unrealircd/doc/RELEASE-NOTES.md

UnrealIRCd 6.0.4.2
===================
Another small update to 6.0.4.x:

* Fix crash when linking. This requires a certain sequence of events: first
  a server is linked in successfully, then we need to REHASH, and then a new
  link attempt has to come in with the same server name (for example because
  there is a network issue and the old link has not timed out yet).
  If all that happens, then an UnreaIRCd 6 server may crash, but not always.
* Two IRCv3 specifications were ratified which we already supported as drafts:
  * Change CAP `draft/extended-monitor` to `extended-monitor`
  * Add message-tag `bot` next to existing (for now) `draft/bot`
* Update Turkish translations

UnrealIRCd 6.0.4.1
===================
This is a small update to 6.0.4. It fixes the following issues that were
present in all 6.0.x versions:

* Fix sporadic crash when linking a server (after successful authentication).
  This feels like a compiler bug. It affected only some people with GCC and
  only in some situations. When compiled with clang there was no problem.
  Hopefully we can work around it this way.
* Make /INVITE bypass (nearly) all channel mode restrictions, as it used to
  be in UnrealIRCd 5.x. Both for invites by channel ops and for OperOverride.
  This also fixes a bug where an IRCOp with OperOverride could not bypass +l
  (limit) and other restrictions and would have to resort back to using
  MODE or SAMODE. Only +b and +i could be bypassed via INVITE OperOverride.

UnrealIRCd 6.0.4
-----------------
This release comes with lots of features and enhancements. In particular,
security groups and mask items now allow you to write cleaner and more
flexible configuration files. There are also JSON logging enhancements and
several bug fixes. Thanks a lot to everyone who tested the release candidates!

If you are already running UnrealIRCd 6 then read below. Otherwise, jump
straight to the [summary about UnrealIRCd 6](#Summary) to learn more
about UnrealIRCd 6.

### Enhancements:
* Show security groups in `WHOIS`
* The [security-group block](https://www.unrealircd.org/docs/Security-group_block)
  has been expanded and the same functionality is now available in
  [mask items](https://www.unrealircd.org/docs/Mask_item) too:
  * This means the existing options like `identified`, `webirc`, `tls` and
    `reputation-score` can be used in `allow::mask` etc.
  * New options (in both security-group and mask) are:
    * `connect-time`: time a user is connected to IRC
    * `security-group`: to check another security group
    * `account`: services account name
    * `country`: country code, as found by GeoIP
    * `realname`: realname (gecos) of the user
    * `certfp`: certificate fingerprint
  * Every option also has an exclude- variant, eg. `exclude-country`.
    If a user matches any `exclude-` option then it is considered not a match.
  * The modules [connthrottle](https://www.unrealircd.org/docs/Connthrottle),
    [restrict-commands](https://www.unrealircd.org/docs/Set_block#set::restrict-commands)
    and [antirandom](https://www.unrealircd.org/docs/Set_block#set::antirandom)
    now use the new `except` sub-block which is a mask item. The old syntax
    (eg <code>set::antirandom::except-webirc</code>) is still accepted by UnrealIRCd
    and converted to the appropriate new setting behind the scenes
    (<code>set::antirandom::except::webirc</code>).
  * The modules [blacklist](https://www.unrealircd.org/docs/Blacklist_block)
    and [antimixedutf8](https://www.unrealircd.org/docs/Set_block#set::antimixedutf8)
    now also support the `except` block (a mask item).
  * Other than that the extended functionality is available in these blocks:
    `allow`, `oper`, `tld`, `vhost`, `deny channel`, `allow channel`.
  * Example of direct use in a ::mask item:
    ```
    /* Spanish MOTD for Spanish speaking countries */
    tld {
        mask { country { ES; AR; BO; CL; CO; CR; DO; EC; SV; GT; HN; MX; NI; PA; PY; PE; PR; UY; VE; } }
        motd "motd.es.txt";
        rules "rules.es.txt";
    }
    ```
  * Example of defining a security group and using it in a mask item later:
    ```
    security-group irccloud {
        mask { ip1; ip2; ip3; ip4; }
    }
    allow {
        mask { security-group irccloud; }
        class clients;
        maxperip 128;
    }
    except ban {
        mask { security-group irccloud; }
        type { blacklist; connect-flood; handshake-data-flood; }
    }
    ```
* Because the mask item is so powerful now, the `password` in the
  [oper block](https://www.unrealircd.org/docs/Oper_block) is optional now.
* We now support oper::auto-login, which means the user will become IRCOp
  automatically if they match the conditions on-connect. This can be used
  in combination with
  [certificate fingerprint](https://www.unrealircd.org/docs/Certificate_fingerprint)
  authentication for example:
  ```
  security-group Syzop { certfp "1234etc."; }
  oper Syzop {
      auto-login yes;
      mask { security-group Syzop; }
      operclass netadmin-with-override;
      class opers;
  }
  except ban {
      mask { security-group Syzop; }
      type all;
  }
  ```
* For [JSON logging](https://www.unrealircd.org/docs/JSON_logging) a number
  of fields were added when a client is expanded:
  * `geoip`: with subitem `country_code` (eg. `NL`)
  * `tls`: with subitems `cipher` and `certfp`
  * Under subitem `users`:
    * `vhost`: if the visible host differs from the realhost then this is
      set (thus for both vhost and cloaked host)
    * `cloakedhost`: this is always set (except for eg. services users), even
      if the user is not cloaked so you can easily search on a cloaked host.
    * `idle_since`: last time the user has spoken (local clients only)
    * `channels`: list of channels (array), with a maximum of 384 chars.
* The JSON logging now also strips ASCII below 32, so color- and
  control codes.
* Support IRCv3 `+draft/channel-context`
* Add `example.es.conf` (Spanish example configuration file)
* The country of users is now communicated in the
  [message-tag](https://www.unrealircd.org/docs/Message_tags)
  `unrealircd.org/geoip` (only to IRCOps).
* Add support for linking servers via UNIX domain sockets
  (`link::outgoing::file`).

### Fixes:
* Crash in `except ban` with `~security-group:xyz`
* Crash if hideserver module was loaded but `LINKS` was not blocked.
* Crash on Windows when using the "Rehash" GUI option.
* Infinite loop if one security-group referred to another.
* Duplicate entries in the `+beI` lists of `+P` channels.
* Regular users were able to -o a service bot (that has umode +S)
* Module manager did not stop on compile error
* [`set::modes-on-join`](https://www.unrealircd.org/docs/Set_block#set::modes-on-join)
  did not work with `+f` + timed bans properly, eg `[3t#b1]:10`
* Several log messages were missing some information.
* Reputation syncing across servers had a small glitch. Fix is mostly
  useful for servers that were not linked to the network for days or weeks.

### Changes:
* Clarified that UnrealIRCd is licensed as "GPLv2 or later"
* Fix use of variables in
  [`set::reject-message](https://www.unrealircd.org/docs/Set_block#set::reject-message)
  and in [`blacklist::reason](https://www.unrealircd.org/docs/Blacklist_block):
  previously short forms of variables were (unintentionally) expanded
  as well, such as `$serv` for `$server`. This is no longer supported, you need
  to use the correct full variable names.

### Developers and protocol:
* The `creationtime` is now communicated of users. Until now this
  information was only known locally (the thing that was communicated
  that came close was "last nick change" but that is not the same).
  This is synced via (early) moddata across servers.
  Module coders can use `get_connected_time()`.
* The `RPL_HOSTHIDDEN` is now sent from `userhost_changed()` so you
  don't explicitly send it yourself anymore.
* The `SVSO` command is back, so services can make people IRCOp again.
  See `HELPOP SVSO` or [the commit](https://github.com/unrealircd/unrealircd/commit/50e5d91c798e7d07ca0c68d9fca302a6b6610786)
  for more information.
* Due to last change the `HOOKTYPE_LOCAL_OPER` parameters were changed.
* Module coders can enhance the
  [JSON logging](https://www.unrealircd.org/docs/JSON_logging)
  expansion items for clients and channels via new hooks like
  `HOOKTYPE_JSON_EXPAND_CLIENT`. This is used by the geoip and tls modules.

UnrealIRCd 6.0.3
-----------------
A number of serious issues were discovered in UnrealIRCd 6. Among these is
an issue which will likely crash the IRCd sooner or later if you /REHASH
with any active clients connected.
We suggest everyone who is running UnrealIRCd 6 to upgrade to 6.0.3.

Fixes:
* Crash in `WATCH` if the IRCd has been rehashed at least once. After doing
  a `REHASH` with active clients it will likely corrupt memory. It may take
  several days until after the rehash for the crash to occur, or even
  weeks/months on smaller networks (accidental triggering, that is).
* A `REHASH` with certain remote includes setups could cause a crash or
  other weird and confusing problems such as complaining about unable
  to open an ipv6-database or missing snomask configuration.
  This only affected some people with remote includes, not all.
* Potential out-of-bounds write in sending code. In practice it seems
  harmless on most servers but this cannot be 100% guaranteed.
* Unlikely triggered log message would log uninitialized stack data to the
  log file or send it to ircops.
* Channel ops could not remove halfops from a user (`-h`).
* After using the `RESTART` command (not recommended) the new IRCd was
  often no longer writing to log files.
* Fix compile problem if you choose to use cURL remote includes but don't
  have cURL on the system and ask UnrealIRCd to compile cURL.

Enhancements:
* The default text log format on disk changed. It now includes the server
  name where the event was generated. Without this, it was sometimes
  difficult to trace problems, since previously it sometimes looked like
  there was a problem on your server when it was actually another server
  on the network.
  * Old log format: `[DATE TIME] subsystem.EVENT_ID loglevel: ........`
  * New log format: `[DATE TIME] servername subsystem.EVENT_ID loglevel: ........`

Changes:
* Any MOTD lines added by services via
  [`SVSMOTD`](https://www.unrealircd.org/docs/MOTD_and_Rules#SVSMOTD)
  are now shown at the end of the MOTD-on-connect (unless using a shortmotd).
  Previously the lines were only shown if you manually ran the `MOTD` command.

Developers and protocol:
* `LIST C<xx` now means: filter on channels that are created less
  than `xx` minutes ago. This is the opposite of what we had earlier.
  `LIST T<xx` is now supported as well (topic changed in last xx minutes),
  it was already advertised in ELIST but support was not enabled previously.

UnrealIRCd 6.0.2
-----------------
UnrealIRCd 6.0.2 comes with several nice feature enhancements along with
some fixes. It also includes a fix for a crash bug that can be triggered
by ordinary users.

Fixes:
* Fix crash that can be triggered by regular users if you have any `deny dcc`
  blocks in the config or any spamfilters with the `d` (DCC) target.
  NOTE: You don't *have* to upgrade to 6.0.2 to fix this, you can also
  hot-patch this issue without restart, see the news announcement.
* Windows: fix crash with IPv6 clients (local or remote) due to GeoIP lookup
* Fix infinite hang on "Loading IRCd configuration" if DNS is not working.
  For example if the 1st DNS server in `/etc/resolv.conf` is down or refusing
  requests.
* Some `MODE` server-to-server commands were missing a timestamp at the end,
  even though this is mandatory for modes coming from a server.
* The [channeldb](https://www.unrealircd.org/docs/Set_block#set::channeldb)
  module now converts letter extbans to named extbans (eg `~a` to `~account`).
  Previously it did not, which caused letter extbans to appear in the banlist.
  Later on, when linking servers, this would cause duplicate entries to appear
  as well, with both the old and new format. The extbans were still effective
  though, so this is mostly a visual +b/+e/+I list issue.
* Some [Extended Server Bans](https://www.unrealircd.org/docs/Extended_server_bans)
  were not working correctly for WEBIRC proxies. In particular, a server ban
  or exempt (ELINE) on `~country:XX` was only checked against the WEBIRC proxy.

Enhancements:
* Support for [logging to a channel](https://www.unrealircd.org/docs/Log_block#Logging_to_a_channel).
  Similar to snomasks but then for channels.
* Command line interface changes:
  * The [CLI tool](https://www.unrealircd.org/docs/Command_Line_Interface) now
    communicates to the running UnrealIRCd process via a UNIX socket to
    send commands and retrieve output.
  * The command `./unrealircd rehash` will now show the rehash output,
    including warnings and errors, and return a proper exit code.
  * The same for `./unrealircd reloadtls`
  * New command `./unrealircd status` to show if UnrealIRCd is running, the
    version, channel and user count, ..
  * The command `./unrealircd genlinkblock` is now
    [documented](https://www.unrealircd.org/docs/Linking_servers_(genlinkblock))
    and is referred to from the
    [Linking servers tutorial](https://www.unrealircd.org/docs/Tutorial:_Linking_servers).
  * On Windows in the `C:\Program Files\UnrealIRCd 6\bin` directory there is
    now an `unrealircdctl.exe` that can be used to do similar things to what
    you can do on *NIX. Supported operations are: `rehash`, `reloadtls`,
    `mkpasswd`, `gencloak` and `spkifp`.
* New option [set::server-notice-show-event](https://www.unrealircd.org/docs/Set_block#set::server-notice-show-event)
  which can be set to `no` to hide the event information (eg `connect.LOCAL_CLIENT_CONNECT`)
  in server notices. This can be overridden per-oper in the
  [Oper block](https://www.unrealircd.org/docs/Oper_block) via oper::server-notice-show-event.
* Support for IRC over UNIX sockets (on the same machine), if you specify a
  file in the [listen block](https://www.unrealircd.org/docs/Listen_block)
  instead of an ip/port. This probably won't be used much, but the option is
  there. Users will show up with a host of `localhost` and IP `127.0.0.1` to
  keep things simple.
* The `MAP` command now shows percentages of users
* Add `WHO` option to search clients by time connected (eg. `WHO <300 t` to
  search for less than 300 seconds)
* Rate limiting of `MODE nick -x` and `-t` via new `vhost-flood` option in
  [set::anti-flood block](https://www.unrealircd.org/docs/Anti-flood_settings).

Changes:
* Update Russian `help.ru.conf`.

Developers and protocol:
* People packaging UnrealIRCd (eg. to an .rpm/.deb):
  * Be sure to pass the new `--with-controlfile` configure option
  * There is now an `unrealircdctl` tool that the `unrealircd` shell script
    uses, it is expected to be in `bindir`.
* `SVSMODE #chan -b nick` will now correctly remove extbans that prevent `nick`
  from joining. This fixes a bug where it would remove too much (for `~time`)
  or not remove extbans (most other extbans, eg `~account`).
  `SVSMODE #chan -b` has also been fixed accordingly (remove all bans
  preventing joins).
  Note that all these commands do not remove bans that do not affect joins,
  such as `~quiet` or `~text`.
* For module coders: setting the `EXTBOPT_CHSVSMODE` flag in `extban.options`
  is no longer useful, the flag is ignored. We now decide based on
  `BANCHK_JOIN` being in `extban.is_banned_events` if the ban should be
  removed or not upon SVS(2)MODE -b.

UnrealIRCd 6.0.1.1
-------------------

Fixes:
* In 6.0.1.1: extended bans were not properly synced between U5 and U6.
  This caused missing extended bans on the U5 side (MODE was working OK,
  this only happened when linking servers)
* Text extbans did not have any effect (`+b ~text:censor:*badword*`)
* Timed bans were not expiring if all servers on the network were on U6
* Channel mode `+f` could place a timed extban with `~t` instead of `~time`
* Crash when unloading any of the vhoaq modules at runtime
* `./unrealircd upgrade` not working on FreeBSD and not with self-compiled cURL
* Some log messages being wrong (`CHGIDENT`, `CHGNAME`)
* Remove confusing high cpu load warning

Enhancements:
* Error on unknown snomask in set::snomask-on-oper and oper::snomask.
* TKL add/remove/expire messages now show `[duration: 60m]` instead of
  the `[expires: ZZZ GMT]` string since that is what people are more
  interested in and is not affected by time zones. The format in all the
  3 notices is also consistent now.

UnrealIRCd 6.0.0
-----------------

Many thanks to k4be for his help during development, other contributors for
their feedback and patches, the people who tested the beta's and release
candidates, translators and everyone else who made this release happen!

Summary
--------
UnrealIRCd 6 comes with a completely redone logging system (with optional
JSON support), named extended bans, four new IRCv3 features,
geoip support and remote includes support built-in.

Additionally, things are more customizable such as what gets sent to
which snomask. All the +vhoaq channel modes are now modular as well,
handy for admins who don't want or need halfops or +q/+a.
For WHOIS it is now customizable in detail who gets to see what.

A summary of the features is available at
[What's new in UnrealIRCd 6](https://www.unrealircd.org/docs/What's_new_in_UnrealIRCd_6).
For complete information, continue reading the release notes below.
The sections below contain all the details.

Upgrading from UnrealIRCd 5
----------------------------
The previous stable series, UnrealIRCd 5, will no longer get any new features.
We still do bug fixes until July 1, 2022. In the 12 months after that, only
security issues will be fixed. Finally, after July 1, 2023,
[all support will stop](https://www.unrealircd.org/docs/UnrealIRCd_5_EOL).

If you want to hold off for a while because you are cautious or if you
depend on 3rd party modules (which may not have been upgraded yet by their
authors) then feel free to wait a while.

If you are upgrading from UnrealIRCd 5 to 6 then you can use your existing
configuration and files. There's no need to start from scratch.
However, you will need to make a few updates, see
[Upgrading from 5.x to 6.x](https://www.unrealircd.org/docs/Upgrading_from_5.x).

Enhancements
-------------
* Completely new log system and snomasks overhaul
  * Both logging and snomask sending is done by a single logging function
  * Support for [JSON logging](https://www.unrealircd.org/docs/JSON_logging)
    to disk, instead of the default text format.
    JSON logging adds lot of detail to log messages and consistently
    expands things like *client* with properties like *hostname*,
    *connected_since*, *reputation*, *modes*, etc.
  * The JSON data is also sent to all IRCOps who request the
    `unrealircd.org/json-log` capability. The data is then sent in
    a message-tag called `unrealircd.org/json-log`. This makes it ideal
    for client scripts and bots to do automated things.
  * A new style log { } block is used to map what log messages should be
    logged to disk, and which ones should be sent to snomasks.
  * The default logging to snomask configuration is in `snomasks.default.conf`
    which everyone should include from unrealircd.conf. That is, unless you
    wish to completely reconfigure which logging goes to which snomasks
    yourself, which is also an option now.
  * See [Snomasks](https://www.unrealircd.org/docs/Snomasks#UnrealIRCd_6)
    on the new snomasks - lots of letters changed!
  * See [FAQ: Converting log { } block](https://www.unrealircd.org/docs/FAQ#old-log-block)
    on how to change your existing log { } blocks for disk logging.
  * We now have a consistent log format and log messages can be multiline.
  * Colors are enabled by default in snomask server notices, these can be disabled via
    [set::server-notice-colors](https://www.unrealircd.org/docs/Set_block#set::server-notice-colors)
    and also in [oper::server-notice-colors](https://www.unrealircd.org/docs/Oper_block)
  * Support for [logging to a channel](https://www.unrealircd.org/docs/Log_block#Logging_to_a_channel).
    Similar to snomasks but then for channels. *Requires UnrealIRCd 6.0.2 or later*
* Almost all channel modes are modularized
  * Only the three list modes (+b/+e/+I) are still in the core
  * The five [level modes](https://www.unrealircd.org/docs/Channel_Modes#Access_levels)
    (+vhoaq) are now also modular. They are all loaded by default but you can
    blacklist one or more if you don't want them. For example to disable halfop:
    `blacklist-module chanmodes/halfop;`
  * Support for compiling without PREFIX_AQ has been removed because
    people often confused it with disabling +a/+q which is something
    different.
* Named extended bans
  * Extbans now no longer show up with single letters but with names.
    For example `+b ~c:#channel` is now `+b ~channel:#channel`.
  * Extbans are automatically converted from the old to the new style,
    both from clients and from/to older UnrealIRCd 5 servers.
    The auto-conversion also works fine with complex extbans such as
    `+b ~t:5:~q:nick!user@host` to `+b ~time:5:~quiet:nick!user@host`.
* New IRCv3 features:
  * [MONITOR](https://ircv3.net/specs/extensions/monitor.html): an
    alternative for `WATCH` to monitor other users ("notify list").
  * draft/extended-monitor: extensions for MONITOR, still in draft.
  * [invite-notify](https://ircv3.net/specs/extensions/invite-notify):
    report channel invites to other chanops (or users) in a machine
    readable way.
  * [setname](https://ircv3.net/specs/extensions/setname.html):
    notify clients about realname (gecos) changes.
* GeoIP lookups are now done by default
  * This shows the country of the user to IRCOps in `WHOIS` and in the
    "user connecting" line.
  * By default the `geoip_classic` module is loaded, for which we
    provide a mirror of database updates at unrealircd.org. This uses
    the classic geolite library that is now shipped with UnrealIRCd
  * Other options are the `geoip_maxmind` and `geoip_csv` modules.
* Configure `WHOIS` output in a very precise way
  * You can now decide which fields (eg modes, geo, certfp, etc) you want
    to expose to who (everyone, self, oper).
  * See [set::whois-details](https://www.unrealircd.org/docs/Set_block#set::whois-details)
    for more details.
* We now ship with 3 cloaking modules and you need to load 1 explicitly
  via `loadmodule`:
  * `cloak_sha256`: the recommended module for anyone starting a *new*
    network. It uses the SHA256 algorithm under the hood.
  * `cloak_md5`: for anyone who is upgrading their network from older
    UnrealIRCd versions. Use this so your cloaked host bans remain the same.
  * `cloak_none`: if you don't want any cloaking, not even as an option
    to your users (rare)
* Remote includes are now supported everywhere in the config file.
  * Support for `https://` fetching is now always available, even
    if you don't compile with libcurl support.
  * Anywhere an URL is encountered on its own, it will be fetched
    automatically. This makes it work not only for includes and motd
    (which was already supported) but also for any other file.
  * To prevent something from being interpreted as a remote include
    URL you can use 'value' instead of "value".
* Invite notification: set `set::normal-user-invite-notification yes;` to make
  chanops receive information about normal users inviting someone to their channel.
  The name of this setting may change in a later version.
* Websocket: you can add a `listen::options::websocket::forward 1.2.3.4` option
  to make unrealircd accept a `Forwarded` (RFC 7239) header from a reverse proxy
  connecting from `1.2.3.4` (plans to accept legacy `X-Forwarded-For` and a proxy
  password too). This feature is currently experimental.

Changes
--------
* TLS cipher and some other information is now visible for remote
  clients as well, also in `[secure: xyz]` connect line.
* Error messages in remote includes use the url instead of a temporary file
* Downgrading from UnrealIRCd 6 is only supported down to 5.2.0 (so not
  lower like 5.0.x). If this is a problem then make a copy of your db files
  (eg: reputation.db).

Removed
--------
* /REHASH -motd and -opermotd are gone, just use /REHASH

Breaking changes
-----------------
See https://www.unrealircd.org/docs/Upgrading_from_5.x, but in short:

You can use the unrealircd.conf from UnrealIRCd 5, but you need to make
a few changes:
* You need to add `include "snomasks.default.conf";`
* You need to load a cloaking module explicitly. Assuming you already
  have a network then add: `loadmodule "cloak_md5";`
* The log block(s) need to be updated, use something like:
  ```
  log {
          source {
              !debug;
              all;
          }
          destination {
              file "ircd.log" { maxsize 100M; }
          }
  }
  ```

Module coders (API changes)
----------------------------
* Be sure to bump the version in the module header from `unrealircd-5` to `unrealircd-6`
* We use a lot more `const char *` now (instead of `char *`). In particular `parv`
  is const now and so are a lot of arguments to hooks. This will mean that in your
  module you have to use more const too. The reason for this change is to indicate
  that certain strings should not be touched, as doing so is dangerous or could
  have had side-effects that were unpredictable.
* Logging has been completely redone. Don't use `ircd_log()`, `sendto_snomask()`,
  `sendto_ops()` and `sendto_realops()` anymore. Instead use `unreal_log()` which
  handles both logging to disk and notifying IRCOps.
* Various struct member names changed, in particular in `ConfigEntry` and `ConfigFile`,
  but also `channel->chname` is `channel->name` now.
* get_channel() is now make_channel() and creates if needed, otherwise use find_channel()
* The Extended Ban API has been changed a lot. We use a `BanContext` struct now
  that we pass around a lot. You also don't need to do `+3` magic anymore on the
  string as it is handled in another layer. When registering the extended ban,
  `.flag` is now `.letter`, and you also need to set a `.name` to a string due
  to named extended bans. Have a look at the built-in extban modules to see
  how to handle the changes.
* ModData now has an option `MODDATA_SYNC_EARLY`. See under *Server protocol*.
* If you want to lag someone up, don't touch `client->since`, but instead use:
  `add_fake_lag(client, msec)`
* Some client/user struct changes, with `client->user->account` (instead of svid)
  and `client->uplink->name` being the most important ones.
* Possibly more, but above is like 90%+ of the changes that you will encounter.

Server protocol
----------------
* When multiple related `SJOIN` messages are generated for the same channel
  then we now only send the current channel modes (eg `+sntk key`) in the
  first SJOIN and not in the other ones as they are unneeded for the
  immediate followup SJOINs, they waste unnecessary bytes and CPU.
  Such messages may be generated when syncing a channel that has dozens
  of users and/or bans/exempts/invexes. Ideally this should not need any
  changes in other software, since we already supported such messages in the
  past and code for handling it exists way back to 3.2.x, but you better
  check to be sure!
* If you send `PROTOCTL NEXTBANS` then you will receive extended bans
  with Named EXTended BANs instead of letters (eg: `+b ~account:xyz`),
  otherwise you receive them with letters (eg: `+b ~a:xyz`).
* Some ModData of users is (also) communicated in the `UID` message while
  syncing using a message tag that only appears in server-to-server traffic,
  `s2s-md/moddataname=value`. Thus, data such as operinfo, tls cipher,
  geoip, certfp, sasl and webirc is communicated at the same time as when
  a remote connection is added.
  This makes it that a "connecting from" server notice can include all this
  information and also so code can make an immediate decission on what to do
  with the user in hooks. ModData modules need to set
  `mreq.sync = MODDATA_SYNC_EARLY;` if they want this.
  Servers of course need to enable `MTAGS` in PROTOCTL to see this.
* The `SLOG` command is used to broadcast logging messages. This is done
  for log::destination remote, as used in doc/conf/snomasks.default.conf,
  for example for link errors, oper ups, flood messages, etc.
  It also includes all JSON data in a message tag when `PROTOCTL MTAGS` is used.
* Bounced modes are gone: these were MODEs that started with a `&` which
  servers were to act on with reversed logic (add becoming remove and
  vice versa) and never to send something back to that server.
  In practice this was almost never used and complicated the code (way)
  too much.

Client protocol
----------------
* Extended bans now have names instead of letters. If a client sends the
  old format with letters (eg `+b ~a:XYZ`) then the server will
  convert it to the new format with names (eg: `+b ~account:XYZ`)
* Support for `MONITOR` and the other IRCv3 features (see *Enhancements*)