yifeian / sol

Lightweight MQTT broker, written from scratch

Sol

Oversimplified MQTT broker written from scratch, which mimick mosquitto features. Implemented for learning how the protocol works, for now it supports almost all MQTT v3.1.1 commands on linux platform; it relies on EPOLL interface for multiplexing I/O. Development process is documented in this series of posts.

Build

$ cmake .
$ make

Quickstart play

The broker can be tested using mosquitto_sub and mosquitto_pub or with paho-mqtt python driver.

To run the broker with DEBUG loggin on:

$ ./sol -v

A simple configuration can be passed in with -c flag:

$ ./sol -c path/to/sol.conf

Features roadmap

It's still a work in progress but it already handle the most of the basic features expected from a MQTT broker.

• Unix/TCP sockets
• All main commands are handled correctly
• QoS 0, 1, 2 are handled
• Trie as underlying structure to handle topic hierarchies
• Periodic tasks like stats publishing
• Wildcards on subscriptions (though simple to implement, will be added soon)
• QoS 1 and 2 tracking of pending clients and re-send
• Session present check and handling
• Authentication
• SSL/TLS connections
• Last will & Testament
• Check on max memory used

It apparently not leak memory as of now, there's probably some corner cases, not deeply investigated yet.

Contributing

Pull requests are welcome, just create an issue and fork it.