Applications Area WG (APPSAWG) L. Hunt, Ed. Internet-Draft Opera Software, ASA. Intended Status: Standards Track M. Yevstifeyev, Ed. Expires: April 19, 2012 October 17, 2011 The 'about' URI Scheme draft-ietf-appsawg-about-uri-scheme-00 Abstract This document defines the 'about' URI scheme, that is widely used by Web browsers and some other applications to designate access to their internal resources, such as settings, application information, hidden built-in functionality, and so on. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. 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 and License Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of Hunt & Yevstifeyev Expires April 19, 2012 [Page 1] INTERNET DRAFT The 'about' URI Scheme October 17, 2011 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. URI Scheme Specification . . . . . . . . . . . . . . . . . . . 3 2.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . . 3 2.2. URI Scheme Semantics . . . . . . . . . . . . . . . . . . . 3 2.2.1. Special-Purpose 'about' URIs . . . . . . . . . . . . . 3 2.2.2. Unrecognized 'about' URIs . . . . . . . . . . . . . . . 4 2.3. Encoding Considerations . . . . . . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 4.1. URI Scheme Registration . . . . . . . . . . . . . . . . . . 5 4.2. A Registry for SPTs . . . . . . . . . . . . . . . . . . . . 5 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Normative References . . . . . . . . . . . . . . . . . . . 6 5.2. Informative References . . . . . . . . . . . . . . . . . . 7 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction This document specifies the 'about' Uniform Resource Identifier (URI) scheme, that is currently widely used by Web browsers and some other applications to designate access to their internal resources, such as settings, application information, so called "Easter eggs" (i.e. hidden feature or joke in an application), and so on. The concept of 'about' URIs has been formed at the times when the applications did not have the "friendly" user interface, in order to provide an access to the aforementioned resources via typing the URIs in the address bar. Even though the user interface of current Internet-targeted software effectively rescinds the issue, and 'about' URIs can be thought to be a rudimentary phenomenon, they are still supported by a variety of Web browsers and are not going to cease to exist. As use of 'about' URIs has been quiet long-lasting, and the URIs have been used without any proper registration and absent any proper specification, the necessity for the the latter two actions arises. The purpose of this document is to provide a stable specification for 'about' URI scheme and correspondingly register it in the IANA registry. Along, several provisions for handling the 'about' URIs are set. Hunt & Yevstifeyev Expires April 19, 2012 [Page 2] INTERNET DRAFT The 'about' URI Scheme October 17, 2011 Please consult RFC 3986 [RFC3986] for definition of generic URIs syntax and RFC 4395 [RFC4395] for description of registration process for new URI schemes. 1.1. Terminology 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 RFC 2119 [RFC2119]. 2. URI Scheme Specification 2.1. URI Scheme Syntax The 'about' URI MUST syntactically conform to the rule below, expressed using Augmented Backus-Naur Form (ABNF) [RFC5234]: about-uri = "about:" about-token [ about-query ] about-token = segment about-query = "?" query segment = query = In terms of RFC 3986, part corresponds to , and to the query component of URI. 2.2. URI Scheme Semantics Generally speaking, the resource a particular 'about' URI resolves to is denoted by part of the URI, and specifies additional information concerning its handling and/or the information that should be returned in the resource a URI is resolved to. However, it is impossible to specify binding between all the possible tokens and the semantics of 'about' URIs that would contain such tokens. Therefore any application MAY resolve an 'about' URI to any desired resource, and MAY redirect such URIs. Several exceptions are defined, though; they are named "special-purpose 'about' URIs" and MUST be handled in strict accordance with provisions set in Section 2.2.1. 2.2.1. Special-Purpose 'about' URIs A small, though expandable, range of s are reserved for use in special-purpose 'about' URIs, abbreviated "SPU" (special- purpose URI). Such tokens are named "special-purpose 'about' URI tokens", and abbreviated "SPT" (special-purpose token). Hunt & Yevstifeyev Expires April 19, 2012 [Page 3] INTERNET DRAFT The 'about' URI Scheme October 17, 2011 An SPU is an 'about' URI containing one of the registered SPTs as the part. An SPU MUST be handled in strict accordance with the rules defined for SPT contained therein. The SPT specification MAY define additional provisions on handling of part in the corresponding SPU; by default, it MUST be ignored for the purpose of handling SPU. SPU MAY be defined to be unresolvable. This means that an application MUST NOT resolve it in some particular resource. Such SPUs may be used as placeholders, or in some other way. One pre-defined SPT is specified: the "blank" SPT. The URI MUST resolve to a blank page; this page need not necessarily contain no data, it should rather represent blank page. There is no additional handling of query component in URIs: both and shall resolve into the blank page. Additional SPTs may be defined via adding the entry in the registry created by this document. Please note that defining an SPT should only be used as a last resort approach, when a strict limitation on handling 'about' URI with such SPT is necessary. 2.2.2. Unrecognized 'about' URIs Naturally, an application will support only a particular range of 'about' URIs; also, some applications will support 'about' URIs that are not supported by an other one. This document specifies the rules for handling unrecognized 'about' URIs. An unrecognized 'about' URIs as a URI that may not be recognized by an application. (Correspondingly, such categorization is per- application, not per-fact.) An unrecognized 'about' URI SHOULD be handled as the URI, although other behavior is possible. 2.3. Encoding Considerations 'about' URIs are subject to encoding rules defined in RFC 3986 [RFC3986]. 'about' IRIs [RFC3987] are not permitted. 3. Security Considerations Generic security considerations for URIs are discussed in Section 7 of RFC 3986 [RFC3986]. However, many of those provisions hardly apply to 'about' URI scheme, as they are mainly scoped to schemes used in the Internet, not internally. Hunt & Yevstifeyev Expires April 19, 2012 [Page 4] INTERNET DRAFT The 'about' URI Scheme October 17, 2011 'about' URIs may sometimes refer to a sensitive information, such as user passwords stored in a cache, or parameter that, if changed, may affect user's data. The application should therefore ensure that user's data is in the safety, and no threats are imposed by 'about' URIs. 4. IANA Considerations 4.1. URI Scheme Registration IANA is asked to update the register the 'about' URI scheme using the following template, per [RFC4395]: URI scheme name: about Status: Permanent URI scheme syntax: see Section 2.1 of RFC xxxx URI scheme semantics: see Section 2.2 of RFC xxxx URI scheme encoding considerations: see Section 2.3 of RFC xxxx Applications/protocols that use the scheme: 'about' URIs are predominantly used by Web browsers, although they may be used by other applications. Security considerations: see Section 3 of RFC xxxx Contact: IESG Author/Change controller: IETF References: see Section 5 of RFC xxxx [RFC Editor: Please replace xxxx with assigned RFC number] 4.2. A Registry for SPTs IANA is asked to set up a new registry entitled "'about' URIs SPTs" following the guidelines below. The registry entries consist of 3 fields: SPT, Description and Reference. The SPT field MUST conform to production defined in Section 2.1. The initial registry contents consist of one entry: Hunt & Yevstifeyev Expires April 19, 2012 [Page 5] INTERNET DRAFT The 'about' URI Scheme October 17, 2011 +----------+----------------------------------------+-----------+ | SPT | Description | Reference | +----------+----------------------------------------+-----------+ | blank | Used in 'about' URIs referring to a | RFC xxxx | | | blank page. | | +----------+----------------------------------------+-----------+ The registration policy for new entries is "Specification Required", as defined in RFC 5226 [RFC5226]. Additionally, the following template MUST be provided by the registrant: o SPT: The desired special-purpose token to be used in 'about' URIs. o Intended usage: A short description of how 'about' URIs with the registered token must be handled; especially, what they must be resolved to, if resolvable. o Resolvable: "Yes" if resolvable (i.e. can be resolved to a particular resource) or "No" if unresolvable (see Section 2.2.1). o Handling query component: It should be mentioned whether there are some provisions on handling query components in the 'about' URIs with the registered token. o Contact/Change controller: An individual or an organization which (1) should be contacted for more details, and (2) is authorized to change the registration. o Published specifications: A reference to the published specification for the registered token. The following is a template for "blank" SPT: o SPT: blank o Intended usage: The URI must resolve to a blank page. o Resolvable: Yes. o Handling query component: No special provisions. o Contact/Change controller: IESG (on behalf of IETF). o Published specifications: This document. 5. References 5.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Hunt & Yevstifeyev Expires April 19, 2012 [Page 6] INTERNET DRAFT The 'about' URI Scheme October 17, 2011 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. 5.2. Informative References [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource Identifiers (IRIs)", RFC 3987, January 2005. [RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and Registration Procedures for New URI Schemes", BCP 35, RFC 4395, February 2006. Appendix A. Acknowledgments This document has been formed from the draft initially authored by, additionally to Lachlan Hunt, the editor of the current one, Joseph Holsten. Additionally, the contributions of are gratefully acknowledged. Authors' Addresses Lachlan Hunt (editor) Opera Software, ASA. EMail: lachlan.hunt@lachy.id.au URI: http://lachy.id.au/ Mykyta Yevstifeyev (editor) 8 Kuzovkov St., Apt. 25 Kotovsk Ukraine EMail: evnikita2@gmail.com Hunt & Yevstifeyev Expires April 19, 2012 [Page 7]