Kick matrix users in bridged rooms if they cannot join the mapped channel for any reason

[kegsay]

We currently already do this based on a list of IRC error codes like err_needreggednick. This can miss certain error codes and notably misses connection issues like reaching i:line limits.

It will be better to make the code failsafe (err on the side of kicking) than failunsafe. This can probably be implemented using a timer along with checking for a join response of some kind. If the timer expires, we give up trying to join and kick the user. This means we will now err on the side of kicking erroneously (due to say join throttling or transient network problems) which will make the UX matrix side slightly worse.

This has been formally requested by Freenode and not negotiable.

[kegsay]

Notably this is going to affect channels which have flood protection enabled as bouncing the bridge will trigger it. Given this issue is highly coupled to Freenode, it looks like ircd-seven has a unique numeric for this which isn't documented on https://www.alien.net.au/irc/irc2numerics.html :

 /* 480 ERR_THROTTLE */ ":%s 480 %s %s :Cannot join channel (+j) - throttle exceeded, try again later"

For cases like this, we should actually try again later rather than giving up.

[kegsay]

Forking off that issue as it really needs to be addressed first.

[ssbarnea]

Does this means the the matrix bridge with freenode is mostly useless if you need to use channels that require registration? ... like openstack or ansible ones?

[gerroon]

So far it has been useless most of the time for me. I am kicked out with this error constantly.

[Half-Shot]

Apparently we didn't kick some users when they got a err_notonchannel, which should have happened.

[wildwestrom]

Just wanna mention, this error (err_needreggednick) still happens with certain libera.chat channels.