rfc2811.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                            C. Kalt
Request for Comments: 2811                                    April 2000
Updates: 1459
Category: Informational


                Internet Relay Chat: Channel Management

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   One of the most notable characteristics of the IRC (Internet Relay
   Chat) protocol is to allow for users to be grouped in forums, called
   channels, providing a mean for multiple users to communicate
   together.

   There was originally a unique type of channels, but with the years,
   new types appeared either as a response to a need, or for
   experimental purposes.

   This document specifies how channels, their characteristics and
   properties are managed by IRC servers.

Table of Contents

   1.  Introduction ...............................................   2
   2.  Channel Characteristics ....................................   3
      2.1  Namespace ..............................................   3
      2.2  Channel Scope ..........................................   3
      2.3  Channel Properties .....................................   4
      2.4  Privileged Channel Members .............................   4
         2.4.1  Channel Operators .................................   5
         2.4.2  Channel Creator ...................................   5
   3.  Channel lifetime ...........................................   5
      3.1  Standard channels ......................................   5
      3.2  Safe Channels ..........................................   6
   4.  Channel Modes ..............................................   7
      4.1  Member Status ..........................................   7
         4.1.1  "Channel Creator" Status ..........................   7



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         4.1.2  Channel Operator Status ...........................   8
         4.1.3  Voice Privilege ...................................   8
      4.2  Channel Flags ..........................................   8
         4.2.1  Anonymous Flag ....................................   8
         4.2.2  Invite Only Flag ..................................   8
         4.2.3  Moderated Channel Flag ............................   9
         4.2.4  No Messages To Channel From Clients On The Outside    9
         4.2.5  Quiet Channel .....................................   9
         4.2.6  Private and Secret Channels .......................   9
         4.2.7  Server Reop Flag ..................................  10
         4.2.8  Topic .............................................  10
         4.2.9  User Limit ........................................  10
         4.2.10  Channel Key ......................................  10
      4.3  Channel Access Control .................................  10
         4.3.1  Channel Ban and Exception .........................  11
         4.3.2  Channel Invitation ................................  11
   5.  Current Implementations ....................................  11
      5.1  Tracking Recently Used Channels ........................  11
      5.2  Safe Channels ..........................................  12
         5.2.1  Channel Identifier ................................  12
         5.2.2  Channel Delay .....................................  12
         5.2.3  Abuse Window ......................................  13
         5.2.4  Preserving Sanity In The Name Space ...............  13
         5.2.5  Server Reop Mechanism .............................  13
   6.  Current problems ...........................................  14
      6.1  Labels .................................................  14
         6.1.1  Channel Delay .....................................  14
         6.1.2  Safe Channels .....................................  15
      6.2  Mode Propagation Delays ................................  15
      6.3  Collisions And Channel Modes ...........................  15
      6.4  Resource Exhaustion ....................................  16
   7.  Security Considerations ....................................  16
      7.1  Access Control .........................................  16
      7.2  Channel Privacy ........................................  16
      7.3 Anonymity ...............................................  17
   8.  Current support and availability ...........................  17
   9.  Acknowledgements ...........................................  17
   10. References ................................................   18
   11. Author's Address ..........................................   18
   12. Full Copyright Statement ...................................  19

1. Introduction

   This document defines in detail on how channels are managed by the
   IRC servers and will be mostly useful to people working on
   implementing an IRC server.





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RFC 2811        Internet Relay Chat: Channel Management       April 2000


   While the concepts defined here are an important part of IRC, they
   remain non essential for implementing clients.  While the trend seems
   to be towards more and more complex and "intelligent" clients which
   are able to take advantage of knowing the internal workings of
   channels to provide the users with a more friendly interface, simple
   clients can be implemented without reading this document.

   Many of the concepts defined here were designed with the IRC
   architecture [IRC-ARCH] in mind and mostly make sense in this
   context.  However, many others could be applied to other
   architectures in order to provide forums for a conferencing system.

   Finally, it is to be noted that IRC users may find some of the
   following sections of interest, in particular sections 2 (Channel
   Characteristics) and 4 (Channel Modes).

2. Channel Characteristics

   A channel is a named group of one or more users which will all
   receive messages addressed to that channel.  A channel is
   characterized by its name, properties and current members.

2.1 Namespace

   Channels names are strings (beginning with a '&', '#', '+' or '!'
   character) of length up to fifty (50) characters.  Channel names are
   case insensitive.

   Apart from the the requirement that the first character being either
   '&', '#', '+' or '!' (hereafter called "channel prefix"). The only
   restriction on a channel name is that it SHALL NOT contain any spaces
   (' '), a control G (^G or ASCII 7), a comma (',' which is used as a
   list item separator by the protocol).  Also, a colon (':') is used as
   a delimiter for the channel mask.  The exact syntax of a channel name
   is defined in "IRC Server Protocol" [IRC-SERVER].

   The use of different prefixes effectively creates four (4) distinct
   namespaces for channel names.  This is important because of the
   protocol limitations regarding namespaces (in general).  See section
   6.1 (Labels) for more details on these limitations.

2.2 Channel Scope

   A channel entity is known by one or more servers on the IRC network.
   A user can only become member of a channel known by the server to
   which the user is directly connected.  The list of servers which know





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   of the existence of a particular channel MUST be a contiguous part of
   the IRC network, in order for the messages addressed to the channel
   to be sent to all the channel members.

   Channels with '&' as prefix are local to the server where they are
   created.

   Other channels are known to one (1) or more servers that are
   connected to the network, depending on the channel mask:

      If there is no channel mask, then the channel is known to all
      the servers.

      If there is a channel mask, then the channel MUST only be known
      to servers which has a local user on the channel, and to its
      neighbours if the mask matches both the local and neighbouring
      server names.  Since other servers have absolutely no knowledge of
      the existence of such a channel, the area formed by the servers
      having a name matching the mask has to be contiguous for the
      channel to be known by all these servers.  Channel masks are best
      used in conjunction with server hostmasking [IRC-SERVER].

2.3 Channel Properties

   Each channel has its own properties, which are defined by channel
   modes.  Channel modes can be manipulated by the channel members.  The
   modes affect the way servers manage the channels.

   Channels with '+' as prefix do not support channel modes.  This means
   that all the modes are unset, with the exception of the 't' channel
   flag which is set.

2.4 Privileged Channel Members

   In order for the channel members to keep some control over a channel,
   and some kind of sanity, some channel members are privileged.  Only
   these members are allowed to perform the following actions on the
   channel:

        INVITE  - Invite a client to an invite-only channel (mode +i)
        KICK    - Eject a client from the channel
        MODE    - Change the channel's mode, as well as
                  members' privileges
        PRIVMSG - Sending messages to the channel (mode +n, +m, +v)
        TOPIC   - Change the channel topic in a mode +t channel






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2.4.1 Channel Operators

   The channel operators (also referred to as a "chop" or "chanop") on a
   given channel are considered to 'own' that channel.  Ownership of a
   channel is shared among channel operators.

   Channel operators are identified by the '@' symbol next to their
   nickname whenever it is associated with a channel (i.e., replies to
   the NAMES, WHO and WHOIS commands).

   Since channels starting with the character '+' as prefix do not
   support channel modes, no member can therefore have the status of
   channel operator.

2.4.2 Channel Creator

   A user who creates a channel with the character '!' as prefix is
   identified as the "channel creator".  Upon creation of the channel,
   this user is also given channel operator status.

   In recognition of this status, the channel creators are endowed with
   the ability to toggle certain modes of the channel which channel
   operators may not manipulate.

   A "channel creator" can be distinguished from a channel operator by
   issuing the proper MODE command.  See the "IRC Client Protocol"
   [IRC-CLIENT] for more information on this topic.

3. Channel lifetime

   In regard to the lifetime of a channel, there are typically two
   groups of channels: standard channels which prefix is either '&', '#'
   or '+', and "safe channels" which prefix is '!'.

3.1 Standard channels

   These channels are created implicitly when the first user joins it,
   and cease to exist when the last user leaves it.  While the channel
   exists, any client can reference the channel using the name of the
   channel.

   The user creating a channel automatically becomes channel operator
   with the notable exception of channels which name is prefixed by the
   character '+', see section 4 (Channel modes).  See section 2.4.1
   (Channel Operators) for more details on this title.






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   In order to avoid the creation of duplicate channels (typically when
   the IRC network becomes disjoint because of a split between two
   servers), channel names SHOULD NOT be allowed to be reused by a user
   if a channel operator (See Section 2.4.1 (Channel Operators)) has
   recently left the channel because of a network split.  If this
   happens, the channel name is temporarily unavailable.  The duration
   while a channel remains unavailable should be tuned on a per IRC
   network basis.  It is important to note that this prevents local
   users from creating a channel using the same name, but does not
   prevent the channel to be recreated by a remote user. The latter
   typically happens when the IRC network rejoins.  Obviously, this
   mechanism only makes sense for channels which name begins with the
   character '#', but MAY be used for channels which name begins with
   the character '+'.  This mechanism is commonly known as "Channel
   Delay".

3.2 Safe Channels

   Unlike other channels, "safe channels" are not implicitly created.  A
   user wishing to create such a channel MUST request the creation by
   sending a special JOIN command to the server in which the channel
   identifier (then unknown) is replaced by the character '!'.  The
   creation process for this type of channel is strictly controlled.
   The user only chooses part of the channel name (known as the channel
   "short name"), the server automatically prepends the user provided
   name with a channel identifier consisting of five (5) characters.
   The channel name resulting from the combination of these two elements
   is unique, making the channel safe from abuses based on network
   splits.

   The user who creates such a channel automatically becomes "channel
   creator".  See section 2.4.2 (Channel Creator) for more details on
   this title.

   A server MUST NOT allow the creation of a new channel if another
   channel with the same short name exists; or if another channel with
   the same short name existed recently AND any of its member(s) left
   because of a network split.  Such channel ceases to exist after last
   user leaves AND no other member recently left the channel because of
   a network split.

   Unlike the mechanism described in section 5.2.2 (Channel Delay), in
   this case, channel names do not become unavailable: these channels
   may continue to exist after the last user left.  Only the user
   creating the channel becomes "channel creator", users joining an
   existing empty channel do not automatically become "channel creator"
   nor "channel operator".




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   To ensure the uniqueness of the channel names, the channel identifier
   created by the server MUST follow specific rules.  For more details
   on this, see section 5.2.1 (Channel Identifier).

4. Channel Modes

   The various modes available for channels are as follows:

        O - give "channel creator" status;
        o - give/take channel operator privilege;
        v - give/take the voice privilege;

        a - toggle the anonymous channel flag;
        i - toggle the invite-only channel flag;