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+======================
+Biboumi(1) User Manual
+======================
+
+.. contents:: :depth: 2
+
+NAME
+====
+
+biboumi - XMPP gateway to IRC
+
+Description
+===========
+
+Biboumi is an XMPP gateway that connects to IRC servers and translates
+between the two protocols. It can be used to access IRC channels using any
+XMPP client as if these channels were XMPP MUCs.
+
+Synopsis
+========
+
+biboumi [*config_filename*\ ]
+
+Options
+=======
+
+Available command line options:
+
+config_filename
+---------------
+
+Specify the file to read for configuration. See *CONFIG* section for more
+details on its content.
+
+Configuration
+=============
+
+The configuration file uses a simple format of the form
+``option=value``. Here is a description of each possible option:
+
+The configuration can be re-read at runtime (you can for example change the
+log level without having to restart biboumi) by sending SIGUSR1 or SIGUSR2
+(see kill(1)) to the process.
+
+hostname
+--------
+
+Mandatory. The hostname served by the XMPP gateway.  This domain must be
+configured in the XMPP server as an external component.  See the manual
+for your XMPP server for more information.  For prosody, see
+http://prosody.im/doc/components#adding_an_external_component
+
+password
+--------
+
+Mandatory. The password used to authenticate the XMPP component to your
+XMPP server.  This password must be configured in the XMPP server,
+associated with the external component on *hostname*.
+
+xmpp_server_ip
+--------------
+
+The IP address to connect to the XMPP server on. The connection to the
+XMPP server is unencrypted, so the biboumi instance and the server should
+normally be on the same host. The default value is 127.0.0.1.
+
+port
+----
+
+The TCP port to use to connect to the local XMPP component. The default
+value is 5347.
+
+admin
+-----
+
+The bare JID of the gateway administrator. This JID will have more
+privileges than other standard users (the admin thus needs to check their
+privileges), for example some administration ad-hoc commands will only be
+available to that JID.
+
+fixed_irc_server
+----------------
+
+If this option contains the hostname of an IRC server (for example
+irc.example.org), then biboumi will enforce the connexion to that IRC
+server only.  This means that a JID like "#chan@biboumi.example.com" must
+be used instead of "#chan%irc.example.org@biboumi.example.com".  In that
+mode, the virtual channel (see `Connect to an IRC server`_) is not
+available and you still need to use the ! separator to send message to an
+IRC user (for example "foo!@biboumi.example.com" to send a message to
+foo), although the in-room JID still work as expected
+("#channel@biboumi.example.com/Nick").  On the other hand, the '%' lose
+any meaning.  It can appear in the JID but will not be interpreted as a
+separator (thus the JID "#channel%hello@biboumi.example.com" points to the
+channel named "#channel%hello" on the configured IRC server) This option
+can for example be used by an administrator that just wants to let their
+users join their own IRC server using an XMPP client, while forbidding
+access to any other IRC server.
+
+realname_customization
+----------------------
+
+If this option is set to “false” (default is “true”), the users will not be
+able to use the ad-hoc commands that lets them configure their realname and
+username.
+
+realname_from_jid
+-----------------
+
+If this option is set to “true”, the realname and username of each biboumi
+user will be extracted from their JID.  The realname is their bare JID, and
+the username is the node-part of their JID.  Note that if
+``realname_customization`` is “true”, each user will still be able to
+customize their realname and username, this option just decides the default
+realname and username.
+
+If this option is set to “false” (the default value), the realname and
+username of each user will be set to the nick they used to connect to the
+IRC server.
+
+webirc_password
+---------------
+
+Configure a password to be communicated to the IRC server, as part of the
+WEBIRC message (see https://kiwiirc.com/docs/webirc).  If this option is
+set, an additional DNS resolution of the hostname of each XMPP server will
+be made when connecting to an IRC server.
+
+log_file
+--------
+
+A filename into which logs are written.  If none is provided, the logs are
+written on standard output.
+
+log_level
+---------
+
+Indicate what type of log messages to write in the logs.  Value can be
+from 0 to 3.  0 is debug, 1 is info, 2 is warning, 3 is error.  The
+default is 0, but a more practical value for production use is 1.
+
+ca_file
+-------
+
+Specifies which file should be use as the list of trusted CA when
+negociating a TLS session. By default this value is unset and biboumi
+tries a list of well-known paths.
+
+outgoing_bind
+-------------
+
+An address (IPv4 or IPv6) to bind the outgoing sockets to.  If no value is
+specified, it will use the one assigned by the operating system.  You can
+for example use outgoing_bind=192.168.1.11 to force biboumi to use the
+interface with this address.  Note that this is only used for connections
+to IRC servers.
+
+Usage
+=====
+
+Biboumi acts as a server, it should be run as a daemon that lives in the
+background for as long as it is needed.  Note that biboumi does not
+daemonize itself, this task should be done by your init system (SysVinit,
+systemd, upstart).
+
+When started, biboumi connects, without encryption (see `Security`_), to the
+local XMPP server on the port ``5347`` and authenticates with the provided
+password.  Biboumi then serves the configured ``hostname``: this means that
+all XMPP stanza with a `to` JID on that domain will be forwarded to biboumi
+by the XMPP server, and biboumi will only send messages coming from that
+hostname.
+
+When a user joins an IRC channel on an IRC server (see `Join an IRC
+channel`_), biboumi connects to the remote IRC server, sets the user’s nick
+as requested, and then tries to join the specified channel.  If the same
+user subsequently tries to connect to an other channel on the same server,
+the same IRC connection is used.  If, however, an other user wants to join
+an IRC channel on that same IRC server, biboumi opens a new connection to
+that server.  Biboumi connects once to each IRC server, for each user on it.
+
+Additionally, if one user is using more than one clients (with the same bare
+JID), they can join the same IRC channel (on the same server) behind one
+single nickname.  Biboumi will forward all the messages (the channel ones and
+the private ones) and the presences to all the resources behind that nick.
+There is no need to have multiple nicknames and multiple connections to be
+able to take part in a conversation (or idle) in a channel from a mobile client
+while the desktop client is still connected, for example.
+
+To cleanly shutdown the component, send a SIGINT or SIGTERM signal to it.
+It will send messages to all connected IRC and XMPP servers to indicate a
+reason why the users are being disconnected.  Biboumi exits when the end of
+communication is acknowledged by all IRC servers.  If one or more IRC
+servers do not respond, biboumi will only exit if it receives the same
+signal again or if a 2 seconds delay has passed.
+
+Addressing
+----------
+
+IRC entities are represented by XMPP JIDs.  The domain part of the JID is
+the domain served by biboumi (the part after the ``@``, biboumi.example.com in
+the examples), and the local part (the part before the ``@``) depends on the
+concerned entity.
+
+IRC channels have a local part formed like this:
+``channel_name`` % ``irc_server``.
+
+If the IRC channel you want to adress starts with the ``'#'`` character (or an
+other character, announced by the IRC server, like ``'&'``, ``'+'`` or ``'!'``),
+then you must include it in the JID.  Some other gateway implementations, as
+well as some IRC clients, do not require them to be started by one of these
+characters, adding an implicit ``'#'`` in that case.  Biboumi does not do that
+because this gets confusing when trying to understand the difference between
+the channels *#foo*, and *##foo*. Note that biboumi does not use the
+presence of these special characters to identify an IRC channel, only the
+presence of the separator `%` is used for that.
+
+The channel name can also be empty (for example ``%irc.example.com``), in that
+case this represents the virtual channel provided by biboumi.  See *Connect
+to an IRC server* for more details.
+
+There is two ways to address an IRC user, using a local part like this:
+``nickname`` ! ``irc_server``
+or by using the in-room address of the participant, like this:
+``channel_name`` % ``irc_server`` @ ``biboumi.example.com`` / ``Nickname``
+
+The second JID is available only to be compatible with XMPP clients when the
+user wants to send a private message to the participant ``Nickname`` in the
+room ``channel_name%irc_server@biboumi.example.com``.
+
+On XMPP, the node part of the JID can only be lowercase.  On the other hand,
+IRC nicknames are case-insensitive, this means that the nicknames toto,
+Toto, tOtO and TOTO all represent the same IRC user.  This means you can
+talk to the user toto, and this will work.
+
+Also note that some IRC nicknames may contain characters that are not
+allowed in the local part of a JID (for example '@').  If you need to send a
+message to a nick containing such a character, you have to use a jid like
+``%irc.example.com@biboumi.example.com/AnnoyingNickn@me``, because the JID
+``AnnoyingNickn@me!irc.example.com@biboumi.example.com`` would not work.
+
+Examples:
+
+* ``#foo%irc.example.com@biboumi.example.com`` is the #foo IRC channel, on the
+  irc.example.com IRC server, and this is served by the biboumi instance on
+  biboumi.example.com
+
+* ``toto!irc.example.com@biboumi.example.com`` is the IRC user named toto, or
+  TotO, etc.
+
+* ``irc.example.com@biboumi.example.com`` is the IRC server irc.example.com.
+
+* ``%irc.example.com@biboumi.example.com`` is the virtual channel provided by
+  biboumi, for the IRC server irc.example.com.
+
+Note: Some JIDs are valid but make no sense in the context of
+biboumi:
+
+* ``!irc.example.com@biboumi.example.com`` is the empty-string nick on the
+  irc.example.com server. It makes no sense to try to send messages to it.
+
+* ``#test%@biboumi.example.com``, or any other JID that does not contain an
+  IRC server is invalid. Any message to that kind of JID will trigger an
+  error, or will be ignored.
+
+If compiled with Libidn, an IRC channel participant has a bare JID
+representing the “hostname” provided by the IRC server.  This JID can only
+be used to set IRC modes (for example to ban a user based on its IP), or to
+identify user. It cannot be used to contact that user using biboumi.
+
+Join an IRC channel
+-------------------
+
+To join an IRC channel ``#foo`` on the IRC server ``irc.example.com``,
+join the XMPP MUC ``#foo%irc.example.com@biboumi.example.com``.
+
+Connect to an IRC server
+------------------------
+
+The connection to the IRC server is automatically made when the user tries
+to join any channel on that IRC server.  The connection is closed whenever
+the last channel on that server is left by the user.  To be able to stay
+connected to an IRC server without having to be in a real IRC channel,
+biboumi provides a virtual channel on the jid
+``%irc.example.com@biboumi.example.com``.  For example if you want to join the
+channel ``#foo`` on the server ``irc.example.com``, but you need to authenticate
+to a bot of the server before you’re allowed to join it, you can first join
+the room ``%irc.example.com@biboumi.example.com`` (this will effectively
+connect you to the IRC server without joining any room), then send your
+authentication message to the user ``bot!irc.example.com@biboumi.example.com``
+and finally join the room ``#foo%irc.example.com@biboumi.example.com``.
+
+Channel messages
+----------------
+
+On XMPP, unlike on IRC, the displayed order of the messages is the same for
+all participants of a MUC.  Biboumi can not however provide this feature, as
+it cannot know whether the IRC server has received and forwarded the
+messages to other users.  This means that the order of the messages
+displayed in your XMPP client may not be the same than the order on other
+IRC users’.
+
+List channels
+-------------
+
+You can list the IRC channels on a given IRC server by sending an XMPP disco
+items request on the IRC server JID.  The number of channels on some servers
+is huge, and biboumi does not (yet) support result set management (XEP 0059)
+so the result stanza may be very big.
+
+Nicknames
+---------
+
+On IRC, nicknames are server-wide.  This means that one user only has one
+single nickname at one given time on all the channels of a server. This is
+different from XMPP where a user can have a different nick on each MUC,
+even if these MUCs are on the same server.
+
+This means that the nick you choose when joining your first IRC channel on a
+given IRC server will be your nickname in all other channels that you join
+on that same IRC server.
+If you explicitely change your nickname on one channel, your nickname will
+be changed on all channels on the same server as well.
+Joining a new channel with a different nick, however, will not change your
+nick.  The provided nick will be ignored, in order to avoid changing your
+nick on the whole server by mistake.  If you want to have a different
+nickname in the channel you’re going to join, you need to do it explicitly
+with the NICK command before joining the channel.
+
+Private messages
+----------------
+
+Private messages are handled differently on IRC and on XMPP.  On IRC, you
+talk directly to one server-user: toto on the channel #foo is the same user
+as toto on the channel #bar (as long as these two channels are on the same
+IRC server).  By default you will receive private messages from the “global”
+user (aka nickname!irc.example.com@biboumi.example.com), unless you
+previously sent a message to an in-room participant (something like
+\#test%irc.example.com@biboumi.example.com/nickname), in which case future
+messages from that same user will be received from that same “in-room” JID.
+
+Notices
+-------
+
+Notices are received exactly like private messages.  It is not possible to
+send a notice.
+
+Kicks and bans
+--------------
+
+Kicks are transparently translated from one protocol to another.  However
+banning an XMPP participant has no effect.  To ban an user you need to set a
+mode +b on that user nick or host (see `IRC modes`_) and then kick it.
+
+Encoding
+--------
+
+On XMPP, the encoding is always ``UTF-8``, whereas on IRC the encoding of
+each message can be anything.
+
+This means that biboumi has to convert everything coming from IRC into UTF-8
+without knowing the encoding of the received messages.  To do so, it checks
+if each message is UTF-8 valid, if not it tries to convert from
+``iso_8859-1`` (because this appears to be the most common case, at least
+on the channels I visit) to ``UTF-8``.  If that conversion fails at some
+point, a placeholder character ``'�'`` is inserted to indicate this
+decoding error.
+
+Messages are always sent in UTF-8 over IRC, no conversion is done in that
+direction.
+
+IRC modes
+---------
+
+One feature that doesn’t exist on XMPP but does on IRC is the ``modes``.
+Although some of these modes have a correspondance in the XMPP world (for
+example the ``+o`` mode on a user corresponds to the ``moderator`` role in
+XMPP), it is impossible to map all these modes to an XMPP feature.  To
+circumvent this problem, biboumi provides a raw notification when modes are
+changed, and lets the user change the modes directly.
+
+To change modes, simply send a message starting with “``/mode``” followed by
+the modes and the arguments you want to send to the IRC server.  For example
+“/mode +aho louiz”.  Note that your XMPP client may interprete messages
+begining with “/” like a command.  To actually send a message starting with
+a slash, you may need to start your message with “//mode” or “/say /mode”,
+depending on your client.
+
+When a mode is changed, the user is notified by a message coming from the
+MUC bare JID, looking like “Mode #foo [+ov] [toto tutu]”.  In addition, if
+the mode change can be translated to an XMPP feature, the user will be
+notified of this XMPP event as well. For example if a mode “+o toto” is
+received, then toto’s role will be changed to moderator.  The mapping
+between IRC modes and XMPP features is as follow:
+
+``+q``
+  Sets the participant’s role to ``moderator`` and its affiliation to ``owner``.
+
+``+a``
+  Sets the participant’s role to ``moderator`` and its affiliation to ``owner``.
+
+``+o``
+  Sets the participant’s role to ``moderator`` and its affiliation to  ``admin``.
+
+``+h``
+  Sets the participant’s role to ``moderator`` and its affiliation to  ``member``.
+
+``+v``
+  Sets the participant’s role to `participant` and its affiliation to ``member``.
+
+Similarly, when a biboumi user changes some participant's affiliation or role, biboumi translates that in an IRC mode change.
+
+Affiliation set to ``none``
+  Sets mode to -vhoaq
+
+Affiliation set to ``member``
+  Sets mode to +v-hoaq
+
+Role set to ``moderator``
+  Sets mode to +h-oaq
+
+Affiliation set to ``admin``
+  Sets mode to +o-aq
+
+Affiliation set to ``owner``
+  Sets mode to +a-q
+
+Ad-hoc commands
+---------------
+
+Biboumi supports a few ad-hoc commands, as described in the XEP 0050.
+Different ad-hoc commands are available for each JID type.
+
+On the gateway itself (e.g on the JID biboumi.example.com):
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- ping: Just respond “pong”
+
+- hello: Provide a form, where the user enters their name, and biboumi
+  responds with a nice greeting.
+
+- disconnect-user: Only available to the administrator. The user provides
+  a list of JIDs, and a quit message. All the selected users are
+  disconnected from all the IRC servers to which they were connected,
+  using the provided quit message. Sending SIGINT to biboumi is equivalent
+  to using this command by selecting all the connected JIDs and using the
+  “Gateway shutdown” quit message, except that biboumi does not exit when
+  using this ad-hoc command.
+
+- disconnect-from-irc-servers: Disconnect a single user from one or more
+  IRC server.  The user is immediately disconnected by closing the socket,
+  no message is sent to the IRC server, but the user is of course notified
+  with an XMPP message.  The administrator can disconnect any user, while
+  the other users can only disconnect themselves.
+
+On a server JID (e.g on the JID chat.freenode.org@biboumi.example.com)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- Configure: Lets each user configure some options that applies to the
+  concerned IRC server.
+
+On a channel JID (e.g on the JID #test%chat.freenode.org@biboumi.example.com)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- Configure: Lets each user configure some options that applies to the
+  concerned IRC channel.  Some of these options, if not configured for a
+  specific channel, defaults to the value configured at the IRC server
+  level.  For example the encoding can be specified for both the channel
+  and the server.  If an encoding is not specified for a channel, the
+  encoding configured in the server applies.
+
+Raw IRC messages
+----------------
+
+Biboumi tries to support as many IRC features as possible, but doesn’t
+handle everything yet (or ever).  In order to let the user send any
+arbitrary IRC message, biboumi forwards any XMPP message received on an IRC
+Server JID (see *ADDRESSING*) as a raw command to that IRC server.
+
+For example, to WHOIS the user Foo on the server irc.example.com, a user can
+send the message “WHOIS Foo” to “irc.example.com@biboumi.example.com”.
+
+The message will be forwarded as is, without any modification appart from
+adding "\r\n" at the end (to make it a valid IRC message).  You need to have
+a little bit of understanding of the IRC protocol to use this feature.
+
+Security
+========
+
+The connection to the XMPP server can only be made on localhost.  The
+XMPP server is not supposed to accept non-local connections from components.
+Thus, encryption is not used to connect to the local XMPP server because it
+is useless.
+
+If compiled with the Botan library, biboumi can use TLS when communicating
+with the IRC serveres.  It will first try ports 6697 and 6670 and use TLS if
+it succeeds, if connection fails on both these ports, the connection is
+established on port 6667 without any encryption.
+
+Biboumi does not check if the received JIDs are properly formatted using
+nodeprep.  This must be done by the XMPP server to which biboumi is directly
+connected.
+
+Note if you use a biboumi that you have no control on: remember that the
+administrator of the gateway you use is able to view all your IRC
+conversations, whether you’re using encryption or not.  This is exactly as
+if you were running your IRC client on someone else’s server.  Only use
+biboumi if you trust its administrator (or, better, if you are the
+administrator) or if you don’t intend to have any private conversation.
+
+Biboumi does not provide a way to ban users from connecting to it, has no
+protection against flood or any sort of abuse that your users may cause on
+the IRC servers. Some XMPP server however offer the possibility to restrict
+what JID can access a gateway. Use that feature if you wish to grant access
+to your biboumi instance only to a list of trusted users.