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/*
* gtp.c
*
* Copyright (C) 2011-21 - 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_GTP
#include "ndpi_api.h"
struct gtp_header_generic {
u_int8_t flags, message_type;
u_int16_t message_len;
u_int32_t teid;
};
static void ndpi_check_gtp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
// const u_int8_t *packet_payload = packet->payload;
u_int32_t payload_len = packet->payload_packet_len;
if((packet->udp != NULL) && (payload_len > sizeof(struct gtp_header_generic))) {
u_int32_t gtp_u = ntohs(2152);
u_int32_t gtp_c = ntohs(2123);
u_int32_t gtp_v0 = ntohs(3386);
if((packet->udp->source == gtp_u) || (packet->udp->dest == gtp_u)
|| (packet->udp->source == gtp_c) || (packet->udp->dest == gtp_c)
|| (packet->udp->source == gtp_v0) || (packet->udp->dest == gtp_v0)
) {
struct gtp_header_generic *gtp = (struct gtp_header_generic*)packet->payload;
u_int8_t gtp_version = (gtp->flags & 0xE0) >> 5;
if((gtp_version == 0) || (gtp_version == 1) || (gtp_version == 2)) {
u_int16_t message_len = ntohs(gtp->message_len);
if(message_len <= (payload_len-sizeof(struct gtp_header_generic))) {
NDPI_LOG_INFO(ndpi_struct, "found gtp\n");
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_GTP, NDPI_PROTOCOL_UNKNOWN);
return;
}
}
}
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
void ndpi_search_gtp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
NDPI_LOG_DBG(ndpi_struct, "search gtp\n");
/* skip marked packets */
if(packet->detected_protocol_stack[0] != NDPI_PROTOCOL_GTP)
ndpi_check_gtp(ndpi_struct, flow);
}
void init_gtp_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection("GTP", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_GTP,
ndpi_search_gtp,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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