draft-reschke-http-status-308-07.txt		draft-reschke-http-status-308-latest.txt
	Network Working Group J. Reschke		Internet Engineering Task Force (IETF) J. Reschke
	Internet-Draft greenbytes		Request for Comments: 7238 greenbytes
	Intended status: Experimental March 26, 2012		Category: Experimental April 2024
	Expires: September 27, 2012		ISSN: 2070-1721
	The Hypertext Transfer Protocol (HTTP) Status Code 308 (Permanent		The Hypertext Transfer Protocol Status Code 308 (Permanent Redirect)
	Redirect)
	draft-reschke-http-status-308-07
	Abstract		Abstract
	This document specifies the additional HyperText Transfer Protocol		This document specifies the additional Hypertext Transfer Protocol
	(HTTP) Status Code 308 (Permanent Redirect).		(HTTP) status code 308 (Permanent Redirect).
	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-
	ietf-http-wg@w3.org [1], which may be joined by sending a message		wg@w3.org [1], which may be joined by sending a message with subject
	with subject "subscribe" to ietf-http-wg-request@w3.org [2].		"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, latest edits, and the issues list for this document are		XML versions, latest edits, and the issues list for this document are
	available from		available from <http://greenbytes.de/tech/webdav/#draft-reschke-http-
	<http://greenbytes.de/tech/webdav/#draft-reschke-http-status-308>.		status-308>.
	Test cases related to redirection in general and the status code 308		_This is a temporary document for the purpose of tracking the
	in particular can be found at		editorial changes made during the AUTH48 (RFC publication) phase._
	<http://greenbytes.de/tech/tc/httpredirects/#l-308>.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This document is not an Internet Standards Track specification; it is
	provisions of BCP 78 and BCP 79.		published for examination, experimental implementation, and
			evaluation.
	Internet-Drafts are working documents of the Internet Engineering		This document defines an Experimental Protocol for the Internet
	Task Force (IETF). Note that other groups may also distribute		community. This document is a product of the Internet Engineering
	working documents as Internet-Drafts. The list of current Internet-		Task Force (IETF). It represents the consensus of the IETF
	Drafts is at http://datatracker.ietf.org/drafts/current/.		community. It has received public review and has been approved for
			publication by the Internet Engineering Steering Group (IESG). Not
			all documents approved by the IESG are candidates for any level of
			Internet Standard; see Section 2 of RFC 7841.
	Internet-Drafts are draft documents valid for a maximum of six months		Information about the current status of this document, any errata,
	and may be updated, replaced, or obsoleted by other documents at any		and how to provide feedback on it may be obtained at
	time. It is inappropriate to use Internet-Drafts as reference		https://www.rfc-editor.org/info/rfc7238.
	material or to cite them other than as "work in progress."
	This Internet-Draft will expire on September 27, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2024 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		(https://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 . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3		2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
	3. 308 Permanent Redirect . . . . . . . . . . . . . . . . . . . . 3		3. 308 Permanent Redirect . . . . . . . . . . . . . . . . . . . 3
	4. Deployment Considerations . . . . . . . . . . . . . . . . . . . 4		4. Deployment Considerations . . . . . . . . . . . . . . . . . . 3
	5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5		5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	8.1. Normative References . . . . . . . . . . . . . . . . . . . 6		8.1. Normative References . . . . . . . . . . . . . . . . . . 5
	8.2. Informative References . . . . . . . . . . . . . . . . . . 6		8.2. Informative References . . . . . . . . . . . . . . . . . 6
	Appendix A. Implementations (to be removed by RFC Editor		8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6
	before publication) . . . . . . . . . . . . . . . . . 7		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
	Appendix B. Change Log (to be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . . 7
	B.1. Since draft-reschke-http-status-308-00 . . . . . . . . . . 7
	B.2. Since draft-reschke-http-status-308-01 . . . . . . . . . . 7
	B.3. Since draft-reschke-http-status-308-02 . . . . . . . . . . 7
	B.4. Since draft-reschke-http-status-308-03 . . . . . . . . . . 7
	B.5. Since draft-reschke-http-status-308-04 . . . . . . . . . . 7
	B.6. Since draft-reschke-http-status-308-05 . . . . . . . . . . 8
	B.7. Since draft-reschke-http-status-308-06 . . . . . . . . . . 8
	Appendix C. Resolved issues (to be removed by RFC Editor
	before publication) . . . . . . . . . . . . . . . . . 8
	C.1. consistency307 . . . . . . . . . . . . . . . . . . . . . . 8
	C.2. sniffing . . . . . . . . . . . . . . . . . . . . . . . . . 8
	Appendix D. Open issues (to be removed by RFC Editor prior to
	publication) . . . . . . . . . . . . . . . . . . . . . 8
	D.1. edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	HTTP defines a set of status codes for the purpose of redirecting a		HTTP defines a set of status codes for the purpose of redirecting a
	request to a different URI ([RFC3986]). The history of these status		request to a different URI ([RFC3986]). The history of these status
	codes is summarized in Section 7.3 of		codes is summarized in Section 6.4 of [RFC7231], which also
	[draft-ietf-httpbis-p2-semantics], which also classifies the existing		classifies the existing status codes into four categories.
	status codes into four categories.
	The first of these categories contains the status codes 301 (Moved		The first of these categories contains the status codes 301 (Moved
	Permanently), 302 (Found), and 307 (Temporary Redirect), which can be		Permanently), 302 (Found), and 307 (Temporary Redirect), which can be
	classified as below:		classified as below:
	+-------------------------------------------+-----------+-----------+		+-------------------------------------------+-----------+-----------+
	| | Permanent | Temporary |		| | Permanent | Temporary |
	+-------------------------------------------+-----------+-----------+		+-------------------------------------------+-----------+-----------+
	| Allows changing the request method from | 301 | 302 |		| Allows changing the request method from | 301 | 302 |
	| POST to GET | | |		| POST to GET | | |
	| Does not allow changing the request | - | 307 |		| Does not allow changing the request | - | 307 |
	| method from POST to GET | | |		| method from POST to GET | | |
	+-------------------------------------------+-----------+-----------+		+-------------------------------------------+-----------+-----------+
	Section 7.3.7 of [draft-ietf-httpbis-p2-semantics] states that HTTP		Section 6.4.7 of [RFC7231] states that HTTP does not define a
	does not define a permanent variant of status code 307; this		permanent variant of status code 307; this specification adds the
	specification adds the status code 308, defining this missing variant		status code 308, defining this missing variant (Section 3).
	(Section 3).
	2. Notational Conventions		2. Notational Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	3. 308 Permanent Redirect		3. 308 Permanent Redirect
	The target resource has been assigned a new permanent URI and any		The "308 (Permanent Redirect)" status code indicates that the target
	future references to this resource SHOULD use one of the returned		resource has been assigned a new permanent URI and any future
	URIs. Clients with link editing capabilities ought to automatically		references to this resource ought to use one of the enclosed URIs.
	re-link references to the effective request URI (Section 5.5 of		Clients with link editing capabilities ought to automatically re-link
	[draft-ietf-httpbis-p1-messaging]) to one or more of the new		references to the effective request URI (Section 5.5 of [RFC7230]) to
	references returned by the server, where possible.		one or more of the new references sent by the server, where possible.
	Caches MAY use a heuristic (see [draft-ietf-httpbis-p6-cache],		The server SHOULD generate a Location header field ([RFC7231],
	Section 2.3.1.1) to determine freshness for 308 responses.		Section 7.1.2) in the response containing a preferred URI reference
			for the new permanent URI. The user agent MAY use the Location field
			value for automatic redirection. The server's response payload
			usually contains a short hypertext note with a hyperlink to the new
			URI(s).
	The new permanent URI SHOULD be given by the Location field in the		A 308 response is cacheable by default; i.e., unless otherwise
	response ([draft-ietf-httpbis-p2-semantics], Section 10.5). A		indicated by the method definition or explicit cache controls (see
	response payload can contain a short hypertext note with a hyperlink		[RFC7234], Section 4.2.2).
	to the new URI(s).
	Note: This status code is similar to 301 Moved Permanently		Note: This status code is similar to 301 (Moved Permanently)
	(Section 7.3.2 of [draft-ietf-httpbis-p2-semantics]), except that		([RFC7231], Section 6.4.2), except that it does not allow changing
	it does not allow rewriting the request method from POST to GET.		the request method from POST to GET.
	4. Deployment Considerations		4. Deployment Considerations
	Section 4 of [draft-ietf-httpbis-p2-semantics] requires recipients to		Section 6 of [RFC7231] requires recipients to treat unknown 3xx
	treat unknown 3xx status codes the same way as status code 300		status codes the same way as status code 300 Multiple Choices
	Multiple Choices ([draft-ietf-httpbis-p2-semantics], Section 7.3.1).		([RFC7231], Section 6.4.1). Thus, servers will not be able to rely
	Thus, servers will not be able to rely on automatic redirection		on automatic redirection happening similar to status codes 301, 302,
	happening similar to status codes 301, 302, or 307.		or 307.
	Therefore, initial use of status code 308 will be restricted to cases		Therefore, initial use of status code 308 will be restricted to cases
	where the server has sufficient confidence in the clients		where the server has sufficient confidence in the client's
	understanding the new code, or when a fallback to the semantics of		understanding the new code or when a fallback to the semantics of
	status code 300 is not problematic. Server implementers are advised		status code 300 is not problematic. Server implementers are advised
	not to vary the status code based on characteristics of the request,		not to vary the status code based on characteristics of the request,
	such as the User-Agent header field ("User-Agent Sniffing") -- doing		such as the User-Agent header field ("User-Agent Sniffing") -- doing
	so usually results in both hard to maintain and hard to debug code		so usually results in code that is both hard to maintain and hard to
	and would also require special attention to caching (i.e., setting a		debug and would also require special attention to caching (i.e.,
	"Vary" response header field, as defined in Section 3.5 of		setting a "Vary" response header field, as defined in Section 7.1.4
	[draft-ietf-httpbis-p6-cache]).		of [RFC7231]).
	Note that many existing HTML-based user agents will emulate a refresh		Note that many existing HTML-based user agents will emulate a refresh
	when encountering an HTML <meta> refresh directive ([HTML]). This		when encountering an HTML <meta> refresh directive ([HTML]). This
	can be used as another fallback. For example:		can be used as another fallback. For example:
	Client request:		Client request:
	GET / HTTP/1.1		GET / HTTP/1.1
	Host: example.com		Host: example.com
	skipping to change at page 5, line 32 ¶		skipping to change at page 5, line 8 ¶
	The document has been moved to		The document has been moved to
	<a href="http://example.com/new"		<a href="http://example.com/new"
	>http://example.com/new</a>.		>http://example.com/new</a>.
	</p>		</p>
	</body>		</body>
	</html>		</html>
	5. Security Considerations		5. Security Considerations
	All security considerations that apply to HTTP redirects apply to the		All security considerations that apply to HTTP redirects apply to the
	308 status code as well (see Section 12 of		308 status code as well (see Section 9 of [RFC7231]).
	[draft-ietf-httpbis-p2-semantics]).
	6. IANA Considerations		6. IANA Considerations
	The registration below shall be added to the HTTP Status Code		The registration below has been added to the "Hypertext Transfer
	Registry (defined in Section 4.2 of [draft-ietf-httpbis-p2-semantics]		Protocol (HTTP) Status Code Registry" (defined in Section 8.2 of
	and located at <http://www.iana.org/assignments/http-status-codes>):		[RFC7231] and located at <http://www.iana.org/assignments/http-
			status-codes>):
	+-------+--------------------+---------------------------------+		+-------+--------------------+----------------------------------+
	| Value | Description | Reference |		| Value | Description | Reference |
	+-------+--------------------+---------------------------------+		+-------+--------------------+----------------------------------+
	| 308 | Permanent Redirect | Section 3 of this specification |		| 308 | Permanent Redirect | Section 3 of this specification |
	+-------+--------------------+---------------------------------+		+-------+--------------------+----------------------------------+
	7. Acknowledgements		7. Acknowledgements
	The definition for the new status code 308 re-uses text from the		The definition for the new status code 308 reuses text from the
	HTTP/1.1 definitions of status codes 301 and 307.		HTTP/1.1 definitions of status codes 301 and 307.
	Furthermore, thanks to Ben Campbell, Cyrus Daboo, Eran Hammer-Lahav,		Furthermore, thanks to Ben Campbell, Cyrus Daboo, Eran Hammer-Lahav,
	Bjoern Hoehrmann, Subramanian Moonesamy, Peter Saint-Andre, and		Bjoern Hoehrmann, Subramanian Moonesamy, Peter Saint-Andre, and
	Robert Sparks for feedback on this document.		Robert Sparks for feedback on this document.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	RFCs to Indicate Requirement		Requirement Levels", BCP 14, RFC 2119,
	Levels", BCP 14, RFC 2119,		DOI 10.17487/RFC2119, March 1997,
	March 1997.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC3986] Berners-Lee, T., Fielding, R., and		[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
	L. Masinter, "Uniform Resource		Resource Identifier (URI): Generic Syntax", STD 66,
	Identifier (URI): Generic Syntax",		RFC 3986, DOI 10.17487/RFC3986, January 2005,
	STD 66, RFC 3986, January 2005.		<https://www.rfc-editor.org/info/rfc3986>.
	[draft-ietf-httpbis-p1-messaging] Fielding, R., Ed., Lafon, Y., Ed.,		[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	and J. Reschke, Ed., "HTTP/1.1,		Protocol (HTTP/1.1): Message Syntax and Routing",
	part 1: URIs, Connections, and		RFC 7230, DOI 10.17487/RFC7230, June 2014,
	Message Parsing",		<https://www.rfc-editor.org/info/rfc7230>.
	draft-ietf-httpbis-p1-messaging-19
	(work in progress), March 2012.
	[draft-ietf-httpbis-p2-semantics] Fielding, R., Ed., Lafon, Y., Ed.,		[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	and J. Reschke, Ed., "HTTP/1.1,		Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
	part 2: Message Semantics",		DOI 10.17487/RFC7231, June 2014,
	draft-ietf-httpbis-p2-semantics-19		<https://www.rfc-editor.org/info/rfc7231>.
	(work in progress), March 2012.
	[draft-ietf-httpbis-p6-cache] Fielding, R., Ed., Lafon, Y., Ed.,		[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Nottingham, M., Ed., and J.		Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
	Reschke, Ed., "HTTP/1.1, part 6:		RFC 7234, DOI 10.17487/RFC7234, June 2014,
	Caching",		<https://www.rfc-editor.org/info/rfc7234>.
	draft-ietf-httpbis-p6-cache-19
	(work in progress), March 2012.
	8.2. Informative References		8.2. Informative References
	[HTML] Raggett, D., Le Hors, A., and I.		[HTML] Raggett, D., Le Hors, A., and I. Jacobs, "HTML 4.01
	Jacobs, "HTML 4.01 Specification",		Specification", W3C Recommendation REC-html401-19991224,
	W3C Recommendation REC-html401-		December 1999,
	19991224, December 1999, <http://		<http://www.w3.org/TR/1999/REC-html401-19991224>.
	www.w3.org/TR/1999/
	REC-html401-19991224>.
	Latest version available at
	<http://www.w3.org/TR/html401>.
	URIs
	[1] <mailto:ietf-http-wg@w3.org>
	[2] <mailto:ietf-http-wg-request@w3.org?subject=subscribe>
	Appendix A. Implementations (to be removed by RFC Editor before
	publication)
	Chrome: Feature requested in Chromium Issue 109012
	(<http://code.google.com/p/chromium/issues/detail?id=109012>).
	Curl (the library): no change was needed (test case:
	<https://github.com/bagder/curl/blob/master/tests/data/test1325>).
	Firefox: now in "nightly" builds, scheduled for release in Firefox 14
	(see <https://bugzilla.mozilla.org/show_bug.cgi?id=714302>).
	Safari: automatically redirects 3xx status codes when a Location
	header field is present, but does not preserve the request method.
	Appendix B. Change Log (to be removed by RFC Editor before publication)
	B.1. Since draft-reschke-http-status-308-00
	Updated HTTPbis reference. Added Appendix A. Added and resolved
	issue "refresh".
	B.2. Since draft-reschke-http-status-308-01
	Added URI spec reference.
	B.3. Since draft-reschke-http-status-308-02
	Tune HTML example. Expand "Implementations" section. Added and
	resolved issue "respformat" (align with new proposed text for 307 in
	HTTPbis P2).
	B.4. Since draft-reschke-http-status-308-03
	Added and resolved issue "uaconfirm".
	B.5. Since draft-reschke-http-status-308-04
	Added and resolved issue "missingconsiderations". Added request
	message to example. Updated the Safari implementation note.
	B.6. Since draft-reschke-http-status-308-05
	Add informative HTML reference. Update HTTPbis references.
	B.7. Since draft-reschke-http-status-308-06
	Added and resolved issues "consistency307" and "sniffing". Updated
	Firefox implementation status.
	Appendix C. Resolved issues (to be removed by RFC Editor before
	publication)
	Issues that were either rejected or resolved in this version of this
	document.
	C.1. consistency307
	In Section 3:
	Type: edit
	ben@nostrum.com (2012-03-16): The 307 definition includes an explicit
	post about that behavior not being allowed. Section 3 of this doc
	does neither.
	Resolution: Import (part of the) note from status code 307
	description.
	C.2. sniffing
	In Section 4:
	Type: edit
	rjsparks@nostrum.com (2012-03-15): Would it be worth adding something
	to the draft explicitily discouraging UA sniffing? A reference to
	something that already explores why that's not a good idea perhaps?
	Resolution: Add advice not to attempt UA sniffing.
	Appendix D. Open issues (to be removed by RFC Editor prior to		Latest version available at <http://www.w3.org/TR/
	publication)		html401>.
	D.1. edit		8.3. URIs
	Type: edit		[1] mailto:ietf-http-wg@w3.org
	julian.reschke@greenbytes.de (2011-04-15): Umbrella issue for		[2] mailto:ietf-http-wg-request@w3.org?subject=subscribe
	editorial fixes/enhancements.
	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
End of changes. 35 change blocks.
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