"ServerTransportListenAddr obfs4 0.0.0.0:7002" becomes "TransportProxy obfs4 [::]:7002" in the state file
We have a bridge operator on #tor (@JFCaringi) who has set
ServerTransportListenAddr obfs4 0.0.0.0:7002
in their torrc file, yet obfs4proxy binds to 7002 ipv6 and not to 7002 ipv4.
After some debugging, it turns out their state file says
TransportProxy obfs4 [::]:7002
So my first question had been "is it Tor that is sending the wrong thing to obfs4proxy, or is obfs4proxy doing the wrong thing on its own", and based on that line in the state file, my guess is it it Tor doing the wrong thing.
It looks like something changed in things like INADDR_ANY in a surprising way?
This same issue was also reported on reddit at https://www.reddit.com/r/TOR/comments/dh9wky/unable_to_force_obfs4proxy_to_listen_on_ipv4/ and it appeared to have no resolution there.