UnrealIRCd 6.2.1-rc2 available for testing

[Bram M. <sy...@un...>]

This is the second Release Candidate for future version 6.2.1. You can 
help us by testing this release and reporting bugs to 
https://bugs.unrealircd.org/

This version focussed on performance improvements but also various small 
new features were added.

As always, you can download UnrealIRCd from unrealircd.org 
<https://www.unrealircd.org/> and on *NIX you can upgrade with the 
command: ./unrealircd upgrade --rc


      Enhancements:

  * A lot of optimizations were done:
      o Writes to SSL/TLS clients use 15-20% less CPU.
      o For hub servers various improvement add up to roughly 30%,
        depending on traffic.
      o Especially 100+ member channels (and even more so 1000+) are
        handled faster now due to various improvements regarding channel
        membership.
      o A concrete peak-load case would be a server losing a link
        (SQUIT) with 10,000 clones all in 10 channels. Previously this
        took 40 seconds at 100% CPU to process, now it takes only 2 seconds.
  * Add set::utf8-only
    <https://www.unrealircd.org/docs/Set_block#set::utf8-only>: setting
    this to |yes| means all IRC traffic is UTF8 only. See the setting
    and the |UTF8ONLY| <https://ircv3.net/specs/extensions/utf8-only>
    specification for more details.
  * Add |server-port| to the security-group block
    <https://www.unrealircd.org/docs/Security-group_block> and mask
    items <https://www.unrealircd.org/docs/Mask_item>. And the
    |server_port()| function in Crule
    <https://www.unrealircd.org/docs/Crule>.
  * When set::send-isupport-updates
    <https://www.unrealircd.org/docs/Set_block#set::send-isupport-updates>
    is enabled, we now send ISUPPORT updates for all values and not only
    for |CHANMODES|/|PREFIX|/|STATUSMSG|. (For example, changing
    set::min-nick-length would broadcast a |MINNICKLEN| change)
  * Add support for IRCv3 |draft/extended-isupport|
    <https://github.com/ircv3/ircv3-specifications/blob/master/extensions/extended-isupport.md>
  * We now support multiple TLS certificates/keys, such as ECDSE +
    ML-DSA (Post Quantum Crypto). Such a dual key approach may make
    sense in the future (see commit)
    <https://github.com/unrealircd/unrealircd/commit/877d151da41f3a20fa277f0a919c69576a4611ac>
  * You can now use |password| multiple times in the config file. This
    can come in handy in the future if we have link blocks with multiple
    passwords but also works with allow::password or vhost::password.
    Simply specify multiple password items and they are treated as a "if
    any of these succeed then the authentication is a PASS" (so it is an
    OR match, not an AND).
  * Add set::tls::signature-algorithms
    <https://www.unrealircd.org/docs/Set_block#set::tls::signature-algorithms>.
    We don't set it at the moment. It's just an additional knob in case
    something needs to be adjusted (e.g. if you need to disable
    something due to a vulnerability).
  * If TLSv1.3 is available on the system then calls to Central
    Blocklist <https://www.unrealircd.org/docs/Central_Spamfilter> and
    Central Spamreport
    <https://www.unrealircd.org/docs/Central_spamreport> will only use
    TLSv1.3.
  * JSON-RPC <https://www.unrealircd.org/docs/JSON-RPC>:
      o Add |away_reason| and |away_since| to the user object
        <https://www.unrealircd.org/docs/JSON-RPC:Client_Object#client.user_object>.
      o Add |server_port| and |local_port| to client objects (also in
        JSON Logging)


      Changes:

  * Best practices now have their own logging category 'advice', which
    is blue.
  * Previous (expired) UnrealIRCd PGP key was removed from |doc/KEYS|
  * JSON-RPC <https://www.unrealircd.org/docs/JSON-RPC>: For the
    |server_ban.*| and similar TKL calls use the "issuer" if the
    |set_by| field is not set.
  * Update offline |doc/unrealircd_wiki.zim| to current wiki


      Fixes:

  * Crash with proxy { } block <https://www.unrealircd.org/docs/Proxy_block>
  * Possible crash in |STATS maxperip| (IRCOp-only)
  * Make Remote includes
    <https://www.unrealircd.org/docs/Remote_includes> work on IPv6-only
    machines.
  * The |TLINE| command did not behave the same as e.g. |GLINE| for
    Extended Server Bans
    <https://www.unrealircd.org/docs/Extended_server_bans> which was
    confusing.
  * Memory leak in DEBUGMODE (only used by developers)


      Developers and protocol:

  * |client->local->caps| changes to a 64 bit unsigned int on all archs
  * We now run quick CI jobs at GitHub as well, e.g. for PRs and
    commits. This is in addition to the self-hosted BuildBot that is not
    public.
  * The (near last) sanitizer question in |./Config| will now not only
    enable AddressSanitizer, but also UndefinedBehaviorSanitizer. As
    always, we recommend developers to turn this on since it will often
    catch bugs.