Fix timestamp handling in udp_multicast on macOS

[felixdivo]

Fix #1275.

[codecov]

Codecov Report

Merging #1278 (e20e47b) into develop (af55b0a) will decrease coverage by 0.02%.
The diff coverage is 56.09%.

@@             Coverage Diff             @@
##           develop    #1278      +/-   ##
===========================================
- Coverage    66.02%   65.99%   -0.03%     
===========================================
  Files           86       86              
  Lines         8915     8943      +28     
===========================================
+ Hits          5886     5902      +16     
- Misses        3029     3041      +12     

[felixdivo]

@Gudoghe Can you check the fix? 🤔

You should be able to install it with pip install git https://github.com/hardbyte/python-can.git@felixdivo-fix-1275?

[felixdivo]

You should now also be able to run the tests, e.g. with:

pip install tox
tox -e py

Could you post the results for the test suite parts BasicTestUdpMulticastBusIPv4 and BasicTestUdpMulticastBusIPv6? They should now run on your system (and not be skipped any more).

[Gudoghe]

@felixdivo The command to install the fix seems to return an error 404, maybe there's some problem with the url?

[felixdivo]

Ah, jup, there's a missing +, sorry. This works for me: pip install git+https://github.com/hardbyte/python-can.git@felixdivo-fix-1275.

[Gudoghe]

The patch and tox were installed successfully but the tox -e py command gives me the following error:
ERROR: tox config file (either pyproject.toml, tox.ini, setup.cfg) not found

Sorry I'm quite new to this tool and environment.

[felixdivo]

Strange ... there should be one. Are you sure that you are running it from the repository root? pwd (on Unix) should give you something ending in /python-can.

Alternatively, you can also try tox -e gh one it works.

[Gudoghe]

Alright I managed to clone the patched repo and do a clean install of python-can from there. I then ran the tests on the cloned repository and all the tests regarding BasicTestUdpMulticastBusIPv4 and BasicTestUdpMulticastBusIPv6 failed, I'm attaching a screenshot.

Moreover I tried to run again the example from the Multicast page and the error i get back changed to the following:

Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/can/interfaces/udp_multicast/bus.py", line 264, in _create_socket
sock.bind(("", self.port))
OSError: [Errno 48] Address already in use

[felixdivo]

Uhm, that's strange. Can you find out what is using that address, or use another one (suitable for multicast, like the default one)? I can't really debug it from here 🙃. But at least the exception from last time is avoided. I suppose the tests fail due to similar problems?

[Gudoghe]

I've tried looking at all processes running with the command ps -fA but nothing seems to be taking up that port.
I've tried changing the port to be assigned in the range of 43001-43187, as to my understanding this seems to be the proper range (https://www.speedguide.net/port.php?port=43113), but I now run into a new error:

Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/can/interfaces/udp_multicast/bus.py", line 273, in _create_socket
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, request)
OSError: [Errno 49] Can't assign requested address

I'm really at a blank for a solution. If you had any suggestions on what to try next that'd be greatly appreciated.
Thank you again for all the support!

[felixdivo]

You're welcome. 😃 I am currently retreating from this repo but since it wrote that interface I figured that I should have a look at this.

Hm ... Are you sure that multicast works elsewhere? I cold not find a simple test command, but I did find this article. It's from 2009, but looks relevant.

[Gudoghe]

I've followed the instructions and I do find a couple of addresses in the multicasting range (239.255.255.250, 224.0.0.251) and if I ping them I get a response, so I assume the multicasting is working.

[felixdivo]

I'm a bit confused: In the exception above you use IPv6 (and it fails) and now you checked IPv4 multicast (and it works). Maybe, you can try IPv4 multicast by using something like DEFAULT_GROUP_IPv4? Maybe macOS only has problems with IPv6 multicast?

[felixdivo]

Okay, so this became kinda stale. I suggest merging at lest these changes, since they at least resolve some problems. If more occur, we can still keep discussing them and add more patches.

Side note: @zariiii9003 I wrote about reducing my contributions and why I do that on the mailing list 🙂

[felixdivo]

Black has a problem. We should just update (psf/black#2964). I added a commit for that to this PR.

[zariiii9003]

@felixdivo Do you know why the UdpMulticast tests are failing randomly?

[felixdivo]

Nope ... the type of error also confuses me.