René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug] can.detect_available_configs(\"socketcan\") fails with KeyError: \"link_type\"","articleBody":"### Describe the bug\r\n\r\nHi, we had here a docker container with host network setting enabled (Ubuntu 22.04 inside and outside). it creates vcan interfaces.\r\n\r\nwhen I create a small file like\r\n\r\n```python\r\nimport can\r\n\r\ncan.detect_available_configs(\"socketcan\")\r\n```\r\nand run it via python, i got the following error:\r\n\r\nTraceback (most recent call last):\r\n  File \"tmp.py\", line 3, in \u003cmodule\u003e\r\n    can.detect_available_configs(\"socketcan\")\r\n  File \"/usr/local/lib/python3.10/dist-packages/can/interface.py\", line 186, in detect_available_configs\r\n    bus_class._detect_available_configs()  # pylint: disable=protected-access\r\n  File \"/usr/local/lib/python3.10/dist-packages/can/interfaces/socketcan/socketcan.py\", line 878, in _detect_available_configs\r\n    for channel in find_available_interfaces()\r\n  File \"/usr/local/lib/python3.10/dist-packages/can/interfaces/socketcan/utils.py\", line 69, in find_available_interfaces\r\n    interfaces = [i[\"ifname\"] for i in output_json if i[\"link_type\"] == \"can\"]\r\n  File \"/usr/local/lib/python3.10/dist-packages/can/interfaces/socketcan/utils.py\", line 69, in \u003clistcomp\u003e\r\n    interfaces = [i[\"ifname\"] for i in output_json if i[\"link_type\"] == \"can\"]\r\nKeyError: 'link_type'\r\n\r\nThe problem here is that the output of\r\n\r\n```bash\r\nip -json link list up\r\n```\r\nresults in\r\n\r\n```json\r\n[\r\n    {\r\n        \"ifindex\": 1,\r\n        \"ifname\": \"lo\",\r\n        \"flags\": [\r\n            \"LOOPBACK\",\r\n            \"UP\",\r\n            \"LOWER_UP\"\r\n        ],\r\n        \"mtu\": 65536,\r\n        \"qdisc\": \"noqueue\",\r\n        \"operstate\": \"UNKNOWN\",\r\n        \"linkmode\": \"DEFAULT\",\r\n        \"group\": \"default\",\r\n        \"txqlen\": 1000,\r\n        \"link_type\": \"loopback\",\r\n        \"address\": \"00:00:00:00:00:00\",\r\n        \"broadcast\": \"00:00:00:00:00:00\"\r\n    },\r\n    {},\r\n    {\r\n        \"ifindex\": 5,\r\n        \"ifname\": \"docker0\",\r\n        \"flags\": [\r\n            \"NO-CARRIER\",\r\n            \"BROADCAST\",\r\n            \"MULTICAST\",\r\n            \"UP\"\r\n        ],\r\n        \"mtu\": 1500,\r\n        \"qdisc\": \"noqueue\",\r\n        \"operstate\": \"DOWN\",\r\n        \"linkmode\": \"DEFAULT\",\r\n        \"group\": \"default\",\r\n        \"link_type\": \"ether\",\r\n        \"address\": \"02:42:48:75:80:6b\",\r\n        \"broadcast\": \"ff:ff:ff:ff:ff:ff\"\r\n    },\r\n...\r\n```\r\n\r\nso especially there is one empty json object in between the other devices. This is the problematic one. So to fix it, in\r\n\r\npython-can/can/interfaces/socketcan/utils.py\r\n\r\nat line 69 one need to check if i is empty or maybe even better if i contains \"link_type\".\r\n\r\n### To Reproduce\r\n\r\nI found no way to easy reproduce this one without our docker container at the moment, it can be simulated if instead of the \"ip -json link list up\" call (python-can/can/interfaces/socketcan/utils.py row 52) in the code some json is read (or python hardcoded list) that contains an empty dict / object. \r\n\r\n### Expected behavior\r\n\r\nThe python script given above should run without errors :-).\r\n\r\n\r\n### Additional context\r\n\r\nOS and version: Ubuntu 22.04 inside docker Ubuntu 22.04\r\nPython version: 3.10.6\r\npython-can version: 4.2.1\r\npython-can interface/s (if applicable): vcan\r\n\r\n\u003cdetails\u003e\u003csummary\u003eTraceback and logs\u003c/summary\u003e\r\n\u003c!-- Has to be followed by an empty line! --\u003e\r\n\r\n\u003c!-- More details such as a minimal script to demonstrate the bug, relevant logs and any tracebacks go here. --\u003e\r\n\r\n\u003c!-- Code examples can be included: --\u003e\r\n\u003c/details\u003e\r\n","author":{"url":"https://github.com/DanielBrandes-FlyNow","@type":"Person","name":"DanielBrandes-FlyNow"},"datePublished":"2023-05-17T11:21:23.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/1598/python-can/issues/1598"}