Redo erc-nickname-in-use-functions as a local module

* etc/ERC-NEWS: Mention new module `services-regain'.
* lisp/erc/erc-backend.el: Rename option.
* lisp/erc/erc-services.el (erc-services-regain-alist): Strategies for
regaining a lost nickname on reconnect.  This option, in addition to
the rest of these changes, is a redo of
`erc-nickname-in-use-functions' from commit 8c0c9826 "Add hook to
regain nickname in ERC", which originally stemmed from bug#62044.
(erc-services-retry-nick-on-connect, erc-services-issue-regain,
erc-services-issue-ghost-and-retry-nick): New function variants for
`erc-services-regain-alist.
(erc-services-regain-mode, erc-services-regain-enable,
erc-services-regain-disable): New local module to activate
nick-regaining behavior.
(erc--nickname-in-use-make-request): New method, a services-specific
implementation.
* lisp/erc/erc.el (erc--nickname-in-use-make-request): New generic
function to request alternate nick when first choice is rejected.
(erc-nickname-in-use): Call `erc--nickname-in-use-make-request' to
request alternate nick.
* test/lisp/erc/erc-scenarios-services-misc.el
(erc-scenarios-services-misc--reconnect-retry-nick): Adopt renamed
version of `erc-scenarios-base-renick-auto-regain'.
(erc-scenarios-services-misc--regain-command,
erc-scenarios-services-misc--ghost-and-retry-nick): New tests.
* test/lisp/erc/resources/services/regain/reconnect-retry-again.eld:
New test data file reusing existing blob c0529052 that once lived at
resources/base/renick/regain/normal-again.eld.
* test/lisp/erc/resources/services/regain/reconnect-retry.eld: New
test data file reusing existing blob 9f4df70e5 that once lived at
resources/base/renick/regain/normal.eld.
* test/lisp/erc/resources/services/regain/taken-ghost.eld: New test
data file.
* test/lisp/erc/resources/services/regain/taken-regain.eld New test
data file.

4 files changed, 193 insertions, 0 deletions

diff --git a/test/lisp/erc/resources/services/regain/reconnect-retry-again.eld b/test/lisp/erc/resources/services/regain/reconnect-retry-again.eld
new file mode 100644
index 00000000000..c0529052c70
--- /dev/null
+++ b/test/lisp/erc/resources/services/regain/reconnect-retry-again.eld
@@ -0,0 +1,56 @@
+;; -*- mode: lisp-data; -*-
+((cap 10 "CAP REQ :sasl"))
+((nick 10 "NICK tester"))
+((user 10 "USER tester 0 * :tester"))
+
+((authenticate 10 "AUTHENTICATE PLAIN")
+ (0.04 ":tantalum.libera.chat NOTICE * :*** Checking Ident")
+ (0.01 ":tantalum.libera.chat NOTICE * :*** Looking up your hostname...")
+ (0.01 ":tantalum.libera.chat NOTICE * :*** Couldn't look up your hostname")
+ (0.06 ":tantalum.libera.chat NOTICE * :*** No Ident response")
+ (0.02 ":tantalum.libera.chat CAP * ACK :sasl")
+ (0.03 ":tantalum.libera.chat 433 * tester :Nickname is already in use."))
+
+((nick 10 "NICK tester`")
+ (0.03 "AUTHENTICATE +"))
+
+((authenticate 10 "AUTHENTICATE AHRlc3RlcgBjaGFuZ2VtZQ==")
+ (0.06 ":tantalum.libera.chat 900 tester` tester`!tester@127.0.0.1 tester :You are now logged in as tester")
+ (0.02 ":tantalum.libera.chat 903 tester` :SASL authentication successful"))
+
+((cap 10 "CAP END")
+ (0.02 ":tantalum.libera.chat 001 tester` :Welcome to the Libera.Chat Internet Relay Chat Network tester`")
+ (0.02 ":tantalum.libera.chat 002 tester` :Your host is tantalum.libera.chat[93.158.237.2/6697], running version solanum-1.0-dev")
+ (0.02 ":tantalum.libera.chat 003 tester` :This server was created Mon Feb 13 2023 at 12:05:04 UTC")
+ (0.01 ":tantalum.libera.chat 004 tester` tantalum.libera.chat solanum-1.0-dev DGMQRSZaghilopsuwz CFILMPQRSTbcefgijklmnopqrstuvz bkloveqjfI")
+ (0.01 ":tantalum.libera.chat 005 tester` WHOX MONITOR=100 SAFELIST ELIST=CMNTU ETRACE FNC CALLERID=g KNOCK CHANTYPES=# EXCEPTS INVEX CHANMODES=eIbq,k,flj,CFLMPQRSTcgimnprstuz :are supported by this server")
+ (0.01 ":tantalum.libera.chat 005 tester` CHANLIMIT=#:250 PREFIX=(ov)@+ MAXLIST=bqeI:100 MODES=4 NETWORK=Libera.Chat STATUSMSG=@+ CASEMAPPING=rfc1459 NICKLEN=16 MAXNICKLEN=16 CHANNELLEN=50 TOPICLEN=390 DEAF=D :are supported by this server")
+ (0.03 ":tantalum.libera.chat 005 tester` TARGMAX=NAMES:1,LIST:1,KICK:1,WHOIS:1,PRIVMSG:4,NOTICE:4,ACCEPT:,MONITOR: EXTBAN=$,ajrxz :are supported by this server")
+ (0.01 ":tantalum.libera.chat 251 tester` :There are 70 users and 42977 invisible on 28 servers")
+ (0.00 ":tantalum.libera.chat 252 tester` 38 :IRC Operators online")
+ (0.00 ":tantalum.libera.chat 253 tester` 87 :unknown connection(s)")
+ (0.00 ":tantalum.libera.chat 254 tester` 22908 :channels formed")
+ (0.00 ":tantalum.libera.chat 255 tester` :I have 2507 clients and 1 servers")
+ (0.00 ":tantalum.libera.chat 265 tester` 2507 3232 :Current local users 2507, max 3232")
+ (0.00 ":tantalum.libera.chat 266 tester` 43047 51777 :Current global users 43047, max 51777")
+ (0.00 ":tantalum.libera.chat 250 tester` :Highest connection count: 3233 (3232 clients) (284887 connections received)")
+ (0.03 ":tantalum.libera.chat 375 tester` :- tantalum.libera.chat Message of the Day - ")
+ (0.00 ":tantalum.libera.chat 372 tester` :- This server provided by Hyperfilter (https://hyperfilter.com)")
+ (0.00 ":tantalum.libera.chat 372 tester` :- Email:                      support@libera.chat")
+ (0.02 ":tantalum.libera.chat 376 tester` :End of /MOTD command."))
+
+((mode 10 "MODE tester` +i")
+ (0.01 ":tester` MODE tester` :+Ziw")
+ (0.02 ":SaslServ!SaslServ@services.libera.chat NOTICE tester` :Last login from: \2~tester@127.0.0.1\2 on Apr 07 01:36:25 2023 +0000."))
+
+((nick 10 "NICK tester")
+ (0.02 ":tester`!~tester@127.0.0.1 NICK :tester"))
+
+((join 10 "JOIN #test")
+ (0.02 ":tester!~tester@127.0.0.1 JOIN #test")
+ (0.02 ":tantalum.libera.chat 353 tester = #test :tester zbyqbepbqre7 pusevgfpu Thrfg2187 zngbeb qnexNssvavgl wrebzr- rqpentt Ilehf grfg2 AvtugZbaxrl pevfgvvbna xrivap_ fnvybePng shohxv gxan arrqyr avpx16 NeanhqW_kzcc jvyyr wrnaogeq Wnarg cnefavc0 Xbentt RcvpArb flfqrs wfgbxre hafcrag__ Lbevpx_")
+ (0.02 ":tantalum.libera.chat 366 tester #test :End of /NAMES list."))
+
+((mode 10 "MODE #test")
+ (0.02 ":tantalum.libera.chat 324 tester #test +nt")
+ (0.02 ":tantalum.libera.chat 329 tester #test 1621432263"))
diff --git a/test/lisp/erc/resources/services/regain/reconnect-retry.eld b/test/lisp/erc/resources/services/regain/reconnect-retry.eld
new file mode 100644
index 00000000000..9f4df70e580
--- /dev/null
+++ b/test/lisp/erc/resources/services/regain/reconnect-retry.eld
@@ -0,0 +1,53 @@
+;; -*- mode: lisp-data; -*-
+((cap 10 "CAP REQ :sasl"))
+((nick 10 "NICK tester"))
+((user 10 "USER tester 0 * :tester"))
+
+((authenticate 10 "AUTHENTICATE PLAIN")
+ (0.02 ":cadmium.libera.chat NOTICE * :*** Checking Ident")
+ (0.01 ":cadmium.libera.chat NOTICE * :*** Looking up your hostname...")
+ (0.01 ":cadmium.libera.chat NOTICE * :*** Couldn't look up your hostname")
+ (0.06 ":cadmium.libera.chat NOTICE * :*** No Ident response")
+ (0.09 ":cadmium.libera.chat CAP * ACK :sasl")
+ (0.01 "AUTHENTICATE +"))
+
+((authenticate 10 "AUTHENTICATE AHRlc3RlcgBjaGFuZ2VtZQ==")
+ (0.03 ":cadmium.libera.chat 900 tester tester!tester@127.0.0.1 tester :You are now logged in as tester")
+ (0.01 ":cadmium.libera.chat 903 tester :SASL authentication successful"))
+
+((cap 10 "CAP END")
+ (0.03 ":cadmium.libera.chat 001 tester :Welcome to the Libera.Chat Internet Relay Chat Network tester")
+ (0.02 ":cadmium.libera.chat 002 tester :Your host is cadmium.libera.chat[103.196.37.95/6697], running version solanum-1.0-dev")
+ (0.01 ":cadmium.libera.chat 003 tester :This server was created Wed Jan 25 2023 at 10:22:45 UTC")
+ (0.01 ":cadmium.libera.chat 004 tester cadmium.libera.chat solanum-1.0-dev DGMQRSZaghilopsuwz CFILMPQRSTbcefgijklmnopqrstuvz bkloveqjfI")
+ (0.00 ":cadmium.libera.chat 005 tester CALLERID=g WHOX ETRACE FNC SAFELIST ELIST=CMNTU KNOCK MONITOR=100 CHANTYPES=# EXCEPTS INVEX CHANMODES=eIbq,k,flj,CFLMPQRSTcgimnprstuz :are supported by this server")
+ (0.01 ":cadmium.libera.chat 005 tester CHANLIMIT=#:250 PREFIX=(ov)@+ MAXLIST=bqeI:100 MODES=4 NETWORK=Libera.Chat STATUSMSG=@+ CASEMAPPING=rfc1459 NICKLEN=16 MAXNICKLEN=16 CHANNELLEN=50 TOPICLEN=390 DEAF=D :are supported by this server")
+ (0.01 ":cadmium.libera.chat 005 tester TARGMAX=NAMES:1,LIST:1,KICK:1,WHOIS:1,PRIVMSG:4,NOTICE:4,ACCEPT:,MONITOR: EXTBAN=$,ajrxz :are supported by this server")
+ (0.01 ":cadmium.libera.chat 251 tester :There are 70 users and 42996 invisible on 28 servers")
+ (0.02 ":cadmium.libera.chat 252 tester 38 :IRC Operators online")
+ (0.01 ":cadmium.libera.chat 253 tester 57 :unknown connection(s)")
+ (0.01 ":cadmium.libera.chat 254 tester 22912 :channels formed")
+ (0.01 ":cadmium.libera.chat 255 tester :I have 2499 clients and 1 servers")
+ (0.01 ":cadmium.libera.chat 265 tester 2499 4187 :Current local users 2499, max 4187")
+ (0.01 ":cadmium.libera.chat 266 tester 43066 51827 :Current global users 43066, max 51827")
+ (0.01 ":cadmium.libera.chat 250 tester :Highest connection count: 4188 (4187 clients) (319420 connections received)")
+ (0.01 ":cadmium.libera.chat 375 tester :- cadmium.libera.chat Message of the Day - ")
+ (0.01 ":cadmium.libera.chat 372 tester :- This server kindly provided by Mach Dilemma (www.m-d.net)")
+ (0.01 ":cadmium.libera.chat 372 tester :- Welcome to Libera Chat, the IRC network for")
+ (0.00 ":cadmium.libera.chat 372 tester :- Email:                      support@libera.chat")
+ (0.00 ":cadmium.libera.chat 376 tester :End of /MOTD command.")
+ (0.00 ":tester MODE tester :+Ziw")
+ (0.02 ":SaslServ!SaslServ@services.libera.chat NOTICE tester :Last login from: \2~tester@127.0.0.1\2 on Apr 07 01:02:11 2023 +0000."))
+
+((mode 10 "MODE tester +i"))
+
+((join 10 "JOIN #test")
+ (0.09 ":tester!~tester@127.0.0.1 JOIN #test"))
+
+((mode 10 "MODE #test")
+ (0.03 ":cadmium.libera.chat 353 tester = #test :tester zbyqbepbqre7 pusevgfpu Thrfg2187 zngbeb qnexNssvavgl wrebzr- rqpentt Ilehf grfg2 AvtugZbaxrl pevfgvvbna xrivap_ fnvybePng shohxv gxan arrqyr avpx16 NeanhqW_kzcc Lbevpx_ hafcrag__ wfgbxre flfqrs RcvpArb Xbentt jvyyr cnefavc0 Wnarg wrnaogeq")
+ (0.02 ":cadmium.libera.chat 366 tester #test :End of /NAMES list.")
+ (0.00 ":cadmium.libera.chat 324 tester #test +nt")
+ (0.01 ":cadmium.libera.chat 329 tester #test 1621432263"))
+
+((drop 0 DROP))
diff --git a/test/lisp/erc/resources/services/regain/taken-ghost.eld b/test/lisp/erc/resources/services/regain/taken-ghost.eld
new file mode 100644
index 00000000000..d5afd124a43
--- /dev/null
+++ b/test/lisp/erc/resources/services/regain/taken-ghost.eld
@@ -0,0 +1,42 @@
+;; -*- mode: lisp-data; -*-
+((cap 10 "CAP REQ :sasl")
+ (0.00 ":irc.example.net NOTICE * :*** Looking up your hostname...")
+ (0.01 ":irc.example.net NOTICE * :*** Could not resolve your hostname: Domain not found; using your IP address (10.0.2.100) instead."))
+((nick 10 "NICK dummy"))
+((user 10 "USER dummy 0 * :tester"))
+((authenticate 10 "AUTHENTICATE PLAIN")
+ (0.00 ":irc.example.net CAP * ACK :sasl")
+ (0.03 ":irc.example.net 433 * dummy :Nickname is already in use.")
+ (0.04 "AUTHENTICATE :+"))
+((nick 10 "NICK dummy`")
+ (0.00 "PING :orrMOjk^|V"))
+((~pong 10 "PONG :orrMOjk^|V"))
+((authenticate 10 "AUTHENTICATE AHRlc3RlcgBjaGFuZ2VtZQ==")
+ (0.01 ":irc.example.net 900 dummy` dummy`!dummy@10.0.2.100 tester :You are now logged in as tester")
+ (0.01 ":irc.example.net 903 dummy` :SASL authentication successful"))
+((cap 10 "CAP END")
+ (0.00 ":irc.example.net 001 dummy` :Welcome to the FooNet IRC Network dummy`!dummy@10.0.2.100")
+ (0.03 ":irc.example.net 002 dummy` :Your host is irc.example.net, running version InspIRCd-3")
+ (0.01 ":irc.example.net 003 dummy` :This server was created 13:01:55 Jun 08 2023")
+ (0.01 ":irc.example.net 004 dummy` irc.example.net InspIRCd-3 BIRcgikorsw ACHIKMORTXabcefghijklmnopqrstvz :HIXabefghjkloqv")
+ (0.00 ":irc.example.net 005 dummy` ACCEPT=30 AWAYLEN=200 BOT=B CALLERID=g CASEMAPPING=ascii CHANLIMIT=#:20 CHANMODES=IXbeg,k,Hfjl,ACKMORTcimnprstz CHANNELLEN=64 CHANTYPES=# ELIST=CMNTU ESILENCE=CcdiNnPpTtx EXCEPTS=e :are supported by this server")
+ (0.01 ":irc.example.net 005 dummy` EXTBAN=,ACORTUacjrwz HOSTLEN=64 INVEX=I KEYLEN=32 KICKLEN=255 LINELEN=512 MAXLIST=I:100,X:100,b:100,e:100,g:100 MAXTARGETS=20 MODES=20 MONITOR=30 NAMELEN=128 NAMESX NETWORK=FooNet :are supported by this server")
+ (0.01 ":irc.example.net 005 dummy` NICKLEN=30 PREFIX=(qaohv)~&@%+ SAFELIST SILENCE=32 STATUSMSG=~&@%+ TOPICLEN=307 UHNAMES USERIP USERLEN=10 USERMODES=,,s,BIRcgikorw WHOX :are supported by this server")
+ (0.01 ":irc.example.net 251 dummy` :There are 2 users and 1 invisible on 2 servers")
+ (0.01 ":irc.example.net 253 dummy` 1 :unknown connections")
+ (0.00 ":irc.example.net 254 dummy` 1 :channels formed")
+ (0.00 ":irc.example.net 255 dummy` :I have 3 clients and 1 servers")
+ (0.00 ":irc.example.net 265 dummy` :Current local users: 3  Max: 4")
+ (0.00 ":irc.example.net 266 dummy` :Current global users: 3  Max: 4")
+ (0.00 ":irc.example.net 375 dummy` :irc.example.net message of the day")
+ (0.00 ":irc.example.net 372 dummy` :       Have fun with the image!")
+ (0.00 ":irc.example.net 376 dummy` :End of message of the day."))
+
+((mode 10 "MODE dummy` +i"))
+((privmsg 10 "PRIVMSG NickServ :GHOST dummy")
+ (0.00 ":irc.example.net 501 dummy` x :is not a recognised user mode.")
+ (0.00 ":irc.example.net NOTICE dummy` :*** You are connected to irc.example.net using TLS (SSL) cipher 'TLS1.3-ECDHE-RSA-AES-256-GCM-AEAD'")
+ (0.03 ":dummy`!dummy@10.0.2.100 MODE dummy` :+i")
+ (0.02 ":NickServ!NickServ@services.int NOTICE dummy` :\2dummy\2 has been ghosted."))
+((nick 10 "NICK dummy")
+ (0.02 ":dummy`!dummy@10.0.2.100 NICK :dummy"))
diff --git a/test/lisp/erc/resources/services/regain/taken-regain.eld b/test/lisp/erc/resources/services/regain/taken-regain.eld
new file mode 100644
index 00000000000..22635d4cc89
--- /dev/null
+++ b/test/lisp/erc/resources/services/regain/taken-regain.eld
@@ -0,0 +1,42 @@
+;; -*- mode: lisp-data; -*-
+((cap 10 "CAP REQ :sasl")
+ (0.00 ":irc.example.net NOTICE * :*** Looking up your hostname...")
+ (0.01 ":irc.example.net NOTICE * :*** Could not resolve your hostname: Domain not found; using your IP address (10.0.2.100) instead."))
+((nick 10 "NICK dummy"))
+((user 10 "USER dummy 0 * :tester"))
+;; This also happens to a test late ACK (see ghost variant for server-sent PING)
+((authenticate 10 "AUTHENTICATE PLAIN")
+ (0.00 ":irc.example.net CAP * ACK :sasl")
+ (0.09 ":irc.example.net 433 * dummy :Nickname is already in use.")
+ (0.04 "AUTHENTICATE :+"))
+((nick 10 "NICK dummy`"))
+((authenticate 10 "AUTHENTICATE AHRlc3RlcgBjaGFuZ2VtZQ==")
+ (0.00 ":irc.example.net 900 dummy` dummy`!dummy@10.0.2.100 tester :You are now logged in as tester")
+ (0.01 ":irc.example.net 903 dummy` :SASL authentication successful"))
+
+((cap 10 "CAP END")
+ (0.00 ":irc.example.net 001 dummy` :Welcome to the FooNet IRC Network dummy`!dummy@10.0.2.100")
+ (0.02 ":irc.example.net 002 dummy` :Your host is irc.example.net, running version InspIRCd-3")
+ (0.02 ":irc.example.net 003 dummy` :This server was created 08:16:52 Jun 08 2023")
+ (0.01 ":irc.example.net 004 dummy` irc.example.net InspIRCd-3 BIRcgikorsw ACHIKMORTXabcefghijklmnopqrstvz :HIXabefghjkloqv")
+ (0.00 ":irc.example.net 005 dummy` ACCEPT=30 AWAYLEN=200 BOT=B CALLERID=g CASEMAPPING=ascii CHANLIMIT=#:20 CHANMODES=IXbeg,k,Hfjl,ACKMORTcimnprstz CHANNELLEN=64 CHANTYPES=# ELIST=CMNTU ESILENCE=CcdiNnPpTtx EXCEPTS=e :are supported by this server")
+ (0.01 ":irc.example.net 005 dummy` EXTBAN=,ACORTUacjrwz HOSTLEN=64 INVEX=I KEYLEN=32 KICKLEN=255 LINELEN=512 MAXLIST=I:100,X:100,b:100,e:100,g:100 MAXTARGETS=20 MODES=20 MONITOR=30 NAMELEN=128 NAMESX NETWORK=FooNet :are supported by this server")
+ (0.01 ":irc.example.net 005 dummy` NICKLEN=30 PREFIX=(qaohv)~&@%+ SAFELIST SILENCE=32 STATUSMSG=~&@%+ TOPICLEN=307 UHNAMES USERIP USERLEN=10 USERMODES=,,s,BIRcgikorw WHOX :are supported by this server")
+ (0.01 ":irc.example.net 251 dummy` :There are 2 users and 1 invisible on 2 servers")
+ (0.01 ":irc.example.net 253 dummy` 1 :unknown connections")
+ (0.00 ":irc.example.net 254 dummy` 1 :channels formed")
+ (0.02 ":irc.example.net 255 dummy` :I have 3 clients and 1 servers")
+ (0.00 ":irc.example.net 265 dummy` :Current local users: 3  Max: 4")
+ (0.00 ":irc.example.net 266 dummy` :Current global users: 3  Max: 4")
+ (0.00 ":irc.example.net 375 dummy` :irc.example.net message of the day")
+ (0.00 ":irc.example.net 372 dummy` :       Have fun with the image!")
+ (0.00 ":irc.example.net 376 dummy` :End of message of the day.")
+ (0.00 ":irc.example.net 501 dummy` x :is not a recognised user mode.")
+ (0.00 ":irc.example.net NOTICE dummy` :*** You are connected to irc.example.net using TLS (SSL) cipher 'TLS1.3-ECDHE-RSA-AES-256-GCM-AEAD'"))
+
+((mode 10 "MODE dummy` +i"))
+
+((privmsg 10 "PRIVMSG NickServ :REGAIN dummy")
+ (0.00 ":dummy`!dummy@10.0.2.100 MODE dummy` :+i")
+ (0.02 ":NickServ!NickServ@services.int NOTICE dummy` :\2dummy\2 has been regained.")
+ (0.02 ":dummy`!dummy@10.0.2.100 NICK :dummy"))