mosquitto_pyplugin

Mosquitto plugin that lets you write your plugins in Python.

Compiling

You need mosquitto version 2.0.0 or higher.

Make sure you have Python dev package installed (apt-get install python-dev or apt-get install python3-dev under Debian/Ubuntu).

You must either have mosquitto header files installed globally in /usr/include, etc. or clone this repository at the top of the mosquitto source directory. Then:

cd mosquitto_pyplugin
make

Pass PYTHON variable to compile with other Python interpreter version than default (pypy3.9):

make PYTHON=python3

If all goes ok, there should be mosquitto_pyplugin.so file in the current directory. Copy it under path accessible for mosquitto daemon, e.g.: /usr/local/lib/mosquitto/.

Troubleshooting

If you get errors while compiling the plugin about -lmosquitto then you have a missing link to libmosquitto. Just check the file /usr/lib/libmosquitto.so or /usr/lib/mosquitto.so.1 exists and create a symlink:

ln -s /usr/lib/libmosquitto.so.1 /usr/lib/libmosquitto.so

And make again the plugin. This time it should work.

Running

Add following line to mosquitto.conf:

plugin /path/to/mosquitto_pyplugin.so

File mosquitto_pyplugin.py must be found by the used python interpreter. You can use PYTHONPATH to adapt this accordingly.

You must also give a pointer to Python module which is going to be loaded (make sure it's in Python path, use PYTHONPATH env variable to the rescue):

plugin_opt_pyplugin_module some_module

Python module

Python module should do required initializations when it's imported and provide following global functions:

• plugin_init(options): called on plugin init, options is a dictionary with all plugin_opt_ params from mosquitto configuration (except plugin_opt_pyplugin_module)

• plugin_cleanup(options): called on plugin cleanup, options is a dictionary with all plugin_opt_ params from mosquitto configuration (except plugin_opt_pyplugin_module)

• basic_auth(client, username, password): return mosquitto_pyplugin.MOSQ_ERR_SUCCESS if given client, username and password combination is allowed to log in or mosquitto_pyplugin.MOSQ_ERR_PLUGIN_DEFER if another module should take care

• acl_check(client, topic, access, payload): return MOSQ_ERR_SUCCESS if given user is allowed to subscribe (access = mosquitto_pyplugin.MOSQ_ACL_SUBSCRIBE), read (access = mosquitto_pyplugin.MOSQ_ACL_READ) or publish (access = mosquitto_pyplugin.MOSQ_ACL_WRITE) to given topic (see mosquitto_pyplugin module below). payload argument holds message payload as bytes, or None if not applicable. Return mosquitto_pyplugin.MOSQ_ERR_PLUGIN_DEFER in case another plugin should take care

• psk_key(client, identity, hint): return PSK string (in hex format without heading 0x) if given identity and hint pair is allowed to connect else return "" for returning MOSQ_ERR_AUTH or None for returning MOSQ_ERR_PLUGIN_DEFER to mosquitto.

• disconnect(client, reason) : inform about disconnection of client with reason code reason

• message(client, message_event) : inform new message event. Message is passed as dictionary If the callback adapts the message, the new information is passed back to mosquitto and the message will be adapted accordingly.

• tick(): tick event. Will be called on every mosquitto main loop iteration

• reload(): reload event. Will be called on reload/security_init by mosquitto

Auxiliary module

Plugin module can import an auxiliary module provided by mosquitto:

import mosquitto_pyplugin

The module provides following function:

• log(loglevel, message): log message into mosquitto's log file with the given loglevel (one of the constants below).

• client_address(client): get client address from client handle

• client_id(client): get client id from client handle

• client_certificate(client): get the client certificate from the client handle

• client_protocol(client): get used client protocol from client handle

• client_protocol_version(client): get used client protocol version from client handle

• client_username(client): get client username from client handle

• set_username(client, username): change client username in client handle to username

• kick_client_by_clientid(client_id, with_will):

• kick_client_by_username(client_username, with_will):

• broker_publish(clientid, topic, payload, qos, retain, properties):

• topic_matches_sub(sub, topic): it mirrors mosquitto_topic_matches_sub from libmosquitto C library - the function checks whether topic matches given sub pattern (for example, it returns True if sub is /foo/# and topic is /foo/bar) and is mostly useful is acl_check function above

The following constants for access parameter in acl_check are provided:

• MOSQ_ACL_NONE
• MOSQ_ACL_SUBSCRIBE
• MOSQ_ACL_READ
• MOSQ_ACL_WRITE

The following constants for loglevel parameter in Log are provided:

• MOSQ_LOG_INFO
• MOSQ_LOG_NOTICE
• MOSQ_LOG_WARNING
• MOSQ_LOG_ERR
• MOSQ_LOG_DEBUG
• MOSQ_LOG_SUBSCRIBE (not recommended for use by plugins)
• MOSQ_LOG_UNSUBSCRIBE (not recommended for use by plugins)

The following constants for errors are provided:

• MOSQ_ERR_SUCCESS
• MOSQ_ERR_INVAL
• MOSQ_ERR_NOMEM
• MOSQ_ERR_AUTH
• MOSQ_ERR_UNKNOWN
• MOSQ_ERR_PLUGIN_DEFER