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Merge pull request #209 from Zadamsa/mqtt
MQTT plugin v3.1.1
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,236 @@ | ||
| /** | ||
| * \file mqtt.hpp | ||
| * \brief MQTT plugin for ipfixprobe | ||
| * \author Damir Zainullin <zaidamilda@gmail.com> | ||
| * \date 2024 | ||
| */ | ||
| /* | ||
| * Copyright (C) 2023 CESNET | ||
| * | ||
| * LICENSE TERMS | ||
| * | ||
| * Redistribution and use in source and binary forms, with or without | ||
| * modification, are permitted provided that the following conditions | ||
| * are met: | ||
| * 1. Redistributions of source code must retain the above copyright | ||
| * notice, this list of conditions and the following disclaimer. | ||
| * 2. Redistributions in binary form must reproduce the above copyright | ||
| * notice, this list of conditions and the following disclaimer in | ||
| * the documentation and/or other materials provided with the | ||
| * distribution. | ||
| * 3. Neither the name of the Company nor the names of its contributors | ||
| * may be used to endorse or promote products derived from this | ||
| * software without specific prior written permission. | ||
| */ | ||
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| #include "mqtt.hpp" | ||
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| #include <cstring> | ||
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| #ifdef DEBUG_MQTT | ||
| static const bool debug_mqtt = true; | ||
| #else | ||
| static const bool debug_mqtt = false; | ||
| #endif | ||
| namespace ipxp { | ||
|
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| int RecordExtMQTT::REGISTERED_ID = -1; | ||
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| __attribute__((constructor)) static void register_this_plugin() | ||
| { | ||
| static PluginRecord rec = PluginRecord("mqtt", []() { return new MQTTPlugin(); }); | ||
| register_plugin(&rec); | ||
| RecordExtMQTT::REGISTERED_ID = register_extension(); | ||
| } | ||
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| int MQTTPlugin::post_create(Flow& rec, const Packet& pkt) | ||
| { | ||
| if (has_mqtt_protocol_name(reinterpret_cast<const char*>(pkt.payload), pkt.payload_len)) | ||
| add_ext_mqtt(reinterpret_cast<const char*>(pkt.payload), pkt.payload_len, rec); | ||
| return 0; | ||
| } | ||
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| int MQTTPlugin::pre_update(Flow& rec, Packet& pkt) | ||
| { | ||
| const char* payload = reinterpret_cast<const char*>(pkt.payload); | ||
| RecordExt* ext = rec.get_extension(RecordExtMQTT::REGISTERED_ID); | ||
| if (ext == nullptr) { | ||
| return 0; | ||
| } else { | ||
| parse_mqtt(payload, pkt.payload_len, static_cast<RecordExtMQTT*>(ext)); | ||
| } | ||
| return 0; | ||
| } | ||
|
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| /** | ||
| * \brief Read variable integer as defined in | ||
| * http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html. \param [in] data Pointer to IP | ||
| * payload. \param [in] payload_len IP payload length. \param [in] last_byte Next after last read | ||
| * byte. \return Pair of read integer and bool. Bool is false in case read was unsuccessful. | ||
| */ | ||
| std::pair<uint32_t, bool> | ||
| MQTTPlugin::read_variable_int(const char* data, int payload_len, uint32_t& last_byte) const noexcept | ||
| { | ||
| uint32_t res = 0; | ||
| bool next; | ||
| for (next = true; next && last_byte < (uint32_t) payload_len; last_byte++) { | ||
| res <<= 8; | ||
| res |= data[last_byte]; | ||
| next = (data[last_byte] & 0b1000'0000); | ||
| } | ||
| return last_byte == (uint32_t) payload_len && next ? std::make_pair(0u, false) | ||
| : std::make_pair(res, true); | ||
| } | ||
|
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| /** | ||
| * \brief Read utf8 encoded string as defined in | ||
| * http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html. \param [in] data Pointer to IP | ||
| * payload. \param [in] payload_len IP payload length. \param [in] last_byte Next after last read | ||
| * byte. \return Tuple of read string, its length and bool. Bool is false in case read was | ||
| * unsuccessful. | ||
| */ | ||
| std::tuple<uint32_t, std::string_view, bool> | ||
| MQTTPlugin::read_utf8_string(const char* data, int payload_len, uint32_t& last_byte) const noexcept | ||
| { | ||
| if (last_byte + 2 >= (uint32_t) payload_len) | ||
| return {0, {}, false}; | ||
| uint16_t string_length = ntohs(*(uint16_t*) &data[last_byte]); | ||
| last_byte += 2; | ||
| if (last_byte + string_length >= (uint32_t) payload_len) | ||
| return {0, {}, false}; | ||
| return {string_length, std::string_view(&data[last_byte], string_length), true}; | ||
| } | ||
|
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| /** | ||
| * \brief Parse buffer to check if it contains MQTT packets. | ||
| * \param [in] data Pointer to IP payload. | ||
| * \param [in] payload_len IP payload length. | ||
| * \param [in,out] rec Record to write MQTT data in. | ||
| * \return True if buffer contains set of valid mqtt packets. | ||
| */ | ||
| bool MQTTPlugin::parse_mqtt(const char* data, int payload_len, RecordExtMQTT* rec) noexcept | ||
| { | ||
| if (payload_len <= 0) | ||
| return false; | ||
| uint32_t last_byte = 0; | ||
| // Each tcp segment may contain more MQTT packets | ||
| while (last_byte < (uint32_t) payload_len) { | ||
| uint8_t type, flags; | ||
| type = flags = data[last_byte++]; | ||
| type >>= 4; | ||
| flags &= 0b00001111; | ||
| rec->type_cumulative |= (0b1 << type); | ||
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| auto [remaining_length, success] = read_variable_int(data, payload_len, last_byte); | ||
| if (!success || last_byte + remaining_length > (uint32_t) payload_len) { | ||
| if constexpr (debug_mqtt) | ||
| std::cout << "Invalid remaining length read" << std::endl; | ||
| return false; | ||
| } | ||
| auto first_byte_after_payload = remaining_length + last_byte; | ||
| // Connect packet | ||
| if (type == 1) { | ||
| if (!has_mqtt_protocol_name(data, payload_len)) { | ||
| if constexpr (debug_mqtt) | ||
| std::cout << "Connection packet doesn't have MQTT label" << std::endl; | ||
| return false; | ||
| } | ||
| last_byte += 6; // Skip "MQTT" label(and its 2-byte length) | ||
| rec->version = data[last_byte++]; | ||
| // Only MQTT v3.1.1 and v5.0 are supported | ||
| if (rec->version != 4 && rec->version != 5) { | ||
| if constexpr (debug_mqtt) | ||
| std::cout << "Unsupported mqtt version" << std::endl; | ||
| return false; | ||
| } | ||
| rec->connection_flags = data[last_byte++]; | ||
| rec->keep_alive = ntohs(*(uint16_t*) &data[last_byte]); | ||
| } | ||
| // Connect ACK packet | ||
| else if (type == 2) { | ||
| rec->session_present_flag = data[last_byte++] & 0b1; /// Connect Acknowledge Flags | ||
| rec->connection_return_code = data[last_byte++]; | ||
| } | ||
| // Publish packet | ||
| else if (type == 3) { | ||
| rec->publish_flags |= flags; | ||
| auto [str_len, str, success] = read_utf8_string(data, payload_len, last_byte); | ||
| if (!success) { | ||
| if constexpr (debug_mqtt) | ||
| std::cout << "Invalid utf8 string read" << std::endl; | ||
| return false; | ||
| } | ||
| if (str.find('#') != std::string::npos) { | ||
| if constexpr (debug_mqtt) | ||
| std::cout << "Topic name contains wildcard char" << std::endl; | ||
| return false; | ||
| } | ||
| // Use '#' as delimiter, as '#' and '?' are only forbidden characters for topic name | ||
| if (rec->topics.count++ < maximal_topic_count) { | ||
| rec->topics.str += std::move(std::string(str.begin(), str.end()).append("#")); | ||
| } | ||
| } | ||
| // Disconnect packet | ||
| else if (type == 14) { | ||
| flow_flush = true; | ||
| } | ||
|
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| last_byte = first_byte_after_payload; // Skip rest of payload | ||
| } | ||
| return true; | ||
| } | ||
|
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| int MQTTPlugin::post_update(Flow& rec, const Packet& pkt) | ||
| { | ||
| if (flow_flush) { | ||
| flow_flush = false; | ||
| return FLOW_FLUSH; | ||
| } | ||
| return 0; | ||
| } | ||
|
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| /** | ||
| * \brief Parse buffer to check if it contains MQTT packets. | ||
| * \param [in] data Pointer to IP payload. | ||
| * \param [in] payload_len IP payload length. | ||
| * \return True if buffer starts with MQTT label as part of connection mqtt packet. | ||
| */ | ||
| bool MQTTPlugin::has_mqtt_protocol_name(const char* data, int payload_len) const noexcept | ||
| { | ||
| if (payload_len <= 1) | ||
| return false; | ||
| auto pos = 1u; | ||
| if (auto [_, success] = read_variable_int(data, payload_len, pos); !success) | ||
| return false; | ||
| auto [string_length, str, success] = read_utf8_string(data, payload_len, pos); | ||
| return success && str == "MQTT"; | ||
| } | ||
|
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| void MQTTPlugin::add_ext_mqtt(const char* data, int payload_len, Flow& flow) | ||
| { | ||
| if (recPrealloc == nullptr) { | ||
| recPrealloc = new RecordExtMQTT(); | ||
| } | ||
| if (!parse_mqtt(data, payload_len, recPrealloc)) | ||
| return; | ||
| flow.add_extension(recPrealloc); | ||
| recPrealloc = nullptr; | ||
| } | ||
|
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| void MQTTPlugin::init(const char* params) | ||
| { | ||
| MQTTOptionsParser parser; | ||
| try { | ||
| parser.parse(params); | ||
| } catch (ParserError& e) { | ||
| throw PluginError(e.what()); | ||
| } | ||
| maximal_topic_count = parser.m_maximal_topic_count; | ||
| } | ||
|
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| ProcessPlugin* MQTTPlugin::copy() | ||
| { | ||
| return new MQTTPlugin(*this); | ||
| } | ||
|
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| } // namespace ipxp |
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