bug#71578: 29.3; ERC 5.5.0.29.1: No documented support for setting server and nickserv authentication per-server

[Richard Sent]

Hi all,

When using ERC, various servers have different policies for nickserv
identification and server authentication. For example, irc.libera.chat
forwards the server password to nickserv, while irc.pine64.org ignores
server password and nickserv is authenticated separately.

By default, erc uses auth-source for server authetication
(erc-auth-source-server-function), and can optionally use auth-source
for nickserv identification (erc-use-auth-source-for-nickserv-password).
These settings are global and affect every server.

This causes problems where credentials may be needlessly
double-decrypted using auth-source. This is particularly annoying when
auth-sources needs to decrypt data and requires manual intervention
(such as touching a yubikey).

This occurs because the auth-source specification for server
authentication and nickserv authentication do not necessarily match so
the cached result is not returned. (For example, libera.chat has
iridium.libera.chat, mercury.libera.chat, etc. which are passed in the
spec for nickserv authentication, while irc.libera.chat is passed for
server authentication.)

Ideally ERC should have a documented method for disabling server
authentication and nickserv authentication on a per-server basis. As a
workaround I found the following methods currently work:

--8<---------------cut here---------------start------------->8---
;; Note that these must be "", not nil

;; Pass :password "" to disable server authentication
(erc-tls :server "irc.pine64.org"  :nick "freakingpenguin" :password "")

;; Set nickserv password to "" to disable nickserv authentication
(setq erc-nickserv-passwords '((Libera.Chat (("freakingpenguin" . "")))))
--8<---------------cut here---------------end--------------->8---

As far as I'm aware this isn't documented anywhere officially so there's
no guarantee it will continue to work in the future.

This is intended as a tracking ticket following discussion on #erc.


In GNU Emacs 29.3 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.41,
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Windowing system distributor 'The X.Org Foundation', version 11.0.12101012
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-- 
Take it easy,
Richard Sent
Making my computer weirder one commit at a time.