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Protocol::IRC(3pm) User Contributed Perl Documentation Protocol::IRC(3pm)


"Protocol::IRC" - IRC protocol handling


This mix-in class provides a base layer of IRC message handling logic. It allows reading of IRC messages from a string buffer and dispatching them to handler methods on its instance.

Protocol::IRC::Client provides an extension to this logic that may be more convenient for IRC client implementations. Much of the code provided here is still useful in client applications, so the reader should be familiar with both modules.


Every incoming message causes a sequence of message handling to occur. First, the message is parsed, and a hash of data about it is created; this is called the hints hash. The message and this hash are then passed down a sequence of potential handlers.

Each handler indicates by return value, whether it considers the message to have been handled. Processing of the message is not interrupted the first time a handler declares to have handled a message. Instead, the hints hash is marked to say it has been handled. Later handlers can still inspect the message or its hints, using this information to decide if they wish to take further action.

A message with a command of "COMMAND" will try handlers in following places:

A method called "on_message_COMMAND"

 $irc->on_message_COMMAND( $message, \%hints )
A method called "on_message"

 $irc->on_message( 'COMMAND', $message, \%hints )

For server numeric replies, if the numeric reply has a known name, it will be attempted first at its known name, before falling back to the numeric if it was not handled. Unrecognised numerics will be attempted only at their numeric value.

Because of the wide variety of messages in IRC involving various types of data the message handling specific cases for certain types of message, including adding extra hints hash items, or invoking extra message handler stages. These details are noted here.

Many of these messages create new events; called synthesized messages. These are messages created by the "Protocol::IRC" object itself, to better represent some of the details derived from the primary ones from the server. These events all take lower-case command names, rather than capitals, and will have a "synthesized" key in the hints hash, set to a true value. These are dispatched and handled identically to regular primary events, detailed above.

If any handler of the synthesized message returns true, then this marks the primary message handled as well.

If a message is received that has a gating disposition, extra processing is applied to it before the processing above. The effect on its gate is given as a string (one of "more", "done", "fail") to handlers in the following places:

A method called "on_message_gate_EFFECT_GATE"

 $irc->on_message_gate_EFFECT_GATE( $message, \%hints )
A method called "on_message_gate_EFFECT"

 $irc->on_message_gate_EFFECT( 'GATE', $message, \%hints )
A method called "on_message_gate"

 $irc->on_message_gate( 'EFFECT', 'GATE', $message, \%hints )

Message Hints

When messages arrive they are passed to the appropriate message handling method, which the implementation may define. As well as the message, a hash of extra information derived from or relating to the message is also given.

The following keys will be present in any message hint hash:

Initially false. Will be set to true the first time a handler returns a true value.
Values split from the message prefix; see the "Protocol::IRC::Message" "prefix_split" method.
Usually the prefix nick, or the hostname in case the nick isn't defined (usually on server messages).
True if the nick mentioned in the prefix refers to this connection.

Added to this set, will be all the values returned by the message's "named_args" method. Some of these values may cause yet more values to be generated.

If the message type defines a "target_name":

  • target_type => STRING

    Either "channel" or "user", as returned by "classify_name".

  • target_is_me => BOOL

    True if the target name is a user and refers to this connection.

Any key whose name ends in "_nick" or "_name" will have a corresponding key added with "_folded" suffixed on its name, containing the value casefolded using "casefold_name". This is for the convenience of string comparisons, hash keys, etc..

Any of these keys that are not the "prefix_name" will additionally have a corresponding key with "_is_me" replacing the "_nick" or "_name", containing the boolean result of calling the "is_nick_me" method on that name. This makes it simpler to detect commands or results affecting the user the connection represents.



   $irc->on_read( $buffer )

Informs the protocol implementation that more bytes have been read from the peer. This method will modify the $buffer directly, and remove from it the prefix of bytes it has consumed. Any bytes remaining should be stored by the caller for next time.

Any messages found in the buffer will be passed, in sequence, to the "incoming_message" method.


   $irc->incoming_message( $message )

Invoked by the "on_read" method for every incoming IRC message. This method implements the actual dispatch into various handler methods as described in the "MESSAGE HANDLING" section above.

This method is exposed so that subclasses can override it, primarily to wrap extra logic before or after the main dispatch (e.g. for logging or other processing).


This method takes arguments in three different forms, depending on their number and type.

If the first argument is a reference then it must contain a "Protocol::IRC::Message" instance which will be sent directly:

   $irc->send_message( $message )

Otherwise, the first argument must be a plain string that gives the command name. If the second argument is a hash, it provides named arguments in a form similar to "new_from_named_args" in Protocol::IRC::Message, otherwise the remaining arguments must be the prefix string and other positional arguments, as plain strings:

   $irc->send_message( $command, { %args } )
   $irc->send_message( $command, $prefix, @args )

Named Argument Mangling

For symmetry with incoming message processing, this method applies some adjustment of named arguments for convenience of callers.

  • Callers may define a named argument of "target"; it will be renamed to "target_name".
  • If a named argument of "text" is defined and an "encoder" exists, the argument value will be encoded using this encoder.


   $irc->send_ctcp( $prefix, $target, $verb, $argstr )

Shortcut to sending a CTCP message. Sends a PRIVMSG to the given target, containing the given verb and argument string.


   $irc->send_ctcprely( $prefix, $target, $verb, $argstr )

Shortcut to sending a CTCP reply. As "send_ctcp" but using a NOTICE instead.


The following methods are controlled by the server information given in the "ISUPPORT" settings. They use the "isupport" required method to query the information required.


   $name_folded = $irc->casefold_name( $name )

Returns the $name, folded in case according to the server's "CASEMAPPING" "ISUPPORT". Such a folded name will compare using "eq" according to whether the server would consider it the same name.

Useful for use in hash keys or similar.


   $cmp = $irc->cmp_prefix_flags( $lhs, $rhs )

Compares two channel occupant prefix flags, and returns a signed integer to indicate which of them has higher priviledge, according to the server's ISUPPORT declaration. Suitable for use in a "sort()" function or similar.


   $cmp = $irc->cmp_prefix_modes( $lhs, $rhs )

Similar to "cmp_prefix_flags", but compares channel occupant "MODE" command flags.


   $flag = $irc->prefix_mode2flag( $mode )

Converts a channel occupant "MODE" flag (such as "o") into a name prefix flag (such as "@").


   $mode = $irc->prefix_flag2mode( $flag )

The inverse of "prefix_mode2flag".


   $classification = $irc->classify_name( $name )

Returns "channel" if the given name matches the pattern of names allowed for channels according to the server's "CHANTYPES" "ISUPPORT". Returns "user" if not.


   $me = $irc->is_nick_me( $nick )

Returns true if the given nick refers to that in use by the connection.


The following messages are handled internally by "Protocol::IRC".


"PING" messages are automatically replied to with "PONG".


Because "NOTICE" and "PRIVMSG" are so similar, they are handled together by synthesized events called "text", "ctcp" and "ctcpreply". Depending on the contents of the text, and whether it was supplied in a "PRIVMSG" or a "NOTICE", one of these three events will be created.

In all cases, the hints hash will contain a "is_notice" key being true or false, depending on whether the original messages was a "NOTICE" or a "PRIVMSG", a "target_name" key containing the message target name, a case-folded version of the name in a "target_name_folded" key, and a classification of the target type in a "target_type" key.

For the "user" target type, it will contain a boolean in "target_is_me" to indicate if the target of the message is the user represented by this connection.

For the "channel" target type, it will contain a "restriction" key containing the channel message restriction, if present.

For normal "text" messages, it will contain a key "text" containing the actual message text.

For either CTCP message type, it will contain keys "ctcp_verb" and "ctcp_args" with the parsed message. The "ctcp_verb" will contain the first space-separated token, and "ctcp_args" will be a string containing the rest of the line, otherwise unmodified. This type of message is also subject to a special stage of handler dispatch, involving the CTCP verb string. For messages with "VERB" as the verb, the following are tried. "CTCP" may stand for either "ctcp" or "ctcpreply".

A method called "on_message_CTCP_VERB"

 $irc->on_message_CTCP_VERB( $message, \%hints )
A method called "on_message_CTCP"

 $irc->on_message_CTCP( 'VERB', $message, \%hintss )
A method called "on_message"

 $irc->on_message( 'CTCP VERB', $message, \%hints )


As this class is an abstract base class, a concrete implementation must provide the following methods to complete it and make it useable.


   $irc->write( $string )

Requests the byte string to be sent to the peer


   $encoder = $irc->encoder

Optional. If supplied, returns an Encode object used to encode or decode the bytes appearing in a "text" field of a message. If set, all text strings will be returned, and should be given, as Unicode strings. They will be encoded or decoded using this object.


   $result = $irc->invoke( $name, @args )

Optional. If provided, invokes the message handling routine called $name with the given arguments. A default implementation is provided which simply attempts to invoke a method of the given name, or return false if no method of that name exists.

If an implementation does override this method, care should be taken to ensure that methods are tested for and invoked if present, in addition to any other work the method wishes to perform, as this is the basis by which derived message handling works.


   $value = $irc->isupport( $field )

Should return the value of the given "ISUPPORT" field.

As well as the all-capitals server-supplied fields, the following fields may be requested. Their names are all lowercase and contain underscores, to distinguish them from server-supplied fields.

The mode characters from "PREFIX" (e.g. "ohv")
The flag characters from "PREFIX" (e.g. "@%+")
A precompiled regexp that matches any of the prefix flags
A map from mode characters to flag characters
A map from flag characters to mode characters
A 4-element array containing the split portions of "CHANMODES";

 [ $listmodes, $argmodes, $argsetmodes, $boolmodes ]
A precompiled regexp that matches any string beginning with a channel prefix character in "CHANTYPES".


   $nick = $irc->nick

Should return the current nick in use by the connection.


   $nick_folded = $irc->nick_folded

Optional. If supplied, should return the current nick as case-folded by the "casefold_name" method. If not provided, this will be performed by case-folding the result from "nick".


Paul Evans <>

2021-01-08 perl v5.32.0