< draft-ietf-httpbis-origin-frame-01.txt		draft-ietf-httpbis-origin-frame-02.txt >
	HTTP Working Group M. Nottingham		HTTP Working Group M. Nottingham
	Internet-Draft E. Nygren		Internet-Draft E. Nygren
	Intended status: Standards Track Akamai		Intended status: Standards Track Akamai
	Expires: April 1, 2017 September 28, 2016		Expires: August 17, 2017 February 13, 2017
	The ORIGIN HTTP/2 Frame		The ORIGIN HTTP/2 Frame
	draft-ietf-httpbis-origin-frame-01		draft-ietf-httpbis-origin-frame-02
	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 41 ¶
	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 April 1, 2017.		This Internet-Draft will expire on August 17, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 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
	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 . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Notational Conventions . . . . . . . . . . . . . . . . . 2		1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
	2. The ORIGIN HTTP/2 Frame . . . . . . . . . . . . . . . . . . . 2		2. The ORIGIN HTTP/2 Frame . . . . . . . . . . . . . . . . . . . 3
	2.1. The Origin Set . . . . . . . . . . . . . . . . . . . . . 3		2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2.2. Processing ORIGIN Frames . . . . . . . . . . . . . . . . 4		2.2. Processing ORIGIN Frames . . . . . . . . . . . . . . . . 3
	3. Security Considerations . . . . . . . . . . . . . . . . . . . 5		2.3. The Origin Set . . . . . . . . . . . . . . . . . . . . . 4
	4. Normative References . . . . . . . . . . . . . . . . . . . . 5		2.4. Authority, Push and Coalescing with ORIGIN . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5		3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
			4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
			5. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
			5.1. Normative References . . . . . . . . . . . . . . . . . . 6
			5.2. Informative References . . . . . . . . . . . . . . . . . 7
			Appendix A. Non-Normative Processing Algorithm . . . . . . . . . 7
			Appendix B. Operational Considerations for Servers . . . . . . . 8
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	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
	misdirected requests, but at the penalty of adding latency. To		misdirected requests, but at the penalty of adding latency. To
	address that, this specification defines a new HTTP/2 frame type,		address that, this specification defines a new HTTP/2 frame type,
	"ORIGIN", to allow servers to indicate what origins a connection is		"ORIGIN", to allow servers to indicate what origins a connection is
	usable for.		usable for.
			Additionally, experience has shown that HTTP/2's requirement to
			establish server authority using both DNS and the server's
			certificate is onerous. This specification relaxes the requirement
			to check DNS when the ORIGIN frame is in use. Doing so has
			additional benefits, such as removing the latency associated with
			some DNS lookups, and improving DNS privacy.
	1.1. Notational Conventions		1.1. 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].
	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 2.1) 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
	The ORIGIN frame type is 0xb (decimal 11).		The ORIGIN frame type is 0xb (decimal 11).
	+-------------------------------+-------------------------------+		+-------------------------------+-------------------------------+
	| Origin-Len (16) | 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 Origin field.		octets, of the ASCII-Origin field.
	Origin: An optional sequence of characters containing the ASCII		Origin: An optional sequence of characters containing the ASCII
	serialization of an origin ([RFC6454], Section 6.2) that the		serialization of an origin ([RFC6454], Section 6.2) that the
	sender believes this connection is or could be authoritative for.		sender believes this connection is or could be authoritative for.
	The ORIGIN frame defines the following flags:		The ORIGIN frame does not define any flags. However, future updates
			to this specification MAY define flags. See Section 2.2.
	CLEAR (0x1): Indicates that the Origin Set MUST be reset to an empty		2.2. Processing ORIGIN Frames
	set before processing the contents of the frame it occurs upon.
	REMOVE (0x2): Indicates that the origin(s) carried in the payload		The ORIGIN frame is a non-critical extension to HTTP/2. Endpoints
	must be removed from the Origin Set, if present; if not present,		that do not support this frame can safely ignore it upon receipt.
	it/they have no effect.
	2.1. The Origin Set		When received by an implementing client, it is used to initialise and
			manipulate the Origin Set (see Section 2.3), thereby changing how the
			client establishes authority for origin servers (see Section 2.4).
			The origin frame MUST be sent on stream 0; an ORIGIN frame on any
			other stream is invalid and MUST be ignored.
			Likewise, the ORIGIN frame is only valid on connections with the "h2"
			protocol identifier, or when specifically nominated by the protocol's
			definition; it MUST be ignored when received on a connection with the
			"h2c" protocol identifier.
			This specification does not define any flags for the ORIGIN frame,
			but future updates might use them to change its semantics. The first
			four flags (0x1, 0x2, 0x4 and 0x8) are reserved for backwards-
			incompatible changes, and therefore when any of them are set, the
			ORIGIN frame containing them MUST be ignored by clients conforming to
			this specification. The remaining flags are reserved for backwards-
			compatible changes, and do not affect processing by clients
			conformant to this specification.
			The ORIGIN frame describes a property of the connection, and
			therefore is processed hop-by-hop. An intermediary MUST NOT forward
			ORIGIN frames. Clients configured to use a proxy MUST ignore any
			ORIGIN frames received from it.
			Each ASCII-Origin field in the frame's payload MUST be parsed as an
			ASCII serialisation of an origin ([RFC6454], Section 6.2). If
			parsing fails, the field MUST be ignored.
			See Appendix A for an illustrative algorithm for processing ORIGIN
			frames.
			2.3. The Origin Set
	The set of origins (as per [RFC6454]) that a given connection might		The set of origins (as per [RFC6454]) that a given connection might
	be used for is known in this specification as the Origin Set.		be used for is known in this specification as the Origin Set.
	When a connection is first established, its Origin Set is defined to		By default, a connections's Origin Set is uninitialised. When an
	be those origins that the client would normally consider the		ORIGIN frame is first received and successfully processed by a
	connection authoritative for; see [RFC7540], Section 10.1.		client, the connection's Origin Set is defined to contain a single
			origin, composed from:
	The ORIGIN frame allows the server to modify the Origin Set. In
	particular:
	1. A server can add to its members by sending an ORIGIN frame		o Scheme: "https"
	(without any flags set);
	2. A server can prune one or more origins from it by sending an		o Host: the value sent in Server Name Indication ([RFC6066]
	ORIGIN frame with the REMOVE flag set;		Section 3), converted to lower case
	3. A server can remove all its members and then add zero or more		o Port: the remote port of the connection (i.e., the server's port)
	members by sending an ORIGIN frame with the CLEAR flag set and a
	payload containing the new origins.
	Adding to the Origin Set (cases 1 and 3 above) does not imply that		The contents of that ORIGIN frame (and subsequent ones) allows the
	the connection is authoritative for the added origins (in the sense		server to incrementally add new origins to the Origin Set, as
	of [RFC7540], Section 10.1) on its own; this MUST be established by		described in Section 2.2.
	some other mechanism.
	A client that implements this specification MUST NOT use a connection		The Origin Set is also affected by the 421 (Misdirected Request)
	for a given origin unless that origin appears in the Origin Set for		response status code, defined in [RFC7540] Section 9.1.2. Upon
	the connection, regardless of whether or not it believes that the		receipt of a response with this status code, implementing clients
	connection is authoritative for that origin.		MUST create the ASCII serialisation of the corresponding request's
			origin (as per [RFC6454], Section 6.2) and remove it from the
			connection's Origin Set, if present.
	2.2. Processing ORIGIN Frames		2.4. Authority, Push and Coalescing with ORIGIN
	The ORIGIN frame is a non-critical extension to HTTP/2. Endpoints		[RFC7540], Section 10.1 uses both DNS and the presented TLS
	that do not support this frame can safely ignore it upon receipt.		certificate to establish the origin server(s) that a connection is
			authoritative for, just as HTTP/1.1 does in [RFC7230]. Furthermore,
			[RFC7540] Section 9.1.1 explicitly allows a connection to be used for
			more than one origin server, if it is authoritative. This affects
			what requests can be sent on the connection, both in HEADERS frame by
			the client and as PUSH_PROMISE frames from the server.
	When received by a client, it can be used to inform HTTP/2 connection		Once an Origin Set has been initialised for a connection, clients
	coalescing (see Section 2.1), but does not relax the requirement		that implement this specification change these behaviors in the
	there that the server is authoritative.		following ways:
	The origin frame MUST be sent on stream 0; an ORIGIN frame on any		o Clients MUST NOT consult DNS to establish the connection's
	other stream is invalid and MUST be ignored.		authority for new requests. The TLS certificate MUST stil be used
			to do so, as described in [RFC7540] Section 9.1.1.
	The ORIGIN frame is processed hop-by-hop. An intermediary MUST NOT		o Clients sending a new request SHOULD use an existing connection if
	forward ORIGIN frames. Clients configured to use a proxy MUST ignore		the request's origin is in that connection's Origin Set, unless
	any ORIGIN frames received from it.		there are operational reasons for creating a new connection.
	The following algorithm illustrates how a client can handle received		o Clients MUST use the Origin Set to determine whether a received
	ORIGIN frames:		PUSH_PROMISE is authoritative, as described in [RFC7540],
			Section 8.2.2.
	1. If the client is configured to use a proxy, ignore the frame and		Note that clients are still required to perform checks on the
	stop processing.		certificate presented by the server for each origin that a connection
			is used for; see [RFC7540] Section 9.1.1 for more information. This
			includes verifying that the host matches a "dNSName" value from the
			certificate "subjectAltName" field (using the wildcard rules defined
			in [RFC2818]; see also [RFC5280] Section 4.2.1.6).
	2. If the frame occurs upon any stream except stream 0, ignore the		Because ORIGIN can change the set of origins a connection is used for
	frame and stop processing.		over time, it is possible that a client might have more than one
			viable connection to an origin open at any time. When this occurs,
			clients SHOULD not emit new requests on any connection whose Origin
			Set is a subset of another connection's Origin Set, and SHOULD close
			it once all outstanding requests are satisfied.
	3. If the CLEAR flag is set, remove all members from the Origin Set.		3. IANA Considerations
	4. For each Origin field "origin_raw" in the frame payload:		This specification adds an entry to the "HTTP/2 Frame Type" registry.
	1. Parse "origin_raw" as an ASCII serialization of an origin		o Frame Type: ORIGIN
	([RFC6454], Section 6.2) and let the result be
	"parsed_origin".
	2. If the REMOVE flag is set, remove any member of the Origin		o Code: 0xb
	Set that is the same as "parsed_origin" (as per [RFC6454],
	Section 5), and continue to the next "parsed_origin".
	3. Otherwise, add "parsed_origin" to the Origin Set.		o Specification: [this document]
	3. 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; hence the reinforcement that		vulnerable to a large number of attacks. See Section 2.4 for
	this specification does not relax the requirement for server		mitigations.
	authority in [RFC7540], Section 10.1.
	4. Normative References		Relaxing the requirement to consult DNS when determining authority
			for an origin means that an attacker who possesses a valid
			certificate no longer needs to be on-path to redirect traffic to
			them; instead of modifying DNS, they need only convince the user to
			visit another Web site, in order to coalesce connections to the
			target onto their existing connection.
			5. References
			5.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
			[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
			DOI 10.17487/RFC2818, May 2000,
			<http://www.rfc-editor.org/info/rfc2818>.
			[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
			Housley, R., and W. Polk, "Internet X.509 Public Key
			Infrastructure Certificate and Certificate Revocation List
			(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
			<http://www.rfc-editor.org/info/rfc5280>.
			[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
			Extensions: Extension Definitions", RFC 6066,
			DOI 10.17487/RFC6066, January 2011,
			<http://www.rfc-editor.org/info/rfc6066>.
	[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,		[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
	DOI 10.17487/RFC6454, December 2011,		DOI 10.17487/RFC6454, December 2011,
	<http://www.rfc-editor.org/info/rfc6454>.		<http://www.rfc-editor.org/info/rfc6454>.
	[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext		[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
	Transfer Protocol Version 2 (HTTP/2)", RFC 7540,		Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
	DOI 10.17487/RFC7540, May 2015,		DOI 10.17487/RFC7540, May 2015,
	<http://www.rfc-editor.org/info/rfc7540>.		<http://www.rfc-editor.org/info/rfc7540>.
			5.2. Informative References
			[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
			DOI 10.17487/RFC5988, October 2010,
			<http://www.rfc-editor.org/info/rfc5988>.
			[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>.
			[RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP
			Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
			April 2016, <http://www.rfc-editor.org/info/rfc7838>.
			Appendix A. Non-Normative Processing Algorithm
			The following algorithm illustrates how a client could handle
			received ORIGIN frames:
			1. If the client is configured to use a proxy for the connection,
			ignore the frame and stop processing.
			2. If the connection is not identified with the "h2" protocol
			identifier or another protocol that has explicitly opted into
			this specification, ignore the frame and stop processing.
			3. If the frame occurs upon any stream except stream 0, ignore the
			frame and stop processing.
			4. If any of the flags 0x1, 0x2, 0x4 or 0x8 are set, ignore the
			frame and stop processing.
			5. If no previous ORIGIN frame on the connection has reached this
			step, initialise the Origin Set as per Section 2.3.
			6. For each Origin field "origin_raw" in the frame payload:
			1. Parse "origin_raw" as an ASCII serialization of an origin
			([RFC6454], Section 6.2) and let the result be
			"parsed_origin". If parsing fails, skip to the next
			"origin_raw".
			2. Add "parsed_origin" to the Origin Set.
			Appendix B. Operational Considerations for Servers
			The ORIGIN frame allows a server to indicate for which origins a
			given connection ought be used.
			For example, it can be used to inform the client that the connection
			is to only be used for the SNI-based origin, by sending an empty
			ORIGIN frame. Or, a larger number of origins can be indicated by
			including a payload.
			Generally, this information is most useful to send before sending any
			part of a response that might initiate a new connection; for example,
			"Link" headers [RFC5988] in a response HEADERS, or links in the
			response body.
			Therefore, the ORIGIN frame ought be sent as soon as possible on a
			connection, ideally before any HEADERS or PUSH_PROMISE frames.
			However, if it's desirable to associate a large number of origins
			with a connection, doing so might introduce end-user perceived
			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
			of origins the connection is used for with subsequent ORIGIN frames
			later (e.g., when the connection is idle).
			Senders should note that, as per [RFC6454] Section 4, the values in
			an ORIGIN header need to be case-normalised before serialisation.
			Finally, servers that allow alternative services [RFC7838] will need
			to explicitly advertise those origins when sending ORIGIN, because
			the default contents of the Origin Set (as per Section 2.3) do not
			contain any Alternative Services, even if they have been used
			previously on the connection.
	Authors' Addresses		Authors' Addresses
	Mark Nottingham		Mark Nottingham
	Akamai		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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