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/*
* websocket.c
*
* Copyright (C) 2018 by Leonn Paiva <leonn.paiva@gmail.com>
*
* 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_WEBSOCKET
#include "ndpi_api.h"
#include "ndpi_private.h"
enum websocket_opcode
{
/*
* CONTINUATION_FRAME is not relevant for the detection and leads to many false positives
CONTINUATION_FRAME = 0x00,
FIN_CONTINUATION_FRAME = 0x80,
*/
TEXT_FRAME = 0x01,
FIN_TEXT_FRAME = 0x81,
BINARY_FRAME = 0x02,
FIN_BINARY_FRAME = 0x82,
CONNECTION_CLOSE_FRAME = 0x08,
FIN_CONNECTION_CLOSE_FRAME = 0x88,
PING_FRAME = 0x09,
FIN_PING_FRAME = 0x89,
PONG_FRAME = 0x0A,
FIN_PONG_FRAME = 0x8A
};
static void set_websocket_detected(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
/* If no custom protocol has been detected */
if (flow->detected_protocol_stack[0] == NDPI_PROTOCOL_UNKNOWN)
{
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WEBSOCKET, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
}
/*************************************************************************************************/
static void ndpi_check_websocket(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
if (packet->payload_packet_len < sizeof(u_int16_t))
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
u_int8_t websocket_payload_length = packet->payload[1] & 0x7F;
u_int8_t websocket_masked = packet->payload[1] & 0x80;
uint8_t hdr_size = (websocket_masked == 1) ? 6 : 2;
if (packet->payload_packet_len != hdr_size + websocket_payload_length)
{
NDPI_LOG_DBG(ndpi_struct, "Invalid WEBSOCKET payload");
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
if (packet->payload[0] == TEXT_FRAME || packet->payload[0] == FIN_TEXT_FRAME ||
packet->payload[0] == BINARY_FRAME || packet->payload[0] == FIN_BINARY_FRAME ||
packet->payload[0] == CONNECTION_CLOSE_FRAME || packet->payload[0] == FIN_CONNECTION_CLOSE_FRAME ||
packet->payload[0] == PING_FRAME || packet->payload[0] == FIN_PING_FRAME ||
packet->payload[0] == PONG_FRAME || packet->payload[0] == FIN_PONG_FRAME) {
set_websocket_detected(ndpi_struct, flow);
} else {
NDPI_LOG_DBG(ndpi_struct, "Invalid WEBSOCKET payload");
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
}
static void ndpi_search_websocket(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
// Break after 6 packets.
if (flow->packet_counter > 10)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
NDPI_LOG_DBG(ndpi_struct, "search WEBSOCKET\n");
ndpi_check_websocket(ndpi_struct, flow);
// Check also some HTTP headers indicating an upcoming WebSocket connection
if (flow->detected_protocol_stack[0] == NDPI_PROTOCOL_HTTP &&
flow->detected_protocol_stack[1] != NDPI_PROTOCOL_WEBSOCKET)
{
struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;
uint16_t i;
NDPI_PARSE_PACKET_LINE_INFO(ndpi_struct, flow, packet);
for (i = 0; i < packet->parsed_lines; i++) {
if (LINE_STARTS(packet->line[i], "upgrade:") != 0 &&
LINE_ENDS(packet->line[i], "websocket") != 0)
{
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WEBSOCKET,
NDPI_PROTOCOL_HTTP, NDPI_CONFIDENCE_DPI);
} else if (LINE_STARTS(packet->line[i], "sec-websocket") != 0) {
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WEBSOCKET,
NDPI_PROTOCOL_HTTP, NDPI_CONFIDENCE_DPI);
if (ndpi_strncasestr((const char *)packet->line[i].ptr, "chisel",
packet->line[i].len) != NULL)
{
ndpi_set_risk(ndpi_struct, flow, NDPI_OBFUSCATED_TRAFFIC,
"Obfuscated SSH-in-HTTP-WebSocket traffic");
}
}
}
if (i == packet->parsed_lines)
{
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
}
return;
}
/* ********************************* */
void init_websocket_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id)
{
ndpi_set_bitmask_protocol_detection("WEBSOCKET", ndpi_struct, *id, NDPI_PROTOCOL_WEBSOCKET,
ndpi_search_websocket, NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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