draft-reschke-http-jfv-01.txt		draft-reschke-http-jfv-02.txt
	Network Working Group J. Reschke		Network Working Group J. Reschke
	Internet-Draft greenbytes		Internet-Draft greenbytes
	Intended status: Standards Track March 9, 2015		Intended status: Standards Track October 5, 2015
	Expires: September 10, 2015		Expires: April 7, 2016
	A JSON Encoding for HTTP Header Field Values		A JSON Encoding for HTTP Header Field Values
	draft-reschke-http-jfv-01		draft-reschke-http-jfv-02
	Abstract		Abstract
	This document establishes a convention for use of JSON-encoded field		This document establishes a convention for use of JSON-encoded field
	values in HTTP header fields.		values in HTTP header fields.
	Editorial Note (To be removed by RFC Editor before publication)		Editorial Note (To be removed by RFC Editor before publication)
	Distribution of this document is unlimited. Although this is not a		Distribution of this document is unlimited. Although this is not a
	work item of the HTTPbis Working Group, comments should be sent to		work item of the HTTPbis Working Group, comments should be sent to
	the Hypertext Transfer Protocol (HTTP) mailing list at		the Hypertext Transfer Protocol (HTTP) mailing list at
	ietf-http-wg@w3.org [1], which may be joined by sending a message		ietf-http-wg@w3.org [1], which may be joined by sending a message
	with subject "subscribe" to ietf-http-wg-request@w3.org [2].		with subject "subscribe" to ietf-http-wg-request@w3.org [2].
	Discussions of the HTTPbis Working Group are archived at		Discussions of the HTTPbis Working Group are archived at
	<http://lists.w3.org/Archives/Public/ietf-http-wg/>.		<http://lists.w3.org/Archives/Public/ietf-http-wg/>.
	XML versions and latest edits for this document are available from		XML versions and latest edits for this document are available from
	<http://greenbytes.de/tech/webdav/#draft-reschke-http-jfv>.		<http://greenbytes.de/tech/webdav/#draft-reschke-http-jfv>.
			The changes in this draft are summarized in Appendix A.2.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
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	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
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	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
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	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on September 10, 2015.		This Internet-Draft will expire on April 7, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2015 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Data Model and Format . . . . . . . . . . . . . . . . . . . . . 3		2. Data Model and Format . . . . . . . . . . . . . . . . . . . . 3
	3. Sender Requirements . . . . . . . . . . . . . . . . . . . . . . 4		3. Sender Requirements . . . . . . . . . . . . . . . . . . . . . 4
	4. Recipient Requirements . . . . . . . . . . . . . . . . . . . . 5		4. Recipient Requirements . . . . . . . . . . . . . . . . . . . . 5
	5. Using this Format in Header Field Definitions . . . . . . . . . 5		5. Using this Format in Header Field Definitions . . . . . . . . 5
	6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5		6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
	6.1. Content-Length . . . . . . . . . . . . . . . . . . . . . . 5		6.1. Content-Length . . . . . . . . . . . . . . . . . . . . . . 5
	6.2. Content-Disposition . . . . . . . . . . . . . . . . . . . . 6		6.2. Content-Disposition . . . . . . . . . . . . . . . . . . . 6
	6.3. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 7		6.3. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 7
	7. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 7		7. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 7
	8. Deployment Considerations . . . . . . . . . . . . . . . . . . . 8		8. Deployment Considerations . . . . . . . . . . . . . . . . . . 8
	9. Internationalization Considerations . . . . . . . . . . . . . . 8		9. Internationalization Considerations . . . . . . . . . . . . . 8
	10. Security Considerations . . . . . . . . . . . . . . . . . . . . 8		10. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8		11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	11.1. Normative References . . . . . . . . . . . . . . . . . . . 8		11.1. Normative References . . . . . . . . . . . . . . . . . . . 8
	11.2. Informative References . . . . . . . . . . . . . . . . . . 9		11.2. Informative References . . . . . . . . . . . . . . . . . . 9
	Appendix A. Change Log (to be removed by RFC Editor before		Appendix A. Change Log (to be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . . 9		publication) . . . . . . . . . . . . . . . . . . . . 10
	A.1. draft-reschke-http-jfv-00 . . . . . . . . . . . . . . . . . 9		A.1. Since draft-reschke-http-jfv-00 . . . . . . . . . . . . . 10
			A.2. Since draft-reschke-http-jfv-01 . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	Defining syntax for new HTTP header fields ([RFC7230], Section 3.2)		Defining syntax for new HTTP header fields ([RFC7230], Section 3.2)
	is non-trivial. Among the commonly encountered problems are:		is non-trivial. Among the commonly encountered problems are:
	o There is no common syntax for complex field values. Several well-		o There is no common syntax for complex field values. Several well-
	known header fields do use a similarly looking syntax, but it is		known header fields do use a similarly looking syntax, but it is
	hard to write generic parsing code that will both correctly handle		hard to write generic parsing code that will both correctly handle
	valid field values but also reject invalid ones.		valid field values but also reject invalid ones.
	skipping to change at page 5, line 24 ¶		skipping to change at page 5, line 24 ¶
	3. run the resulting octet sequence through a JSON parser.		3. run the resulting octet sequence through a JSON parser.
	The result of the parsing operation is either an error (in which case		The result of the parsing operation is either an error (in which case
	the header field values needs to be considered invalid), or a JSON		the header field values needs to be considered invalid), or a JSON
	array.		array.
	5. Using this Format in Header Field Definitions		5. Using this Format in Header Field Definitions
	[[anchor5: Explain what a definition of a new header field needs to		[[anchor5: Explain what a definition of a new header field needs to
	do precisely to use this format]]		do precisely to use this format, mention must-ignore extensibiliy]]
	6. Examples		6. Examples
	This section shows how some of the existing HTTP header fields would		This section shows how some of the existing HTTP header fields would
	look like if they would use the format defined by this specification.		look like if they would use the format defined by this specification.
	6.1. Content-Length		6.1. Content-Length
	"Content-Length" is defined in Section 3.3.2 of [RFC7230], with the		"Content-Length" is defined in Section 3.3.2 of [RFC7230], with the
	field value's ABNF being:		field value's ABNF being:
	skipping to change at page 7, line 7 ¶		skipping to change at page 7, line 7 ¶
	definition of Content-Disposition would have used the format proposed		definition of Content-Disposition would have used the format proposed
	here, the workaround involving the "parameter*" syntax would not have		here, the workaround involving the "parameter*" syntax would not have
	been needed at all.		been needed at all.
	The JSON representation of this value could then be:		The JSON representation of this value could then be:
	{ "attachment": { "filename" : "\u20AC rates" } }		{ "attachment": { "filename" : "\u20AC rates" } }
	6.3. WWW-Authenticate		6.3. WWW-Authenticate
	The WWW-Authenticate is defined in Section 4.1 of [RFC7235] as a list		The WWW-Authenticate header field value is defined in Section 4.1 of
	of "challenges":		[RFC7235] as a list of "challenges":
	WWW-Authenticate = 1#challenge		WWW-Authenticate = 1#challenge
	...where a challenge consists of a scheme with optional parameters:		...where a challenge consists of a scheme with optional parameters:
	challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ]		challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
	An example for a complex header field value given in the definition		An example for a complex header field value given in the definition
	of the header field is:		of the header field is:
	skipping to change at page 7, line 52 ¶		skipping to change at page 7, line 52 ¶
	...which would translate to a header field value of:		...which would translate to a header field value of:
	{ "Newauth" : { "realm": "apps", "type" : 1,		{ "Newauth" : { "realm": "apps", "type" : 1,
	"title": "Login to \"apps\"" }},		"title": "Login to \"apps\"" }},
	{ "Basic" : { "realm": "simple"}}		{ "Basic" : { "realm": "simple"}}
	7. Discussion		7. Discussion
	This approach uses a default of "JSON array", using implicit array		This approach uses a default of "JSON array", using implicit array
	markers. An alternative would be a default of "JSON object". This		markers. An alternative would be a default of "JSON object". This
	would simplify the syntax for non-list-typed haeders, but all the		would simplify the syntax for non-list-typed header fields, but all
	benefits of having the same data model for both types of header		the benefits of having the same data model for both types of header
	fields would be gone. A hybrid approach might make sense, as long as		fields would be gone. A hybrid approach might make sense, as long as
	it doesn't require any heuristics on the recipient's side.		it doesn't require any heuristics on the recipient's side.
	[[anchor7: Use of generic libs vs compactness of field values..]]		[[anchor7: Use of generic libs vs compactness of field values..]]
	8. Deployment Considerations		8. Deployment Considerations
	This JSON-based syntax will only apply to newly introduced header		This JSON-based syntax will only apply to newly introduced header
	fields, thus backwards compatibility is not a problem. That being		fields, thus backwards compatibility is not a problem. That being
	said, it is conceivable that there is existing code that might trip		said, it is conceivable that there is existing code that might trip
	over double quotes not being used for HTTP's quoted-string syntax		over double quotes not being used for HTTP's quoted-string syntax
	(Section 3.2.6 of [RFC7230]).		(Section 3.2.6 of [RFC7230]).
	9. Internationalization Considerations		9. Internationalization Considerations
	[[anchor10: TBD, mention migration path to message format that is		[[anchor10: TBD, mention migration path to message format that is
	robust wrt UTF-8, or other binary encodings of JSON]]		robust wrt UTF-8, or other binary encodings of JSON]]
	10. Security Considerations		10. Security Considerations
	[[anchor12: TBD]]		Using JSON-shaped field values is believed to not introduce any new
			threads beyond those described in Section 12 of [RFC7159], namely the
			risk of recipients using the wrong tools to parse them.
			Other than that, any syntax that makes extensions easy can be used to
			smuggle information through field values; however, this concern is
			shared with other widely used formats, such as those using parameters
			in the form of name/value pairs.
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[RFC0020] Cerf, V., "ASCII format for network interchange",		[RFC0020] Cerf, V., "ASCII format for network interchange",
	STD 80, RFC 20, October 1969.		STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969,
			<http://www.rfc-editor.org/info/rfc20>.
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
	Syntax Specifications: ABNF", STD 68, RFC 5234,		Syntax Specifications: ABNF", STD 68, RFC 5234,
	January 2008.		DOI 10.17487/RFC5234, January 2008,
			<http://www.rfc-editor.org/info/rfc5234>.
	[RFC7159] Bray, T., "The JavaScript Object Notation (JSON)		[RFC7159] Bray, T., "The JavaScript Object Notation (JSON)
	Data Interchange Format", RFC 7159, March 2014.		Data Interchange Format", RFC 7159, DOI 10.17487/
			RFC7159, March 2014,
			<http://www.rfc-editor.org/info/rfc7159>.
	[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext		[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
	Transfer Protocol (HTTP/1.1): Message Syntax and		Transfer Protocol (HTTP/1.1): Message Syntax and
	Routing", RFC 7230, June 2014.		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		[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
	Transfer Protocol (HTTP/1.1): Semantics and		Transfer Protocol (HTTP/1.1): Semantics and
	Content", RFC 7231, June 2014.		Content", RFC 7231, DOI 10.17487/RFC7231,
			June 2014,
			<http://www.rfc-editor.org/info/rfc7231>.
	11.2. Informative References		11.2. Informative References
	[ISO-8859-1] International Organization for Standardization,		[ISO-8859-1] International Organization for Standardization,
	"Information technology -- 8-bit single-byte coded		"Information technology -- 8-bit single-byte coded
	graphic character sets -- Part 1: Latin alphabet		graphic character sets -- Part 1: Latin alphabet
	No. 1", ISO/IEC 8859-1:1998, 1998.		No. 1", ISO/IEC 8859-1:1998, 1998.
	[RFC5987] Reschke, J., "Character Set and Language Encoding		[RFC5987] Reschke, J., "Character Set and Language Encoding
	for Hypertext Transfer Protocol (HTTP) Header Field		for Hypertext Transfer Protocol (HTTP) Header Field
	Parameters", RFC 5987, August 2010.		Parameters", RFC 5987, DOI 10.17487/RFC5987,
			August 2010,
			<http://www.rfc-editor.org/info/rfc5987>.
	[RFC6266] Reschke, J., "Use of the Content-Disposition Header		[RFC6266] Reschke, J., "Use of the Content-Disposition Header
	Field in the Hypertext Transfer Protocol (HTTP)",		Field in the Hypertext Transfer Protocol (HTTP)",
	RFC 6266, June 2011.		RFC 6266, DOI 10.17487/RFC6266, June 2011,
			<http://www.rfc-editor.org/info/rfc6266>.
	[RFC6365] Hoffman, P. and J. Klensin, "Terminology Used in		[RFC6365] Hoffman, P. and J. Klensin, "Terminology Used in
	Internationalization in the IETF", BCP 166,		Internationalization in the IETF", BCP 166,
	RFC 6365, September 2011.		RFC 6365, DOI 10.17487/RFC6365, September 2011,
			<http://www.rfc-editor.org/info/rfc6365>.
	[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext		[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
	Transfer Protocol (HTTP/1.1): Authentication",		Transfer Protocol (HTTP/1.1): Authentication",
	RFC 7235, June 2014.		RFC 7235, DOI 10.17487/RFC7235, June 2014,
			<http://www.rfc-editor.org/info/rfc7235>.
	[XMLHttpRequest] van Kesteren, A., Aubourg, J., Song, J., and H.		[XMLHttpRequest] van Kesteren, A., Aubourg, J., Song, J., and H.
	Steen, "XMLHttpRequest Level 1", W3C Working		Steen, "XMLHttpRequest Level 1", W3C Working
	Draft WD-XMLHttpRequest-20140130, January 2014, <ht		Draft WD-XMLHttpRequest-20140130, January 2014, <ht
	tp://www.w3.org/TR/2014/		tp://www.w3.org/TR/2014/
	WD-XMLHttpRequest-20140130/>.		WD-XMLHttpRequest-20140130/>.
	Latest version available at		Latest version available at
	<http://www.w3.org/TR/XMLHttpRequest/>.		<http://www.w3.org/TR/XMLHttpRequest/>.
	URIs		URIs
	[1] <mailto:ietf-http-wg@w3.org>		[1] <mailto:ietf-http-wg@w3.org>
	[2] <mailto:ietf-http-wg-request@w3.org?subject=subscribe>		[2] <mailto:ietf-http-wg-request@w3.org?subject=subscribe>
	Appendix A. Change Log (to be removed by RFC Editor before publication)		Appendix A. Change Log (to be removed by RFC Editor before publication)
	A.1. draft-reschke-http-jfv-00		A.1. Since draft-reschke-http-jfv-00
	Editorial fixes + working on the TODOs.		Editorial fixes + working on the TODOs.
			A.2. Since draft-reschke-http-jfv-01
			Mention slightly increased risk of smuggling information in header
			field values.
	Author's Address		Author's Address
	Julian F. Reschke		Julian F. Reschke
	greenbytes GmbH		greenbytes GmbH
	Hafenweg 16		Hafenweg 16
	Muenster, NW 48155		Muenster, NW 48155
	Germany		Germany
	EMail: julian.reschke@greenbytes.de		EMail: julian.reschke@greenbytes.de
	URI: http://greenbytes.de/tech/webdav/		URI: http://greenbytes.de/tech/webdav/
End of changes. 22 change blocks.
	39 lines changed or deleted		66 lines changed or added
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