macos CI runner returning `EHOSTUNREACH` in udp `multicast_join_test`

[squeek502]

Example:

https://github.com/luvit/luv/actions/runs/17858456546/job/50833303436?pr=780

Will submit a PR in a bit to temporarily disable this test when EHOSTUNREACH is returned. This issue is for determine what the proper fix should be.

[Bilal2453]

I've only noticed this test failing on MacOS. Is it platform related or just random networking errors?

[squeek502]

See the existing logic for Linux:

luv/tests/test-udp.lua

Lines 246 to 255 in 2d21390

	-- EPERM here likely means that a firewall has denied the send, which
	-- can happen in some build/CI environments, e.g. the Fedora build system.
	-- Reproducible on Linux with iptables by doing:
	-- iptables --policy OUTPUT DROP
	-- iptables -A OUTPUT -s 127.0.0.1 -j ACCEPT
	-- and for ipv6:
	-- ip6tables --policy OUTPUT DROP
	-- ip6tables -A OUTPUT -s ::1 -j ACCEPT
	if err == "EPERM" then
	print("send to multicast ip was likely denied by firewall, skipping")

Wouldn't surprise me if it was something similar.

[Bilal2453]

My first assumption was firewall/permissions related things yeah. Looking it up on Google, I can notice many similar reports of EHOSTUNREACH errors on MacOS due to permissions like this one.