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/*
* mqtt.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_MQTT
#include "ndpi_api.h"
/**
* The type of control messages in mqtt version 3.1.1
* see http://docs.oasis-open.org/mqtt/mqtt/v3.1.1
*/
enum MQTT_PACKET_TYPES {
CONNECT = 1,
CONNACK = 2,
PUBLISH = 3,
PUBACK = 4,
PUBREC = 5,
PUBREL = 6,
PUBCOMP = 7,
SUBSCRIBE = 8,
SUBACK = 9,
UNSUBSCRIBE = 10,
UNSUBACK = 11,
PINGREQ = 12,
PINGRESP = 13,
DISCONNECT = 14
};
/**
* Entry point when protocol is identified.
*/
static void ndpi_int_mqtt_add_connection (struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
ndpi_set_detected_protocol(ndpi_struct,flow,NDPI_PROTOCOL_MQTT,NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
NDPI_LOG_INFO(ndpi_struct, "found Mqtt\n");
}
static int64_t get_var_int(const unsigned char *buf, int buf_len, u_int8_t *num_bytes)
{
int i, multiplier = 1;
u_int32_t value = 0;
u_int8_t encodedByte;
*num_bytes= 0;
for (i = 0; i < 4; i++) {
if (i >= buf_len)
return -1;
(*num_bytes)++;
encodedByte = buf[i];
value += ((encodedByte & 127) * multiplier);
if ((encodedByte & 128) == 0)
break;
multiplier *= 128;
}
return value;
}
/**
* Dissector function that searches Mqtt headers
*/
void ndpi_search_mqtt (struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
u_int8_t pt,flags, rl_len;
int64_t rl;
NDPI_LOG_DBG(ndpi_struct, "search Mqtt\n");
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
if (flow->detected_protocol_stack[0] != NDPI_PROTOCOL_UNKNOWN) {
return;
}
if (flow->packet_counter > 10) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt .. mandatory header not found!\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
NDPI_LOG_DBG2(ndpi_struct, "====>>>> Mqtt header: %4x%4x%4x%4x [len: %u]\n",
packet->payload_packet_len > 0 ? packet->payload[0] : '.',
packet->payload_packet_len > 1 ? packet->payload[1] : '.',
packet->payload_packet_len > 2 ? packet->payload[2] : '.',
packet->payload_packet_len > 3 ? packet->payload[3] : '.',
packet->payload_packet_len);
if (packet->payload_packet_len < 2) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt .. mandatory header not found!\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
// we extract the remaining length
rl = get_var_int(&packet->payload[1], packet->payload_packet_len - 1, &rl_len);
if (rl < 0) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt .. invalid length!\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
NDPI_LOG_DBG(ndpi_struct, "Mqtt: msg_len %d\n", (unsigned long long)rl);
if (packet->payload_packet_len != rl + 1 + rl_len) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt .. maximum packet size exceeded!\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
// we extract the packet type
pt = (u_int8_t) ((packet->payload[0] & 0xF0) >> 4);
NDPI_LOG_DBG2(ndpi_struct,"====>>>> Mqtt packet type: [%d]\n",pt);
if ((pt == 0) || (pt == 15)) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt .. invalid packet type!\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
// we extract the flags
flags = (u_int8_t) (packet->payload[0] & 0x0F);
NDPI_LOG_DBG2(ndpi_struct,"====>>>> Mqtt flags type: [%d]\n",flags);
// first stage verification
if (((pt == CONNECT) || (pt == CONNACK) || (pt == PUBACK) || (pt == PUBREC) ||
(pt == PUBCOMP) || (pt == SUBACK) || (pt == UNSUBACK) || (pt == PINGREQ) ||
(pt == PINGRESP) || (pt == DISCONNECT)) && (flags > 0)) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid Packet-Flag combination flag!=0\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
if (((pt == PUBREL) || (pt == SUBSCRIBE) || (pt == UNSUBSCRIBE)) && (flags != 2)) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid Packet-Flag combination flag!=2\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
NDPI_LOG_DBG2(ndpi_struct,"====>>>> Passed first stage of identification\n");
// second stage verification (no payload, just variable headers)
if ((pt == CONNACK) || (pt == PUBACK) || (pt == PUBREL) ||
(pt == PUBREC) || (pt == PUBCOMP) || (pt == UNSUBACK)) {
if (packet->payload_packet_len != 4) { // these packets are always 4 bytes long
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid Packet-Length < 4 \n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
} else {
NDPI_LOG_INFO(ndpi_struct, "found Mqtt CONNACK/PUBACK/PUBREL/PUBREC/PUBCOMP/UNSUBACK\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
}
if ((pt == PINGREQ) || (pt == PINGRESP) || (pt == DISCONNECT)) {
if (packet->payload_packet_len != 2) { // these packets are always 2 bytes long
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid Packet-Length <2 \n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
} else {
NDPI_LOG_INFO(ndpi_struct, "found Mqtt PING/PINGRESP/DISCONNECT\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
}
NDPI_LOG_DBG2(ndpi_struct,"====>>>> Passed second stage of identification\n");
// third stage verification (payload)
if (pt == CONNECT) {
NDPI_LOG_DBG(ndpi_struct, "found Mqtt CONNECT\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
if (pt == PUBLISH) {
// payload CAN be zero bytes length (section 3.3.3 of MQTT standard)
u_int8_t qos = (u_int8_t) (flags & 0x06);
u_int8_t retain = (u_int8_t) (flags & 0x01);
u_int8_t dup = (u_int8_t) (flags & 0x04);
if (qos > 2) { // qos values possible are 0,1,2
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid PUBLISH qos\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
if (retain > 1) { // retain flag possible 0,1
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid PUBLISH retain\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
if (dup > 1) { // dup flag possible 0,1
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid PUBLISH dup\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
if (qos == 0) {
if (dup != 0) {
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid PUBLISH qos0 and dup combination\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
if (packet->payload_packet_len < 5) { // at least topic (3Bytes + 2Bytes fixed header)
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid PUBLISH qos0 size\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
}
if ((qos == 1) || (qos == 2)) {
if (packet->payload_packet_len < 7 ) { // at least topic + pkt identifier (3Bytes + 2Bytes + 2Bytes fixed header)
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid PUBLISH qos1&2\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
}
}
NDPI_LOG_INFO(ndpi_struct, "found Mqtt PUBLISH\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
if (pt == SUBSCRIBE) {
if (packet->payload_packet_len < 8) { // at least one topic+filter is required in the payload
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid SUBSCRIBE\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
} else {
NDPI_LOG_INFO(ndpi_struct, "found Mqtt SUBSCRIBE\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
}
if (pt == SUBACK ) {
if (packet->payload_packet_len <5 ) { // must have at least a response code
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid SUBACK\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
} else {
NDPI_LOG_INFO(ndpi_struct, "found Mqtt SUBACK\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
}
if (pt == UNSUBSCRIBE) {
if (packet->payload_packet_len < 7) { // at least a topic
NDPI_LOG_DBG(ndpi_struct, "Excluding Mqtt invalid UNSUBSCRIBE\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MQTT);
return;
} else {
NDPI_LOG_INFO(ndpi_struct, "found Mqtt UNSUBSCRIBE\n");
ndpi_int_mqtt_add_connection(ndpi_struct,flow);
return;
}
}
NDPI_LOG_DBG2(ndpi_struct,"====>>>> Passed third stage of identification");
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
/**
* Entry point for the ndpi library
*/
void init_mqtt_dissector (struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection ("MQTT", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_MQTT,
ndpi_search_mqtt,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK);
*id +=1;
}
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