master 4da7d24988a 06/37: Add MOTD command to ERC

[F. Jason Park]

branch: master
commit 4da7d24988ae096d757021eb8ed9d014990de16e
Author: F. Jason Park <jp@neverwas.me>
Commit: F. Jason Park <jp@neverwas.me>

    Add MOTD command to ERC
    
    * lisp/erc/erc-backend.el (erc-server-402, erc-server-402-functions):
    Add new response handler and hook.
    * lisp/erc/erc.el (erc-cmd-MOTD): New function to shield erc-network
    from handling post-connection MOTD replies.  Thanks to Emanuel Berg
    for reporting this (bug#62151).
    (erc-message-english-s402): Define new ERR_NOSUCHSERVER message
    template.
    * test/lisp/erc/erc-scenarios-base-misc-regressions.el: New file.
    * test/lisp/erc/resources/base/commands/motd.eld: New file.
---
 lisp/erc/erc-backend.el                            |  7 +++-
 lisp/erc/erc.el                                    | 17 ++++++++
 .../erc/erc-scenarios-base-misc-regressions.el     | 44 ++++++++++++++++++++
 test/lisp/erc/resources/base/commands/motd.eld     | 48 ++++++++++++++++++++++
 4 files changed, 115 insertions(+), 1 deletion(-)

diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index 567443f5329..bf3c2b5b308 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -2236,6 +2236,11 @@ See `erc-display-server-message'." nil
     (erc-display-message parsed '(notice error) 'active
                          's401 ?n nick/channel)))
 
+(define-erc-response-handler (402)
+  "No such server." nil
+  (erc-display-message parsed '(notice error) 'active
+                       's402 ?c (cadr (erc-response.command-args parsed))))
+
 (define-erc-response-handler (403)
   "No such channel." nil
   (erc-display-message parsed '(notice error) 'active
@@ -2383,7 +2388,7 @@ See `erc-display-error-notice'." nil
 ;; (define-erc-response-handler (323 364 365 381 382 392 393 394 395
 ;;                               200 201 202 203 204 205 206 208 209 211 212 
213
 ;;                               214 215 216 217 218 219 241 242 243 244 249 
261
-;;                               262 302 342 351 402 407 409 411 413 414 415
+;;                               262 302 342 351 407 409 411 413 414 415
 ;;                               423 424 436 441 443 444 467 471 472 473 KILL)
 ;;   nil nil
 ;;   (ignore proc parsed))
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index f76c770f585..66bc4985027 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -4051,6 +4051,22 @@ means that the user has a +o flag in the channel's 
access list)."
    (t (erc-server-send "TIME"))))
 (defalias 'erc-cmd-DATE #'erc-cmd-TIME)
 
+(defun erc-cmd-MOTD (&optional target)
+  "Ask server to send the current MOTD.
+Some IRCds simply ignore TARGET."
+  (letrec ((oneoff (lambda (proc parsed)
+                     (with-current-buffer (erc-server-buffer)
+                       (cl-assert (eq (current-buffer) (process-buffer proc)))
+                       (remove-hook 'erc-server-402-functions h402 t)
+                       (remove-hook 'erc-server-376-functions h376 t)
+                       (remove-hook 'erc-server-422-functions h422 t))
+                     (erc-server-MOTD proc parsed)
+                     t))
+           (h402 (erc-once-with-server-event 402 oneoff))
+           (h376 (erc-once-with-server-event 376 oneoff))
+           (h422 (erc-once-with-server-event 422 oneoff)))
+    (erc-server-send (concat "MOTD" (and target " ") target))))
+
 (defun erc-cmd-TOPIC (topic)
   "Set or request the topic for a channel.
 LINE has the format: \"#CHANNEL TOPIC\", \"#CHANNEL\", \"TOPIC\"
@@ -7136,6 +7152,7 @@ All windows are opened in the current frame."
    (s379   . "%c: Forwarded to %f")
    (s391   . "The time at %s is %t")
    (s401   . "%n: No such nick/channel")
+   (s402   . "%c: No such server")
    (s403   . "%c: No such channel")
    (s404   . "%c: Cannot send to channel")
    (s405   . "%c: You have joined too many channels")
diff --git a/test/lisp/erc/erc-scenarios-base-misc-regressions.el 
b/test/lisp/erc/erc-scenarios-base-misc-regressions.el
index 16b2cb355d1..c1915d088a0 100644
--- a/test/lisp/erc/erc-scenarios-base-misc-regressions.el
+++ b/test/lisp/erc/erc-scenarios-base-misc-regressions.el
@@ -124,4 +124,48 @@ Originally from scenario rebuffed/gapless as explained in 
Bug#48598:
       (with-current-buffer (erc-d-t-wait-for 5 (get-buffer "#chan"))
         (erc-d-t-search-for 10 "and be prosperous")))))
 
+;; This defends against a partial regression in which an /MOTD caused
+;; 376 and 422 handlers in erc-networks to run.
+
+(ert-deftest erc-cmd-MOTD ()
+  :tags '(:expensive-test)
+  (erc-scenarios-common-with-cleanup
+      ((erc-scenarios-common-dialog "base/commands")
+       (erc-server-flood-penalty 0.1)
+       (dumb-server (erc-d-run "localhost" t 'motd))
+       (port (process-contact dumb-server :service))
+       (expect (erc-d-t-make-expecter)))
+
+    (ert-info ("Connect to server")
+      (with-current-buffer (erc :server "127.0.0.1"
+                                :port port
+                                :nick "tester"
+                                :full-name "tester")
+        (funcall expect 10 "This is the default Ergo MOTD")
+        (funcall expect 10 "debug mode")))
+
+    (ert-info ("Send plain MOTD")
+      (with-current-buffer "foonet"
+        (erc-cmd-MOTD)
+        (funcall expect -0.2 "Unexpected state detected")
+        (funcall expect 10 "This is the default Ergo MOTD")))
+
+    (ert-info ("Send MOTD with known target")
+      (with-current-buffer "foonet"
+        (erc-scenarios-common-say "/MOTD irc1.foonet.org")
+        (funcall expect -0.2 "Unexpected state detected")
+        (funcall expect 10 "This is the default Ergo MOTD")))
+
+    (ert-info ("Send MOTD with erroneous target")
+      (with-current-buffer "foonet"
+        (erc-scenarios-common-say "/MOTD fake.foonet.org")
+        (funcall expect -0.2 "Unexpected state detected")
+        (funcall expect 10 "No such server")
+        ;; Message may show up before the handler runs.
+        (erc-d-t-wait-for 10
+            (not (local-variable-p 'erc-server-402-functions)))
+        (should-not (local-variable-p 'erc-server-376-functions))
+        (should-not (local-variable-p 'erc-server-422-functions))
+        (erc-cmd-QUIT "")))))
+
 ;;; erc-scenarios-base-misc-regressions.el ends here
diff --git a/test/lisp/erc/resources/base/commands/motd.eld 
b/test/lisp/erc/resources/base/commands/motd.eld
new file mode 100644
index 00000000000..6d10ee122e2
--- /dev/null
+++ b/test/lisp/erc/resources/base/commands/motd.eld
@@ -0,0 +1,48 @@
+;; -*- mode: lisp-data; -*-
+((nick 10 "NICK tester"))
+((user 10 "USER user 0 * :tester")
+ (0.00 ":irc.foonet.org 001 tester :Welcome to the foonet IRC Network tester")
+ (0.01 ":irc.foonet.org 002 tester :Your host is irc.foonet.org, running 
version ergo-v2.11.1")
+ (0.01 ":irc.foonet.org 003 tester :This server was created Sun, 12 Mar 2023 
02:30:29 UTC")
+ (0.00 ":irc.foonet.org 004 tester irc.foonet.org ergo-v2.11.1 BERTZios 
CEIMRUabefhiklmnoqstuv Iabefhkloqv")
+ (0.00 ":irc.foonet.org 005 tester AWAYLEN=390 BOT=B CASEMAPPING=ascii 
CHANLIMIT=#:100 CHANMODES=Ibe,k,fl,CEMRUimnstu CHANNELLEN=64 CHANTYPES=# 
CHATHISTORY=1000 ELIST=U EXCEPTS EXTBAN=,m FORWARD=f INVEX :are supported by 
this server")
+ (0.01 ":irc.foonet.org 005 tester KICKLEN=390 MAXLIST=beI:60 MAXTARGETS=4 
MODES MONITOR=100 NETWORK=foonet NICKLEN=32 PREFIX=(qaohv)~&@%+ STATUSMSG=~&@%+ 
TARGMAX=NAMES:1,LIST:1,KICK:,WHOIS:1,USERHOST:10,PRIVMSG:4,TAGMSG:4,NOTICE:4,MONITOR:100
 TOPICLEN=390 UTF8ONLY WHOX :are supported by this server")
+ (0.01 ":irc.foonet.org 005 tester draft/CHATHISTORY=1000 :are supported by 
this server")
+ (0.00 ":irc.foonet.org 251 tester :There are 0 users and 3 invisible on 1 
server(s)")
+ (0.00 ":irc.foonet.org 252 tester 0 :IRC Operators online")
+ (0.00 ":irc.foonet.org 253 tester 0 :unregistered connections")
+ (0.00 ":irc.foonet.org 254 tester 1 :channels formed")
+ (0.00 ":irc.foonet.org 255 tester :I have 3 clients and 0 servers")
+ (0.00 ":irc.foonet.org 265 tester 3 3 :Current local users 3, max 3")
+ (0.00 ":irc.foonet.org 266 tester 3 3 :Current global users 3, max 3")
+ (0.00 ":irc.foonet.org 375 tester :- irc.foonet.org Message of the day - ")
+ (0.00 ":irc.foonet.org 372 tester :- This is the default Ergo MOTD.")
+ (0.01 ":irc.foonet.org 372 tester :- ")
+ (0.02 ":irc.foonet.org 372 tester :- For more information on using these, see 
MOTDFORMATTING.md")
+ (0.00 ":irc.foonet.org 376 tester :End of MOTD command"))
+
+((mode 10 "MODE tester +i")
+ (0.00 ":irc.foonet.org 221 tester +i")
+ (0.00 ":irc.foonet.org NOTICE tester :This server is in debug mode and is 
logging all user I/O. If you do not wish for everything you send to be readable 
by the server owner(s), please disconnect.")
+ (0.05 ":irc.foonet.org 221 tester +i"))
+
+((motd-1 10 "MOTD")
+ (0.08 ":irc.foonet.org 375 tester :- irc.foonet.org Message of the day - ")
+ (0.02 ":irc.foonet.org 372 tester :- This is the default Ergo MOTD.")
+ (0.01 ":irc.foonet.org 372 tester :- ")
+ (0.00 ":irc.foonet.org 372 tester :- For more information on using these, see 
MOTDFORMATTING.md")
+ (0.00 ":irc.foonet.org 376 tester :End of MOTD command"))
+
+((motd-2 10 "MOTD irc1.foonet.org")
+ (0.08 ":irc1.foonet.org 375 tester :- irc1.foonet.org Message of the day - ")
+ (0.02 ":irc1.foonet.org 372 tester :- This is the default Ergo MOTD.")
+ (0.01 ":irc1.foonet.org 372 tester :- ")
+ (0.00 ":irc1.foonet.org 372 tester :- For more information on using these, 
see MOTDFORMATTING.md")
+ (0.00 ":irc1.foonet.org 376 tester :End of MOTD command"))
+
+((motd-3 10 "MOTD fake.foonet.org")
+ (0.00 ":irc.foonet.org 402 tester fake.foonet.org :No such server"))
+
+((quit 10 "QUIT :\2ERC\2")
+ (0.07 ":tester!~u@h3f95zveyc38a.irc QUIT :Quit: \2ERC\2 5.5 (IRC client for 
GNU Emacs 30.0.50)")
+ (0.01 "ERROR :Quit: \2ERC\2 5.5 (IRC client for GNU Emacs 30.0.50)"))