TIdIRCServer = class(TIdTCPServer)

• RFC 1459 - Internet Relay Chat Protocol (IRC) (http://www.rfc-editor.org/rfc/rfc1459.txt)

The IRC protocol provides users with a way to chat among themselves in "chat rooms". The IRC protocol is a text-based conferencing protocol that uses TCP/IP as the network transport.

A typical IRC environment involves a single process (the server) that forms a central point for client (or other server) connections, performing the required message delivery/multiplexing and other functions. IRC allows various forms of message delivery including user-to-user, user-to-list, user-to-group, user-to-server, and server-to-server communication modes.

The only network configuration allowed for IRC servers is that of a spanning tree where each server acts as a central node for the rest of the network visible to the server.

An IRC client can be any socket-enable application capable of connecting to an IRC server that is not already an IRC server.

TIdIRCServer uses the standard port number IdPORT_IRC reserved for the IRC protocol to listen for client connections. TIdIRCServer, like TIdTCPServer, is a multithreaded application where new connections are respresented by a TIdPeerThread that is serviced by the TIdIRCServer.

TIdIRCServer recognizes the following IRC commands as defined in the RFC specification:

• ADMIN

• AWAY

• CONNECT

• ERROR

• INFO

• INVITE

• ISON

• JOIN

• KICK

• KILL

• LINKS

• LIST

• MODE

• NAMES

• NICK

• NOTICE

• OPER

• PART

• PASS

• PING

• PONG

• PRIVMSG

• QUIT

• REHASH

• RESTART

• SERVER

• SQUIT

• STATS

• SUMMON

• TIME

• TOPIC

• TRACE

• USER

• USERHOST

• USERS

• VERSION

• WALLOPS

• WHO

• WHOIS

• WHOWAS

TIdIRCServer provides an event handler architecture for all IRC commands that allow the IRC server application to determine the appropriate mechanism used to respond to an IRC command. TIdIRCServer does not provide an implementation for the event handlers.

constructor Create(AOwner: TComponent); override;

property OnCommandAdmin: TIdIrcOneParmEvent;

Parm can contain wildcard characters to indicate that the first server matching the host name mask. For example:

• irc.wvnet.edu - request a specific server.

• *.edu - request the first server found in the edu domain.

property OnCommandAway: TIdIrcOneParmEvent;

When Parm contains text, the user is not available to receive additional messages and the text in Parm should be sent by the server to any clients sending messages to the user. When Parm is an empty string, the user is on-line and can resume receipt of IRC messages. For example:

• "Gone to Lunch. Back in 30 minutes." - The Away message is active.

• "" - Away message inactive. User receives messages.

property OnCommandConnect: TIdIrcThreeParmEvent;

Parm1 is the target server will be the endpoint for the connection.

Parm2 is an optional port number to use for the connection.

Parm3 is an optional server that represents the origin point for the new connection. When Parm3 is an empty string, the origin is the current server.

property OnCommandError: TIdIrcOneParmEvent;

An ERROR message is used to report errors which occur on the server-to-server link only. An ERROR message is sent to a server at the connection endpoint and all operators currently connected. It is not to be passed onto any other servers by a server if it is received from a server. When a server sends a received ERROR message to operators, the message should be encapsulated in a NOTICE message, indicating that the client was not responsible for the error.

property OnCommandInfo: TIdIrcOneParmEvent;

Parm can contain a server name, a host name mask with wildcard characters, or a user nickname that identifies the target of the INFO request. For example:

• csd.bu.edu - request information for a specific server.

• *.edu - request information from the first available server.

• MyNick - request information from the server where MyNick is connected.

property OnCommandInvite: TIdIrcTwoParmEvent;

Parm1 contains the Nickname of the user to be invited to a channel.

Parm2 contains the Channel name where the user is to be invited. There is no requirement that Parm2 identifying an existing or valid channel.

To invite a user to a channel which is by invitation only, the client sending the invite must be recognized as being a channel operator on the given channel.

property OnCommandIsOn: TIdIrcOneParmEvent;

Parm is a user nickname or space-delimited list of user nicknames. For each nickname in the list, the server adds that to its reply string when the user is connected. The list returned may be empty, the same as the original list, or a subset of the original list in Parm. Parm cannot exceed 512 characters.

ISON may only be processed by the server for the client sending the command, and cannot be passed to other servers for further processing.

property OnCommandJoin: TIdIrcTwoParmEvent;

Permissions to join a channel are determined by the server that hosts the client connection. All other servers should add the user to the channel when it is received from the origin server. The local server can add a user under the following circumstances:

• The user must be invited if the channel is by invitation only.

• The user's nick/username/hostname must not match any active bans.

• The correct key (password) must be given if it is set.

When a user has joined a channel, they will receive notice about all commands for their server that affect the channel.

Parm1 contains a channel name, or a list of comma-delimited channel names, where the client should listen for IRC messages.

Parm2 contains a key (password), or a list of comma-delimited keys, for all channels where keys are required.

property OnCommandKick: TIdIrcThreeParmEvent;

Each server that receives a KICK message checks that the user is a valid channel operator before removing the victim in Parm2 from the channel.

property OnCommandKill: TIdIrcTwoParmEvent;

Parm1 is the user NickName for the connection to be closed.

Parm2 is a comment that reflects the reason that the connection is closed. The name of the user generating the message and all servers in the IRC network path is prepended to Parm2.

property OnCommandLinks: TIdIrcTwoParmEvent;

Remote server can be a server name, or a server name mask that identifies the server where the command is forwarded for processing. For example:

• LINKS *.au - lists all servers with a name that matches *.au

• LINKS *.bu.edu *.edu - lists all servers with a name that matches *.bu.edu on the first server matching *.edu

property OnCommandList: TIdIrcTwoParmEvent;

Parm1 is an optional parameter that identifies a comma-delimited list of channel names where status and topic information should be retrieved.

Parm2 is the server where the list command should be performed.

property OnCommandMode: TIdIrcFiveParmEvent;

Channel mode is provided to allow channel operators to change the characteristics of the channel. In channel mode, Parm2 indicates channel options that include a "+" or "-" character, indicating the action, and one or more of the following channel option characters:

• o - Give/take channel operator privileges.

• p - Private channel flag.

• s - Secret channel flag.

• i - Invite-only channel flag.

• t - Topic settable by channel operator only flag.

• n - No messages to channel from clients on the outside.

• m - Moderated channel.

• l - Set the user limit to channel.

• b - Set a ban mask to keep users out.

• v - Give/take the ability to speak on a moderated channel.

• k - Set a channel key (password).

When using the 'o' and 'b' options, a restriction on a total of three per mode command has been imposed.

User mode is provided to allow changes that affect how the user is seen by others, and what extra messages are seen by the client. In User mode, Parm2 indicates user options that include a "+" or "-" character, indicating the action, and one or more of the following user option characters:

• i - Marks a users as invisible.

• s - Marks a user for receipt of server notices.

• w - User receives wallops.

• o - Operator flag.

If a user attempts to make themselves an operator using the "+o" flag, the attempt should be ignored. There is no restriction, however, on a user removing their operator option flag.

property OnCommandNames: TIdIrcOneParmEvent;

Parm should not contain private or secret channels. When Parm is blank, a list of all users on any channel on the server is returned. Users on not on the server, or a visible channel on the server, are placed at the end of the list on channel "*".

property OnCommandNick: TIdIrcTwoParmEvent;

Parm2 is an optional parameter that contains the number of hops from the home server for the user. A local connection has a hop count of 0. If Parm2 is supplied by a client, it is ignored.

The server cannot allow two users to have an identical Nickname. If a Nickname collision occurs, both connection with the Nickname are closed and the entries are removed from the server database.

property OnCommandNotice: TIdIrcTwoParmEvent;

property OnCommandOper: TIdIrcTwoParmEvent;

Param1 contains the user requesting operator privileges.

Param2 contains the password for the user requesting operator privileges.

If the user and password are valid, the server will inform the remainder of the IRC network using the "MODE +o" command for the client nickname.

property OnCommandOther: TIdIrcOtherEvent;

property OnCommandPart: TIdIrcOneParmEvent;

property OnCommandPass: TIdIrcOneParmEvent;

property OnCommandPing: TIdIrcTwoParmEvent;

Parm1 is the name of the server where a client PONG response must be sent, and normally represents the server that issued the PING request.

Parm2 is an optional parameter that contains the name of a server where a client PONG response should be forwarded.

property OnCommandPong: TIdIrcTwoParmEvent;

property OnCommandPrivMsg: TIdIrcTwoParmEvent;

Parm1 contains a nickname, a comma-delimited list of nicknames or channels, or a host/server mask that identifies the destination for the message in Parm2.

property OnCommandQuit: TIdIrcOneParmEvent;

If Parm is not specified, the NickName is sent as the test for the message. When two server connections are involved, the text for the message is the space-delimited names of the servers.

property OnCommandRehash: TIdIrcGetEvent;

property OnCommandRestart: TIdIrcGetEvent;

RESTART is optional since it may be viewed as a risk to allow arbitrary people to connect to a server as an operator and execute this command, causing (at least) a disruption to service.

The RESTART command must always be fully processed by the server to which the sending client is connected and not be passed onto other connected servers.

property OnCommandServer: TIdIrcServerEvent;

HopCount is used to give all servers some internal information on how far away all servers are. With a full server list, it would be possible to construct a map of the entire server tree, but hostmasks prevent this from being done.

If a SERVER message is parsed and attempts to introduce a server which is already known to the receiving server, the connection from which that message must be closed (following the correct procedures), since a duplicate route to a server has formed and the acyclic nature of the IRC tree broken.

property OnCommandSQuit: TIdIrcTwoParmEvent;

This command is also available operators to help keep a network of IRC servers connected in an orderly fashion. Operators may also issue an SQUIT message for a remote server connection. In this case, the SQUIT must be parsed by each server in between the operator and the remote server, updating the view of the network held by each server as explained below.

Parm2 should be supplied by all operators who execute a SQUIT for a remote server (that is not connected to the server they are currently on) so that other operators are aware for the reason of this action. Parm2 is also filled in by servers which may place an error or similar message here.

Both of the servers which are on either side of the connection being closed are required to send out a SQUIT message (to all its other server connections) for all other servers which are considered to be behind that link.

Similarly, a QUIT message must be sent to the other connected servers rest of the network on behalf of all clients behind that link. In addition to this, all channel members of a channel which lost a member due to the split must be sent a QUIT message.

If a server connection is terminated prematurely (e.g. the server on the other end of the link died), the server which detects this disconnection is required to inform the rest of the network that the connection has closed and fill in the comment field with something appropriate.

property OnCommandStats: TIdIrcTwoParmEvent;

If Parm2 is omitted, only the end of stats reply is sent back. The implementation of this command is highly dependent on the server which replies, although the server must be able to supply information as described by the queries below (or similar).

A query may be given by any single letter which is only checked by the destination server (if given as the Parm2 parameter) and is otherwise passed on by intermediate servers, ignored and unaltered.

The following queries are those found in the current IRC implementation and provide a large portion of the setup information for that server. Although these may not be supported in the same way by other versions, all servers should be able to supply a valid reply to a STATS query which is consistent with the reply formats currently used and the purpose of the query.

The currently supported queries are:

• c - returns a list of servers which the server may connect to or allow connections from.

• h - returns a list of servers which are either forced to be treated as leaves or allowed to act as hubs.

• i - returns a list of hosts which the server allows a client to connect from.

• k - returns a list of banned username/hostname combinations for that server.

• l - returns a list of the server's connections, showing how long each connection has been established and the traffic over that connection in bytes and messages for each direction.

• m - returns a list of commands supported by the server and the usage count for each if the usage count is non zero.

• o - returns a list of hosts from which normal clients may become operators.

• y - show Y (Class) lines from server's configuration file.

• u - returns a string showing how long the server has been up.

property OnCommandSummon: TIdIrcTwoParmEvent;

If Parm2 is given, this is the target server for the message. If summon is not enabled in a server, it must return the ERR_SUMMONDISABLED numeric and pass the summon message to other IRC servers.

property OnCommandTime: TIdIrcOneParmEvent;

property OnCommandTopic: TIdIrcTwoParmEvent;

Parm1 is the channel to be affected by the message.

Parm2 is the topic for the specified channel.

If Parm2 is not specified, the current topic for Parm1 will be retrieved.

property OnCommandTrace: TIdIrcOneParmEvent;

Each server that processes this message must tell the sender about it by sending a reply indicating it is a pass-through link, forming a chain of replies similar to that gained from using "traceroute". After sending this reply back, it must then send the TRACE message to the next server until given server is reached. If Parm is omitted, it is recommended that TRACE command send a message to the sender telling which servers the current server has direct connection to.

property OnCommandUser: TIdIrcUserEvent;

USER messages between IRC servers must to be prefixed with client's NICKname. Note that hostname and servername are normally ignored by the IRC server when the USER command comes from a directly connected client (for security reasons), but they are used in server to server communication. This means that a NICK must always be sent to a remote server when a new user is being introduced to the rest of the network before the accompanying USER is sent.

It must be noted that realname parameter must be the last parameter, because it may contain space characters and must be prefixed with a colon (':') to make sure this is recognized as such.

Since it is easy for a client to lie about its username by relying solely on the USER message, the use of an "Identity Server" is recommended. If the host which a user connects from has such a server enabled the username is set to that as in the reply from the "Identity Server".

property OnCommandUserHost: TIdIrcOneParmEvent;

property OnCommandUsers: TIdIrcOneParmEvent;

property OnCommandVersion: TIdIrcOneParmEvent;

property OnCommandWallops: TIdIrcOneParmEvent;

property OnCommandWho: TIdIrcTwoParmEvent;

In the absence of the Parm1 parameter, all visible (users who aren't invisible (user mode +i) and who don't have a common channel with the requesting client) are listed. The same result can be achieved by using a Parm1 of "0" or any wildcard which will end up matching every entry possible.

The Parm1 passed to WHO is matched against users' host, server, real name and nickname if the channel Parm1 cannot be found.

If the "o" parameter is passed only operators are returned according to the name mask supplied.

property OnCommandWhoIs: TIdIrcTwoParmEvent;

The latter version sends the query to a specific server. It is useful if you want to know how long the user in question has been idle as only local server (ie. the server the user is directly connected to) knows that information, while everything else is globally known.

property OnCommandWhoWas: TIdIrcThreeParmEvent;

In response to this query, the server searches through its nickname history, looking for any nicks which are lexically the same (no wild card matching here). The history is searched backward, returning the most recent entry first. If there are multiple entries, up to Parm2 replies will be returned (or all of them if no Parm2 parameter is given). If a non-positive number is passed as being Parm2, then a full search is done.