INTERNET-DRAFT Simon Butcher Expires May 2004 Alien Internet Services November 2003 Uniform Resource Locator Schemes for Internet Relay Chat Entities <draft-butcher-irc-url-03.txt> Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. Distribution of this document is unlimited. Comments should be sent to the "irc-url" mailing list, specified at the end of this document. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document specifies two URL (Uniform Resource Locator) schemes, using the URI (Uniform Resource Indicator) names "irc" and "ircs", for the location of IRC (Internet Relay Chat) servers. These URLs allow for easy location of an IRC server, optionally also specifying an IRC channel to join or person to contact upon connection. S. Butcher Expires May 2004 [Page 1]
INTERNET-DRAFT URL Schemes for IRC November 2003 1. Introduction Since its introduction, Internet Relay Chat (IRC) has become widely known and used within the Internet Community as a real-time chat medium. IRC networks are steadily growing larger, not only with regards to the number of regular uses, but also the number of channels and servers required to support the demand. Due to the nature of IRC as a simple real-time chat service, it has been known to be used for a wide variety of uses such as software support, job interviews, and of course just for a casual chat. While IRC is progressing, the need for an appropriate Uniform Resource Locator (URL) scheme has become apparent. Applications for such a scheme would range quite widely, including IRC network server lists on a website, software support contact details, or even a meeting location with an e-mail including a specific IRC channel. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. In this document, the term "client" is defined as the IRC client software, and the term "user" is the end-user of that software. The term "entity" refers to an IRC entity such as a user, service, or channel. 2. URL Definition An IRC URL begins with either the Uniform Resource Identifiers (URIs) "irc" or "ircs", denoting normal and secured connections respectively. Normal sessions are via existing transport (such as in [RFC2812]), and secured sessions are the same, only via a secure transport layer such as [SSL], or with [TLS] negotiated. The URL scheme for IRC follows the Generic URL Syntax ([RFC2396]). The action the URL instigates is to open a connection to the specified IRC server using whatever protocol necessary, and make contact with the given user, service or channel. At the time of writing, only one protocol is defined to do this, as defined in RFC 2812. There is no requirement for IRC client software implementing the "irc" scheme to also implement the "ircs" scheme, and vice-versa. It is, however, RECOMMENDED that clients implementing "ircs" are also capable of handling a normal connection via "irc". S. Butcher Expires May 2004 [Page 2]
INTERNET-DRAFT URL Schemes for IRC November 2003 2.1. ABNF Syntax The following is the definition for an IRC URL in [ABNF] grammar: ircURL = ircURI "://" location "/" [ entity ] [ "?" options ] ircURI = "irc" / "ircs" ; See Section 2, above, for details. location = [ authinfo "@" ] hostport ; See Section 3.2.2 of [RFC2396] for the definition ; of 'hostport'. authinfo = [ username ] [ ":" password ] ; See Section 2.2 of this document for details. username = *( escaped / unreserved ) password = *( escaped / unreserved ) [ ";" passtype ] passtype = ; Reserved for future use. entity = [ entname ] [ "," enttype ] entname = [ "#" ] *( escaped / unreserved ) ; Note the prefix, "#", may be used for channel names ; without escapes. Please see Section 2.5.1. enttype = "isuser" / "ischan" options = "?" option *( "&" option ) option = optname [ "=" optvalue ] optname = *( ALPHA / "-" ) ; Option names are case-insensitive. optvalue = optparam *( "," optparam ) optparam = *( escaped / unreserved ) The definition of "escaped" and "unreserved" is in sections 2.4.1 and 2.3 of [RFC2396] respectively. Clients MUST be aware of protocol limitations. For example, "IRC-2", as specified in [RFC2812], disallows the space character (U+0020) in names as it is used as a parameter delimiter. S. Butcher Expires May 2004 [Page 3]
INTERNET-DRAFT URL Schemes for IRC November 2003 2.2. Authentication To allow for complete authentication of a session, a username MAY be provided with the password. The username MUST NOT be passed to the server as a nickname. For example, while registering a connection using the "IRC-2" protocol, the username would be passed as the first parameter of the "USER" command (See Section 3.1.3 of [RFC2812]). The characters available for use in a username may be restricted by the protocol used, and the IRC server software used. The use of the password field is not recommended, as it presents a significant security problem. Authors of IRC URLs using the authentication field, including a password, should make themselves aware of the security issues discussed in Section 6 of this document. See Section 3 for examples of username/password pair authentication, and traditional server password only authentication. 2.3. Server Names If the host name used is not a raw address (such as an IPv4, IPv6, or other network address), the name cannot be resolved (through DNS or other means), and does not contain a period character (code point U+002E), the client MAY consider the given host name as a network name to find an appropriate IRC server. As many modern IRC clients maintain lists of major IRC networks and their servers, this task should be trivial. 2.4. Server Ports Special consideration must be given to URLs without ports specified. Almost all IRC servers are contactable on a variety of standard ports as allocated by the IANA. Should an IRC URL be specified without a port, a client MAY try a number of standard ports: - For the "irc" URI, the client MAY attempt connection to the ports 6667, 194, 6665, 6666, 6668 and 6669, in that order. Port 194 is likely to be a more "authentic" server, however most IRC servers are available on ports 6667, at least. - For the "ircs" URI, it is RECOMMENDED that the default port used is 994. User-space ports (those above port 1023) may have questionable authenticity, and SHOULD NOT be used unless explicitly specified. S. Butcher Expires May 2004 [Page 4]
INTERNET-DRAFT URL Schemes for IRC November 2003 Port numbers shown are in decimal, and have been assigned by the IANA. Section 3.2.2 of [RFC2396] suggests only one port may be used as a default port, and does not state a preference for or against port hunting. The act of port hunting for the "irc" scheme when no port is specified is therefore left up to the discretion of client authors. For URL equivalency, clients SHOULD only consider well-known ports (those below port 1024). For example, <irc://foo/> and <irc://foo:194/> should be considered equivalent, as should <ircs://foo/> and <ircs://foo:994/>. 2.5. Entity Names Only one entity may be named per URL. The named entity SHOULD be presumed to be a channel name, unless the "enttype" section (see Section 2.1) of the URL is provided to determine the entity type. An automated message MUST NOT be sent to the entity. 2.5.1. Channel Names When "enttype" contains "ischan", or "enttype" is omitted completely, the entity name provided is a channel name. While it is discouraged, channel names prefixed with the "#" (U+0023) character may be specified without encoding the character (as "%23") in the URL. Implementers MAY accept this, despite it being an exception to Section 2.4.3 of [RFC2396], because channels of this type are currently very common, and will remain so in the foreseeable future. Clients SHOULD attempt to determine valid channel name prefix characters from the server it has connected to, such as via an "RPL_ISUPPORT" reply. If the client is unable to determine valid prefix characters for the server it is connected to, the client SHOULD attempt to join the channel without modifying its name. If joining the channel failed, the prefix character "#" may be used. S. Butcher Expires May 2004 [Page 5]
INTERNET-DRAFT URL Schemes for IRC November 2003 If the client discovers the channel name given is considered to be invalid because it is missing a valid prefix character, the client SHOULD prepend a default prefix character to the name. Since default prefix characters for channels may differ between IRC servers, the client SHOULD try to determine the default channel prefix for the server it is connected to, such as the first prefix character given by "CHANTYPES" in "RPL_ISUPPORT". If the client is still unable to determine a prefix character, a prefix character of '#' (U+0023) MAY be presumed. 2.5.2. Nicknames When "enttype" contains "isuser", the entity given refers to a user. The given entity name may simply be a nickname, or it may contain more specific information such as the user's hostname, username, or a server they often use. A user entity is referred to using the following syntax (in [ABNF] grammar): userent = nickhost / userhost nickhost = nickname [ "%21" username "%40" hostname ] userhost = username ( unhost / unserver / ( unhost unserver ) ) unhost = "%25" hostname unserver = "%40" server The definitions of "nickname", "username", "hostname" and "server" are all identical to the definition of "entname", defined in Section 2.1 of this document. Note that the above form is compatible with the target for the "PRIVMSG" command, defined in Section 3.3.1 of [RFC2812]. S. Butcher Expires May 2004 [Page 6]
INTERNET-DRAFT URL Schemes for IRC November 2003 2.6. Additional Options Additional options may be added to control what action the client software may take following connection to the IRC server. Unsupported options MUST be ignored by the client. The client author is not obligated to utilise the "options" section (see Section 2.1) of the URL, but it is RECOMMENDED to do so. These options listed here may be expanded on at a later date by future documents. 2.6.1. The "key" Option This option is only valid if the entity name given is a channel name. If the entity name is not a channel name, then this option MUST simply be ignored. The option's value provides a "key" to be given to the server when joining the given channel name, and is used for channels which require a "key" to join them. If a channel key is found to be required and one is not provided with this option, the IRC client may wish to prompt the user for the key. Please see Section 6 of this document. 3. Examples While examples of every situation cannot be shown here because of space considerations, the following examples provide a rough overview of how the IRC URL can be used. <irc://irc.undernet.org/> In its simplest form, the above complete URL can be used to direct a client to a specific IRC server, which in this case is "irc.undernet.org". The client should presume to use default port settings. <irc://%C4%B0dil:g%C3%BCzel@irc.austnet.org/> This shows a properly [UTF-8] encoded URL, specifying the username "Idil" (with the first character being a Turkish Latin capital letter "I" with a dot above it, [Unicode] codepoint U+0130) and the password "guzel" (with a diaeresis on the u, codepoint U+00FC). S. Butcher Expires May 2004 [Page 7]
INTERNET-DRAFT URL Schemes for IRC November 2003 <irc://:pass@irc.efnet.org:6667/> The above URL specifies that the IRC client should try to connect to "irc.efnet.org" on the port 6667, rather than use whatever is considered the default. It also tells the IRC client it should try to connect to the server using the server password "pass". <irc://irc.ircnet.net/#worldchat,ischan> <irc://irc.ircnet.net/%23worldchat,ischan> <irc://irc.ircnet.net/#worldchat> <irc://irc.ircnet.net/%23worldchat> All four of these URLs connects to the IRCnet network, and will join the client to the channel "#worldchat" upon connection. Notice the use without the "ischan" keyword, where the entity type is presumed to be a channel. <irc://irc.alien.net.au/pickle,isuser> This will connect to the server "irc.alien.net.au" and will provoke the client to open up a window (or similar) associated with sending messages to the nickname 'pickle'. <irc://irc.austnet.org/%23foobar?key=bazqux> This will connect to AUSTnet and join the channel "#foobar", using the channel key "bazqux". <irc://undernet/pickle%25butcher.id.au,isuser> This will open a dialogue box prepared to send a message to "pickle%butcher.id.au". Please refer to Section 3.3.1 of [RFC2812] for more details on what this means. This URL will connect to the network named as "undernet". For this to work correctly, the client must be configured appropriately to know of at least one associated with this name. S. Butcher Expires May 2004 [Page 8]
INTERNET-DRAFT URL Schemes for IRC November 2003 4. Internationalisation Considerations With the inevitable adoption of [Unicode] on IRC, and indeed the Internet as a whole, URLs MUST be encoded using the [UTF-8] character set, with (potentially) unsafe octets encoded using %HH notation (where HH is a hexadecimal value), as per Section 2.2.5 of [RFC-2718]. An example of this in action can be found in Section 3. Some IRC servers use such character sets as US-ASCII and KOI-8. It is left up to the client and the server to negotiate an appropriate character set for communication between the two, as more servers are implementing specific character-set preferences. It is also left up to the client to convert entity names from UTF-8 into the appropriate character set. At the time of writing, [UTF-8] is set to become the popular choice (announced via RPL_ISUPPORT) as it's easy to implement with very minimal changes to existing server software. Other IRC servers are opting to announce a preferred character set, but allow the client to switch character sets on the fly, using CAP/CAPAB negotiation, oft implemented using the UNIX98 iconv() (or similar) function. The latter appears destined to be the future, as it appears at the time of writing. 5. Interoperability Considerations Many existing implementations fail to acknowledge the correct use of the generic URL syntax defined in [RFC2396], but continue to use the format regardless. Some current implementations will need slight modification to accept the extended format defined in this specification, however most implementations which parse the URL in a standard form will continue to work for most simple IRC URLs. The presumption of a channel name without explicitly specifying the entity type is designed to maintain compatibility with the existing implementations. The practise of omitting the channel prefix character, or not encoding it, is also for compatibility, but is strongly discouraged. There are interoperability issues with existing IRC servers as a result of the restricted characters available for channel names and nicknames. The restriction of acceptable characters has been left up to the IRC server authors and not the URL scheme, in order to allow for advances in IRC protocols and servers. S. Butcher Expires May 2004 [Page 9]
INTERNET-DRAFT URL Schemes for IRC November 2003 6. Security Considerations Security problems naturally arise when a server password and/or a channel key is specified (using the "key" option). While the use of the password/key extensions is considered to be rare, they have been included for use in shortcut/bookmark lists, or when the URL is used as a user command. As the passwords and channel keys are unfortunately passed as clear text, any user using the IRC URL should be aware of obvious insecurities. It is strongly discouraged to use these fields in a public sense, such as on a website. Furthermore, it is recommended that user software does not automatically initiate the connection specified by the URL without the knowledge and consent of the user. To do so would open the implementation up to a variety of malicious activities including, but not limited to, the purposes of direct advertising or channel advertising (known as "spam") via "pop-ups" or other means. When connecting using a secure connection ("ircs://"), user-space ports (those above port 1023) should be treated with suspicion, as their authority could be questionable. If a secure connection cannot be established, the client MUST NOT automatically default to an insecure ("irc://") connection. To do so would denigrate the "ircs" scheme and restrict its usefulness. Automated messages MUST NOT be sent to any entity upon connection to an IRC server as a direct result of execution of an IRC URL. Sending messages to channels and other users should be left up to the user, not the URL author or the client software. The facility to send automated messages to other users has been explicitly avoided in this document to avoid abuse, common with IRC. Beyond this, there are security concerns with regards with associated protocols, including the IRC server-to-user protocols themselves, [TLS] and [UTF-8], which must be taken into consideration, but are beyond the scope of this document. S. Butcher Expires May 2004 [Page 10]
INTERNET-DRAFT URL Schemes for IRC November 2003 7. IANA Considerations The following is registration for the URL schemes as per [RFC2717]: URL scheme name: Two URI's are described herein: "irc" and "ircs". URL scheme syntax: See Section 2.1, and indeed Section 2 as a whole. Character encoding considerations: Characters must be encoded in UTF-8 and escaped. See Section 4. Intended usage: The scheme initiates connection to an IRC server, normally through the execution of IRC Client software. Further- more, the scheme may then initiate further commands, such as joining channels, as outlined above. Interoperability considerations: See Section 5. Security considerations: See Section 6. Relevant publications: The IRC protocol is defined by [RFC2812]. Either [SSL] or [TLS] may be used for the "ircs" scheme, depending on client and server configuration. Person & email address to contact for further information: The Author; See Section 10 for details. Author/Change controller: The Author's details are contained within Section 10. The IETF is to maintain change control. 8. Acknowledgments I acknowledge the previous work of Mandar Mirashi who originally wrote an Internet-Draft to similar effect. The input of Petr Baudis, Robert Ginda, Piotr Kucharski, Perry Lorier, Khaled Mardam-Bey, Dominick Meglio, and Samuel Sieb, was greatly appreciated, and this draft would not exist without their valued participation. I would also like to acknowledge those members of the IRC development community who encouraged me to publish this document, after more than 18 months of pretermission. S. Butcher Expires May 2004 [Page 11]
INTERNET-DRAFT URL Schemes for IRC November 2003 9. References [ABNF] Crocker, D., and Overell, P., "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [PICS] Miller, J., Resnick, P., Singer, D., "Rating Services and Rating Systems (and Their Machine Readable Descriptions)", Version 1.1, <http://www.w3.org/TR/REC-PICS-services>, October 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2368] Hoffman, P., Masinter, L., Zawinski, J., "The mailto URL scheme", RFC 2368, July 1998. [RFC2396] Berners-Lee, T, Fielding, T., Masinter, L., "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [RFC2717] Petke, R., King, I., "Registration Procedures for URL Scheme Names", RFC 2717, November 1999. [RFC2718] Masinter, L., Alvestrand, H., Zigmond, D., Petke, R., "Guidelines for new URL Schemes", RFC 2718, November 1999. [RFC2811] Kalt, C., "Internet Relay Chat: Channel Management", RFC 2811, April 2000. [RFC2812] Kalt, C., "Internet Relay Chat: Client Protocol", RFC 2812, April 2000. [SSL] Hickman, K., "The SSL Protocol", Netscape Communications Corp., February 9, 1995. [TLS] Dierks, T. and Allen, C., "The TLS Protocol Version 1.0", RFC 2246, January 1999. [Unicode] The Unicode Consortium. The Unicode Standard, Version 4.0.0, (Reading, MA, Addison-Wesley, 2003. ISBN 0-321-18578-1). [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC 2279, January 1998. S. Butcher Expires May 2004 [Page 12]
INTERNET-DRAFT URL Schemes for IRC November 2003 10. Author's Address Simon Butcher Alien Internet Services PO Box 7041 Croydon South VIC 3136 Australia Phone: +61-3-9879-8052 Fax: +61-3-9893-2793 Email: simonb@alien.net.au simon@butcher.name simon@butcher.id.au 11. Intellectual Property Rights Notice The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. S. Butcher Expires May 2004 [Page 13]
INTERNET-DRAFT URL Schemes for IRC November 2003 12. Full Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Document Discussion Forum Discussion for this document is currently taking place using the "irc-url@alien.net.au" mailing list in order to keep discussion open and archived appropriately. Those interested in this document are strongly encouraged to join in on the discussion. To subscribe to the mailing list, see: <http://alien.net.au/mailman/listinfo/irc-url_alien.net.au> Archives of the mailing list are available at: <http://alien.net.au/pipermail/irc-url_alien.net.au> Document Expiration and Filename Please note that this is a draft document and it shall expire May 2004. Its filename is draft-butcher-irc-url-03.txt S. Butcher Expires May 2004 [Page 14]