OpenBSD IPV6_V6ONLY — qbittorrent-nox connection refused

[Veraellyunjie]

On OpenBSD, with the default setting WebUI\Address=*, there is no connection to qbittorrent-nox via IPv4.
OpenBSD has a readme for qbittorrent-nox /usr/local/share/doc/pkg-readmes/qbittorrent-nox which suggests WebUI\Address=127.0.0.1, which also gives no connection via IPv4.

The issue was discussed here: https://www.unitedbsd.com/d/634-qbittorrent-nox-connection-refused

The cause apparently is IPV6_V6ONLY option:

IPV6_V6ONLY int *
Get or set whether only IPv6 connections can be made to this socket. For wildcard
sockets, this can restrict connections to IPv6 only. With OpenBSD IPv6 sockets are
always IPv6-only, so the socket option is read-only (not modifiable).

As user rvp@unitedbsd explains,

I think (I haven't read the code, mind) that qbittorrent is setting that option to 0 when the WebUI\Address= field is * (listen on all), expecting the server will listen on both IPv6 & IPv4 addresses, but, this doesn't work on OpenBSD.

I personally have settled with WebUI\Address=0.0.0.0 which works for my setup.

I sent an email qbittorrent-nox email.txt to OpenBSD port maintainer Elias M. Mariani and readme author Rafael Sadowski but no reply has followed in 20 days and there have been no changes in ports's CVS.

Herein, I inform the qbittorrent devs and community of the issue and ask what can be done.

[Veraellyunjie]

The openbsd-misc mailing list has been asked, you can read the thread here:
https://marc.info/?t=164986437300003&r=1&w=2

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Highlights:

the ideal fix for qbittorrent-nox would be if it created separate socket bindings, one for IPv4, one for IPv6

This issue does affect various software in packages, it is a common
thing you need to deal with if you're using various software on OpenBSD.
It doesn't really feel right to me to mention it in a pkg-readme for
one specific package when it affects a wide range of them. Perhaps an
FAQ section might be a better idea.

In qbittorrent-nox case, Qt5's network socket listener, when told to
listen for connections to "Any" address, binds only a v6 socket. To
have it do something different, software using this API would need
to listen for "AnyIPv6" and/or "AnyIPv4" instead.

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The port maintainer was contacted with a patch proposal with no response.
The port has been updated though.