CTCP

CTCP , Client-to-client protocol - a special type of connection between clients using IRC (Internet Relay Chat) protocol.

CTCP is a widely used protocol used by today's largest IRC clients. CTCP extends the original IRC protocol, giving users the ability to access other clients or channels, allowing clients from the channel to respond via CTCP. In addition, CTCP can be used to encode messages that the original IRC protocol does not allow to transmit over the connection, like messages containing a line feed character or with a zero byte . CTCP does not establish a direct relationship between clients; however, DCC connections are typically used for two-way conversations.

CTCP, among other things, allows users to request the client software version (using the CTCP VERSION command), time ( CTCP TIME command) from the remote client, or receive information about the remote user ( CTCP USERINFO ). The protocol is also used to implement the group of / me commands ( CTCP ACTION command).

A CTCP message is implemented as PRIVMSG or NOTICE in cases where the first and last characters of the message have an ASCII value of 0x01. Characters not permitted by the IRC protocol are replaced by ESC sequences . As a standard, NOTICE does not generate another NOTICE message in response, CTCP messages are sent as PRIVMSG and the response is made by a NOTICE message instead of PRIVMSG .