This is in furtherance of commit 3fdf26aa19 which added
functionality to reply with a TLS record layer alert for D-Lined TLS
clients. It turns out that there are other plaintext error messages
in this same function that should receive the same treatment.
Also move another error string to a variable and use a compile-time
optimised-out strlen for it too, to use the same approach as an
existing error string.
Finally, use a different alert (internal_error) for the case where
IRCd is simply unable to accept more connections.
rejectcache entries can now use either a K-line aconf or a static
string as a reason. This will be sent in a 465 numeric before the usual
ERROR. In the case of K-lines, it resembles the 465 you would have been
sent without being rejected:
; nc -s 127.6.6.6 127.0.0.1 5000
:staberinde.local 465 * :You are banned from this server- Temporary
K-line 4320 min. - abc123 (2019/12/31 01.07)
ERROR :Closing Link: (*** Banned (cache))
; nc -s 127.128.0.0 127.0.0.1 5000
:staberinde.local 465 * :You are not authorised to use this server.
ERROR :Closing Link: (*** Banned (cache))
