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/*
* coap.c
*
* Copyright (C) 2016 Sorin Zamfir <sorin.zamfir@yahoo.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_COAP
#include "ndpi_api.h"
#define CON 0
#define NO_CON 1
#define ACK 2
#define RST 3
struct ndpi_coap_hdr
{
#if defined(__BIG_ENDIAN__)
u_int8_t version:2, type:2, tkl:4;
#elif defined(__LITTLE_ENDIAN__)
u_int8_t tkl:4, type:2, version:2;
#endif
u_int8_t code;
u_int16_t message_id; //if needed, remember to convert in host number
};
/**
VALUE OF -CODE- FIELD
[0] = "Empty",
[1] = "GET",
[2] = "POST",
[3] = "PUT",
[4] = "DELETE",
[65] = "2.01 Created",
[66] = "2.02 Deleted",
[67] = "2.03 Valid",
[68] = "2.04 Changed",
[69] = "2.05 Content",
[128] = "4.00 Bad Request",
[129] = "4.01 Unauthorized",
[130] = "4.02 Bad Option",
[131] = "4.03 Forbidden",
[132] = "4.04 Not Found",
[133] = "4.05 Method Not Allowed",
[134] = "4.06 Not Acceptable",
[140] = "4.12 Precondition Failed",
[141] = "4.13 Request Entity Too Large",
[143] = "4.15 Unsupported Content-Format",
[160] = "5.00 Internal Server Error",
[161] = "5.01 Not Implemented",
[162] = "5.02 Bad Gateway",
[163] = "5.03 Service Unavailable",
[164] = "5.04 Gateway Timeout",
[165] = "5.05 Proxying Not Supported"
**/
/**
* Entry point when protocol is identified.
*/
static void ndpi_int_coap_add_connection (struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
ndpi_set_detected_protocol(ndpi_struct,flow,NDPI_PROTOCOL_COAP,NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
/**
* Check if the default port is acceptable
*
* UDP Port 5683 (mandatory)
* UDP Ports 61616-61631 compressed 6lowPAN
*/
static int isCoAPport(u_int16_t port) {
if((port == 5683)
|| ((port >= 61616) && (port <= 61631)))
return(1);
else
return(0);
}
/**
* Dissector function that searches CoAP headers
*/
void ndpi_search_coap (struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
struct ndpi_coap_hdr * h = (struct ndpi_coap_hdr*) packet->payload;
if(flow->detected_protocol_stack[0] != NDPI_PROTOCOL_UNKNOWN) {
return;
}
// search for udp packet
if(packet->udp != NULL) {
u_int16_t s_port = ntohs(packet->udp->source);
u_int16_t d_port = ntohs(packet->udp->dest);
if((!isCoAPport(s_port) && !isCoAPport(d_port))
|| (packet->payload_packet_len < 4) ) { // header too short
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
NDPI_LOG_DBG2(ndpi_struct, "calculating coap over udp\n");
// check values in header
if(h->version == 1) {
if(h->type == CON || h->type == NO_CON || h->type == ACK || h->type == RST ) {
if(h->tkl < 8) {
if((/* h->code >= 0 && */ h->code <= 5) || (h->code >= 65 && h->code <= 69) ||
(h->code >= 128 && h->code <= 134) || (h->code >= 140 && h->code <= 143) ||
(h->code >= 160 && h->code <= 165)) {
NDPI_LOG_INFO(ndpi_struct, "found Coap\n");
ndpi_int_coap_add_connection(ndpi_struct,flow);
return;
}
}
}
}
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
/**
* Entry point for the ndpi library
*/
void init_coap_dissector (struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection ("COAP", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_COAP,
ndpi_search_coap,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK);
*id +=1;
}
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