draft-ietf-httpbis-origin-frame-02.txt		draft-ietf-httpbis-origin-frame-03.txt
	HTTP Working Group M. Nottingham		HTTP Working Group M. Nottingham
	Internet-Draft E. Nygren		Internet-Draft
	Intended status: Standards Track Akamai		Intended status: Standards Track E. Nygren
	Expires: August 17, 2017 February 13, 2017		Expires: October 22, 2017 Akamai
			April 20, 2017
	The ORIGIN HTTP/2 Frame		The ORIGIN HTTP/2 Frame
	draft-ietf-httpbis-origin-frame-02		draft-ietf-httpbis-origin-frame-03
	Abstract		Abstract
	This document specifies the ORIGIN frame for HTTP/2, to indicate what		This document specifies the ORIGIN frame for HTTP/2, to indicate what
	origins are available on a given connection.		origins are available on a given connection.
	Note to Readers		Note to Readers
	Discussion of this draft takes place on the HTTP working group		Discussion of this draft takes place on the HTTP working group
	mailing list (ietf-http-wg@w3.org), which is archived at		mailing list (ietf-http-wg@w3.org), which is archived at
	skipping to change at page 1, line 41 ¶		skipping to change at page 1, line 42 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	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 August 17, 2017.		This Internet-Draft will expire on October 22, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 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
	skipping to change at page 2, line 28 ¶		skipping to change at page 2, line 31 ¶
	2.2. Processing ORIGIN Frames . . . . . . . . . . . . . . . . 3		2.2. Processing ORIGIN Frames . . . . . . . . . . . . . . . . 3
	2.3. The Origin Set . . . . . . . . . . . . . . . . . . . . . 4		2.3. The Origin Set . . . . . . . . . . . . . . . . . . . . . 4
	2.4. Authority, Push and Coalescing with ORIGIN . . . . . . . 5		2.4. Authority, Push and Coalescing with ORIGIN . . . . . . . 5
	3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6		3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 6		4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
	5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6		5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
	5.1. Normative References . . . . . . . . . . . . . . . . . . 6		5.1. Normative References . . . . . . . . . . . . . . . . . . 6
	5.2. Informative References . . . . . . . . . . . . . . . . . 7		5.2. Informative References . . . . . . . . . . . . . . . . . 7
	Appendix A. Non-Normative Processing Algorithm . . . . . . . . . 7		Appendix A. Non-Normative Processing Algorithm . . . . . . . . . 7
	Appendix B. Operational Considerations for Servers . . . . . . . 8		Appendix B. Operational Considerations for Servers . . . . . . . 8
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	HTTP/2 [RFC7540] allows clients to coalesce different origins		HTTP/2 [RFC7540] allows clients to coalesce different origins
	[RFC6454] onto the same connection when certain conditions are met.		[RFC6454] onto the same connection when certain conditions are met.
	However, in certain cases, a connection is is not usable for a		However, in certain cases, a connection is is not usable for a
	coalesced origin, so the 421 (Misdirected Request) status code		coalesced origin, so the 421 (Misdirected Request) status code
	([RFC7540], Section 9.1.2) was defined.		([RFC7540], Section 9.1.2) was defined.
	Using a status code in this manner allows clients to recover from		Using a status code in this manner allows clients to recover from
	skipping to change at page 3, line 20 ¶		skipping to change at page 3, line 20 ¶
	2. The ORIGIN HTTP/2 Frame		2. The ORIGIN HTTP/2 Frame
	The ORIGIN HTTP/2 frame ([RFC7540], Section 4) allows a server to		The ORIGIN HTTP/2 frame ([RFC7540], Section 4) allows a server to
	indicate what origin(s) [RFC6454] the server would like the client to		indicate what origin(s) [RFC6454] the server would like the client to
	consider as members of the Origin Set (Section 2.3) for the		consider as members of the Origin Set (Section 2.3) for the
	connection it occurs within.		connection it occurs within.
	2.1. Syntax		2.1. Syntax
	The ORIGIN frame type is 0xb (decimal 11).		The ORIGIN frame type is 0xc (decimal 12).
	+-------------------------------+-------------------------------+		+-------------------------------+-------------------------------+
	| Origin-Len (16) | ASCII-Origin? (*) ...		| Origin-Len (16) | ASCII-Origin? (*) ...
	+-------------------------------+-------------------------------+		+-------------------------------+-------------------------------+
	The ORIGIN frame's payload contains the following fields, sets of		The ORIGIN frame's payload contains the following fields, sets of
	which may be repeated within the frame to indicate multiple origins:		which may be repeated within the frame to indicate multiple origins:
	Origin-Len: An unsigned, 16-bit integer indicating the length, in		Origin-Len: An unsigned, 16-bit integer indicating the length, in
	octets, of the ASCII-Origin field.		octets, of the ASCII-Origin field.
	skipping to change at page 4, line 15 ¶		skipping to change at page 4, line 12 ¶
	Likewise, the ORIGIN frame is only valid on connections with the "h2"		Likewise, the ORIGIN frame is only valid on connections with the "h2"
	protocol identifier, or when specifically nominated by the protocol's		protocol identifier, or when specifically nominated by the protocol's
	definition; it MUST be ignored when received on a connection with the		definition; it MUST be ignored when received on a connection with the
	"h2c" protocol identifier.		"h2c" protocol identifier.
	This specification does not define any flags for the ORIGIN frame,		This specification does not define any flags for the ORIGIN frame,
	but future updates might use them to change its semantics. The first		but future updates might use them to change its semantics. The first
	four flags (0x1, 0x2, 0x4 and 0x8) are reserved for backwards-		four flags (0x1, 0x2, 0x4 and 0x8) are reserved for backwards-
	incompatible changes, and therefore when any of them are set, the		incompatible changes, and therefore when any of them are set, the
	ORIGIN frame containing them MUST be ignored by clients conforming to		ORIGIN frame containing them MUST be ignored by clients conforming to
	this specification. The remaining flags are reserved for backwards-		this specification, unless the flag's semantics are understood. The
	compatible changes, and do not affect processing by clients		remaining flags are reserved for backwards-compatible changes, and do
	conformant to this specification.		not affect processing by clients conformant to this specification.
	The ORIGIN frame describes a property of the connection, and		The ORIGIN frame describes a property of the connection, and
	therefore is processed hop-by-hop. An intermediary MUST NOT forward		therefore is processed hop-by-hop. An intermediary MUST NOT forward
	ORIGIN frames. Clients configured to use a proxy MUST ignore any		ORIGIN frames. Clients configured to use a proxy MUST ignore any
	ORIGIN frames received from it.		ORIGIN frames received from it.
	Each ASCII-Origin field in the frame's payload MUST be parsed as an		Each ASCII-Origin field in the frame's payload MUST be parsed as an
	ASCII serialisation of an origin ([RFC6454], Section 6.2). If		ASCII serialisation of an origin ([RFC6454], Section 6.2). If
	parsing fails, the field MUST be ignored.		parsing fails, the field MUST be ignored.
	skipping to change at page 6, line 11 ¶		skipping to change at page 6, line 11 ¶
	clients SHOULD not emit new requests on any connection whose Origin		clients SHOULD not emit new requests on any connection whose Origin
	Set is a subset of another connection's Origin Set, and SHOULD close		Set is a subset of another connection's Origin Set, and SHOULD close
	it once all outstanding requests are satisfied.		it once all outstanding requests are satisfied.
	3. IANA Considerations		3. IANA Considerations
	This specification adds an entry to the "HTTP/2 Frame Type" registry.		This specification adds an entry to the "HTTP/2 Frame Type" registry.
	o Frame Type: ORIGIN		o Frame Type: ORIGIN
	o Code: 0xb		o Code: 0xc
	o Specification: [this document]		o Specification: [this document]
	4. Security Considerations		4. Security Considerations
	Clients that blindly trust the ORIGIN frame's contents will be		Clients that blindly trust the ORIGIN frame's contents will be
	vulnerable to a large number of attacks. See Section 2.4 for		vulnerable to a large number of attacks. See Section 2.4 for
	mitigations.		mitigations.
	Relaxing the requirement to consult DNS when determining authority		Relaxing the requirement to consult DNS when determining authority
	skipping to change at page 8, line 37 ¶		skipping to change at page 8, line 37 ¶
	Therefore, the ORIGIN frame ought be sent as soon as possible on a		Therefore, the ORIGIN frame ought be sent as soon as possible on a
	connection, ideally before any HEADERS or PUSH_PROMISE frames.		connection, ideally before any HEADERS or PUSH_PROMISE frames.
	However, if it's desirable to associate a large number of origins		However, if it's desirable to associate a large number of origins
	with a connection, doing so might introduce end-user perceived		with a connection, doing so might introduce end-user perceived
	latency, due to their size. As a result, it might be necessary to		latency, due to their size. As a result, it might be necessary to
	select a "core" set of origins to send initially, expanding the set		select a "core" set of origins to send initially, expanding the set
	of origins the connection is used for with subsequent ORIGIN frames		of origins the connection is used for with subsequent ORIGIN frames
	later (e.g., when the connection is idle).		later (e.g., when the connection is idle).
	Senders should note that, as per [RFC6454] Section 4, the values in		That said, senders are encouraged to include as many origins as
	an ORIGIN header need to be case-normalised before serialisation.		practical within a single ORIGIN frame; clients need to make
			decisions about creating connections on the fly, and if the origin
			set is split across many frames, their behaviour might be suboptimal.
	Finally, servers that allow alternative services [RFC7838] will need		Senders take note that, as per [RFC6454] Section 4, the values in an
	to explicitly advertise those origins when sending ORIGIN, because		ORIGIN header need to be case-normalised before serialisation.
			Finally, servers that host alternative services [RFC7838] will need
			to explicitly advertise their origins when sending ORIGIN, because
	the default contents of the Origin Set (as per Section 2.3) do not		the default contents of the Origin Set (as per Section 2.3) do not
	contain any Alternative Services, even if they have been used		contain any Alternative Services' origins, even if they have been
	previously on the connection.		used previously on the connection.
	Authors' Addresses		Authors' Addresses
	Mark Nottingham		Mark Nottingham
	Akamai
	Email: mnot@mnot.net		Email: mnot@mnot.net
	URI: https://www.mnot.net/		URI: https://www.mnot.net/
	Erik Nygren		Erik Nygren
	Akamai		Akamai
	Email: nygren@akamai.com		Email: nygren@akamai.com
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