_PROTOCOL_LINE_CALL, NDPI_CONFIDENCE_DPI);
}
void ndpi_search_line(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;
NDPI_LOG_DBG(ndpi_struct, "searching LineCall\n");
/* Some "random" UDP packets before the standard RTP stream:
it seems that the 4th bytes of these packets is some kind of packet
number. Look for 4 packets per direction with consecutive numbers. */
if(packet->payload_packet_len > 10) {
if(flow->l4.udp.line_pkts[packet->packet_direction] == 0) {
flow->l4.udp.line_base_cnt[packet->packet_direction] = packet->payload[3];
flow->l4.udp.line_pkts[packet->packet_direction] += 1;
return;
} else {
/* It might be a RTP/RTCP packet. Ignore it and keep looking for the
LINE packet numbers */
/* Basic RTP detection */
if((packet->payload[0] >> 6) == 2 && /* Version 2 */
(packet->payload[1] == 201 || /* RTCP, Receiver Report */
packet->payload[1] == 200 || /* RTCP, Sender Report */
is_valid_rtp_payload_type(packet->payload[1] & 0x7F)) /* RTP */) {
NDPI_LOG_DBG(ndpi_struct, "Probably RTP; keep looking for LINE");
return;
} else {
if((u_int8_t)(flow->l4.udp.line_base_cnt[packet->packet_direction] +
flow->l4.udp.line_pkts[packet->packet_direction]) == packet->payload[3]) {
flow->l4.udp.line_pkts[packet->packet_direction] += 1;
if(flow->l4.udp.line_pkts[0] >= 4 && flow->l4.udp.line_pkts[1] >= 4)
ndpi_int_line_add_connection(ndpi_struct, flow);
return;
}
}
}
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
void init_line_dissector(struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection("LineCall", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_LINE_CALL,
ndpi_search_line,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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