Networking Group | J. Oikarinen
|
Networking Group | J. Oikarinen
|
The IRC protocol has been developed on systems using the TCP/IP network protocol, although there is no requirement that this remain the only sphere in which it operates.
IRC itself is a teleconferencing system, which (through the use of
the client-server model) is well-suited to running on many machines
in a distributed fashion. A typical setup involves a single process
(the server) forming a central point for clients (or other servers)
to connect to, performing the required message delivery/multiplexing
and other functions.
1.1 Servers
The server forms the backbone of IRC, providing a point to which
clients may connect to to talk to each other, and a point for other
servers to connect to, forming an IRC network. The only network
configuration allowed for IRC servers is that of a spanning tree [see
Fig. 1] where each server acts as a central node for the rest of the
net it sees.
[ Server 15 ] [ Server 13 ] [ Server 14]
/ \ /
/ \ /
[ Server 11 ] ------ [ Server 1 ] [ Server 12]
/ \ /
/ \ /
[ Server 2 ] [ Server 3 ]
/ \ \
/ \ \
[ Server 4 ] [ Server 5 ] [ Server 6 ]
/ | \ /
/ | \ /
/ | \____ /
/ | \ /
[ Server 7 ] [ Server 8 ] [ Server 9 ] [ Server 10 ]
:
[ etc. ]
:
A more controversial power of operators is the ability to remove a
user from the connected network by 'force', i.e. operators are able
to close the connection between any client and server.The
justification for this is delicate since its abuse is both
destructive and annoying. For further details on this type of
action, see section 4.6.1 (KILL).
1.3 Channels
A channel is a named group of one or more clients which will all
receive messages addressed to that channel. The channel is created
implicitly when the first client joins it, and the channel ceases to
exist when the last client leaves it. While channel exists, any
client can reference the channel using the name of the channel.
Channels names are strings (beginning with a '&' or '#' character) of length up to 200 characters. Apart from the the requirement that the first character being either '&' or '#'; the only restriction on a channel name is that it may not contain any spaces (' '), a control G (^G or ASCII 7), or a comma (',' which is used as a list item separator by the protocol).
There are two types of channels allowed by this protocol. One is a distributed channel which is known to all the servers that are connected to the network. These channels are marked by the first character being a only clients on the server where it exists may join it. These are distinguished by a leading '&' character. On top of these two types, there are the various channel modes available to alter the characteristics of individual channels. See section 4.2.3 (MODE command) for more details on this.
To create a new channel or become part of an existing channel, a user is required to JOIN the channel. If the channel doesn't exist prior to joining, the channel is created and the creating user becomes a channel operator. If the channel already exists, whether or not your request to JOIN that channel is honoured depends on the current modes of the channel. For example, if the channel is invite-only, (+i), then you may only join if invited. As part of the protocol, a user may be a part of several channels at once, but a limit of ten (10) channels is recommended as being ample for both experienced and novice users. See section 8.13 for more information on this.
If the IRC network becomes disjoint because of a split between two
servers, the channel on each side is only composed of those clients
which are connected to servers on the respective sides of the split,
possibly ceasing to exist on one side of the split. When the split
is healed, the connecting servers announce to each other who they
think is in each channel and the mode of that channel. If the
channel exists on both sides, the JOINs and
MODEs are interpreted
in an inclusive manner so that both sides of the new connection will
agree about which clients are in the channel and what modes the
channel has.
1.3.1 Channel Operators
The channel operator (also referred to as a "chop" or "chanop") on a
given channel is considered to 'own' that channel. In recognition of
this status, channel operators are endowed with certain powers which
enable them to keep control and some sort of sanity in their channel.
As an owner of a channel, a channel operator is not required to have
reasons for their actions, although if their actions are generally
antisocial or otherwise abusive, it might be reasonable to ask an IRC
operator to intervene, or for the usersjust leave and go elsewhere
and form their own channel.
The commands which may only be used by channel operators are:
KICK - Eject a client from the channel
MODE - Change the channel's mode
INVITE - Invite a client to an invite-only channel (mode +i)
TOPIC - Change the channel topic in a mode +t channel
A channel operator is identified by the '@' symbol next to their nickname whenever it is associated with a channel (ie replies to the NAMES, WHO and WHOIS commands).
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