Python library for Generic Netlink

This is a library for doing Gener Netlink interactions in a way that leverages the strengths of high-level Python. It originally existed as an internal tool at Blu Wireless for NL80211 wireless device configuration, then the generic components were extracted to form this library.

Netlink and Generic Netlink themselves aren't very complicated, but the attribute system can result in reams of boilerplate code. The aim of this library is to reduce that boilerplate. The key observation is that for some/most/all genl families, given knowledge about which attributes appear in which context and what type their payload should have, attribute sets can be mapped to Python dictionaries. So to use this library you provide a schema expressing that knowledge about attribute semantics in the protocol you're using, and it gives you an ergonomic way to build and parse messages.

The best way to see what this really means is to take a look at nl80211.py, where we define an example schema for NL80211 commands, and examples/nl80211_dump.py, which uses that schema to query NL80211 for information about a given WiFi adapter.

Works on both Python 2 and 3. Pure Python, no dependencies.

Known limitations

• It would make sense for this library to help you build and parse multi-part Netlink messages, but it doesn't.

• No HTML documentation. There are docstrings in the code, though. The most interesting bit is nlattr.NlAttrSchema.

Setup

Can by installed with usual Python package installation procedures. The cleanest way is usually with Pipenv:

• sudo apt install python-pip # Or equivalent for your OS
• pip install --user pipenv
• export PIPENV_VENV_IN_PROJECT=1 # Explained below
• cd <root directory of your application source code>
• pipenv install <root directory of this repository>

If your application needs to be privileged

There are some complications if your application needs to run as root: The above procedure installs the library in a virtualenv, which root will not automatically have access to. One way around this is to run your application via a sudo command that passes your user's Python environment into the sudo environment:

• pipenv shell
• sudo --preserve-env $(which python) <your app's entrypoint>

The reason we exported PIPENV_VENV_IN_PROJECT=1 above, then, helps you ensure that the root user has read permission on your virtualenv files.

If you are okay with modifying the target system's global configuration, a simpler alternative is to forego virtualenvs and install the library globally:

• cd <root directory of this repository>
• sudo pip3 install . # (Assuming you will be using Python 3, else use 'pip')

Running tests

• pip install --user tox
• cd <root directory of this repository>
• tox