linux(64)-compat and ipv6 setsockopt

[Joe Love]

I’ve been using FreeBSD 11 with the linux64 support, and have been using the not-included centos6.7-64bit ports patch to run some programs which depend on a more modern linux installation.  Specifically, I’ve been using them for Steamcmd, Ark:Survival Evolved, and Factorio (headless).  The latest of which started this journey.

It seems that a piece of code related to setting a particular socket option for IPv6 sockets fails under the linux compat layer:

int ipv6only = 1;
setsockopt(this->fd6, IPPROTO_IPV6, IPV6_V6ONLY, &ipv6only, sizeof(ipv6only));

Both Steamcmd and Factorio would spit out error messages like this (this one being from Factorio):
1.132 Error MultiplayerManager.cpp:108: MultiplayerManager failed: "Setsockopt failed: Protocol not available”

One of the devs for Factorio looked through a more complete trace, and their code, and realized that the above line of code was singled out as causing the error.


In trying to understand the issue, I tried their advice - disable IPv6 (which involved a buildworld/buildkernel) and tried the process again.  In doing so, their code completely skips trying to setup IPv6 at all, so the program runs fine.  Steamcmd also stopped producing the message, so I assume its issue is similar, or at least also related to  IPv6 support.  I think steamcmd is actually 32bit, so it should be able to verify that same message on a 10.2 system.

Ultimately, I’m wondering if there’s a known issue with IPv6 support of linux apps running using the linux compat module.

Thanks,
-Joe