Use ip link JSON output for SocketCAN find_available_interfaces

[lumagi]

Until now, the helper method to find locally available SocketCAN interfaces uses string manipulations to parse the ip link output. Additionally, it uses a regular expression to parse the interface name and determine which of these interfaces are CAN interfaces. As a result, it does not properly detect CAN interfaces with customized names (see #1475 ).

python-can/can/interfaces/socketcan/utils.py

Lines 41 to 69 in 5e5b950

	_PATTERN_CAN_INTERFACE = re.compile(r"(sl|v|vx)?can\d+")
	def find_available_interfaces() -> Iterable[str]:
	"""Returns the names of all open can/vcan interfaces using
	the ``ip link list`` command. If the lookup fails, an error
	is logged to the console and an empty list is returned.
	"""
	try:
	# adding "type vcan" would exclude physical can devices
	command = ["ip", "-o", "link", "list", "up"]
	output = subprocess.check_output(command, text=True)
	except Exception as e: # pylint: disable=broad-except
	# subprocess.CalledProcessError is too specific
	log.error("failed to fetch opened can devices: %s", e)
	return []
	else:
	# log.debug("find_available_interfaces(): output=\n%s", output)
	# output contains some lines like "1: vcan42: <NOARP,UP,LOWER_UP> ..."
	# extract the "vcan42" of each line
	interfaces = [line.split(": ", 3)[1] for line in output.splitlines()]
	log.debug(
	"find_available_interfaces(): detected these interfaces (before filtering): %s",
	interfaces,
	)
	return filter(_PATTERN_CAN_INTERFACE.match, interfaces)

In #1475 , @1atabey1 proposed a more reliable approach to instead use the interface link_type for CAN interface detection. This pull request additionally uses the ip link (Changelog) JSON output option to make parsing the information easier.

JSON output has been available in ip link since version 4.14.0. All Debian / Ubuntu versions with the minimum supported Python version 3.7 also ship with an ip link version > 4.14.0.

[1atabey1]

Thanks for the nicer implementation, gave it a try and works for me as well!

[zariiii9003]

Looks good, thanks you both