bluetooth_monitor

Description

This node monitors a Bluetooth connection to a wireless device by using L2ping.
L2ping generates PING echo command on Bluetooth L2CAP layer, and it is able to receive and check echo response from a wireless device.

Block diagram

L2ping is only allowed for root by default, so this package provides the following approach to minimize security risks as much as possible:

• Provide a small program named l2ping_service which performs L2ping and provides wireless device information to bluetooth_monitor by using socket programming.
• bluetooth_monitor is able to know wireless device information and L2ping status as an unprivileged user since those information are sent by socket communication.

Output

bluetooth_monitor: bluetooth_connection

[summary]

level	message
OK	OK
WARN	RTT warning
ERROR	Lost
	Function error

[values]

key	value (example)
Device [0-9]: Status	OK / RTT warning / Verify error / Lost / Ping rejected / Function error
Device [0-9]: Name	Wireless Controller
Device [0-9]: Manufacturer	MediaTek, Inc.
Device [0-9]: Address	AA:BB:CC:DD:EE:FF
Device [0-9]: RTT	0.00ms

• The following key will be added when bluetooth_monitor reports Function error.
  ex.) The connect system call failed.

key (example)	value (example)
Device [0-9]: connect	No such file or directory

Parameters

Name	Type	Description	Default	Range
addresses	array	Bluetooth addresses of the device to monitor	['4C:B9:9B:6E:7F:9A']	N/A
port	integer	Port number to connect to L2ping service on the host	7640	N/A
timeout	integer	Time in seconds to wait for a response from the device	5	N/A
rtt_warn	float	Time in seconds to warn if the round trip time is greater than this value	0.1	N/A

• rtt_warn
  • 0.00(zero): Disable checking RTT
  • otherwise: Check RTT with specified seconds

• addresses
  • *: All connected devices
  • AA:BB:CC:DD:EE:FF: You can specify a device to monitor by setting a Bluetooth address

Instructions before starting

• You can skip this instructions if you run l2ping_service as root user.

1. Assign capability to l2ping_service since L2ping requires cap_net_raw+eip capability.

   sudo setcap 'cap_net_raw+eip' ./build/bluetooth_monitor/l2ping_service
   

2. Run l2ping_service and bluetooth_monitor.

   ./build/bluetooth_monitor/l2ping_service
   ros2 launch autoware_bluetooth_monitor bluetooth_monitor.launch.xml
   

Known limitations and issues

None.