#bluetooth #linux-bluetooth #gatt #mesh #l2cap #read-write #rfcomm

bluer

BlueR: official Rust interface to the Linux Bluetooth protocol stack (BlueZ)

31 releases

0.17.1 Mar 14, 2024
0.17.0-pre1 Nov 17, 2023
0.16.0-pre1 Jun 20, 2023
0.15.7 Jan 31, 2023
0.10.3 Jul 18, 2021

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BSD-2-Clause

430KB
8K SLoC

BlueR — Official BlueZ Bindings for Rust

crates.io page docs.rs page BSD-2-Clause license

This library provides the official Rust interface to the Linux Bluetooth protocol stack (BlueZ). Both publishing local and consuming remote GATT services using idiomatic Rust code is supported. L2CAP and RFCOMM sockets are presented using an API similar to Tokio networking.

The following functionality is provided:

  • Bluetooth adapters
    • enumeration
    • configuration of power, discoverability, name, etc.
    • hot-plug support through change events stream
  • Bluetooth devices
    • discovery with custom filters
    • querying of address, name, class, signal strength (RSSI), etc.
    • Bluetooth Low Energy advertisements
    • change events stream
    • connecting and pairing
    • passive LE advertisement monitoring
  • consumption of remote GATT services
    • GATT service discovery
    • read, write and notify operations on characteristics
    • read and write operations on characteristic descriptors
    • optional use of low-overhead AsyncRead and AsyncWrite streams for notify and write operations
  • publishing local GATT services
    • read, write and notify operations on characteristics
    • read and write operations on characteristic descriptors
    • two programming models supported
      • callback-based interface
      • low-overhead AsyncRead and AsyncWrite streams
  • sending Bluetooth Low Energy advertisements
  • Bluetooth authorization agent
  • efficient event dispatching
    • not affected by D-Bus match rule count
    • O(1) in number of subscriptions
  • L2CAP sockets
    • support for both classic Bluetooth (BR/EDR) and Bluetooth LE
    • stream oriented
    • sequential packet oriented
    • datagram oriented
    • async IO interface with AsyncRead and AsyncWrite support
  • RFCOMM sockets
    • support for classic Bluetooth (BR/EDR)
    • stream oriented
    • async IO interface with AsyncRead and AsyncWrite support
  • Bluetooth Mesh
    • provision and join networks
    • send and receive messages
  • database of assigned numbers
    • manufacturer ids
    • service classes, GATT services, characteristics and descriptors

Currently, some classic Bluetooth (BR/EDR) functionality is missing. However, pull requests and contributions are welcome!

Usage

To use BlueR as a library, run the following command in your project directory:

cargo add -F full bluer

This will add the latest version of BlueR with all features enabled as a dependency to your Cargo.toml.

Crate features

The following crate features are available.

  • bluetoothd: Enables all functions requiring a running Bluetooth daemon. For building, D-Bus library headers, provided by libdbus-1-dev on Debian, must be installed.
  • id: Enables database of assigned numbers.
  • l2cap: Enables L2CAP sockets.
  • rfcomm: Enables RFCOMM sockets.
  • mesh: Enables Bluetooth mesh functionality.
  • serde: Enables serialization and deserialization of some data types.

To enable all crate features specify the full crate feature.

Requirements

The minimum support Rust version (MSRV) is 1.75.

This library has been tested with BlueZ 5.60. Older versions might work, but be aware that many bugs related to GATT handling exist. Refer to the official changelog for details.

If any bluetoothd feature is used the Bluetooth daemon must be running and configured for access over D-Bus. On most distributions this should work out of the box.

For mesh feature Bluetooth mesh daemon must be running and configured for access over D-Bus.

Configuration

The following options in /etc/bluetooth/main.conf are helpful when working with GATT services.

[GATT]
Cache = no
Channels = 1

This disables the GATT cache to avoid stale data during device discovery.

By only allowing one channel the extended attribute protocol (EATT) is disabled. If EATT is enabled, all GATT commands and notifications are sent over multiple L2CAP channels and can be reordered arbitrarily by lower layers of the protocol stack. This makes sequential data transmission over GATT characteristics more difficult.

Building

When cloning this repository make sure to use the following command. Otherwise the build will fail with file not found errors.

git clone --recursive https://github.com/bluez/bluer.git

D-Bus development headers are required for building.

Troubleshooting

The library returns detailed errors received from BlueZ.

Set the Rust log level to trace to see all D-Bus communications with BlueZ.

In some cases checking the Bluetooth system log might provide further insights. On Debian-based systems it can be displayed by executing journalctl -u bluetooth. Check the bluetoothd man page for increasing the log level.

Sometimes deleting the system Bluetooth cache at /var/lib/bluetooth and restarting bluetoothd fixes persistent issues with device connectivity.

Examples

Refer to the API documentation and examples folder for examples.

The following example applications are provided.

  • discover_devices: Discover Bluetooth devices and print their properties.

  • gatt_client: Simple GATT client that calls read, write and notify on a characteristic.

  • gatt_server_cb: Corresponding GATT server implemented using callback programming model.

  • gatt_server_io: Corresponding GATT server implemented using IO programming model.

  • gatt_echo_client: Simple GATT client that connects to a server and sends and receives test data.

  • gatt_echo_server: Corresponding GATT server that echos received data.

  • l2cap_client: Simple L2CAP socket client that connects to a socket and sends and receives test data.

  • l2cap_server: Corresponding L2CAP socket server that echos received data.

  • le_advertise: Register Bluetooth LE advertisement.

  • le_passive_scan: LE passive scan & subscribe to updates for discovered peripheral(s).

  • list_adapters: List installed Bluetooth adapters and their properties.

  • mesh_sensor_client: Simple Bluetooth mesh client sending sensor model messages

  • mesh_sensor_server: Simple Bluetooth mesh server receiving sensor model messages

  • mesh_provisioner: Simple Bluetooth mesh provisioner

Use cargo run --all-features --example <name> to run a particular example application.

Tools

See the BlueR tools crate for tools that build on this library.

History

This project started as a fork of blurz but has since then become a full rewrite. It was published under the name blez before it was designated the official Rust interface to BlueZ and renamed to BlueR. Documentation has been mostly copied from the BlueZ API specification, but also adapted where it makes sense.

Dependencies

~5–16MB
~205K SLoC