Internet DRAFT - draft-ietf-httpbis-rfc5987bis
draft-ietf-httpbis-rfc5987bis
HTTP Working Group J. Reschke
Internet-Draft greenbytes
Obsoletes: 5987 (if approved) March 2, 2017
Intended status: Standards Track
Expires: September 3, 2017
Indicating Character Encoding and Language for HTTP Header Field
Parameters
draft-ietf-httpbis-rfc5987bis-05
Abstract
By default, header field values in Hypertext Transfer Protocol (HTTP)
messages cannot easily carry characters outside the US-ASCII coded
character set. RFC 2231 defines an encoding mechanism for use in
parameters inside Multipurpose Internet Mail Extensions (MIME) header
field values. This document specifies an encoding suitable for use
in HTTP header fields that is compatible with a simplified profile of
the encoding defined in RFC 2231.
This document obsoletes RFC 5987.
Editorial Note (To be removed by RFC Editor before publication)
Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at
<https://lists.w3.org/Archives/Public/ietf-http-wg/>.
Working Group information can be found at <http://httpwg.github.io/>;
source code and issues list for this draft can be found at
<https://github.com/httpwg/http-extensions>.
The changes in this draft are summarized in Appendix C.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 3, 2017.
Copyright Notice
Copyright (c) 2017 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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 4
3. Comparison to RFC 2231 and Definition of the Encoding . . . . 5
3.1. Parameter Continuations . . . . . . . . . . . . . . . . . 5
3.2. Parameter Value Character Encoding and Language
Information . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.1. Definition . . . . . . . . . . . . . . . . . . . . . . 6
3.2.2. Historical Notes . . . . . . . . . . . . . . . . . . . 7
3.2.3. Examples . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. Language Specification in Encoded Words . . . . . . . . . 8
4. Guidelines for Usage in HTTP Header Field Definitions . . . . 9
4.1. When to Use the Extension . . . . . . . . . . . . . . . . 9
4.2. Error Handling . . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Normative References . . . . . . . . . . . . . . . . . . . 11
7.2. Informative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Changes from RFC 5987 . . . . . . . . . . . . . . . . 13
Appendix B. Implementation Report . . . . . . . . . . . . . . . . 14
Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 14
C.1. Since RFC5987 . . . . . . . . . . . . . . . . . . . . . . 15
C.2. Since draft-reschke-rfc5987bis-00 . . . . . . . . . . . . 15
C.3. Since draft-reschke-rfc5987bis-01 . . . . . . . . . . . . 15
C.4. Since draft-reschke-rfc5987bis-02 . . . . . . . . . . . . 15
C.5. Since draft-reschke-rfc5987bis-03 . . . . . . . . . . . . 15
C.6. Since draft-reschke-rfc5987bis-04 . . . . . . . . . . . . 15
C.7. Since draft-reschke-rfc5987bis-05 . . . . . . . . . . . . 15
C.8. Since draft-reschke-rfc5987bis-06 . . . . . . . . . . . . 15
C.9. Since draft-ietf-httpbis-rfc5987bis-00 . . . . . . . . . . 15
C.10. Since draft-ietf-httpbis-rfc5987bis-01 . . . . . . . . . . 15
C.11. Since draft-ietf-httpbis-rfc5987bis-02 . . . . . . . . . . 16
C.12. Since draft-ietf-httpbis-rfc5987bis-03 . . . . . . . . . . 16
C.13. Since draft-ietf-httpbis-rfc5987bis-04 . . . . . . . . . . 16
Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 16
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1. Introduction
Use of characters outside the US-ASCII coded character set
([RFC0020]) in HTTP header fields ([RFC7230]) is non-trivial:
o The HTTP specification discourages use of non-US-ASCII characters
in field values, placing them into the "obs-text" ABNF production
([RFC7230], Section 3.2).
o Furthermore, it stays silent about default character encoding
schemes for field values, so any use of non-US-ASCII characters
would need to be specific to the field definition, or would
require some other kind of out-of-band information.
o Finally, some APIs assume a default character encoding scheme in
order to map from the octet sequences (obtained from the HTTP
message) to character sequences: for instance, the XMLHttpRequest
API ([XMLHttpRequest]) uses the Interface Definition Language type
"ByteString", effectively resulting in the ISO-8859-1 character
encoding scheme [ISO-8859-1] being used.
On the other hand, RFC 2231 defines an encoding mechanism for
parameters inside MIME header fields ([RFC2231]), which, as opposed
to HTTP messages, do need to be sent over non-binary transports.
This document specifies an encoding suitable for use in HTTP header
fields that is compatible with a simplified profile of the encoding
defined in RFC 2231. It can be applied to any HTTP header field that
uses the common "parameter" ("name=value") syntax.
This document obsoletes [RFC5987] and moves it to "historic" status;
the changes are summarized in Appendix A.
Note: in the remainder of this document, RFC 2231 is only
referenced for the purpose of explaining the choice of features
that were adopted; they are therefore purely informative.
Note: this encoding does not apply to message payloads transmitted
over HTTP, such as when using the media type "multipart/form-data"
([RFC7578]).
2. Notational Conventions
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].
This specification uses the ABNF (Augmented Backus-Naur Form)
notation defined in [RFC5234]. The following core rules are included
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by reference, as defined in [RFC5234], Appendix B.1: ALPHA (letters),
DIGIT (decimal 0-9), HEXDIG (hexadecimal 0-9/A-F/a-f), and LWSP
(linear whitespace).
This specification uses terminology defined in [RFC6365], namely:
"character encoding scheme" (below abbreviated to "character
encoding"), "charset" and "coded character set".
Note that this differs from RFC 2231, which uses the term "character
set" for "character encoding scheme".
3. Comparison to RFC 2231 and Definition of the Encoding
RFC 2231 defines several extensions to MIME. The sections below
discuss if and how they apply to HTTP header fields.
In short:
o Parameter Continuations aren't needed (Section 3.1),
o Character Encoding and Language Information are useful, therefore
a simple subset is specified (Section 3.2), and
o Language Specifications in Encoded Words aren't needed
(Section 3.3).
3.1. Parameter Continuations
Section 3 of [RFC2231] defines a mechanism that deals with the length
limitations that apply to MIME headers. These limitations do not
apply to HTTP ([RFC7231], Appendix A.6).
Thus, parameter continuations are not part of the encoding defined by
this specification.
3.2. Parameter Value Character Encoding and Language Information
Section 4 of [RFC2231] specifies how to embed language information
into parameter values, and also how to encode non-ASCII characters,
dealing with restrictions both in MIME and HTTP header field
parameters.
However, RFC 2231 does not specify a mandatory-to-implement character
encoding, making it hard for senders to decide which encoding to use.
Thus, recipients implementing this specification MUST support the
"UTF-8" character encoding [RFC3629].
Furthermore, RFC 2231 allows the character encoding information to be
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left out. The encoding defined by this specification does not allow
that.
3.2.1. Definition
The presence of extended parameter values usually is indicated by a
parameter name ending in an asterisk character. Note however that
this is just a convention, and that it needs to be explicitly
specified in the definition of the header field using this extension
(see Section 4).
The ABNF for extended parameter values is specified below:
ext-value = charset "'" [ language ] "'" value-chars
; like RFC 2231's <extended-initial-value>
; (see [RFC2231], Section 7)
charset = "UTF-8" / mime-charset
mime-charset = 1*mime-charsetc
mime-charsetc = ALPHA / DIGIT
/ "!" / "#" / "$" / "%" / "&"
/ "+" / "-" / "^" / "_" / "`"
/ "{" / "}" / "~"
; as <mime-charset> in Section 2.3 of [RFC2978]
; except that the single quote is not included
; SHOULD be registered in the IANA charset registry
language = <Language-Tag, see [RFC5646], Section 2.1>
value-chars = *( pct-encoded / attr-char )
pct-encoded = "%" HEXDIG HEXDIG
; see [RFC3986], Section 2.1
attr-char = ALPHA / DIGIT
/ "!" / "#" / "$" / "&" / "+" / "-" / "."
/ "^" / "_" / "`" / "|" / "~"
; token except ( "*" / "'" / "%" )
The value part of an extended parameter (ext-value) is a token that
consists of three parts:
1. the REQUIRED character encoding name (charset),
2. the OPTIONAL language information (language), and
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3. a character sequence representing the actual value (value-chars),
separated by single quote characters.
Note that both character encoding names and language tags are
restricted to the US-ASCII coded character set, and are matched case-
insensitively (see [RFC2978], Section 2.3 and [RFC5646], Section
2.1.1).
Inside the value part, characters not contained in attr-char are
encoded into an octet sequence using the specified character
encoding. That octet sequence is then percent-encoded as specified
in Section 2.1 of [RFC3986].
Producers MUST use the "UTF-8" ([RFC3629]) character encoding.
Extension character encodings (mime-charset) are reserved for future
use.
Note: recipients should be prepared to handle encoding errors,
such as malformed or incomplete percent escape sequences, or non-
decodable octet sequences, in a robust manner. This specification
does not mandate any specific behavior, for instance, the
following strategies are all acceptable:
* ignoring the parameter,
* stripping a non-decodable octet sequence,
* substituting a non-decodable octet sequence by a replacement
character, such as the Unicode character U+FFFD (Replacement
Character).
3.2.2. Historical Notes
The RFC 7230 token production ([RFC7230], Section 3.2.6) differs from
the production used in RFC 2231 (imported from Section 5.1 of
[RFC2045]) in that curly braces ("{" and "}") are excluded. Thus,
these two characters are excluded from the attr-char production as
well.
The <mime-charset> ABNF defined here differs from the one in Section
2.3 of [RFC2978] in that it does not allow the single quote character
(see also RFC Errata ID 1912 [Err1912]). In practice, no character
encoding names using that character have been registered at the time
of this writing.
For backwards compatibility with RFC 2231, the encoding defined by
this specification deviates from common parameter syntax in that the
quoted-string notation is not allowed. Implementations using generic
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parser components might not be able to detect the use of quoted-
string notation and thus might accept that format, although invalid,
as well.
[RFC5987] did require support for ISO-8859-1 ([ISO-8859-1]), too; for
compatibility with legacy code, recipients are encouraged to support
this encoding as well.
3.2.3. Examples
Non-extended notation, using "token":
foo: bar; title=Economy
Non-extended notation, using "quoted-string":
foo: bar; title="US-$ rates"
Extended notation, using the Unicode character U+00A3 ("£", POUND
SIGN):
foo: bar; title*=utf-8'en'%C2%A3%20rates
Note: the Unicode pound sign character U+00A3 was encoded into the
octet sequence C2 A3 using the UTF-8 character encoding, then
percent-encoded. Also, note that the space character was encoded as
%20, as it is not contained in attr-char.
Extended notation, using the Unicode characters U+00A3 ("£", POUND
SIGN) and U+20AC ("€", EURO SIGN):
foo: bar; title*=UTF-8''%c2%a3%20and%20%e2%82%ac%20rates
Note: the Unicode pound sign character U+00A3 was encoded into the
octet sequence C2 A3 using the UTF-8 character encoding, then
percent-encoded. Likewise, the Unicode euro sign character U+20AC
was encoded into the octet sequence E2 82 AC, then percent-encoded.
Also note that HEXDIG allows both lowercase and uppercase characters,
so recipients must understand both, and that the language information
is optional, while the character encoding is not.
3.3. Language Specification in Encoded Words
Section 5 of [RFC2231] extends the encoding defined in [RFC2047] to
also support language specification in encoded words. RFC 2616, the
now-obsolete HTTP/1.1 specification, did refer to RFC 2047
([RFC2616], Section 2.2). However, it wasn't clear to which header
field it applied. Consequently, the current revision of the HTTP/1.1
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specification has deprecated use of the encoding forms defined in RFC
2047 (see Section 3.2.4 of [RFC7230]).
Thus, this specification does not include this feature.
4. Guidelines for Usage in HTTP Header Field Definitions
Specifications of HTTP header fields that use the extensions defined
in Section 3.2 ought to clearly state that. A simple way to achieve
this is to normatively reference this specification, and to include
the ext-value production into the ABNF for specific header field
parameters.
For instance:
foo = token ";" LWSP title-param
title-param = "title" LWSP "=" LWSP value
/ "title*" LWSP "=" LWSP ext-value
ext-value = <see draft-ietf-httpbis-rfc5987bis, Section 3.2>
[[pub: Upon publication as RFC, the string
"draft-ietf-httpbis-rfc5987bis" needs to be replaced with the RFC
name, and this comment needs to be removed.]]
Note: The Parameter Value Continuation feature defined in Section
3 of [RFC2231] makes it impossible to have multiple instances of
extended parameters with identical names, as the processing of
continuations would become ambiguous. Thus, specifications using
this extension are advised to disallow this case for compatibility
with RFC 2231.
Note: This specification does not automatically assign a new
interpretation to parameter names ending in an asterisk. As
pointed out above, it's up to the specification for the non-
extended parameter to "opt in" to the syntax defined here. That
being said, some existing implementations are known to
automatically switch to the use of this notation when a parameter
name ends with an asterisk, thus using parameter names ending in
an asterisk for something else is likely to cause interoperability
problems.
4.1. When to Use the Extension
Section 4.2 of [RFC2277] requires that protocol elements containing
human-readable text are able to carry language information. Thus,
the ext-value production ought to be always used when the parameter
value is of textual nature and its language is known.
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Furthermore, the extension ought to also be used whenever the
parameter value needs to carry characters not present in the US-ASCII
([RFC0020]) coded character set (note that it would be unacceptable
to define a new parameter that would be restricted to a subset of the
Unicode character set).
4.2. Error Handling
Header field specifications need to define whether multiple instances
of parameters with identical names are allowed, and how they should
be processed. This specification suggests that a parameter using the
extended syntax takes precedence. This would allow producers to use
both formats without breaking recipients that do not understand the
extended syntax yet.
Example:
foo: bar; title="EURO exchange rates";
title*=utf-8''%e2%82%ac%20exchange%20rates
In this case, the sender provides an ASCII version of the title for
legacy recipients, but also includes an internationalized version for
recipients understanding this specification -- the latter obviously
ought to prefer the new syntax over the old one.
5. Security Considerations
The format described in this document makes it possible to transport
non-ASCII characters, and thus enables character "spoofing"
scenarios, in which a displayed value appears to be something other
than it is.
Furthermore, there are known attack scenarios relating to decoding
UTF-8.
See Section 10 of [RFC3629] for more information on both topics.
In addition, the extension specified in this document makes it
possible to transport multiple language variants for a single
parameter, and such use might allow spoofing attacks, where different
language versions of the same parameter are not equivalent. Whether
this attack is useful as an attack depends on the parameter
specified.
6. IANA Considerations
There are no IANA Considerations related to this specification.
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7. References
7.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange",
STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969,
<http://www.rfc-editor.org/info/rfc20>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2978] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 19, RFC 2978, DOI 10.17487/
RFC2978, October 2000,
<http://www.rfc-editor.org/info/rfc2978>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629,
November 2003,
<http://www.rfc-editor.org/info/rfc3629>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter,
"Uniform Resource Identifier (URI): Generic
Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986,
January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for
Identifying Languages", BCP 47, RFC 5646,
DOI 10.17487/RFC5646, September 2009,
<http://www.rfc-editor.org/info/rfc5646>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Message Syntax and
Routing", RFC 7230, DOI 10.17487/RFC7230,
June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and
Content", RFC 7231, DOI 10.17487/RFC7231,
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June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
7.2. Informative References
[Err1912] RFC Errata, "Errata ID 1912, RFC 2978",
October 2009, <http://www.rfc-editor.org>.
[ISO-8859-1] International Organization for Standardization,
"Information technology -- 8-bit single-byte coded
graphic character sets -- Part 1: Latin alphabet
No. 1", ISO/IEC 8859-1:1998, 1998.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet
Mail Extensions (MIME) Part One: Format of Internet
Message Bodies", RFC 2045, DOI 10.17487/RFC2045,
November 1996,
<http://www.rfc-editor.org/info/rfc2045>.
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail
Extensions) Part Three: Message Header Extensions
for Non-ASCII Text", RFC 2047, DOI 10.17487/
RFC2047, November 1996,
<http://www.rfc-editor.org/info/rfc2047>.
[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and
Encoded Word Extensions: Character Sets, Languages,
and Continuations", RFC 2231, DOI 10.17487/RFC2231,
November 1997,
<http://www.rfc-editor.org/info/rfc2231>.
[RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277,
January 1998,
<http://www.rfc-editor.org/info/rfc2277>.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee,
"Hypertext Transfer Protocol -- HTTP/1.1",
RFC 2616, DOI 10.17487/RFC2616, June 1999,
<http://www.rfc-editor.org/info/rfc2616>.
[RFC5987] Reschke, J., "Character Set and Language Encoding
for Hypertext Transfer Protocol (HTTP) Header Field
Parameters", RFC 5987, DOI 10.17487/RFC5987,
August 2010,
<http://www.rfc-editor.org/info/rfc5987>.
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[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
DOI 10.17487/RFC5988, October 2010,
<http://www.rfc-editor.org/info/rfc5988>.
[RFC6266] Reschke, J., "Use of the Content-Disposition Header
Field in the Hypertext Transfer Protocol (HTTP)",
RFC 6266, DOI 10.17487/RFC6266, June 2011,
<http://www.rfc-editor.org/info/rfc6266>.
[RFC6365] Hoffman, P. and J. Klensin, "Terminology Used in
Internationalization in the IETF", BCP 166,
RFC 6365, DOI 10.17487/RFC6365, September 2011,
<http://www.rfc-editor.org/info/rfc6365>.
[RFC7578] Masinter, L., "Returning Values from Forms:
multipart/form-data", RFC 7578, DOI 10.17487/
RFC7578, July 2015,
<http://www.rfc-editor.org/info/rfc7578>.
[RFC7616] Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer,
"HTTP Digest Access Authentication", RFC 7616,
DOI 10.17487/RFC7616, September 2015,
<http://www.rfc-editor.org/info/rfc7616>.
[RFC8053] Oiwa, Y., Watanabe, H., Takagi, H., Maeda, K.,
Hayashi, T., and Y. Ioku, "HTTP Authentication
Extensions for Interactive Clients", RFC 8053,
DOI 10.17487/RFC8053, January 2017,
<http://www.rfc-editor.org/info/rfc8053>.
[XMLHttpRequest] WhatWG, "XMLHttpRequest",
<https://xhr.spec.whatwg.org/>.
Appendix A. Changes from RFC 5987
This section summarizes the changes compared to [RFC5987]:
o The document title was changed to "Indicating Character Encoding
and Language for HTTP Header Field Parameters".
o The introduction was rewritten to better explain the issues around
non-ASCII characters in field values.
o The requirement to support the "ISO-8859-1" encoding was removed.
o The document does not attempt to re-define a generic "parameter"
ABNF anymore (it turned out that there really isn't a generic
definition of parameters in HTTP; for instance, there are subtle
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differences with respect to whitespace handling).
o A note about defects in error handling in current implementations
was removed, as it wasn't accurate anymore.
Appendix B. Implementation Report
The encoding defined in this document currently is used in four
different HTTP header fields:
o "Authentication-Control", defined in [RFC8053],
o "Authorization" (as used in HTTP Digest Authentication, defined in
[RFC7616]),
o "Content-Disposition", defined in [RFC6266], and
o "Link", defined in [RFC5988].
As the encoding is a profile/clarification of the one defined in
[RFC2231] in 1997, many user agents already supported it for use in
"Content-Disposition" when [RFC5987] got published.
Since the publication of [RFC5987], three more popular desktop user
agents have added support for this encoding; see <http://purl.org/
NET/http/content-disposition-tests#encoding-2231-char> for details.
At this time, the current versions of all major desktop user agents
support it.
Note that the implementation in Internet Explorer 9 does not support
the ISO-8859-1 character encoding; this document revision
acknowledges that UTF-8 is sufficient for expressing all code points,
and removes the requirement to support ISO-8859-1.
The "Link" header field, on the other hand, was more recently
specified in [RFC5988]. At the time of this writing, no User Agent
except Firefox supported the "title*" parameter (starting with
release 15).
Section 3.4 of [RFC7616] defines the "username*" parameter for use in
HTTP Digest Authentication. At the time of writing, no User Agent
implemented this extension.
Appendix C. Change Log (to be removed by RFC Editor before publication)
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C.1. Since RFC5987
Only editorial changes for the purpose of starting the revision
process (obs5987).
C.2. Since draft-reschke-rfc5987bis-00
Resolved issues "iso-8859-1" and "title" (title simplified). Added
and resolved issue "historic5987".
C.3. Since draft-reschke-rfc5987bis-01
Added issues "httpbis", "parmsyntax", "terminology" and
"valuesyntax". Closed issue "impls".
C.4. Since draft-reschke-rfc5987bis-02
Resolved issue "terminology".
C.5. Since draft-reschke-rfc5987bis-03
In Section 3.2, pull historical notes into a separate subsection.
Resolved issues "valuesyntax" and "parmsyntax".
C.6. Since draft-reschke-rfc5987bis-04
Update status of Firefox support in HTTP Link Header field.
C.7. Since draft-reschke-rfc5987bis-05
Update status of Firefox support in HTTP Link Header field.
C.8. Since draft-reschke-rfc5987bis-06
Update status with respect to Safari 6.
Started work on update with respect to RFC 723x.
C.9. Since draft-ietf-httpbis-rfc5987bis-00
Editorial changes; introducing non-ASCII characters into author's
address, acknowledgements, and examples.
C.10. Since draft-ietf-httpbis-rfc5987bis-01
Removed mention of RFC 2616 from Abstract and Introduction.
Reference RFC 20 for US-ASCII.
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Do not attempt to define a generic parameter ABNF; just concentrate
on the parameter value syntax.
C.11. Since draft-ietf-httpbis-rfc5987bis-02
RFC 2388 -> RFC 7578.
Expand on the motivation (see
<https://github.com/httpwg/http-extensions/issues/213>).
Mention RFC 7616 in implementation report.
C.12. Since draft-ietf-httpbis-rfc5987bis-03
Fixed one editorial issue. Updated XHR reference.
Fixed <https://github.com/httpwg/http-extensions/issues/266>: use of
now undefined term "parmname".
Include WG into Acknowledgements for this revision.
Mention RFC 5987 in the abstract
(<https://github.com/httpwg/http-extensions/issues/271>).
C.13. Since draft-ietf-httpbis-rfc5987bis-04
Mention RFC8053 in Implementation Report.
Appendix D. Acknowledgements
Thanks to Martin Dürst and Frank Ellermann for help figuring out
ABNF details, to Graham Klyne and Alexey Melnikov for general review,
to Chris Newman for pointing out an RFC 2231 incompatibility, and to
Benjamin Carlyle, Roar Lauritzsen, Eric Lawrence, and James Manger
for implementer's feedback.
Furthermore thanks to the members of the IETF HTTP Working Group for
the feedback specific to this update of RFC 5987.
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Author's Address
Julian F. Reschke
greenbytes GmbH
Hafenweg 16
Münster, NW 48155
Germany
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/
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