MQTT v3.1.1

In this project, I wrote an MQTT server (version 3.1.1). I found this protocol interesting. I tried to write a server based on the documentation as much as possible, but I could make mistakes or miss some details. The project was tested with mosquitto

Supported Technologies:

• QoS (all levels)
• Reconnect to session (clean session)
• Sending WillMessage on client connection to WilTopic subscribers
• All main commands

What is not yet

• SSL/TSL connections
• Authentication

Peculiarities:

• For this project, I specifically wrote a prefix tree class
• I changed the PINGREQ timeout (increased by 2 times, instead of 1.5)
• When reconnecting to the session, all packets that remain are sent to the user.
• The project is written using Boost.Asio and C++20, so make sure your computer has it.

Build the program

cmake ..
cmake --build .

Server initialization

./mqtt_server -f filename -p port

Note: it is not necessary to initialize both parameters, the default parameters are set inside the program (filename - file.log, port - 1883)

Other

• Testing program: https://mosquitto.org/
• Documentation: http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1/1-os.html