Adapters

Messenger delegates low-level frame I/O to an adapter.

Default Adapter

By default, Messenger uses CanMessenger::Adapter::Socketcan, which:

• Opens Linux raw CAN sockets.
• Builds/parses classic CAN and CAN FD frame layouts.
• Detects and exposes extended frame flag.

Adapter Contract

Custom adapters should subclass CanMessenger::Adapter::Base and implement:

• open_socket(can_fd: false)
• build_can_frame(id:, data:, extended_id: false, can_fd: false)
• receive_message(socket:, can_fd: false)
• parse_frame(frame:, can_fd: false)

Socketcan#parse_frame additionally supports can_fd: nil as an auto-detect mode when parsing raw frames directly:

• nil: infer CAN FD from frame size (>= CANFD_FRAME_SIZE).
• false: force classic CAN parse.
• true: force CAN FD parse.

For custom adapters, keep the base signature compatible, and if you expose direct frame parsing outside the listener path, consider supporting a similar auto-detect sentinel.

Injecting an Adapter

You can pass either a class or an already-built instance:

# Class injection
messenger = CanMessenger::Messenger.new(
  interface_name: 'can0',
  adapter: MyAdapterClass
)

# Instance injection
adapter = MyAdapterClass.new(interface_name: 'can0', logger: Logger.new($stdout), endianness: :native)
messenger = CanMessenger::Messenger.new(interface_name: 'can0', adapter: adapter)

When a class is passed, Messenger initializes it with interface_name, logger, and endianness.