bug#54824: 29.0.50; Add 'user' parameter to ERC entry-point commands

["J.P." <jp@neverwas.me>]

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Tags: patch

One of the first messages emitted in a traditional IRC exchange is the
USER command [1]. Its first parameter is referred to variously as
username, login, and user ID. Historically, IRCds would sometimes derive
the user portion of a message's "source" field, from this parameter,
yielding something like :nick!~user@hostname for messages relayed on a
client's behalf. But that spot was long ago usurped by the account
services username, and over time, the role of the plain username has
diminished to the point where some progressives now consider it
essentially meaningless. ERC was perhaps ahead of its time in this
regard, having only ever afforded it second-class status.

However. This perceived irrelevance hasn't stopped various IRCds and
bouncers from requisitioning the field for their own devices. One
example is the quasi convention of

  <bouncer-account>@<client-id>/<configured-network-id>

popularized by BNCs like ZNC. A common source of frustration for new ERC
users relying on such endpoints is finding a way to specify a value for
this temporarily, for a single entry-point invocation. Central to this
issue is the fact that by default, ERC connections are "asynchronous."
Indeed, let-binding this variable while invoking an entry point often
fails because its extent evaporates before it can exert any influence.
As such, users are tripped up when wanting to fire off multiple
entry-point commands at once or in rapid succession.

This patch aims to change that. See #48598 for accompanying tweaks to
doc/misc/erc.texi. Thanks.

P.S. Bonus question: should the username be configurable when invoking
an entry point interactively? Or would that just be excess noise?


[1] https://modern.ircdocs.horse/#user-message


In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.31, cairo version 1.17.4)
 of 2022-04-05 built on localhost
Repository revision: e2fb5ecaea67497224455fdbfe4850a5a74c9d00
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
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From 273bd46760fbe01b57874d7e74e5ff41ee1817c4 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Sun, 3 Apr 2022 14:24:24 -0700
Subject: [PATCH] Accept user keyword arg in ERC entry-point commands

* lisp/erc/erc-backend.el (erc-server-reconnect): Reuse the username
argument from the previous session's USER command when reconnecting.
Also pass the existing client certificate, fixing an issue related to
bug#47788.
(erc-session-user-full-name): Move variable here from erc.el.
(erc-session-username): Add new local variable to store entry point
parameter.

* lisp/erc/erc.el (erc-session-user-full-name): Move variable to
erc-backend.
(erc-open, erc-determine-parameters, erc, erc-tls): Accept new
optional user parameter.
(erc-query): Preserve current `erc-session-username' when calling
`erc-open'.
(erc-login): Use `erc-session-username' instead of deriving it.
(erc-compute-user): Add new function to determine user name from
explicit argument or user options.
---
 lisp/erc/erc-backend.el | 12 +++++++++++-
 lisp/erc/erc.el         | 32 ++++++++++++++++++++------------
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index 398fe6cc9e..101c9e199d 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -124,6 +124,14 @@ erc-server-current-nick
   "Nickname on the current server.
 Use `erc-current-nick' to access this.")
 
+(defvar-local erc-session-user-full-name nil
+  "Real name used for the current session.
+Sent as the last argument to the USER command.")
+
+(defvar-local erc-session-username nil
+  "Username used for the current session.
+Sent as the first argument of the USER command.")
+
 ;;; Server attributes
 
 (defvar-local erc-server-process nil
@@ -585,7 +593,9 @@ erc-server-reconnect
       (let ((erc-server-connect-function (or erc-session-connector
                                              #'erc-open-network-stream)))
         (erc-open erc-session-server erc-session-port erc-server-current-nick
-                  erc-session-user-full-name t erc-session-password)))))
+                  erc-session-user-full-name t erc-session-password
+                  nil nil nil erc-session-client-certificate
+                  erc-session-username)))))
 
 (defun erc-server-delayed-reconnect (buffer)
   (if (buffer-live-p buffer)
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 52fe106f2d..f2106db5f3 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -1802,9 +1802,6 @@ erc-buffer-list-with-nick
 (defvar-local erc-default-recipients nil
   "List of default recipients of the current buffer.")
 
-(defvar-local erc-session-user-full-name nil
-  "Full name of the user on the current server.")
-
 (defvar-local erc-channel-user-limit nil
   "Limit of users per channel.")
 
@@ -1971,8 +1968,8 @@ erc-setup-buffer
 
 (defun erc-open (&optional server port nick full-name
                            connect passwd tgt-list channel process
-                           client-certificate)
-  "Connect to SERVER on PORT as NICK with FULL-NAME.
+                           client-certificate user)
+  "Connect to SERVER on PORT as NICK with USER and FULL-NAME.
 
 If CONNECT is non-nil, connect to the server.  Otherwise assume
 already connected and just create a separate buffer for the new
@@ -2079,7 +2076,7 @@ erc-open
       (erc-display-prompt)
       (goto-char (point-max)))
 
-    (erc-determine-parameters server port nick full-name)
+    (erc-determine-parameters server port nick full-name user)
 
     ;; Saving log file on exit
     (run-hook-with-args 'erc-connect-pre-hook buffer)
@@ -2200,6 +2197,7 @@ erc-select-read-args
 (cl-defun erc (&key (server (erc-compute-server))
                     (port   (erc-compute-port))
                     (nick   (erc-compute-nick))
+                    (user   (erc-compute-user))
                     password
                     (full-name (erc-compute-full-name)))
   "ERC is a powerful, modular, and extensible IRC client.
@@ -2211,6 +2209,7 @@ erc
    (server (erc-compute-server))
    (port   (erc-compute-port))
    (nick   (erc-compute-nick))
+   (user   (erc-compute-user))
    password
    (full-name (erc-compute-full-name))
 
@@ -2222,7 +2221,7 @@ erc
 whereas `erc-compute-port' and `erc-compute-nick' will be invoked
 for the values of the other parameters."
   (interactive (erc-select-read-args))
-  (erc-open server port nick full-name t password))
+  (erc-open server port nick full-name t password nil nil nil nil user))
 
 ;;;###autoload
 (defalias 'erc-select #'erc)
@@ -2232,6 +2231,7 @@ 'erc-ssl
 (cl-defun erc-tls (&key (server (erc-compute-server))
                         (port   (erc-compute-port))
                         (nick   (erc-compute-nick))
+                        (user   (erc-compute-user))
                         password
                         (full-name (erc-compute-full-name))
                         client-certificate)
@@ -2275,7 +2275,7 @@ erc-tls
 		 (erc-select-read-args)))
   (let ((erc-server-connect-function 'erc-open-tls-stream))
     (erc-open server port nick full-name t password
-              nil nil nil client-certificate)))
+              nil nil nil client-certificate user)))
 
 (defun erc-open-tls-stream (name buffer host port &rest parameters)
   "Open an TLS stream to an IRC server.
@@ -4305,7 +4305,8 @@ erc-query
                        nil
                        (list target)
                        target
-                       erc-server-process)))
+                       erc-server-process
+                       erc-session-username)))
     (unless buf
       (error "Couldn't open query window"))
     (erc-update-mode-line)
@@ -6147,14 +6148,14 @@ erc-login
   (erc-server-send
    (format "USER %s %s %s :%s"
            ;; hacked - S.B.
-           (if erc-anonymous-login erc-email-userid (user-login-name))
+           erc-session-username
            "0" "*"
            erc-session-user-full-name))
   (erc-update-mode-line))
 
 ;; connection properties' heuristics
 
-(defun erc-determine-parameters (&optional server port nick name)
+(defun erc-determine-parameters (&optional server port nick name user)
   "Determine the connection and authentication parameters.
 Sets the buffer local variables:
 
@@ -6162,11 +6163,13 @@ erc-determine-parameters
 - `erc-session-server'
 - `erc-session-port'
 - `erc-session-user-full-name'
+- `erc-session-username'
 - `erc-server-current-nick'"
   (setq erc-session-connector erc-server-connect-function
         erc-session-server (erc-compute-server server)
         erc-session-port (or port erc-default-port)
-        erc-session-user-full-name (erc-compute-full-name name))
+        erc-session-user-full-name (erc-compute-full-name name)
+        erc-session-username (erc-compute-user user))
   (erc-set-current-nick (erc-compute-nick nick)))
 
 (defun erc-compute-server (&optional server)
@@ -6184,6 +6187,10 @@ erc-compute-server
       (getenv "IRCSERVER")
       erc-default-server))
 
+(defun erc-compute-user (&optional user)
+  "Return a suitable value for the session user name."
+  (or user (if erc-anonymous-login erc-email-userid (user-login-name))))
+
 (defun erc-compute-nick (&optional nick)
   "Return user's IRC nick.
 
@@ -7012,6 +7019,7 @@ erc-get-parsed-vector-type
 ;; Teach url.el how to open irc:// URLs with ERC.
 ;; To activate, customize `url-irc-function' to `url-irc-erc'.
 
+;; FIXME change user to nick, and use API to find server buffer
 ;;;###autoload
 (defun erc-handle-irc-url (host port channel user password)
   "Use ERC to IRC on HOST:PORT in CHANNEL as USER with PASSWORD.
-- 
2.35.1