⚡ FT_IRC ⚡

Proudly coded by @tmanolis, @QnYosa and @marineks ❤️

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💫 Summary

1. About the project

• Definition
• Subject requirements
• Commands that we implemented

2. Some tips, graphs and other ressources

• Helpful links
• Tips

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🎒 About this project

The objective of this project is to reproduce the functioning of an IRC server.

_ 🔮 Definition

"IRC (Internet Relay Chat) is a protocol for real-time text messaging between internet-connected computers created in 1988. It is mainly used for group discussion in chat rooms called “channels” although it supports private messages between two users, data transfer, and various server-side and client-side commands. As of April 2011, the top 100 IRC networks served over 500,000 users at a time on hundreds of thousands of channels." (source)

_ 💾 Subject requirements

1. Code the IRC server in C++98 2. Your binary should look like this : ./ircserv <port> <password> 3. You should use poll() and only once. 4. The client/server communication will be TCP/IP (v4 or v6) 5. The following features are mandatory :

i) You should be able to register, i.e to define a nickname, a username

ii) You should be able to join a channel, send or receive private messages

iii) Every message sent by a client in a channel must be received by all of the clients who have joined this channel

iv) You should have normal users and operators, and implement the operators' specific commands 6. No leaks (even still reachables) and handle the signals (partial messages with CTRL+D, suspended process with CTRL+Z, and obviously SIGINT (CTRL+C)) 7. (bonuses) implement a bot + file transfer.

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🔆 Commands that we implemented :

Command	Description
Invite	The INVITE command is used to invite a user to a channel.
Join	The JOIN command indicates that the client wants to join the given channel(s), each channel using the given key for it.
Kick	The KICK command can be used to request the forced removal of a user from a channel.
Kill	The KILL command is used to close the connection between a given client and the server they are connected to. KILL is a privileged command and is available only to IRC Operators.
List	The LIST command is used to get a list of channels along with some information about each channel.
Mode	The MODE command is used to set or remove options (or modes) from a given target. Our user modes : i, o. Our channels modes: b,k,m,o,p,s,t,v
Motd	The MOTD command is used to get the “Message of the Day” of the given server.
Names	The NAMES command is used to view the nicknames joined to a channel and their channel membership prefixes.
Nick	The NICK command is used to give the client a nickname or change the previous one.
Notice	The NOTICE command is used to send notices between users, as well as to send notices to channels. The difference between NOTICE and PRIVMSG is that automatic replies must never be sent in response to a NOTICE message.
Oper	The OPER command is used by a normal user to obtain IRC operator privileges.
Part	The PART command removes the client from the given channel(s).
Pass	The PASS command is used to set a ‘connection password’. If set, the password must be set before any attempt to register the connection is made.
Ping	The PING command is sent by either clients or servers to check the other side of the connection is still connected and/or to check for connection latency, at the application layer.
Privmsg	The PRIVMSG command is used to send private messages between users, as well as to send messages to channels.
Quit	The QUIT command is used to terminate a client’s connection to the server. The server acknowledges this by replying with an ERROR message and closing the connection to the client.
Topic	The TOPIC command is used to change or view the topic of the given channel.
User	The USER command is used at the beginning of a connection to specify the username and realname of a new user.

🎁 Some tips, graphs and other ressources

_ 📚 Helpful links

• To understand what exactly is an IRC and begin the project : Chirc (An irc subject from a Chicago uni) and the next pages too.

• Regarding the client/server connection : Beej's Guide to network programming. This is super super helpful to better understand what is a socket, what the poll() function entails, which system calls we should use or in which order, and so on.

• A link to the IRC Client Protocol with a good formatting : Modern IRC Client Protocol. You will find there a description of all the commands with correct syntax, expected Numerical Replies,...

_ 📫 Tips

• A suggestion of project roadmap : 1- Begin by establishing a working client/server socket connection, 2- Then build on that : add the signals handling (CTRL+C, CTRL+D, CTRL+Z); 3- Only then begin the client registration system (NICK, USER, PASS), 4- The server commands (PING, OPER, KILL...) and 5- The channel operations commands (JOIN, PART, INVITE, KICK, PRIVMSG, NOTICE...).

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• Help, my code works perfectly with irssi but not with nc! If you have this kind of issue, this is because, like us, you made the mistake of coding with irssi first and not nc 😬 Keep in mind that nc is very "minimalist" compared to irssi. That means that irssi will send you everything at once : the command, and the CRLF ending (\r\n). It will also append the : in some cases (for instance TOPIC #channel :message).

  This is not the case with nc : you will have to concatenate the messages sent by the Client until you find the proper "end" (the CRLF). That means that you should have a (read) buffer ==for each client== connected to your server. Bonus: this will take care of he CTRL+D signal too! 😏

  So now, if you follow us, you should guess that, for each client, you will need a (send) buffer as well! This will be very efficient in taking care of the CTRL+Z signal 😇 . Don't forget to also check the POLLIN and POLLOUT revents in your server loop...

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• How to know how to correctly format a RPL to be understood by your IRC client of reference (for instance, irssi) ? .

  Join an existing server (try /connect DALNET), then enter the command /RAWLOG OPEN debug.log (more doc), and try the commands you're having some troubles with. This will open a log file in your workspace containing the all the exact client/server interactions for these commands, such as :

   // [...]
   << JOIN #help // from the client
   >> :nickname!username@host JOIN :#help // reply from the server
   // [...]

  Voilà ! Now you know you forgot the : before the channel name! ;)

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• Okay, now you have a good format but the code is not clean at all? Try to use dynamic macros in this way (we guarantee this is a life changer/saver!) :

    #define user_id(nickname, username) (":" + nickname + "!" + username + "@localhost")
    #define RPL_INVITE(user_id, invited, channel) (user_id + " INVITE " + invited + " #" + channel + "\r\n")
    // [...]
    #define ERR_INVALIDMODEPARAM(client, channel, mode, password) ("696 " + client + " #" + channel + " " + mode + " " + password + " : password must only contained alphabetic character\r\n")