X (Undernet) authentication method

[dgw]

Requested Feature

Specifically, supporting Login on Connect. https://www.undernet.org/docs/x-commands-english

Problems Solved

Login on Connect support would let Sopel bots authenticate to CService accounts without ever revealing their IPs. As most of us already know, revealing one's actual IP on IRC can be an invitation for DDoSes and other script kiddie shenanigans.

Alternatives

Manual configuration using commands_on_connect, or abusing the modes setting, would technically allow doing this without special support in core.

Notes

This was in my note of random ideas, toward the top. It's probably left over from when someone mentioned the idea on IRC ages ago and we just never got around to making an issue to formalize it as an idea.