From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc2397.txt | 283 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 283 insertions(+) create mode 100644 doc/rfc/rfc2397.txt (limited to 'doc/rfc/rfc2397.txt') diff --git a/doc/rfc/rfc2397.txt b/doc/rfc/rfc2397.txt new file mode 100644 index 0000000..e9b1460 --- /dev/null +++ b/doc/rfc/rfc2397.txt @@ -0,0 +1,283 @@ + + + + + + +Network Working Group L. Masinter +Request for Comments: 2397 Xerox Corporation +Category: Standards Track August 1998 + + + The "data" URL scheme + +Status of this Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (1998). All Rights Reserved. + +1. Abstract + + A new URL scheme, "data", is defined. It allows inclusion of small + data items as "immediate" data, as if it had been included + externally. + +2. Description + + Some applications that use URLs also have a need to embed (small) + media type data directly inline. This document defines a new URL + scheme that would work like 'immediate addressing'. The URLs are of + the form: + + data:[][;base64], + + The is an Internet media type specification (with + optional parameters.) The appearance of ";base64" means that the data + is encoded as base64. Without ";base64", the data (as a sequence of + octets) is represented using ASCII encoding for octets inside the + range of safe URL characters and using the standard %xx hex encoding + of URLs for octets outside that range. If is omitted, it + defaults to text/plain;charset=US-ASCII. As a shorthand, + "text/plain" can be omitted but the charset parameter supplied. + + The "data:" URL scheme is only useful for short values. Note that + some applications that use URLs may impose a length limit; for + example, URLs embedded within anchors in HTML have a length limit + determined by the SGML declaration for HTML [RFC1866]. The LITLEN + (1024) limits the number of characters which can appear in a single + + + +Masinter Standards Track [Page 1] + +RFC 2397 The "data" URL scheme August 1998 + + + attribute value literal, the ATTSPLEN (2100) limits the sum of all + lengths of all attribute value specifications which appear in a tag, + and the TAGLEN (2100) limits the overall length of a tag. + + The "data" URL scheme has no relative URL forms. + +3. Syntax + + dataurl := "data:" [ mediatype ] [ ";base64" ] "," data + mediatype := [ type "/" subtype ] *( ";" parameter ) + data := *urlchar + parameter := attribute "=" value + + where "urlchar" is imported from [RFC2396], and "type", "subtype", + "attribute" and "value" are the corresponding tokens from [RFC2045], + represented using URL escaped encoding of [RFC2396] as necessary. + + Attribute values in [RFC2045] are allowed to be either represented as + tokens or as quoted strings. However, within a "data" URL, the + "quoted-string" representation would be awkward, since the quote mark + is itself not a valid urlchar. For this reason, parameter values + should use the URL Escaped encoding instead of quoted string if the + parameter values contain any "tspecial". + + The ";base64" extension is distinguishable from a content-type + parameter by the fact that it doesn't have a following "=" sign. + +4. Examples + + A data URL might be used for arbitrary types of data. The URL + + data:,A%20brief%20note + + encodes the text/plain string "A brief note", which might be useful + in a footnote link. + + The HTML fragment: + + Larry + + + + +Masinter Standards Track [Page 2] + +RFC 2397 The "data" URL scheme August 1998 + + + could be used for a small inline image in a HTML document. (The + embedded image is probably near the limit of utility. For anything + else larger, data URLs are likely to be inappropriate.) + + A data URL scheme's media type specification can include other + parameters; for example, one might specify a charset parameter. + + data:text/plain;charset=iso-8859-7,%be%fg%be + + can be used for a short sequence of greek characters. + + Some applications may use the "data" URL scheme in order to provide + setup parameters for other kinds of networking applications. For + example, one might create a media type + application/vnd-xxx-query + + whose content consists of a query string and a database identifier + for the "xxx" vendor's databases. A URL of the form: + + data:application/vnd-xxx- + query,select_vcount,fcol_from_fieldtable/local + + could then be used in a local application to launch the "helper" for + application/vnd-xxx-query and give it the immediate data included. + +5. History + + This idea was originally proposed August 1995. Some versions of the + data URL scheme have been used in the definition of VRML, and a + version has appeared as part of a proposal for embedded data in HTML. + Various changes have been made, based on requests, to elide the media + type, pack the indication of the base64 encoding more tightly, and + eliminate "quoted printable" as an encoding since it would not easily + yield valid URLs without additional %xx encoding, which itself is + sufficient. The "data" URL scheme is in use in VRML, new applications + of HTML, and various commercial products. It is being used for object + parameters in Java and ActiveX applications. + +6. Security + + Interpretation of the data within a "data" URL has the same security + considerations as any implementation of the given media type. An + application should not interpret the contents of a data URL which is + marked with a media type that has been disallowed for processing by + the application's configuration. + + + + + + +Masinter Standards Track [Page 3] + +RFC 2397 The "data" URL scheme August 1998 + + + Sites which use firewall proxies to disallow the retrieval of certain + media types (such as application script languages or types with known + security problems) will find it difficult to screen against the + inclusion of such types using the "data" URL scheme. However, they + should be aware of the threat and take whatever precautions are + considered necessary within their domain. + + The effect of using long "data" URLs in applications is currently + unknown; some software packages may exhibit unreasonable behavior + when confronted with data that exceeds its allocated buffer size. + +7. References + + [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, + "Uniform Resource Identifiers (URI): Generic Syntax", RFC + 2396, August 1998. + + [RFC1866] Berners-Lee, T., and D. Connolly, "Hypertext Markup + Language - 2.0.", RFC 1866, November 1995. + + [RFC2045] Freed N., and N. Borenstein., "Multipurpose Internet Mail + Extensions (MIME) Part One: Format of Internet Message + Bodies", RFC 2045, November 1996. + +Author contact information: + + Larry Masinter + Xerox Palo Alto Research Center + 3333 Coyote Hill Road + Palo Alto, CA 94304 + + EMail: masinter@parc.xerox.com + + + + + + + + + + + + + + + + + + + +Masinter Standards Track [Page 4] + +RFC 2397 The "data" URL scheme August 1998 + + +Full Copyright Statement + + Copyright (C) The Internet Society (1998). 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. + + + + + + + + + + + + + + + + + + + + + + + + +Masinter Standards Track [Page 5] + -- cgit v1.2.3