janus-plugin-rs

Library for creating Rust plugins and event handlers for Janus. Still moderately unstable.

[dependencies]
janus-plugin = "0.13.0"

Compatibility

Currently compatible with Janus versions >= 0.10.9; Janus makes breaking changes relatively frequently to the plugin API, so expect this library to require updating and recompilation for plugins to continue to work with new Janus versions.

Building

Requires the Jansson native library (Ubuntu: libjansson-dev) to link against; tested as compatible with versions >= 2.5.

$ cargo build --all

Testing

$ cargo test --all

Basic usage

Janus expects to dynamically link plugins as libraries and then call a create function on them to return a janus_plugin struct, which has a variety of function pointers that Janus will call when plugin-related events in the core happen.

These bindings provide a build_plugin! macro that accepts as arguments plugin metadata and a set of (extern C) Rust functions, producing a Rust version of the janus_plugin struct, and an export_plugin! macro that defines the create function to return that struct. So to implement a plugin, you should write some handler functions, and then use those macros like so:

use std::os::raw::c_char;

// helper macro for generating C-style strings from Rust string literals at compile time
macro_rules! c_str {
    ($lit:expr) => {
        unsafe {
            std::ffi::CStr::from_ptr(concat!($lit, "\0").as_ptr() as *const c_char)
        }
    }
}

extern "C" fn init(callbacks: *mut PluginCallbacks, config_path: *const c_char) -> c_int {
    janus_info!("Plugin loaded!");
    0
}

extern "C" fn destroy() {
    janus_info!("Plugin destroyed!");
}

// ...other handlers omitted: see
// https://janus.conf.meetecho.com/docs/plugin_8h.html#details

const PLUGIN: Plugin = build_plugin!(
    LibraryMetadata {
        // The Janus plugin API version. The version compiled into the plugin
        // must be identical to the version in the Janus which loads the plugin.
        api_version: 15,
        // Incrementing plugin version number for your own use.
        version: 1,
        // Human-readable metadata which Janus can query.
        name: c_str!("My plugin name"),
        package: c_str!("My plugin package name"),
        version_str: c_str!(env!("CARGO_PKG_VERSION")),
        description: c_str!(env!("CARGO_PKG_DESCRIPTION")),
        author: c_str!(env!("CARGO_PKG_AUTHORS")),
    },
    init,
    destroy,
    // ...other handlers omitted: see
    // https://janus.conf.meetecho.com/docs/plugin_8h.html#details
);

export_plugin!(&PLUGIN);

Examples

Here are some projects which are using these bindings:

• https://github.com/mozilla/janus-plugin-sfu
• https://github.com/ivanovaleksey/janus-echotest-rs
• https://github.com/netology-group/janus-conference/