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Trying to write an IRC client but struggling to find a good resource regarding codes and connection protocol

Tags:

c#

irc

I've looked at the RFC but I am still struggling. I've written a basic client in C# but I cannot find documentation for how to connect properly.

Once I connect and transmit NICK and USER information, I need to join a channel. If I do a JOIN straight away, nothing happens - presumably because it's too soon. I have to delay it, but I don't know which command I need to wait for to know it's okay to go ahead.

I get stuff like:

:irc.fish.net NOTICE AUTH :looking up your hostname...

and

:irc.fish.net 001 FishBot :Welcome

as well as stuff with codes 002, 003, 005, 251, 252, etc. but I can't find anywhere online that shows me what these are.

So my basic 2 questions are: What do you send a JOIN in response to, and where can I find what the IRC codes above correspond to? The RFC document was useless!

like image 543
NibblyPig Avatar asked Dec 13 '11 13:12

NibblyPig


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How do you search in IRC?

One of the best way to find channels you are interested in on a specific network once you are logged in is with the list command. You can also find channels by geographic location. There are many IRC channels established for people from various cities, although of course anyone in the world may join them.


2 Answers

The RFC documents are certainly not useless! You are correct that you need to send USER followed by NICK. The NOTICE you are getting is that the IRC server is attempting to connect back to your PC via a protocol called IDENTD. It's a relatively simple protocol but the upshot of it is that it wants to know that a program on the host that is connected to the server, is using the local/remote ports that the server has.

Chances are, your firewall is preventing this (and you're probably not running an IDENTD server). This is not a huge problem, though a fully-fledged IRC client will implement it. You can find out more here. That goes in to much more detail. It's relatively simple to implement.

Most IRC servers will give up if it cannot connect to you, and I've forgotten the exact side-effect of this (it has been a while), but the next messages you want to look out for are the MOTD_START/MOTD/MOTD_END and ERR_NOMOTD. Only after you have received the end of the Message of the day, or handled the ERR_NOMOTD (there isn't one), can you then use JOIN to join channels.

Incidentally, this is a good RegEx for matching input from an IRC Server:

^(?:[:@]([^\\s]+) )?([^\\s]+)(?: ((?:[^:\\s][^\\s]* ?)*))?(?: ?:(.*))?$

The IRC RFCs list all the possible codes and what they mean. I'm not sure why you think they are useless. Which ones have you been referencing?

EDIT

I looked up my old C++ code for IRC so I could be a bit more helpful. After connecting, it enters a stage (that I have labelled) negotiating:

Negotiating Stage:

  1. If a password has been specified for the server, send it PASS mypassword.
  2. Send the USER command.
  3. Enter the Negotiate Nickname Stage
  4. Wait for ERR_NOMOTD, END_OFMOTD. Until one of these comes, you're not "officially connected".

Negotiate Nickname Stage:

It's entirely possible that during connection, the nickname you want to use is already in use. Therefore the client should:

  1. Issue a NICK command
  2. If you receive a ERR_NICKINUSE response, issue it again. If you have no more nicknames to use, you can either bailout or prompt the user for another one.

Some other thing to consider:

  • Look our for the PING command. The server will send this when you're idle. Handle this as high-priority and return PONG with the data the server gave you. Failure to do this will ensure you get disconnected and when you're testing an IRC client, this can be a pain in the rear-end.

Bonus Fun

This is my enum for the IRC commands, you should be able to put this in to C# easily enough:

    // reply ids
    enum Reply
    {
        RplNone             = 0,
        // Initial
        RplWelcome          = 001,                  // :Welcome to the Internet Relay Network <nickname>
        RplYourHost         = 002,                  // :Your host is <server>, running version <ver>
        RplCreated          = 003,                  // :This server was created <datetime>
        RplMyInfo           = 004,                  // <server> <ver> <usermode> <chanmode>
        RplMap              = 005,                  // :map
        RplEndOfMap         = 007,                  // :End of /MAP
        RplMotdStart        = 375,                  // :- server Message of the Day
        RplMotd             = 372,                  // :- <info>
        RplMotdAlt          = 377,                  // :- <info>                                                                        (some)
        RplMotdAlt2         = 378,                  // :- <info>                                                                        (some)
        RplMotdEnd          = 376,                  // :End of /MOTD command.
        RplUModeIs          = 221,                  // <mode>

        // IsOn/UserHost
        RplUserHost         = 302,                  // :userhosts
        RplIsOn             = 303,                  // :nicknames

        // Away
        RplAway             = 301,                  // <nick> :away
        RplUnAway           = 305,                  // :You are no longer marked as being away
        RplNowAway          = 306,                  // :You have been marked as being away

        // WHOIS/WHOWAS
        RplWhoisHelper      = 310,                  // <nick> :looks very helpful                                                       DALNET
        RplWhoIsUser        = 311,                  // <nick> <username> <address> * :<info>
        RplWhoIsServer      = 312,                  // <nick> <server> :<info>
        RplWhoIsOperator    = 313,                  // <nick> :is an IRC Operator
        RplWhoIsIdle        = 317,                  // <nick> <seconds> <signon> :<info>
        RplEndOfWhois       = 318,                  // <request> :End of /WHOIS list.
        RplWhoIsChannels    = 319,                  // <nick> :<channels>
        RplWhoWasUser       = 314,                  // <nick> <username> <address> * :<info>
        RplEndOfWhoWas      = 369,                  // <request> :End of WHOWAS
        RplWhoReply         = 352,                  // <channel> <username> <address> <server> <nick> <flags> :<hops> <info>
        RplEndOfWho         = 315,                  // <request> :End of /WHO list.
        RplUserIPs          = 307,                  // :userips                                                                         UNDERNET
        RplUserIP           = 340,                  // <nick> :<nickname>=+<user>@<IP.address>                                          UNDERNET

        // List
        RplListStart        = 321,                  // Channel :Users Name
        RplList             = 322,                  // <channel> <users> :<topic>
        RplListEnd          = 323,                  // :End of /LIST
        RplLinks            = 364,                  // <server> <hub> :<hops> <info>
        RplEndOfLinks       = 365,                  // <mask> :End of /LINKS list.

        // Post-Channel Join
        RplUniqOpIs         = 325,
        RplChannelModeIs    = 324,                  // <channel> <mode>
        RplChannelUrl       = 328,                  // <channel> :url                                                                   DALNET
        RplChannelCreated   = 329,                  // <channel> <time>
        RplNoTopic          = 331,                  // <channel> :No topic is set.
        RplTopic            = 332,                  // <channel> :<topic>
        RplTopicSetBy       = 333,                  // <channel> <nickname> <time>
        RplNamReply         = 353,                  // = <channel> :<names>
        RplEndOfNames       = 366,                  // <channel> :End of /NAMES list.

        // Invitational
        RplInviting         = 341,                  // <nick> <channel>
        RplSummoning        = 342,

        // Channel Lists
        RplInviteList       = 346,                  // <channel> <invite> <nick> <time>                                                 IRCNET
        RplEndOfInviteList  = 357,                  // <channel> :End of Channel Invite List                                            IRCNET
        RplExceptList       = 348,                  // <channel> <exception> <nick> <time>                                              IRCNET
        RplEndOfExceptList  = 349,                  // <channel> :End of Channel Exception List                                         IRCNET
        RplBanList          = 367,                  // <channel> <ban> <nick> <time>
        RplEndOfBanList     = 368,                  // <channel> :End of Channel Ban List


        // server/misc
        RplVersion          = 351,                  // <version>.<debug> <server> :<info>
        RplInfo             = 371,                  // :<info>
        RplEndOfInfo        = 374,                  // :End of /INFO list.
        RplYoureOper        = 381,                  // :You are now an IRC Operator
        RplRehashing        = 382,                  // <file> :Rehashing
        RplYoureService     = 383,
        RplTime             = 391,                  // <server> :<time>
        RplUsersStart       = 392,
        RplUsers            = 393,
        RplEndOfUsers       = 394,
        RplNoUsers          = 395,
        RplServList         = 234,
        RplServListEnd      = 235,
        RplAdminMe          = 256,                  // :Administrative info about server
        RplAdminLoc1        = 257,                  // :<info>
        RplAdminLoc2        = 258,                  // :<info>
        RplAdminEMail       = 259,                  // :<info>
        RplTryAgain         = 263,                  // :Server load is temporarily too heavy. Please wait a while and try again.

        // tracing
        RplTraceLink        = 200,
        RplTraceConnecting  = 201,
        RplTraceHandshake   = 202,
        RplTraceUnknown     = 203,
        RplTraceOperator    = 204,
        RplTraceUser        = 205,
        RplTraceServer      = 206,
        RplTraceService     = 207,
        RplTraceNewType     = 208,
        RplTraceClass       = 209,
        RplTraceReconnect   = 210,
        RplTraceLog         = 261,
        RplTraceEnd         = 262,

        // stats
        RplStatsLinkInfo    = 211,                  // <connection> <sendq> <sentmsg> <sentbyte> <recdmsg> <recdbyte> :<open>
        RplStatsCommands    = 212,                  // <command> <uses> <bytes>
        RplStatsCLine       = 213,                  // C <address> * <server> <port> <class>
        RplStatsNLine       = 214,                  // N <address> * <server> <port> <class>
        RplStatsILine       = 215,                  // I <ipmask> * <hostmask> <port> <class>
        RplStatsKLine       = 216,                  // k <address> * <username> <details>
        RplStatsPLine       = 217,                  // P <port> <??> <??>
        RplStatsQLine       = 222,                  // <mask> :<comment>
        RplStatsELine       = 223,                  // E <hostmask> * <username> <??> <??>
        RplStatsDLine       = 224,                  // D <ipmask> * <username> <??> <??>
        RplStatsLLine       = 241,                  // L <address> * <server> <??> <??>
        RplStatsuLine       = 242,                  // :Server Up <num> days, <time>
        RplStatsoLine       = 243,                  // o <mask> <password> <user> <??> <class>
        RplStatsHLine       = 244,                  // H <address> * <server> <??> <??>
        RplStatsGLine       = 247,                  // G <address> <timestamp> :<reason>
        RplStatsULine       = 248,                  // U <host> * <??> <??> <??>
        RplStatsZLine       = 249,                  // :info
        RplStatsYLine       = 218,                  // Y <class> <ping> <freq> <maxconnect> <sendq>
        RplEndOfStats       = 219,                  // <char> :End of /STATS report
        RplStatsUptime      = 242,

        // GLINE
        RplGLineList        = 280,                  // <address> <timestamp> <reason>                                                   UNDERNET
        RplEndOfGLineList   = 281,                  // :End of G-line List                                                              UNDERNET

        // Silence
        RplSilenceList      = 271,                  // <nick> <mask>                                                                    UNDERNET/DALNET
        RplEndOfSilenceList = 272,                  // <nick> :End of Silence List                                                      UNDERNET/DALNET

        // LUser
        RplLUserClient      = 251,                  // :There are <user> users and <invis> invisible on <serv> servers
        RplLUserOp          = 252,                  // <num> :operator(s) online
        RplLUserUnknown     = 253,                  // <num> :unknown connection(s)
        RplLUserChannels    = 254,                  // <num> :channels formed
        RplLUserMe          = 255,                  // :I have <user> clients and <serv> servers
        RplLUserLocalUser   = 265,                  // :Current local users: <curr> Max: <max>
        RplLUserGlobalUser  = 266,                  // :Current global users: <curr> Max: <max>


        // Errors
        ErrNoSuchNick       = 401,                  // <nickname> :No such nick
        ErrNoSuchServer     = 402,                  // <server> :No such server
        ErrNoSuchChannel    = 403,                  // <channel> :No such channel
        ErrCannotSendToChan = 404,                  // <channel> :Cannot send to channel
        ErrTooManyChannels  = 405,                  // <channel> :You have joined too many channels
        ErrWasNoSuchNick    = 406,                  // <nickname> :There was no such nickname
        ErrTooManyTargets   = 407,                  // <target> :Duplicate recipients. No message delivered
        ErrNoColors         = 408,                  // <nickname> #<channel> :You cannot use colors on this channel. Not sent: <text>   DALNET
        ErrNoOrigin         = 409,                  // :No origin specified
        ErrNoRecipient      = 411,                  // :No recipient given (<command>)
        ErrNoTextToSend     = 412,                  // :No text to send
        ErrNoTopLevel       = 413,                  // <mask> :No toplevel domain specified
        ErrWildTopLevel     = 414,                  // <mask> :Wildcard in toplevel Domain
        ErrBadMask          = 415,
        ErrTooMuchInfo      = 416,                  // <command> :Too many lines in the output, restrict your query                     UNDERNET
        ErrUnknownCommand   = 421,                  // <command> :Unknown command
        ErrNoMotd           = 422,                  // :MOTD File is missing
        ErrNoAdminInfo      = 423,                  // <server> :No administrative info available
        ErrFileError        = 424,
        ErrNoNicknameGiven  = 431,                  // :No nickname given
        ErrErroneusNickname = 432,                  // <nickname> :Erroneus Nickname
        ErrNickNameInUse    = 433,                  // <nickname> :Nickname is already in use.
        ErrNickCollision    = 436,                  // <nickname> :Nickname collision KILL
        ErrUnAvailResource  = 437,                  // <channel> :Cannot change nickname while banned on channel
        ErrNickTooFast      = 438,                  // <nick> :Nick change too fast. Please wait <sec> seconds.                         (most)
        ErrTargetTooFast    = 439,                  // <target> :Target change too fast. Please wait <sec> seconds.                     DALNET/UNDERNET
        ErrUserNotInChannel = 441,                  // <nickname> <channel> :They aren't on that channel
        ErrNotOnChannel     = 442,                  // <channel> :You're not on that channel
        ErrUserOnChannel    = 443,                  // <nickname> <channel> :is already on channel
        ErrNoLogin          = 444,
        ErrSummonDisabled   = 445,                  // :SUMMON has been disabled
        ErrUsersDisabled    = 446,                  // :USERS has been disabled
        ErrNotRegistered    = 451,                  // <command> :Register first.
        ErrNeedMoreParams   = 461,                  // <command> :Not enough parameters
        ErrAlreadyRegistered= 462,                  // :You may not reregister
        ErrNoPermForHost    = 463,
        ErrPasswdMistmatch  = 464,
        ErrYoureBannedCreep = 465,
        ErrYouWillBeBanned  = 466,
        ErrKeySet           = 467,                  // <channel> :Channel key already set
        ErrServerCanChange  = 468,                  // <channel> :Only servers can change that mode                                     DALNET
        ErrChannelIsFull    = 471,                  // <channel> :Cannot join channel (+l)
        ErrUnknownMode      = 472,                  // <char> :is unknown mode char to me
        ErrInviteOnlyChan   = 473,                  // <channel> :Cannot join channel (+i)
        ErrBannedFromChan   = 474,                  // <channel> :Cannot join channel (+b)
        ErrBadChannelKey    = 475,                  // <channel> :Cannot join channel (+k)
        ErrBadChanMask      = 476,
        ErrNickNotRegistered= 477,                  // <channel> :You need a registered nick to join that channel.                      DALNET
        ErrBanListFull      = 478,                  // <channel> <ban> :Channel ban/ignore list is full
        ErrNoPrivileges     = 481,                  // :Permission Denied- You're not an IRC operator
        ErrChanOPrivsNeeded = 482,                  // <channel> :You're not channel operator
        ErrCantKillServer   = 483,                  // :You cant kill a server!
        ErrRestricted       = 484,                  // <nick> <channel> :Cannot kill, kick or deop channel service                      UNDERNET
        ErrUniqOPrivsNeeded = 485,                  // <channel> :Cannot join channel (reason)
        ErrNoOperHost       = 491,                  // :No O-lines for your host
        ErrUModeUnknownFlag = 501,                  // :Unknown MODE flag
        ErrUsersDontMatch   = 502,                  // :Cant change mode for other users
        ErrSilenceListFull  = 511                   // <mask> :Your silence list is full                                                UNDERNET/DALNET

    };  // eo enum Reply
like image 148
Moo-Juice Avatar answered Nov 29 '22 11:11

Moo-Juice


Maybe you looked at an old version (RFC 1459) instead of the current version (RFC 2812) of the standard?

The latter one lists the numeric codes in Section 5 "Replies":

   001    RPL_WELCOME
          "Welcome to the Internet Relay Network
           <nick>!<user>@<host>"
   002    RPL_YOURHOST
          "Your host is <servername>, running version <ver>"
   003    RPL_CREATED
          "This server was created <date>"
   ...

(That should answer your second question; unfortunately, I'm not familiar enough with the protocol to answer your first. A simple solution to get you on the right track might be to trace the connection of an existing IRC client using some packet sniffer.)

like image 23
Heinzi Avatar answered Nov 29 '22 11:11

Heinzi