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/*
* source_engine.c
*
* Source Engine Protocol (Valve’s A2S protocol)
*
* Copyright (C) 2023 - 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_SOURCE_ENGINE
#include "ndpi_api.h"
#include "ndpi_private.h"
static void ndpi_int_source_engine_add_connection(struct ndpi_detection_module_struct * const ndpi_struct,
struct ndpi_flow_struct * const flow)
{
NDPI_LOG_INFO(ndpi_struct, "found Source Engine\n");
ndpi_set_detected_protocol(ndpi_struct, flow,
NDPI_PROTOCOL_SOURCE_ENGINE,
NDPI_PROTOCOL_UNKNOWN,
NDPI_CONFIDENCE_DPI);
}
/* ***************************************************** */
static void ndpi_search_source_engine(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, "search Source Engine\n");
/* https://developer.valvesoftware.com/wiki/Server_queries */
/* A2S request */
if (current_pkt_from_client_to_server(ndpi_struct, flow) &&
(packet->payload_packet_len > 8 && packet->payload_packet_len < 30) &&
get_u_int32_t(packet->payload, 0) == 0xFFFFFFFF)
{
if (packet->payload[4] == 'T' || /* A2S_INFO */
packet->payload[4] == 'U' || /* A2S_PLAYER */
packet->payload[4] == 'V') /* A2S_RULES */
{
ndpi_int_source_engine_add_connection(ndpi_struct, flow);
return;
}
}
/* A2S response */
if (current_pkt_from_server_to_client(ndpi_struct, flow))
{
/* Challenge response */
if (packet->payload_packet_len == 9 &&
get_u_int32_t(packet->payload, 0) == 0xFFFFFFFF &&
packet->payload[4] == 'A')
{
ndpi_int_source_engine_add_connection(ndpi_struct, flow);
return;
}
if (packet->payload_packet_len > 30 && /* A reasonable length for euristics */
get_u_int32_t(packet->payload, 0) == 0xFFFFFFFF)
{
if (packet->payload[4] == 'I' || /* A2S_INFO */
packet->payload[4] == 'D' || /* A2S_PLAYER */
packet->payload[4] == 'E') /* A2S_RULES */
{
ndpi_int_source_engine_add_connection(ndpi_struct, flow);
return;
}
}
}
NDPI_EXCLUDE_DISSECTOR(ndpi_struct, flow);
}
/* ***************************************************** */
void init_source_engine_dissector(struct ndpi_detection_module_struct *ndpi_struct)
{
register_dissector("Source_Engine", ndpi_struct,
ndpi_search_source_engine,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
1, NDPI_PROTOCOL_SOURCE_ENGINE);
}
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