IRC Hacks [Electronic resources] نسخه متنی

Hack 31 IRC Over Telnet

Make a raw connection to an IRC server and
spend a little time trying out the IRC protocol commands
you'll be using in your program directly.

Jarkko Oikarinen first
introduced IRC to the world in 1988. Five years later, he clearly
defined the IRC
protocol in RFC 1459, which made the whole protocol much more
accessible. Armed with this information, you can get a better
understanding of this simple text-based protocol and learn how to
connect to IRC servers without using a special client. Once you have
mastered this, you should find it a trivial task to write programs
that connect to IRC.

You can find all of the Internet RFC (Request for Comments) documents on http://www.faqs.org/rfcs. You can search the archives by word or document number. RFC 1459 can be found at http://www.faqs.org/rfcs/rfc1459l.

Fortunately, you do not need to know about the full specification to
connect to an IRC server. Connecting to an IRC server requires only a
few commands be sent. A good way of understanding how these commands
work is to connect directly to an IRC server with Telnet and type
these commands in directly. Telnet allows you to establish a TCP
connection to a port on a remote machine and simply start typing in
commands for the service listening on that port.

Most IRC servers run on port 6667, although you may find a
few that operate on different port numbers to assist users who are
stuck behind corporate firewalls. For this example, you can try
connecting to the freenode IRC network by running
Telnet from a command
prompt with the following command-line parameters:

% telnet  irc.freenode.net 6667 

If the connection was successful, you will see the server respond
with something similar to this:

NOTICE AUTH :*** Looking up your hostname...
NOTICE AUTH :*** Found your hostname, welcome back
NOTICE AUTH :*** Checking ident
NOTICE AUTH :*** No identd (auth) response

Although the socket is physically connected to the IRC server, you
still need to do a couple of things. The IRC server will need to know
your login, your real name, and the nickname you want to use.

The NICK command is used to set your
nickname. This is pretty
straightforward, so if I wanted my nickname to be
"Paul," I would type the following
into the Telnet window and press Enter:

NICK Paul

If the nickname you choose is already in use on the server, you will
be told so and you will have to keep sending the same command with a
different nickname each time, until you find one that is available.
This is the kind of message you will see if the nickname is already
in use:

:kornbluth.freenode.net 433 * Paul :Nickname is already in use.

The USER command is used to set the

login, user modes, and real
name. If I wanted to have a login of
"paul," I would type the following,
followed by Enter:

USER  paul 8 *  : Paul Mutton

Most servers these days respect
commands from
the updated IRC
RFC 2812. This USER command makes use of some
features specified in this updated document. In particular, the
8 is a numeric mode parameter that is used to
automatically set user modes when registering with the server. This
parameter is a bit mask, with bit 2 representing user mode
w and bit 3 representing user mode
i, so using a value of 8 means that you are asking
the server to set you to be invisible. Currently, only these two bits
have any significance. Also note that the text after the : is where you would enter your real name.

After successfully sending the NICK and
USER commands, the server will send several lines
of text to you. If nothing seems to be happening for a while,
don't worrythe server may impose an
artificial delay of up to a minute if it did not find an Ident server
running on your machine. At first, the lines sent from the server may
look rather confusing, but you may recognize some of them as being
part of the message of the day. You are now connected to the IRC
server!

Ident (Identification Protocol) is documented in RFC 1413. See http://www.faqs.org/rfcs/rfc1413l for more details.

Now that you are connected, you are able to perform anything a fully
functional IRC client would be capable of doing.

5.2.1 Staying Alive

Sometimes it is difficult for IRC
servers to keep track of who is still connected. One trick they
employ is to send PING commands to clients that
have not exhibited any recent activity. The client is expected to
respond with a PONG message to effectively say,
"Hey, I'm still
here!" If the client does not respond in a timely
fashion, the server will close the connection. As a general rule, the
PONG reply must include the arguments that were
sent as part of the PING command from the server.
So if you were to receive the following message:

PING :kornbluth.freenode.net

You would reply with the following PONG command:

PONG  :kornbluth.freenode.net 

5.2.2 Joining Channels and Sending Messages

The usual IRC client
commands like /join and /msg
won't work here, as you are dealing with the raw
protocol. You can think of your Telnet connection as a form of
primitive IRC clientyou can still do anything an IRC client
can do, but it just looks a little ugly and the commands are
different. Despite this, it is still pretty easy to join a channel
and send messages to other users. To join the channel
#irchacks, you just have to enter:

JOIN #irchacks

If all went well, you should see the IRC server replying with a few
lines of text. IRC clients use these lines to determine who is in the
channel so they can update their user lists. For now though, you
needn't worry about how to parse that information.

Sending
messages is slightly less intuitive and is
achieved with the
PRIVMSG command. As you might expect from the
name, this command can be used to send private messages to other
users; however, it is also the command used to send messages to
entire channels. To send a message to the channel
#irchacks, you could try the following:

PRIVMSG  #irchacks :Hello everybody! 

Sending private messages is just as
easysimply use the recipient's nickname in
place of the channel name. If you want to send a private message to
the user with the nickname "Dave,"
you would enter:

PRIVMSG 
Dave 
:
Hi Dave.

When you get bored with showing off your newfound protocol skills,
you can quit from the server with the
QUIT command. Using this command will cause
the server to close your connection.

QUIT

The QUIT command can also take an optional
parameter. The parameter must be immediately preceded by a
: character. Whatever you supply here will be
displayed to other users as your reason for quitting from the server:

QUIT  :Telnet sucks! 

Whichever method you use to quit from the server, before it
disconnects you, it will respond with something along the lines of:

ERROR :Closing Link: Paul (Client Quit)

It is also possible for you to close the connection by closing
Telnet, but this does not allow you to specify a reason for quitting.

While all
commands should be capitalized, you may
find that most servers are quite relaxed about this policy. Now that
you know what to type to connect to IRC, the rest of the hacks in
this chapter will show you how to create programs that connect to an
IRC server.