path: root/doc/en/weechat_relay_protocol.en.adoc

= WeeChat Relay protocol
:author: Sébastien Helleu
:email: flashcode@flashtux.org
:lang: en
:toc: left
:toclevels: 3
:sectnums:
:docinfo1:


[[introduction]]
== Introduction

This document is the specification of WeeChat Relay protocol: the protocol used
to relay WeeChat data to clients, which are mostly remote interfaces.

[[terminology]]
=== Terminology

The following terms are used in this document:

* _relay_: this is the WeeChat with relay plugin, which acts as "server" and
  allows _clients_ to connect
* _client_: this is another software, connected to _relay_ via a network
  connection; in most cases, this _client_ is a remote interface.

[[network_diagram]]
=== Network diagram

The _clients_ are connected to _relay_ like shown in this diagram:

....
                                              ┌──────────┐ Workstation
 ┌────────┐                               ┌───┤ client 1 │ (Linux, Windows,
 │  irc   │◄──┐  ╔═══════════╤═══════╗    │   └──────────┘ BSD, macOS ...)
 └────────┘   └──╢           │       ║◄───┘   ┌──────────┐
   ......        ║  WeeChat  │ Relay ║◄───────┤ client 2 │ Mobile device
 ┌────────┐   ┌──╢           │       ║◄───┐   └──────────┘ (Android, iPhone ...)
 │ jabber │◄──┘  ╚═══════════╧═══════╝    │      ......
 └────────┘                               │   ┌──────────┐
   ......                                 └───┤ client N │ Other devices
                                              └──────────┘


└────────────┘   └───────────────────┘╘══════╛└────────────────────────────────┘
network servers    ncurses interface    relay         remote interfaces
                                      protocol
....

[NOTE]
All clients here are clients using _weechat_ protocol in _relay_ plugin. The
_relay_ plugin also allows IRC clients, then _relay_ plugin acts as an
_IRC proxy_ (not described in this document).

[[protocol_generalities]]
== Protocol generalities

* Connections from _client_ to _relay_ are made using TCP sockets on IP/port
  used by _relay_ plugin to listen to new connections.
* Number of _clients_ is limited by the option _relay.network.max_clients_.
* Each _client_ is independent from other clients.
* Messages from _client_ to _relay_ are called _commands_, they are sent as text
  (a string).
* Messages from _relay_ to _client_ are called _messages_, they are sent as
  binary data.

[[commands]]
== Commands (client → relay)

Commands have format:

----
(id) command arguments\n
----

Fields are:

* _id_: optional message identifier that will be sent in answer from _relay_;
  it must be enclosed in parentheses, and must not start with an underscore
  (ids starting with underscore are reserved for WeeChat _event_ messages)
* _command_: a command (see table below)
* _arguments_: optional arguments for command (many arguments are separated by
  spaces).

List of available commands (detail in next chapters):

[width="100%",cols="1m,8",options="header"]
|===
| Command    | Description
| handshake  | Handshake: prepare client authentication and set options, before _init_ command.
| init       | Authenticate with _relay_.
| hdata      | Request a _hdata_.
| info       | Request an _info_.
| infolist   | Request an _infolist_.
| nicklist   | Request a _nicklist_.
| input      | Send data to a buffer (text or command).
| completion | Request completion of a string.
| sync       | Synchronize buffer(s): get updates for buffer(s).
| desync     | Desynchronize buffer(s): stop updates for buffer(s).
| quit       | Disconnect from _relay_.
|===

[[command_handshake]]
=== handshake

_WeeChat ≥ 2.9, updated in version 3.5._

Perform an handshake between the client and WeeChat: this is required in most
cases to know the session settings and prepare the authentication with the
_init_ command.

Only one handshake is allowed before the _init_ command.

Syntax:

----
(id) handshake [<option>=<value>,[<option>=<value>,...]]
----

Arguments:

* _option_: one of following options:
** _password_hash_algo_: list of hash algorithms supported by the client
   (separated by colons), allowed values are:
*** _plain_: plain text password (no hash)
*** _sha256_: password salted and hashed with SHA256 algorithm
*** _sha512_: password salted and hashed with SHA512 algorithm
*** _pbkdf2+sha256_: password salted and hashed with PBKDF2 algorithm (using SHA256 hash)
*** _pbkdf2+sha512_: password salted and hashed with PBKDF2 algorithm (using SHA512 hash)
** _compression_: list of supported compression types supported by the client
   (separated by colons and sorted from most important to the fallback value);
   if compression is enabled, messages from _relay_ to client are compressed
   to save bandwidth; allowed values are:
*** _off_: no compression (default if option is not given)
*** _zlib_: compress with https://zlib.net/[zlib ^↗^,window=_blank] _(WeeChat ≥ 0.3.7)_
*** _zstd_: compress with https://facebook.github.io/zstd/[Zstandard ^↗^,window=_blank]:
    better compression and much faster than _zlib_ for both compression and decompression
    _(WeeChat ≥ 3.5)_

Notes about option _password_hash_algo_:

* If the option is not given (or if the _handshake_ command is not sent by the
  client), _relay_ uses automatically _plain_ authentication (if allowed on
  _relay_ side).
* _Relay_ chooses the most secure algorithm available on both client and
  _relay_, by order of priority from first (most secure) to last used:
  . _pbkdf2+sha512_
  . _pbkdf2+sha256_
  . _sha512_
  . _sha256_
  . _plain_

WeeChat replies with a hashtable containing the following keys and values:

* _password_hash_algo_: the password authentication negotiated: supported by
  both the client and _relay_:
** (empty value): negotiation failed, password authentication is *NOT* possible;
   in this case the connection with the client is immediately closed
** _plain_
** _sha256_
** _sha512_
** _pbkdf2+sha256_
** _pbkdf2+sha512_
* _password_hash_iterations_: number of iterations for hash
  (for the PBKDF2 algorithm only)
* _totp_:
** _on_: Time-based One-Time Password (TOTP) is configured and expected
   in the _init_ command
** _off_: Time-based One-Time Password (TOTP) is not enabled and not needed
   in the _init_ command
* _nonce_: a buffer of unpredictable bytes, sent as hexadecimal, to prevent
  replay attacks; if _password_hash_algo_ is a hash algorithm, the client must
  compute the hash of password on this nonce, concatenated with a client nonce
  and the user password (the _relay_ nonce + the client nonce is the salt used
  in the password hash algorithm)
* _compression_: compression type:
** _off_: messages are not compressed
** _zlib_: messages are compressed with https://zlib.net/[zlib ^↗^,window=_blank]
** _zstd_: messages are compressed with https://facebook.github.io/zstd/[Zstandard ^↗^,window=_blank]

[TIP]
With WeeChat ≤ 2.8, the command _handshake_ is not implemented, WeeChat silently
ignores this command, even if it is sent before the _init_ command. +
So it is safe to send this command to any WeeChat version.

Examples:

* Nothing offered by the client, authentication password "plain" will be used
if allowed on relay side:

----
(handshake) handshake
----

Response:

[source,python]
----
id: 'handshake'
htb: {
    'password_hash_algo': 'plain',
    'password_hash_iterations': '100000',
    'totp': 'on',
    'nonce': '85B1EE00695A5B254E14F4885538DF0D',
    'compression': 'off',
}
----

* Only "plain" is supported by the client:

----
(handshake) handshake password_hash_algo=plain
----

Response:

[source,python]
----
id: 'handshake'
htb: {
    'password_hash_algo': 'plain',
    'password_hash_iterations': '100000',
    'totp': 'on',
    'nonce': '85B1EE00695A5B254E14F4885538DF0D',
    'compression': 'off',
}
----

* Only "plain", "sha256" and "pbkdf2+sha256" are supported by the client:

----
(handshake) handshake password_hash_algo=plain:sha256:pbkdf2+sha256
----

Response:

[source,python]
----
id: 'handshake'
htb: {
    'password_hash_algo': 'pbkdf2+sha256',
    'password_hash_iterations': '100000',
    'totp': 'on',
    'nonce': '85B1EE00695A5B254E14F4885538DF0D',
    'compression': 'off',
}
----

The client can authenticate with this command (see <<command_init,init command>>),
the salt is the _relay_ nonce + client nonce ("A4B73207F5AAE4" in hexadecimal),
the password is "test" in this example:

----
init password_hash=pbkdf2+sha256:85b1ee00695a5b254e14f4885538df0da4b73207f5aae4:100000:ba7facc3edb89cd06ae810e29ced85980ff36de2bb596fcf513aaab626876440
----

* Only "sha256" and "sha512" are supported by the client, enable zstd (preferred)
or zlib compression:

----
(handshake) handshake password_hash_algo=sha256:sha512,compression=zstd:zlib
----

Response:

[source,python]
----
id: 'handshake'
htb: {
    'password_hash_algo': 'sha512',
    'password_hash_iterations': '100000',
    'totp': 'on',
    'nonce': '85B1EE00695A5B254E14F4885538DF0D',
    'compression': 'zstd',
}
----

[[command_init]]
=== init

_Updated in versions 2.4, 2.8, 2.9, 3.5._

Authenticate with _relay_.

This must be first command sent to _relay_ (only _handshake_ command can be sent
before _init_). +
If not sent, _relay_ will close connection on first command received (except
_handshake_), without warning.

Syntax:

----
(id) init [<option>=<value>,[<option>=<value>,...]]
----

Arguments:

* _option_: one of following options:
** _password_: password used to authenticate on _relay_
   (option _relay.network.password_ in WeeChat)
** _password_hash_: hash of password used to authenticate on _relay_
   (option _relay.network.password_ in WeeChat), see below for the format
   _(WeeChat ≥ 2.8)_
** _totp_: Time-based One-Time Password (TOTP) used as secondary authentication
   factor, in addition to the password
   (option _relay.network.totp_secret_ in WeeChat)
   _(WeeChat ≥ 2.4)_

[NOTE]
With WeeChat ≥ 1.6, commas can be escaped in the value, for example
`+init password=foo\,bar+` to send the password "foo,bar".

Format of hashed password is one of the following, where _hash_ is the hashed
password as hexadecimal:

* `+sha256:salt:hash+` with:
** _salt_: salt (hexadecimal), which must start with the server nonce,
   concatenated to the client nonce
** _hash_: the hashed salt + password (hexadecimal)
* `+sha512:salt:hash+` with:
** _salt_: salt (hexadecimal), which must start with the server nonce,
   concatenated to the client nonce
** _hash_: the hashed salt + password (hexadecimal)
* `+pbkdf2+sha256:salt:iterations:hash+` with:
** _salt_: salt (hexadecimal), which must start with the server nonce,
   concatenated to the client nonce
** _iterations_: number of iterations
** _hash_: the hashed salt + password with SHA256 algorithm (hexadecimal)
* `+pbkdf2+sha512:salt:iterations:hash+` with:
** _salt_: salt (hexadecimal), which must start with the server nonce,
   concatenated to the client nonce
** _iterations_: number of iterations
** _hash_: the hashed salt + password with SHA512 algorithm (hexadecimal)

[NOTE]
Hexadecimal strings can be lower or upper case, _relay_ can decode both.

Examples:

* Initialize with password:

----
init password=mypass
----

* Initialize with commas in the password _(WeeChat ≥ 1.6)_:

----
init password=mypass\,with\,commas
----

* Initialize with password and TOTP _(WeeChat ≥ 2.4)_:

----
init password=mypass,totp=123456
----

* Initialize with hashed password "test" (SHA256: salt=relay nonce + client nonce)
  _(WeeChat ≥ 2.9)_:

----
init password_hash=sha256:85b1ee00695a5b254e14f4885538df0da4b73207f5aae4:2c6ed12eb0109fca3aedc03bf03d9b6e804cd60a23e1731fd17794da423e21db
----

* Initialize with hashed password "test" (SHA512: salt=relay nonce + client nonce)
  _(WeeChat ≥ 2.9)_:

----
init password_hash=sha512:85b1ee00695a5b254e14f4885538df0da4b73207f5aae4:0a1f0172a542916bd86e0cbceebc1c38ed791f6be246120452825f0d74ef1078c79e9812de8b0ab3dfaf598b6ca14522374ec6a8653a46df3f96a6b54ac1f0f8
----

* Initialize with hashed password "test" (PBKDF2: SHA256, salt=relay nonce + client nonce,
  100000 iterations) _(WeeChat ≥ 2.9)_:

----
init password_hash=pbkdf2+sha256:85b1ee00695a5b254e14f4885538df0da4b73207f5aae4:100000:ba7facc3edb89cd06ae810e29ced85980ff36de2bb596fcf513aaab626876440
----

[[command_hdata]]
=== hdata

Request a _hdata_.

Syntax:

----
(id) hdata <path> [<keys>]
----

Arguments:

* _path_: path to a hdata, with format: "hdata:pointer/var/var/.../var", the
  last var is the hdata returned:
** _hdata_: name of hdata
** _pointer_: pointer (eg: "0x1234abcd") or list name (for example: "gui_buffers")
   (count allowed, see below)
** _var_: a variable name in parent hdata (previous name in path)
   (count allowed, see below)
* _keys_: comma-separated list of keys to return in hdata (if not specified, all
  keys are returned, which is not recommended on large hdata structures)

A count is allowed after pointer and variables, with format "(N)". Possible
values are:

* positive number: iterate using next element, N times
* negative number: iterate using previous element, N times
* _*_: iterate using next element, until end of list

[NOTE]
With WeeChat ≥ 1.6, if the hdata path is invalid or if a NULL pointer is found,
an empty hdata is returned (see example in <<object_hdata,hdata object>>). +
With older versions, nothing was returned.

Examples:

* Request "number" and "full_name" of all buffers:

----
(hdata_buffers) hdata buffer:gui_buffers(*) number,full_name
----

Response:

[source,python]
----
id: 'hdata_buffers'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
    }
    path: ['buffer']
    item 1:
        __path: ['0x558d61ea3e60']
        number: 1
        full_name: 'core.weechat'
    item 2:
        __path: ['0x558d62840ea0']
        number: 1
        full_name: 'irc.server.libera'
    item 3:
        __path: ['0x558d62a9cea0']
        number: 2
        full_name: 'irc.libera.#weechat'
----

* Request all lines of first buffer:

----
(hdata_lines) hdata buffer:gui_buffers/own_lines/first_line(*)/data
----

Response:

[source,python]
----
id: 'hdata_lines'
hda:
    keys: {
        'buffer': 'ptr',
        'y': 'int',
        'date': 'tim',
        'date_printed': 'tim',
        'str_time': 'str',
        'tags_count': 'int',
        'tags_array': 'arr',
        'displayed': 'chr',
        'notify_level': 'chr',
        'highlight': 'chr',
        'refresh_needed': 'chr',
        'prefix': 'str',
        'prefix_length': 'int',
        'message': 'str',
    }
    path: ['buffer', 'lines', 'line', 'line_data']
    item 1:
        __path: ['0x558d61ea3e60', '0x558d61ea40e0', '0x558d62920d80', '0x558d62abf040']
        buffer: '0x558d61ea3e60'
        y: -1
        date: 1588404926
        date_printed: 1588404926
        str_time: 'F@0025209F@0024535F@0024026'
        tags_count: 0
        tags_array: []
        displayed: 1
        notify_level: 0
        highlight: 0
        refresh_needed: 0
        prefix: ''
        prefix_length: 0
        message: 'this is the first line'
    item 2:
        __path: ['0x558d61ea3e60', '0x558d61ea40e0', '0x558d626779f0', '0x558d62af9700']
        buffer: '0x558d61ea3e60'
        y: -1
        date: 1588404930
        date_printed: 1588404930
        str_time: 'F@0025209F@0024535F@0024030'
        tags_count: 0
        tags_array: []
        displayed: 1
        notify_level: 0
        highlight: 0
        refresh_needed: 0
        prefix: ''
        prefix_length: 0
        message: 'this is the second line'
----

* Request the hotlist content:

----
(hdata_hotlist) hdata hotlist:gui_hotlist(*)
----

Response:

[source,python]
----
id: 'hdata_hotlist'
hda:
    keys: {
        'priority': 'int',
        'creation_time.tv_sec': 'tim',
        'creation_time.tv_usec': 'lon',
        'buffer': 'ptr',
        'count': 'arr',
        'prev_hotlist': 'ptr',
        'next_hotlist': 'ptr',
    }
    path: ['hotlist']
    item 1:
        __path: ['0x558d629601b0']
        priority: 3
        creation_time.tv_sec: 1588405398
        creation_time.tv_usec: 355383
        buffer: '0x558d62a9cea0'
        count: [1, 1, 0, 1]
        prev_hotlist: '0x0'
        next_hotlist: '0x0'
----

[[command_info]]
=== info

Request an _info_.

Syntax:

----
(id) info <name> [<arguments>]
----

Arguments:

* _name_: name of info to retrieve
* _arguments_: arguments (optional)

Examples:

* Request WeeChat version:

----
(info_version) info version
----

Response:

[source,python]
----
id: 'info_version'
inf: ('version', '2.9-dev')
----

* Request WeeChat version as number:

----
(info_version_number) info version_number
----

Response:

[source,python]
----
id: 'info_version_number'
inf: ('version_number', '34144256')
----

* Request WeeChat directory:

----
(info_weechat_config_dir) info weechat_config_dir
----

Response:

[source,python]
----
id: 'info_weechat_config_dir'
inf: ('weechat_config_dir', '/home/user/.config/weechat')
----

[[command_infolist]]
=== infolist

Request an _infolist_.

[IMPORTANT]
Content of infolist is a duplication of actual data. Wherever possible, use
command <<command_hdata,hdata>>, which is direct access to data (it is
faster, uses less memory and returns smaller objects in message).

Syntax:

----
(id) infolist <name> [<pointer> [<arguments>]]
----

Arguments:

* _name_: name of infolist to retrieve
* _pointer_: pointer (optional)
* _arguments_: arguments (optional)

Examples:

* Request infolist "buffer":

----
(infolist_buffer) infolist buffer
----

Response:

[source,python]
----
id: 'infolist_buffer'
inl:
    name: buffer
    item 1:
        pointer: '0x558d61ea3e60'
        current_buffer: 1
        plugin: '0x0'
        plugin_name: 'core'
        number: 1
        layout_number: 1
        layout_number_merge_order: 0
        name: 'weechat'
        full_name: 'core.weechat'
        old_full_name: None
        short_name: 'weechat'
        type: 0
        notify: 3
        num_displayed: 1
        active: 1
        hidden: 0
        zoomed: 0
        print_hooks_enabled: 1
        day_change: 1
        clear: 1
        filter: 1
        closing: 0
        first_line_not_read: 0
        lines_hidden: 0
        prefix_max_length: 0
        time_for_each_line: 1
        nicklist_case_sensitive: 0
        nicklist_display_groups: 1
        nicklist_max_length: 0
        nicklist_count: 0
        nicklist_groups_count: 0
        nicklist_nicks_count: 0
        nicklist_visible_count: 0
        title: 'WeeChat 2.9-dev (C) 2003-2020 - https://weechat.org/'
        input: 1
        input_get_unknown_commands: 0
        input_get_empty: 0
        input_multiline: 0
        input_buffer: ''
        input_buffer_alloc: 256
        input_buffer_size: 0
        input_buffer_length: 0
        input_buffer_pos: 0
        input_buffer_1st_display: 0
        num_history: 0
        text_search: 0
        text_search_exact: 0
        text_search_regex: 0
        text_search_regex_compiled: '0x0'
        text_search_where: 0
        text_search_found: 0
        text_search_input: None
        highlight_words: None
        highlight_disable_regex: None
        highlight_disable_regex_compiled: '0x0'
        highlight_regex: None
        highlight_regex_compiled: '0x0'
        highlight_tags_restrict: None
        highlight_tags: None
        hotlist_max_level_nicks: None
        keys_count: 0
        localvar_name_00000: 'plugin'
        localvar_value_00000: 'core'
        localvar_name_00001: 'name'
        localvar_value_00001: 'weechat'
----

* Request infolist "window":

----
(infolist_window) infolist window
----

Response:

[source,python]
----
id: 'infolist_window'
inl:
    name: window
    item 1:
        pointer: '0x558d61ddc800'
        current_window: 1
        number: 1
        x: 14
        y: 0
        width: 259
        height: 71
        width_pct: 100
        height_pct: 100
        chat_x: 14
        chat_y: 1
        chat_width: 259
        chat_height: 68
        buffer: '0x558d61ea3e60'
        start_line_y: 0
----

[[command_nicklist]]
=== nicklist

Request a _nicklist_, for one or all buffers.

Syntax:

----
(id) nicklist [<buffer>]
----

Arguments:

* _buffer_: pointer (eg: "0x1234abcd") or full name of buffer (for example:
  _core.weechat_ or _irc.libera.#weechat_)

Examples:

* Request nicklist for all buffers:

----
(nicklist_all) nicklist
----

Response:

[source,python]
----
id: 'nicklist_all'
hda:
    keys: {
        'group': 'chr',
        'visible': 'chr',
        'level': 'int',
        'name': 'str',
        'color': 'str',
        'prefix': 'str',
        'prefix_color': 'str',
    }
    path: ['buffer', 'nicklist_item']
    item 1:
        __path: ['0x558d61ea3e60', '0x558d61ea4120']
        group: 1
        visible: 0
        level: 0
        name: 'root'
        color: None
        prefix: None
        prefix_color: None
    item 2:
        __path: ['0x558d62840ea0', '0x558d61e75f90']
        group: 1
        visible: 0
        level: 0
        name: 'root'
        color: None
        prefix: None
        prefix_color: None
    item 3:
        __path: ['0x558d62a9cea0', '0x558d62abf2e0']
        group: 1
        visible: 0
        level: 0
        name: 'root'
        color: None
        prefix: None
        prefix_color: None
    item 4:
        __path: ['0x558d62a9cea0', '0x558d62afb9d0']
        group: 1
        visible: 1
        level: 1
        name: '000|o'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 5:
        __path: ['0x558d62a9cea0', '0x558d62aff930']
        group: 0
        visible: 1
        level: 0
        name: 'FlashCode'
        color: 'weechat.color.chat_nick_self'
        prefix: '@'
        prefix_color: 'lightgreen'
    item 6:
        __path: ['0x558d62a9cea0', '0x558d62af9930']
        group: 1
        visible: 1
        level: 1
        name: '001|v'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 7:
        __path: ['0x558d62a9cea0', '0x558d62afc510']
        group: 1
        visible: 1
        level: 1
        name: '999|...'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 8:
        __path: ['0x558d62a9cea0', '0x558d6292c290']
        group: 0
        visible: 1
        level: 0
        name: 'flashy'
        color: '142'
        prefix: ' '
        prefix_color: 'lightblue'
    item 9:
        __path: ['0x558d62914680', '0x558d62afc4b0']
        group: 1
        visible: 0
        level: 0
        name: 'root'
        color: None
        prefix: None
        prefix_color: None
----

* Request nicklist for buffer "irc.libera.#weechat":

----
(nicklist_weechat) nicklist irc.libera.#weechat
----

Response:

[source,python]
----
id: 'nicklist_weechat'
hda:
    keys: {
        'group': 'chr',
        'visible': 'chr',
        'level': 'int',
        'name': 'str',
        'color': 'str',
        'prefix': 'str',
        'prefix_color': 'str',
    }
    path: ['buffer', 'nicklist_item']
    item 1:
        __path: ['0x558d62a9cea0', '0x558d62abf2e0']
        group: 1
        visible: 0
        level: 0
        name: 'root'
        color: None
        prefix: None
        prefix_color: None
    item 2:
        __path: ['0x558d62a9cea0', '0x558d62afb9d0']
        group: 1
        visible: 1
        level: 1
        name: '000|o'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 3:
        __path: ['0x558d62a9cea0', '0x558d62aff930']
        group: 0
        visible: 1
        level: 0
        name: 'FlashCode'
        color: 'weechat.color.chat_nick_self'
        prefix: '@'
        prefix_color: 'lightgreen'
    item 4:
        __path: ['0x558d62a9cea0', '0x558d62af9930']
        group: 1
        visible: 1
        level: 1
        name: '001|v'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 5:
        __path: ['0x558d62a9cea0', '0x558d62afc510']
        group: 1
        visible: 1
        level: 1
        name: '999|...'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 6:
        __path: ['0x558d62a9cea0', '0x558d6292c290']
        group: 0
        visible: 1
        level: 0
        name: 'flashy'
        color: '142'
        prefix: ' '
        prefix_color: 'lightblue'
----

[[command_input]]
=== input

Send data to a buffer.

Syntax:

----
(id) input <buffer> <data>
----

Arguments:

* _buffer_: pointer (eg: "0x1234abcd") or full name of buffer (for example:
  _core.weechat_ or _irc.libera.#weechat_)
* _data_: data to send to buffer: if beginning by `/`, this will be executed as
   a command on buffer, otherwise text is sent as input of buffer

Examples:

* Send command "/help filter" on WeeChat core bufer:

----
input core.weechat /help filter
----

* Send message "hello!" to #weechat channel:

----
input irc.libera.#weechat hello!
----

[[command_completion]]
=== completion

_WeeChat ≥ 2.9._

Request completion of a string: list of possible words at a given position in
a string for a given buffer.

Syntax:

----
(id) completion <buffer> <position> [<data>]
----

Arguments:

* _buffer_: pointer (eg: "0x1234abcd") or full name of buffer (for example:
  _core.weechat_ or _irc.libera.#weechat_)
* _position_: position for completion in string (starts to 0);
  if the value is -1, the position is the length of _data_ (so the completion
  is made at the end of _data_)
* _data_: the input string; if not given, completion is performed on an empty
  string

WeeChat replies with a hdata:

[width="100%",cols="2m,3,14",options="header"]
|===
| Name      | Type             | Description
| context   | string           | Completion context: "null" (no completion), "command", "command_arg", "auto".
| base_word | string           | The base word used for completion.
| pos_start | integer          | Index of first char to replace (starts to 0).
| pos_end   | integer          | Index of last char to replace (starts to 0).
| add_space | integer          | 1 if a space must be added after words, 0 otherwise.
| list      | array of strings | List of words found; empty if nothing was found to complete at asked position.
|===

[NOTE]
In case of error, for example invalid buffer or internal error on WeeChat side,
an empty hdata is returned.

Examples:

* Completion of a command argument:

----
(completion_help) completion core.weechat -1 /help fi
----

Response:

[source,python]
----
id: 'completion_help'
hda:
    keys: {
        'context': 'str',
        'base_word': 'str',
        'pos_start': 'int',
        'pos_end': 'int',
        'add_space': 'int',
        'list': 'arr',
    }
    path: ['completion']
    item 1:
      __path: ['0x55d0ccc842c0']
      context: 'command_arg'
      base_word: 'fi'
      pos_start: 6
      pos_end: 7
      add_space: 0
      list: [
          'fifo',
          'fifo.file.enabled',
          'fifo.file.path',
          'filter',
      ]
----

* Completion of a command in the middle of a word:

----
(completion_query) completion core.weechat 5 /quernick
----

Response:

[source,python]
----
id: 'completion_query'
hda:
    keys: {
        'context': 'str',
        'base_word': 'str',
        'pos_start': 'int',
        'pos_end': 'int',
        'add_space': 'int',
        'list': 'arr',
    }
    path: ['completion']
    item 1:
        __path: ['0x55d0ccc88470']
        context: 'command'
        base_word: 'quer'
        pos_start: 1
        pos_end: 4
        add_space: 1
        list: ['query']
----

* Nothing to complete:

----
(completion_abcdefghijkl) completion core.weechat -1 abcdefghijkl
----

Response:

[source,python]
----
id: 'completion_abcdefghijkl'
hda:
    keys: {
        'context': 'str',
        'base_word': 'str',
        'pos_start': 'int',
        'pos_end': 'int',
        'add_space': 'int',
        'list': 'arr',
    }
    path: ['completion']
    item 1:
        __path: ['0x55d0ccc88470']
        context: 'auto'
        base_word: 'abcdefghijkl'
        pos_start: 0
        pos_end: 11
        add_space: 1
        list: []
----

* Completion on an invalid buffer:

----
(completion_help) completion buffer.does.not.exist -1 /help fi
----

Response:

[source,python]
----
id: 'completion_help'
hda:
    keys: {}
    path: ['completion']
----

[[command_sync]]
=== sync

_Updated in version 0.4.1._

Synchronize one or more buffers, to get updates.

[IMPORTANT]
It is recommended to send this command immediately after you asked
data for buffers (lines, ...). It can be send in same message (after a new
line char: "\n").

Syntax:

----
(id) sync [<buffer>[,<buffer>...] <option>[,<option>...]]
----

Arguments:

* _buffer_: pointer (eg: "0x1234abcd") or full name of buffer (for example:
  _core.weechat_ or _irc.libera.#weechat_); name "*" can be used to
  specify all buffers
* _options_: one of following keywords, separated by commas (default is
  _buffers,upgrade,buffer,nicklist_ for "*" and _buffer,nicklist_ for a buffer):
** _buffers_: receive signals about buffers (opened/closed, moved, renamed,
   merged/unmerged, hidden/unhidden); this can be used only with name "*"
   _(WeeChat ≥ 0.4.1)_
** _upgrade_: receive signals about WeeChat upgrade (upgrade, upgrade ended);
   this can be used only with name "*"
   _(WeeChat ≥ 0.4.1)_
** _buffer_: receive signals about buffer (new lines, type changed, title
   changed, local variable added/removed, and same signals as _buffers_ for the
   buffer) _(updated in version 0.4.1)_
** _nicklist_: receive nicklist after changes

Examples:

* Synchronize all buffers with nicklist (the 3 commands are equivalent,
but the first one is recommended for compatibility with future versions):

----
sync
sync *
sync * buffers,upgrade,buffer,nicklist
----

* Synchronize WeeChat core buffer:

----
sync core.buffer
----

* Synchronize #weechat channel, without nicklist:

----
sync irc.libera.#weechat buffer
----

* Get general signals + all signals for #weechat channel:

----
sync * buffers,upgrade
sync irc.libera.#weechat
----

[[command_desync]]
=== desync

_Updated in version 0.4.1._

Desynchronize one or more buffers, to stop updates.

[NOTE]
This will remove _options_ for buffers. If some options are still active for
buffers, the client will still receive updates for these buffers.

Syntax:

----
(id) desync [<buffer>[,<buffer>...] <option>[,<option>...]]
----

Arguments:

* _buffer_: pointer (eg: "0x1234abcd") or full name of buffer (for example:
  _core.weechat_ or _irc.libera.#weechat_); name "*" can be used to
  specify all buffers
* _options_: one of following keywords, separated by commas (default is
  _buffers,upgrade,buffer,nicklist_ for "*" and _buffer,nicklist_ for a buffer);
  see <<command_sync,command sync>> for values

[NOTE]
When using buffer "*", the other buffers synchronized (using a name) are kept. +
So if you send: "sync *", then "sync irc.libera.#weechat", then "desync *",
the updates on #weechat channel will still be sent by WeeChat (you must remove
it explicitly to stop updates).

Examples:

* Desynchronize all buffers (the 3 commands are equivalent, but the first one
  is recommended for compatibility with future versions):

----
desync
desync *
desync * buffers,upgrade,buffer,nicklist
----

* Desynchronize nicklist for #weechat channel (keep buffer updates):

----
desync irc.libera.#weechat nicklist
----

* Desynchronize #weechat channel:

----
desync irc.libera.#weechat
----

[[command_test]]
=== test

Test command: WeeChat will reply with various different objects.

This command is useful to test the decoding of binary objects returned by
WeeChat.

Syntax:

----
(id) test
----

Returned objects (in this order):

[width="80%",cols="1m,2,6m",options="header"]
|===
| Type    | Description       | Value
| chr     | char              | 65 ("A")
| int     | integer           | 123456
| int     | integer           | -123456
| lon     | long              | 1234567890
| lon     | long              | -1234567890
| str     | string            | "a string"
| str     | string            | ""
| str     | string            | NULL
| buf     | buffer            | "buffer"
| buf     | buffer            | NULL
| ptr     | pointer           | 0x1234abcd
| ptr     | pointer           | NULL
| tim     | time              | 1321993456
| arr str | array of strings  | [ "abc", "de" ]
| arr int | array of integers | [ 123, 456, 789 ]
|===

[IMPORTANT]
You must not use the pointer values returned by this command, they are not
valid. This command must be used only to test decoding of a message sent by
WeeChat.

Example:

----
(test) test
----

Response:

----
id: 'test'
chr: 65
int: 123456
int: -123456
lon: 1234567890
lon: -1234567890
str: 'a string'
str: ''
str: None
buf: 'buffer'
buf: None
ptr: '0x1234abcd'
ptr: '0x0'
tim: 1321993456
arr: ['abc', 'de']
arr: [123, 456, 789]
----

[[command_ping]]
=== ping

_WeeChat ≥ 0.4.2._

Send a ping to WeeChat which will reply with a message "_pong" and same arguments.

This command is useful to test that connection with WeeChat is still alive and
measure the response time.

Syntax:

----
(id) ping [<arguments>]
----

Example:

----
ping 1370802127000
----

Response:

----
id:'_pong'
str: '1370802127000'
----

[[command_quit]]
=== quit

Disconnect from _relay_.

Syntax:

----
(id) quit
----

Example:

----
quit
----

[[messages]]
== Messages (relay → client)

Messages are sent as binary data, using following format (with size in bytes):

....
┌────────╥─────────────╥─────────╥────────┬──────────╥───────╥────────┬──────────┐
│ length ║ compression ║   id    ║ type 1 │ object 1 ║  ...  ║ type N │ object N │
└────────╨─────────────╨─────────╨────────┴──────────╨───────╨────────┴──────────┘
 └──────┘ └───────────┘ └───────┘ └──────┘ └────────┘         └──────┘ └────────┘
     4          1        4 + str      3        ??                 3        ??
 └────────────────────┘ └───────────────────────────────────────────────────────┘
       header (5)                          compressed data (??)
 └──────────────────────────────────────────────────────────────────────────────┘
                               'length' bytes
....

* _length_ (unsigned integer, 4 bytes): number of bytes of whole message
  (including this field)
* _compression_ (byte): flag:
** _0x00_: following data is not compressed
** _0x01_: following data is compressed with https://zlib.net/[zlib ^↗^,window=_blank]
** _0x02_: following data is compressed with https://facebook.github.io/zstd/[Zstandard ^↗^,window=_blank]
* _id_ (string, 4 bytes + content): identifier sent by client (before command name); it can be
  empty (string with zero length and no content) if no identifier was given in
  command
* _type_ (3 chars): a type: 3 letters (see table below)
* _object_: an object (see table below)

[[message_compression]]
=== Compression

If flag _compression_ is equal to 0x01 or 0x02, then *all* data after is compressed
with https://zlib.net/[zlib ^↗^,window=_blank] or
https://facebook.github.io/zstd/[Zstandard ^↗^,window=_blank],
and therefore must be uncompressed before being processed.

[[message_identifier]]
=== Identifier

There are two types of identifiers (_id_):

* _id_ sent by _client_: _relay_ will answer with same _id_ in its answer
* _id_ of an event: on some events, _relay_ will send message to _client_ using
  a specific _id_, beginning with underscore (see table below)

WeeChat reserved identifiers:

[width="100%",cols="5m,5,3,4,7",options="header"]
|===
| Identifier | Received with _sync_ | Data sent
| Description | Recommended action in client

| _buffer_opened | buffers / buffer | hdata: buffer
| Buffer opened. | Open buffer.

| _buffer_type_changed | buffers / buffer | hdata: buffer
| Type of buffer changed. | Change type of buffer.

| _buffer_moved | buffers / buffer | hdata: buffer
| Buffer moved. | Move buffer.

| _buffer_merged | buffers / buffer | hdata: buffer
| Buffer merged. | Merge buffer.

| _buffer_unmerged | buffers / buffer | hdata: buffer
| Buffer unmerged. | Unmerge buffer.

| _buffer_hidden | buffers / buffer | hdata: buffer
| Buffer hidden. | Hide buffer.

| _buffer_unhidden | buffers / buffer | hdata: buffer
| Buffer unhidden. | Unhide buffer.

| _buffer_renamed | buffers / buffer | hdata: buffer
| Buffer renamed. | Rename buffer.

| _buffer_title_changed | buffers / buffer | hdata: buffer
| Title of buffer changed. | Change title of buffer.

| _buffer_localvar_added | buffers / buffer | hdata: buffer
| Local variable added. | Add local variable in buffer.

| _buffer_localvar_changed | buffers / buffer | hdata: buffer
| Local variable changed. | Change local variable in buffer.

| _buffer_localvar_removed | buffers / buffer | hdata: buffer
| Local variable removed. | Remove local variable from buffer.

| _buffer_closing | buffers / buffer | hdata: buffer
| Buffer closing. | Close buffer.

| _buffer_cleared | buffer | hdata: buffer
| Buffer cleared. | Clear buffer.

| _buffer_line_added | buffer | hdata: line
| Line added in buffer. | Display line in buffer.

| _nicklist | nicklist | hdata: nicklist_item
| Nicklist for a buffer. | Replace nicklist.

| _nicklist_diff | nicklist | hdata: nicklist_item
| Nicklist diffs for a buffer . | Update nicklist.

| _pong | (always) | string: ping arguments
| Answer to a "ping". | Measure response time.

| _upgrade | upgrade | (empty)
| WeeChat is upgrading. | Desync from WeeChat (or disconnect).

| _upgrade_ended | upgrade | (empty)
| Upgrade of WeeChat done. | Sync/resync with WeeChat.
|===

[[message_buffer_opened]]
==== _buffer_opened

This message is sent to the client when the signal "buffer_opened" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name            | Type      | Description
| number          | integer   | Buffer number (≥ 1).
| full_name       | string    | Full name (example: _irc.libera.#weechat_).
| short_name      | string    | Short name (example: _#weechat_).
| nicklist        | integer   | 1 if buffer has a nicklist, otherwise 0.
| title           | string    | Buffer title.
| local_variables | hashtable | Local variables.
| prev_buffer     | pointer   | Pointer to previous buffer.
| next_buffer     | pointer   | Pointer to next buffer.
|===

Example: channel _#weechat_ joined on libera, new buffer
_irc.libera.#weechat_:

[source,python]
----
id: '_buffer_opened'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'short_name': 'str',
        'nicklist': 'int',
        'title': 'str',
        'local_variables': 'htb',
        'prev_buffer': 'ptr',
        'next_buffer': 'ptr',
    }
    path: ['buffer']
    item 1:
        __path: ['0x35a8a60']
        number: 3
        full_name: 'irc.libera.#weechat'
        short_name: None
        nicklist: 0
        title: None
        local_variables: {
            'plugin': 'irc',
            'name': 'libera.#weechat',
        }
        prev_buffer: '0x34e7400'
        next_buffer: '0x0'
----

[[message_buffer_moved]]
==== _buffer_moved

This message is sent to the client when the signal "buffer_moved" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name        | Type    | Description
| number      | integer | Buffer number (≥ 1).
| full_name   | string  | Full name (example: _irc.libera.#weechat_).
| prev_buffer | pointer | Pointer to previous buffer.
| next_buffer | pointer | Pointer to next buffer.
|===

Example: buffer _irc.libera.#weechat_ moved to number 2:

[source,python]
----
id: '_buffer_moved'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'prev_buffer': 'ptr',
        'next_buffer': 'ptr',
    }
    path: ['buffer']
    item 1:
        __path: ['0x34588c0']
        number: 2
        full_name: 'irc.libera.#weechat'
        prev_buffer: '0x347b9f0'
        next_buffer: '0x3471bc0'
----

[[message_buffer_merged]]
==== _buffer_merged

This message is sent to the client when the signal "buffer_merged" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name        | Type    | Description
| number      | integer | Buffer number (≥ 1).
| full_name   | string  | Full name (example: _irc.libera.#weechat_).
| prev_buffer | pointer | Pointer to previous buffer.
| next_buffer | pointer | Pointer to next buffer.
|===

Example: buffer _irc.libera.#weechat_ merged with buffer #2:

[source,python]
----
id: '_buffer_merged'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'prev_buffer': 'ptr',
        'next_buffer': 'ptr',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4db4c00']
        number: 2
        full_name: 'irc.libera.#weechat'
        prev_buffer: '0x4cef9b0'
        next_buffer: '0x0'
----

[[message_buffer_unmerged]]
==== _buffer_unmerged

This message is sent to the client when the signal "buffer_unmerged" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name        | Type    | Description
| number      | integer | Buffer number (≥ 1).
| full_name   | string  | Full name (example: _irc.libera.#weechat_).
| prev_buffer | pointer | Pointer to previous buffer.
| next_buffer | pointer | Pointer to next buffer.
|===

Example: buffer _irc.libera.#weechat_ unmerged:

[source,python]
----
id: '_buffer_unmerged'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'prev_buffer': 'ptr',
        'next_buffer': 'ptr',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4db4c00']
        number: 3
        full_name: 'irc.libera.#weechat'
        prev_buffer: '0x4cef9b0'
        next_buffer: '0x0'
----

[[message_buffer_hidden]]
==== _buffer_hidden

_WeeChat ≥ 1.0._

This message is sent to the client when the signal "buffer_hidden" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name        | Type    | Description
| number      | integer | Buffer number (≥ 1).
| full_name   | string  | Full name (example: _irc.libera.#weechat_).
| prev_buffer | pointer | Pointer to previous buffer.
| next_buffer | pointer | Pointer to next buffer.
|===

Example: buffer _irc.libera.#weechat_ hidden:

[source,python]
----
id: '_buffer_hidden'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'prev_buffer': 'ptr',
        'next_buffer': 'ptr',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4db4c00']
        number: 2
        full_name: 'irc.libera.#weechat'
        prev_buffer: '0x4cef9b0'
        next_buffer: '0x0'
----

[[message_buffer_unhidden]]
==== _buffer_unhidden

_WeeChat ≥ 1.0._

This message is sent to the client when the signal "buffer_unhidden" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name        | Type    | Description
| number      | integer | Buffer number (≥ 1).
| full_name   | string  | Full name (example: _irc.libera.#weechat_).
| prev_buffer | pointer | Pointer to previous buffer.
| next_buffer | pointer | Pointer to next buffer.
|===

Example: buffer _irc.libera.#weechat_ unhidden:

[source,python]
----
id: '_buffer_unhidden'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'prev_buffer': 'ptr',
        'next_buffer': 'ptr',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4db4c00']
        number: 3
        full_name: 'irc.libera.#weechat'
        prev_buffer: '0x4cef9b0'
        next_buffer: '0x0'
----

[[message_buffer_renamed]]
==== _buffer_renamed

This message is sent to the client when the signal "buffer_renamed" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name            | Type      | Description
| number          | integer   | Buffer number (≥ 1).
| full_name       | string    | Full name (example: _irc.libera.#weechat_).
| short_name      | string    | Short name (example: _#weechat_).
| local_variables | hashtable | Local variables.
|===

Example: private buffer renamed from _FlashCode_ to _Flash2_:

[source,python]
----
id: '_buffer_renamed'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'short_name': 'str',
        'local_variables': 'htb',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4df7b80']
        number: 5
        full_name: 'irc.libera.Flash2'
        short_name: 'Flash2'
        local_variables: {
            'server': 'libera',
            'plugin': 'irc',
            'type': 'private',
            'channel': 'FlashCode',
            'nick': 'test',
            'name': 'libera.Flash2',
        }
----

[[message_buffer_title_changed]]
==== _buffer_title_changed

This message is sent to the client when the signal "buffer_title_changed" is
sent by WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name      | Type    | Description
| number    | integer | Buffer number (≥ 1).
| full_name | string  | Full name (example: _irc.libera.#weechat_).
| title     | string  | Buffer title.
|===

Example: topic changed on channel _#weechat_:

[source,python]
----
id: '_buffer_title_changed'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'title': 'str',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4a715d0']
        number: 3
        full_name: 'irc.libera.#weechat'
        title: 'Welcome on #weechat!  https://weechat.org/'
----

[[message_buffer_cleared]]
==== _buffer_cleared

_WeeChat ≥ 1.0._

This message is sent to the client when the signal "buffer_cleared" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name      | Type    | Description
| number    | integer | Buffer number (≥ 1).
| full_name | string  | Full name (example: _irc.libera.#weechat_).
|===

Example: buffer _irc.libera.#weechat_ has been cleared:

[source,python]
----
id: '_buffer_cleared'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4a715d0']
        number: 3
        full_name: 'irc.libera.#weechat'
----

[[message_buffer_type_changed]]
==== _buffer_type_changed

This message is sent to the client when the signal "buffer_type_changed" is sent
by WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name      | Type    | Description
| number    | integer | Buffer number (≥ 1).
| full_name | string  | Full name (example: _irc.libera.#weechat_).
| type      | integer | Buffer type: 0 = formatted (default), 1 = free content.
|===

Example: type of buffer _script.scripts_ changed from formatted (0) to free
content (1):

[source,python]
----
id: '_buffer_type_changed'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'type': 'int',
    }
    path: ['buffer']
    item 1:
        __path: ['0x27c9a70']
        number: 4
        full_name: 'script.scripts'
        type: 1
----

[[message_buffer_localvar_added]]
==== _buffer_localvar_added

This message is sent to the client when the signal "buffer_localvar_added" is
sent by WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name            | Type      | Description
| number          | integer   | Buffer number (≥ 1).
| full_name       | string    | Full name (example: _irc.libera.#weechat_).
| local_variables | hashtable | Local variables.
|===

Example: local variable _test_ added in buffer _irc.libera.#weechat_:

[source,python]
----
id='_buffer_localvar_added', objects:
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'local_variables': 'htb',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4a73de0']
        number: 3
        full_name: 'irc.libera.#weechat'
        local_variables: {
            'server': 'libera',
            'test': 'value',
            'plugin': 'irc',
            'type': 'channel',
            'channel': '#weechat',
            'nick': 'test',
            'name': 'libera.#weechat',
        }
----

[[message_buffer_localvar_changed]]
==== _buffer_localvar_changed

This message is sent to the client when the signal "buffer_localvar_changed" is
sent by WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name            | Type      | Description
| number          | integer   | Buffer number (≥ 1).
| full_name       | string    | Full name (example: _irc.libera.#weechat_).
| local_variables | hashtable | Local variables.
|===

Example: local variable _test_ updated in buffer _irc.libera.#weechat_:

[source,python]
----
id='_buffer_localvar_changed', objects:
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'local_variables': 'htb',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4a73de0']
        number: 3
        full_name: 'irc.libera.#weechat'
        local_variables: {
            'server': 'local',
            'test': 'value2',
            'plugin': 'irc',
            'type': 'channel',
            'channel': '#weechat',
            'nick': 'test',
            'name': 'libera.#weechat',
        }
----

[[message_buffer_localvar_removed]]
==== _buffer_localvar_removed

This message is sent to the client when the signal "buffer_localvar_removed" is
sent by WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name            | Type      | Description
| number          | integer   | Buffer number (≥ 1).
| full_name       | string    | Full name (example: _irc.libera.#weechat_).
| local_variables | hashtable | Local variables.
|===

Example: local variable _test_ removed from buffer _irc.libera.#weechat_:

[source,python]
----
id: '_buffer_localvar_removed'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
        'local_variables': 'htb',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4a73de0']
        number: 3
        full_name: 'irc.libera.#prout'
        local_variables: {
            'server': 'local',
            'plugin': 'irc',
            'type': 'channel',
            'channel': '#weechat',
            'nick': 'test',
            'name': 'libera.#weechat',
        }
----

[[message_buffer_line_added]]
==== _buffer_line_added

This message is sent to the client when the signal "buffer_line_added" is sent
by WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name         | Type             | Description
| buffer       | pointer          | Buffer pointer.
| date         | time             | Date of message.
| date_printed | time             | Date when WeeChat displayed message.
| displayed    | char             | 1 if message is displayed, 0 if message is filtered (hidden).
| notify_level | char             | Notify level: -1 = notify disabled, 0 = low, 1 = message, 2 = private, 3 = highlight.
| highlight    | char             | 1 if line has a highlight, otherwise 0.
| tags_array   | array of strings | List of tags for line.
| prefix       | string           | Prefix.
| message      | string           | Message.
|===

Example: new message _hello!_ from nick _FlashCode_ on buffer _irc.libera.#weechat_:

[source,python]
----
id: '_buffer_line_added'
hda:
    keys: {
        'buffer': 'ptr',
        'date': 'tim',
        'date_printed': 'tim',
        'displayed': 'chr',
        'notify_level': 'chr',
        'highlight': 'chr',
        'tags_array': 'arr',
        'prefix': 'str',
        'message': 'str',
    }
    path: ['line_data']
    item 1:
        __path: ['0x4a49600']
        buffer: '0x4a715d0'
        date: 1362728993
        date_printed: 1362728993
        displayed: 1
        notify_level: 1
        highlight: 0
        tags_array: [
            'irc_privmsg',
            'notify_message',
            'prefix_nick_142',
            'nick_FlashCode',
            'log1',
        ]
        prefix: 'F06@F@00142FlashCode'
        message: 'hello!'
----

[[message_buffer_closing]]
==== _buffer_closing

This message is sent to the client when the signal "buffer_closing" is sent by
WeeChat.

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name      | Type    | Description
| number    | integer | Buffer number (≥ 1).
| full_name | string  | Full name (example: _irc.libera.#weechat_).
|===

Example: buffer _irc.libera.#weechat_ is being closed by WeeChat:

[source,python]
----
id: '_buffer_closing'
hda:
    keys: {
        'number': 'int',
        'full_name': 'str',
    }
    path: ['buffer']
    item 1:
        __path: ['0x4a715d0']
        number: 3
        full_name: 'irc.libera.#weechat'
----

[[message_nicklist]]
==== _nicklist

This message is sent to the client when large updates are made on a nicklist
(groups/nicks added/removed/changed). The message contains full nicklist.

When small updates are made on a nicklist (for example just add one nick),
another message with identifier __nicklist_diff_ is sent (see below).

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name         | Type    | Description
| group        | char    | 1 for a group, 0 for a nick.
| visible      | char    | 1 if group/nick is displayed, otherwise 0.
| level        | integer | Level of group (0 for a nick).
| name         | string  | Name of group/nick.
| color        | string  | Name color.
| prefix       | string  | Prefix (only for a nick).
| prefix_color | string  | Prefix color (only for a nick).
|===

Example: nicklist for buffer _irc.libera.#weechat_:

[source,python]
----
id: '_nicklist'
hda:
    keys: {
        'group': 'chr',
        'visible': 'chr',
        'level': 'int',
        'name': 'str',
        'color': 'str',
        'prefix': 'str',
        'prefix_color': 'str',
    }
    path: ['buffer', 'nicklist_item']
    item 1:
        __path: ['0x4a75cd0', '0x31e95d0']
        group: 1
        visible: 0
        level: 0
        name: 'root'
        color: None
        prefix: None
        prefix_color: None
    item 2:
        __path: ['0x4a75cd0', '0x41247b0']
        group: 1
        visible: 1
        level: 1
        name: '000|o'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 3:
        __path: ['0x4a75cd0', '0x4a60d20']
        group: 0
        visible: 1
        level: 0
        name: 'FlashCode'
        color: '142'
        prefix: '@'
        prefix_color: 'lightgreen'
    item 4:
        __path: ['0x4a75cd0', '0x4aafaf0']
        group: 1
        visible: 1
        level: 1
        name: '001|v'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 5:
        __path: ['0x4a75cd0', '0x4a48d80']
        group: 1
        visible: 1
        level: 1
        name: '999|...'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 6:
        __path: ['0x4a75cd0', '0x4a5f560']
        group: 0
        visible: 1
        level: 0
        name: 'test'
        color: 'weechat.color.chat_nick_self'
        prefix: ' '
        prefix_color: ''
----

[[message_nicklist_diff]]
==== _nicklist_diff

_WeeChat ≥ 0.4.1._

This message is sent to the client when small updates are made on a nicklist
(groups/nicks added/removed/changed). The message contains nicklist differences
(between old nicklist and current one).

Data sent as hdata:

[width="100%",cols="3m,2,10",options="header"]
|===
| Name         | Type    | Description
| _diff        | char    | Type of diff (see below).
| group        | char    | 1 for a group, 0 for a nick.
| visible      | char    | 1 if group/nick is displayed, otherwise 0.
| level        | integer | Level of group (0 for a nick).
| name         | string  | Name of group/nick.
| color        | string  | Name color.
| prefix       | string  | Prefix (only for a nick).
| prefix_color | string  | Prefix color (only for a nick).
|===

The value of __diff_ can be:

* `+^+`: the parent group: group(s) or nick(s) after this one are related to this
  group
* `+++`: group/nick added in the parent group
* `+-+`: group/nick removed from the parent group
* `+*+`: group/nick updated in the parent group

Example: nick _master_ added in group _000|o_ (channel ops on an IRC channel),
nicks _nick1_ and _nick2_ added in group _999|..._ (standard users on an IRC
channel):

[source,python]
----
id: '_nicklist_diff'
hda:
    keys: {
        '_diff': 'chr',
        'group': 'chr',
        'visible': 'chr',
        'level': 'int',
        'name': 'str',
        'color': 'str',
        'prefix': 'str',
        'prefix_color': 'str',
    }
    path: ['buffer', 'nicklist_item']
    item 1:
        __path: ['0x46f2ee0', '0x343c9b0']
        _diff: 94 ('^')
        group: 1
        visible: 1
        level: 1
        name: '000|o'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 2:
        __path: ['0x46f2ee0', '0x47e7f60']
        _diff: 43 ('+')
        group: 0
        visible: 1
        level: 0
        name: 'master'
        color: 'magenta'
        prefix: '@'
        prefix_color: 'lightgreen'
    item 3:
        __path: ['0x46f2ee0', '0x46b8e70']
        _diff: 94 ('^')
        group: 1
        visible: 1
        level: 1
        name: '999|...'
        color: 'weechat.color.nicklist_group'
        prefix: None
        prefix_color: None
    item 4:
        __path: ['0x46f2ee0', '0x3dba240']
        _diff: 43 ('+')
        group: 0
        visible: 1
        level: 0
        name: 'nick1'
        color: 'green'
        prefix: ' '
        prefix_color: ''
    item 5:
        __path: ['0x46f2ee0', '0x3c379d0']
        _diff: 43 ('+')
        group: 0
        visible: 1
        level: 0
        name: 'nick2'
        color: 'lightblue'
        prefix: ' '
        prefix_color: ''
----

[[message_pong]]
==== _pong

_WeeChat ≥ 0.4.2._

This message is sent to the client when _relay_ receives a "ping" message.

Data sent as string: arguments received in the "ping" message.

The recommended action in client is to measure the response time and disconnect
if it is high.

[[message_upgrade]]
==== _upgrade

_WeeChat ≥ 0.3.8._

This message is sent to the client when WeeChat is starting upgrade process.

There is no data in the message.

The recommended action in client is to desynchronize from WeeChat (send command
_desync_), or to disconnect from WeeChat (because after upgrade, all pointers
will change).

[NOTE]
During WeeChat upgrade, the socket remains opened (except if connection uses
TLS).

[[message_upgrade_ended]]
==== _upgrade_ended

_WeeChat ≥ 0.3.8._

This message is sent to the client when WeeChat has finished the upgrade
process.

There is no data in the message.

The recommended action in client is to resynchronize with WeeChat: resend all
commands sent on startup after the _init_.

[[objects]]
=== Objects

Objects are identified by 3 letters, called _type_. Following types are used:

[width="100%",cols="1m,2,8",options="header"]
|===
| Type | Value                | Length
| chr  | Signed char          | 1 byte
| int  | Signed integer       | 4 bytes
| lon  | Signed long integer  | 1 byte + length of integer as string
| str  | String               | 4 bytes + length of string (without final `\0`)
| buf  | Buffer of bytes      | 4 bytes + length of data
| ptr  | Pointer              | 1 byte + length of pointer as string
| tim  | Time                 | 1 byte + length of time as string
| htb  | Hashtable            | Variable
| hda  | Hdata content        | Variable
| inf  | Info: name + content | Variable
| inl  | Infolist content     | Variable
| arr  | Array of objects     | 3 bytes (type) + number of objects + data
|===

[[object_char]]
==== Char

A signed char is stored as 1 byte.

Example:

....
┌────┐
│ 41 │ ────► 65 (0x41: "A")
└────┘
....

[[object_integer]]
==== Integer

A signed integer is stored as 4 bytes, encoded as big-endian format (most
significant byte first).

Range: -2147483648 to 2147483647.

Examples:

....
┌────┬────┬────┬────┐
│ 00 │ 01 │ E2 │ 40 │ ────► 123456
└────┴────┴────┴────┘

┌────┬────┬────┬────┐
│ FF │ FE │ 1D │ C0 │ ────► -123456
└────┴────┴────┴────┘
....

[[object_long_integer]]
==== Long integer

A signed long integer is encoded as a string, with length on one byte.

Range: -9223372036854775808 to 9223372036854775807.

Examples:

....
┌────╥────┬────┬────┬────┬────┬────┬────┬────┬────┬────┐
│ 0A ║ 31 │ 32 │ 33 │ 34 │ 35 │ 36 │ 37 │ 38 │ 39 │ 30 │ ────► 1234567890
└────╨────┴────┴────┴────┴────┴────┴────┴────┴────┴────┘
 └──┘ └───────────────────────────────────────────────┘
length '1'  '2'  '3'  '4'  '5'  '6'  '7'  '8'  '9'  '0'

┌────╥────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬────┐
│ 0B ║ 2D │ 31 │ 32 │ 33 │ 34 │ 35 │ 36 │ 37 │ 38 │ 39 │ 30 │ ────► -1234567890
└────╨────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴────┘
 └──┘ └────────────────────────────────────────────────────┘
length '-'  '1'  '2'  '3'  '4'  '5'  '6'  '7'  '8'  '9'  '0'
....

[[object_string]]
==== String

A string is a length (integer on 4 bytes) + content of string (without final `\0`).

Example:

....
┌────┬────┬────┬────╥────┬────┬────┬────┬────┐
│ 00 │ 00 │ 00 │ 05 ║ 68 │ 65 │ 6C │ 6C │ 6F │ ────► "hello"
└────┴────┴────┴────╨────┴────┴────┴────┴────┘
 └─────────────────┘ └──────────────────────┘
       length         'h'  'e'  'l'  'l'  'o'
....

An empty string has a length of zero:

....
┌────┬────┬────┬────┐
│ 00 │ 00 │ 00 │ 00 │ ────► ""
└────┴────┴────┴────┘
 └─────────────────┘
       length
....

A _NULL_ string (NULL pointer in C) has a length of -1:

....
┌────┬────┬────┬────┐
│ FF │ FF │ FF │ FF │ ────► NULL
└────┴────┴────┴────┘
 └─────────────────┘
       length
....

[[object_buffer]]
==== Buffer

Same format as <<object_string,string>>; content is just an array of bytes.

[[object_pointer]]
==== Pointer

A pointer is encoded as string (hex), with length on one byte.

Example:

....
┌────╥────┬────┬────┬────┬────┬────┬────┬────┬────┐
│ 09 ║ 31 │ 61 │ 32 │ 62 │ 33 │ 63 │ 34 │ 64 │ 35 │ ────► 0x1a2b3c4d5
└────╨────┴────┴────┴────┴────┴────┴────┴────┴────┘
 └──┘ └──────────────────────────────────────────┘
length '1'  'a'  '2'  'b'  '3'  'c'  '4'  'd'  '5'
....

A _NULL_ pointer has a length of 1 with value 0:

....
┌────╥────┐
│ 01 ║ 30 │ ────► NULL (0x0)
└────╨────┘
 └──┘ └──┘
length '0'
....

[[object_time]]
==== Time

A time (number of seconds) is encoded as a string, with length on one byte.

Example:

....
┌────╥────┬────┬────┬────┬────┬────┬────┬────┬────┬────┐
│ 0A ║ 31 │ 33 │ 32 │ 31 │ 39 │ 39 │ 33 │ 34 │ 35 │ 36 │ ────► 1321993456
└────╨────┴────┴────┴────┴────┴────┴────┴────┴────┴────┘
 └──┘ └───────────────────────────────────────────────┘
length '1'  '3'  '2'  '1'  '9'  '9'  '3'  '4'  '5'  '6'
....

[[object_hashtable]]
==== Hashtable

A hashtable contains type for keys, type for values, number of items in
hashtable (integer on 4 bytes), and then keys and values of items.

....
┌───────────┬─────────────┬───────╥───────┬─────────╥─────╥───────┬─────────┐
│ type_keys │ type_values │ count ║ key 1 │ value 1 ║ ... ║ key N │ value N │
└───────────┴─────────────┴───────╨───────┴─────────╨─────╨───────┴─────────┘
....

Example:

....
┌─────┬─────┬───╥──────┬─────╥──────┬─────┐
│ str │ str │ 2 ║ key1 │ abc ║ key2 │ def │ ────► { 'key1' => 'abc',
└─────┴─────┴───╨──────┴─────╨──────┴─────┘         'key2' => 'def' }
 └───┘ └───┘ └─┘ └──────────┘ └──────────┘
 type  type count   item 1       item 2
 keys values
....

[[object_hdata]]
==== Hdata

A _hdata_ contains a path with hdata names, list of keys, number of set of
objects, and then set of objects (path with pointers, then objects).

....
┌────────┬──────┬───────╥────────┬─────────────────────╥─────╥────────┬─────────────────────╥─────┐
│ h-path │ keys │ count ║ p-path │ value 1 ... value N ║ ... ║ p-path │ value 1 ... value N ║ ... │
└────────┴──────┴───────╨────────┴─────────────────────╨─────╨────────┴─────────────────────╨─────┘
....

* _h-path_ (string): path used to reach hdata (example:
  _buffer/lines/line/line_data_); the last element in path is the hdata returned
* _keys_ (string): string with list of _key:type_ (separated by commas),
  example: _number:int,name:str_
* _count_ (integer): number of set of objects
* _p-path_: path with pointers to objects (number of pointers here is number of
  elements in path)
* _values_: list of values (number of values is number of keys returned for
  hdata)

Example of hdata with two buffers (weechat core and libera server) and two
keys (_number_ and _full_name_):

....
# command
hdata buffer:gui_buffers(*) number,full_name

# response
┌────────┬──────────────────────────┬───╥─────────┬───┬──────────────╥─────────┬───┬───────────────────┐
│ buffer │ number:int,full_name:str │ 2 ║ 0x12345 │ 1 │ core.weechat ║ 0x6789a │ 2 │ irc.server.libera │
└────────┴──────────────────────────┴───╨─────────┴───┴──────────────╨─────────┴───┴───────────────────┘
 └──────┘ └────────────────────────┘ └─┘ └──────────────────────────┘ └───────────────────────────────┘
  h-path          keys              count          buffer 1                        buffer 2
....

Example of hdata with lines of core buffer:

....
# command
hdata buffer:gui_buffers(*)/lines/first_line(*)/data

# response
┌─────────────────────────────┬─────┬────╥──
│ buffer/lines/line/line_data │ ... │ 50 ║ ...
└─────────────────────────────┴─────┴────╨──
 └───────────────────────────┘ └───┘ └──┘
      h-path (hdata names)     keys  count

   ──╥───────────┬───────────┬───────────┬───────────┬───────╥──
 ... ║ 0x23cf970 │ 0x23cfb60 │ 0x23d5f40 │ 0x23d8a10 │ ..... ║ ...
   ──╨───────────┴───────────┴───────────┴───────────┴───────╨──
      └─────────────────────────────────────────────┘ └─────┘
                    p-path (pointers)                 objects
      └─────────────────────────────────────────────────────┘
                              line 1

   ──╥───────────┬───────────┬───────────┬───────────┬───────╥──────────────┐
 ... ║ 0x23cf970 │ 0x23cfb60 │ 0x23d6110 │ 0x23d9420 │ ..... ║ ............ │
   ──╨───────────┴───────────┴───────────┴───────────┴───────╨──────────────┘
      └─────────────────────────────────────────────┘ └─────┘
                    p-path (pointers)                 objects
      └─────────────────────────────────────────────────────┘ └────────────┘
                         line 2                                 lines 3-50
....

Example of hdata with nicklist:

....
# command
nicklist

# response
┌───────────────────┬──
│ buffer/nick_group │ ...
└───────────────────┴──
 └─────────────────┘
        h-path

   ──╥───────────────────────────────────────────────────────────┬────╥──
 ... ║ group:chr,visible:chr,name:str,color:str,prefix:str,(...) │ 12 ║ ...
   ──╨───────────────────────────────────────────────────────────┴────╨──
      └─────────────────────────────────────────────────────────┘ └──┘
                                 keys                             count

   ──╥─────────┬─────────┬───┬───┬──────┬─┬─┬─┬───╥──
 ... ║ 0x12345 │ 0x6789a │ 1 │ 0 │ root │ │ │ │ 0 ║ ...
   ──╨─────────┴─────────┴───┴───┴──────┴─┴─┴─┴───╨──
      └─────────────────┘ └──────────────────────┘
             p-path               objects
      └──────────────────────────────────────────┘
                  group (nicklist root)

   ──╥─────────┬─────────┬───┬───┬───────┬─┬─┬─┬───╥──
 ... ║ 0x123cf │ 0x678d4 │ 1 │ 0 │ 000|o │ │ │ │ 1 ║ ...
   ──╨─────────┴─────────┴───┴───┴───────┴─┴─┴─┴───╨──
      └─────────────────┘ └───────────────────────┘
             p-path                objects
      └───────────────────────────────────────────┘
                    group (channel ops)

   ──╥─────────┬─────────┬───┬───┬──────────┬──────┬───┬────────────┬───╥──
 ... ║ 0x128a7 │ 0x67ab2 │ 0 │ 1 │ ChanServ │ blue │ @ │ lightgreen │ 0 ║ ...
   ──╨─────────┴─────────┴───┴───┴──────────┴──────┴───┴────────────┴───╨──
      └─────────────────┘ └────────────────────────────────────────────┘
             p-path                          objects
      └────────────────────────────────────────────────────────────────┘
                               nick (@ChanServ)
....

Example of empty hdata (hotlist is empty in WeeChat):

....
# command
hdata hotlist:gui_hotlist(*)

# response
┌────────┬────────┬───┐
│ (NULL) │ (NULL) │ 0 │
└────────┴────────┴───┘
 └──────┘ └──────┘ └─┘
  h-path    keys  count
....

[[object_info]]
==== Info

A _info_ contains a name and a value (both are strings).

....
┌──────┬───────┐
│ name │ value │
└──────┴───────┘
....

* _name_ (string): name of info
* _value_ (string): value

Example of info _version_:

....
┌─────────┬───────────────────┐
│ version │ WeeChat 0.3.7-dev │
└─────────┴───────────────────┘
....

[[object_infolist]]
==== Infolist

A _infolist_ contains a name, number of items, and then items (set of
variables).

....
┌──────┬───────╥────────╥─────╥────────┐
│ name │ count ║ item 1 ║ ... ║ item N │
└──────┴───────╨────────╨─────╨────────┘
....

An item is:

....
┌───────╥────────┬────────┬─────────╥─────╥────────┬────────┬─────────┐
│ count ║ name 1 │ type 1 │ value 1 ║ ... ║ name N │ type N │ value N │
└───────╨────────┴────────┴─────────╨─────╨────────┴────────┴─────────┘
....

* _name_ (string): name of infolist (_buffer_, _window_, _bar_, ...)
* _count_ (integer): number of items
* _item_:
** _count_: number of variables in item
** _name_: name of variable
** _type_: type of variable (_int_, _str_, ...)
** _value_: value of variable

Example of infolist with two buffers (weechat core and libera server):

....
# command
infolist buffer

# response
┌────────┬───╥────┬─────────┬─────┬─────────┬─────╥────┬─────────┬─────┬─────────┬─────┐
│ buffer │ 2 ║ 42 │ pointer │ ptr │ 0x12345 │ ... ║ 42 │ pointer │ ptr │ 0x6789a │ ... │
└────────┴───╨────┴─────────┴─────┴─────────┴─────╨────┴─────────┴─────┴─────────┴─────┘
 └──────┘ └─┘ └──────────────────────────────────┘ └──────────────────────────────────┘
   name  count              item 1                               item 2
....

[[object_array]]
==== Array

An array is a type (3 bytes) + number of objects (integer on 4 bytes) + data.

Example of array with two strings:

....
┌─────╥────┬────┬────┬────╥────┬────┬────┬────╥────┬────┬────╥────┬────┬────┬────╥────┬────┐
│ str ║ 00 │ 00 │ 00 │ 02 ║ 00 │ 00 │ 00 │ 03 ║ 61 │ 62 │ 63 ║ 00 │ 00 │ 00 │ 02 ║ 64 │ 65 │ ────► [ "abc", "de" ]
└─────╨────┴────┴────┴────╨────┴────┴────┴────╨────┴────┴────╨────┴────┴────┴────╨────┴────┘
 └───┘ └─────────────────┘ └─────────────────┘ └────────────┘ └─────────────────┘ └───────┘
 type   number of strings        length         'a'  'b'  'c'       length         'd'  'e'
....

Example of array with three integers:

....
┌─────╥────┬────┬────┬────╥────┬────┬────┬────╥────┬────┬────┬────╥────┬────┬────┬────┐
│ int ║ 00 │ 00 │ 00 │ 03 ║ 00 │ 00 │ 00 │ 7B ║ 00 │ 00 │ 01 │ C8 ║ 00 │ 00 │ 03 │ 15 │ ────► [ 123, 456, 789 ]
└─────╨────┴────┴────┴────╨────┴────┴────┴────╨────┴────┴────┴────╨────┴────┴────┴────┘
 └───┘ └─────────────────┘ └─────────────────┘ └─────────────────┘ └─────────────────┘
 type   number of integers      123 (0x7B)         456 (0x1C8)         789 (0x315)
....

A _NULL_ array:

....
┌─────╥────┬────┬────┬────┐
│ str ║ 00 │ 00 │ 00 │ 00 │ ────► NULL
└─────╨────┴────┴────┴────┘
 └───┘ └─────────────────┘
 type   number of strings
....

[[typical_session]]
== Typical session

....
    ┌────────┐                         ┌───────┐                ┌─────────┐
    │ Client ├ ─ ─ ─ ─(network)─ ─ ─ ─ ┤ Relay ├────────────────┤ WeeChat │
    └────────┘                         └───────┘                └─────────┘
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ open socket                     ║ add client              ║
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ cmd: handshake ...              ║ negotiate algos         ║
         ║                                 ║ and options             ║
         ║ ◄───────────────────────────────╢                         ║
         ║        msg: id: "handshake" ... ║                         ║
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ cmd: init password=xxx,...      ║ authenticate client     ║
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ cmd: hdata buffer ...           ╟───────────────────────► ║
         ║      sync ...                   ║ request hdata           ║ read hdata
         ║                                 ║                         ║ values
         ║                                 ║ ◄───────────────────────╢
         ║ ◄───────────────────────────────╢                   hdata ║
  create ║                 msg: hda buffer ║                         ║
 buffers ║                                 ║                         ║
         ║            ........             ║         ........        ║
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ cmd: input ...                  ╟───────────────────────► ║
         ║                                 ║ send data to buffer     ║ send data
         ║                                 ║                         ║ to buffer
         ║            ........             ║         ........        ║
         ║                                 ║                         ║ signal
         ║                                 ║ ◄───────────────────────╢ received
         ║ ◄───────────────────────────────╢              signal XXX ║ (hooked by
 update  ║          msg: id: "_buffer_..." ║                         ║ relay)
 buffers ║                                 ║                         ║
         ║            ........             ║         ........        ║
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ cmd: ping ...                   ║                         ║
         ║                                 ║                         ║
         ║ ◄───────────────────────────────╢                         ║
 measure ║            msg: id: "_pong" ... ║                         ║
response ║                                 ║                         ║
    time ║            ........             ║         ........        ║
         ║                                 ║                         ║
         ╟───────────────────────────────► ║                         ║
         ║ cmd: quit                       ║ disconnect client       ║
         ║                                 ║                         ║
....