< draft-ietf-httpbis-alt-svc-06.txt		draft-ietf-httpbis-alt-svc-07.txt >
	HTTPbis Working Group M. Nottingham		HTTP Working Group M. Nottingham
	Internet-Draft Akamai		Internet-Draft Akamai
	Intended status: Standards Track P. McManus		Intended status: Standards Track P. McManus
	Expires: August 9, 2015 Mozilla		Expires: November 16, 2015 Mozilla
	J. Reschke		J. Reschke
	greenbytes		greenbytes
	February 5, 2015		May 15, 2015
	HTTP Alternative Services		HTTP Alternative Services
	draft-ietf-httpbis-alt-svc-06		draft-ietf-httpbis-alt-svc-07
	Abstract		Abstract
	This document specifies "alternative services" for HTTP, which allow		This document specifies "alternative services" for HTTP, which allow
	an origin's resources to be authoritatively available at a separate		an origin's resources to be authoritatively available at a separate
	network location, possibly accessed with a different protocol		network location, possibly accessed with a different protocol
	configuration.		configuration.
	Editorial Note (To be removed by RFC Editor)		Editorial Note (To be removed by RFC Editor)
	skipping to change at page 1, line 49 ¶		skipping to change at page 1, line 49 ¶
	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 9, 2015.		This Internet-Draft will expire on November 16, 2015.
	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
	skipping to change at page 3, line 16 ¶		skipping to change at page 3, line 16 ¶
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4		1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 4
	2. Alternative Services Concepts . . . . . . . . . . . . . . . . 5		2. Alternative Services Concepts . . . . . . . . . . . . . . . . 5
	2.1. Host Authentication . . . . . . . . . . . . . . . . . . . 6		2.1. Host Authentication . . . . . . . . . . . . . . . . . . . 6
	2.2. Alternative Service Caching . . . . . . . . . . . . . . . 7		2.2. Alternative Service Caching . . . . . . . . . . . . . . . 7
	2.3. Requiring Server Name Indication . . . . . . . . . . . . . 7		2.3. Requiring Server Name Indication . . . . . . . . . . . . . 7
	2.4. Using Alternative Services . . . . . . . . . . . . . . . . 7		2.4. Using Alternative Services . . . . . . . . . . . . . . . . 7
	3. The Alt-Svc HTTP Header Field . . . . . . . . . . . . . . . . 8		3. The Alt-Svc HTTP Header Field . . . . . . . . . . . . . . . . 8
	3.1. Caching Alt-Svc Header Field Values . . . . . . . . . . . 10		3.1. Caching Alt-Svc Header Field Values . . . . . . . . . . . 10
	4. The ALTSVC HTTP/2 Frame . . . . . . . . . . . . . . . . . . . 10		4. The ALTSVC HTTP/2 Frame . . . . . . . . . . . . . . . . . . . 11
	5. The Alt-Used HTTP Header Field . . . . . . . . . . . . . . . . 12		5. The Alt-Used HTTP Header Field . . . . . . . . . . . . . . . . 12
	6. The 421 Misdirected Request HTTP Status Code . . . . . . . . . 12		6. The 421 Misdirected Request HTTP Status Code . . . . . . . . . 12
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
	7.1. Header Field Registrations . . . . . . . . . . . . . . . . 13		7.1. Header Field Registrations . . . . . . . . . . . . . . . . 13
	7.2. The ALTSVC HTTP/2 Frame Type . . . . . . . . . . . . . . . 13		7.2. The ALTSVC HTTP/2 Frame Type . . . . . . . . . . . . . . . 13
	8. Internationalization Considerations . . . . . . . . . . . . . 13		8. Internationalization Considerations . . . . . . . . . . . . . 14
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 13		9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
	9.1. Changing Ports . . . . . . . . . . . . . . . . . . . . . . 13		9.1. Changing Ports . . . . . . . . . . . . . . . . . . . . . . 14
	9.2. Changing Hosts . . . . . . . . . . . . . . . . . . . . . . 14		9.2. Changing Hosts . . . . . . . . . . . . . . . . . . . . . . 14
	9.3. Changing Protocols . . . . . . . . . . . . . . . . . . . . 14		9.3. Changing Protocols . . . . . . . . . . . . . . . . . . . . 15
	9.4. Tracking Clients Using Alternative Services . . . . . . . 15		9.4. Tracking Clients Using Alternative Services . . . . . . . 15
	10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15		9.5. Confusion Regarding Request Scheme . . . . . . . . . . . . 15
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15		10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
	11.1. Normative References . . . . . . . . . . . . . . . . . . . 15		10.1. Normative References . . . . . . . . . . . . . . . . . . . 15
	11.2. Informative References . . . . . . . . . . . . . . . . . . 16		10.2. Informative References . . . . . . . . . . . . . . . . . . 16
	Appendix A. Change Log (to be removed by RFC Editor before		Appendix A. Change Log (to be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . 16		publication) . . . . . . . . . . . . . . . . . . . . 17
	A.1. Since draft-nottingham-httpbis-alt-svc-05 . . . . . . . . 16		A.1. Since draft-nottingham-httpbis-alt-svc-05 . . . . . . . . 17
	A.2. Since draft-ietf-httpbis-alt-svc-00 . . . . . . . . . . . 16		A.2. Since draft-ietf-httpbis-alt-svc-00 . . . . . . . . . . . 17
	A.3. Since draft-ietf-httpbis-alt-svc-01 . . . . . . . . . . . 17		A.3. Since draft-ietf-httpbis-alt-svc-01 . . . . . . . . . . . 17
	A.4. Since draft-ietf-httpbis-alt-svc-02 . . . . . . . . . . . 17		A.4. Since draft-ietf-httpbis-alt-svc-02 . . . . . . . . . . . 17
	A.5. Since draft-ietf-httpbis-alt-svc-03 . . . . . . . . . . . 17		A.5. Since draft-ietf-httpbis-alt-svc-03 . . . . . . . . . . . 17
	A.6. Since draft-ietf-httpbis-alt-svc-04 . . . . . . . . . . . 17		A.6. Since draft-ietf-httpbis-alt-svc-04 . . . . . . . . . . . 18
	A.7. Since draft-ietf-httpbis-alt-svc-05 . . . . . . . . . . . 18		A.7. Since draft-ietf-httpbis-alt-svc-05 . . . . . . . . . . . 18
			A.8. Since draft-ietf-httpbis-alt-svc-06 . . . . . . . . . . . 18
			Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 19
	1. Introduction		1. Introduction
	HTTP [RFC7230] conflates the identification of resources with their		HTTP [RFC7230] conflates the identification of resources with their
	location. In other words, "http://" (and "https://") URLs are used		location. In other words, "http://" (and "https://") URLs are used
	to both name and find things to interact with.		to both name and find things to interact with.
	In some cases, it is desirable to separate identification and		In some cases, it is desirable to separate identification and
	location in HTTP; keeping the same identifier for a resource, but		location in HTTP; keeping the same identifier for a resource, but
	interacting with it at a different location on the network.		interacting with it at a different location on the network.
	For example:		For example:
	o An origin server might wish to redirect a client to a different		o An origin server might wish to redirect a client to a different
	server when it needs to go down for maintenance, or it has found a		server when it needs to go down for maintenance, or it has found a
	server in a location that is more local to the client.		server in a location that is more local to the client.
	o An origin server might wish to offer access to its resources using		o An origin server might wish to offer access to its resources using
	a new protocol (such as HTTP/2, see [HTTP2]) or one using improved		a new protocol (such as HTTP/2, see [RFC7540]) or one using
	security (such as Transport Layer Security (TLS), see [RFC5246]).		improved security (such as Transport Layer Security (TLS), see
			[RFC5246]).
	o An origin server might wish to segment its clients into groups of		o An origin server might wish to segment its clients into groups of
	capabilities, such as those supporting Server Name Indication		capabilities, such as those supporting Server Name Indication
	(SNI, see Section 3 of [RFC6066]) and those not supporting it, for		(SNI, see Section 3 of [RFC6066]) and those not supporting it, for
	operational purposes.		operational purposes.
	This specification defines a new concept in HTTP, "Alternative		This specification defines a new concept in HTTP, "Alternative
	Services", that allows an origin server to nominate additional means		Services", that allows an origin server to nominate additional means
	of interacting with it on the network. It defines a general		of interacting with it on the network. It defines a general
	framework for this in Section 2, along with specific mechanisms for		framework for this in Section 2, along with specific mechanisms for
	advertising their existence using HTTP header fields (Section 3) or		advertising their existence using HTTP header fields (Section 3) or
	an HTTP/2 frame type (Section 4).		HTTP/2 frames (Section 4), plus a way to indicate that an alternative
			service was used (Section 5).
	It also introduces a new status code in Section 6, so that origin		It also introduces a new status code in Section 6, so that origin
	servers (or their nominated alternatives) can indicate that they are		servers (or their nominated alternatives) can indicate that they are
	not authoritative for a given origin, in cases where the wrong		not authoritative for a given origin, in cases where the wrong
	location is used.		location is used.
	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].
	This document uses the Augmented BNF defined in [RFC5234] along with		This document uses the Augmented BNF defined in [RFC5234] along with
	the "OWS", "delta-seconds", "parameter", "port", "quoted-string",		the "#rule" extension defined in Section 7 of [RFC7230]. The rules
	"token", and "uri-host" rules from [RFC7230], and uses the "#rule"		below are defined in [RFC7230] and [RFC7234]:
	extension defined in Section 7 of that document.
			OWS = <OWS, see [RFC7230], Section 3.2.3>
			delta-seconds = <delta-seconds; see [RFC7234], Section 1.2.1>
			port = <port, see [RFC7230], Section 2.7>
			quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
			token = <token, see [RFC7230], Section 3.2.6>
			uri-host = <uri-host, see [RFC7230], Section 2.7>
	2. Alternative Services Concepts		2. Alternative Services Concepts
	This specification defines a new concept in HTTP, the "alternative		This specification defines a new concept in HTTP, the "alternative
	service". When an origin (see [RFC6454]) has resources that are		service". When an origin (see [RFC6454]) has resources that are
	accessible through a different protocol / host / port combination, it		accessible through a different protocol / host / port combination, it
	is said to have an alternative service available.		is said to have an alternative service available.
	An alternative service can be used to interact with the resources on		An alternative service can be used to interact with the resources on
	an origin server at a separate location on the network, possibly		an origin server at a separate location on the network, possibly
	skipping to change at page 6, line 6 ¶		skipping to change at page 6, line 13 ¶
	options for that protocol.		options for that protocol.
	This means that clients using an alternative service can change the		This means that clients using an alternative service can change the
	host, port and protocol that they are using to fetch resources, but		host, port and protocol that they are using to fetch resources, but
	these changes MUST NOT be propagated to the application that is using		these changes MUST NOT be propagated to the application that is using
	HTTP; from that standpoint, the URI being accessed and all		HTTP; from that standpoint, the URI being accessed and all
	information derived from it (scheme, host, port) are the same as		information derived from it (scheme, host, port) are the same as
	before.		before.
	Importantly, this includes its security context; in particular, when		Importantly, this includes its security context; in particular, when
	TLS [RFC5246] is in use, the alternative service will need to present		TLS [RFC5246] is used to authenticate, the alternative service will
	a certificate for the origin's host name, not that of the		need to present a certificate for the origin's host name, not that of
	alternative. Likewise, the Host header field ([RFC7230], Section		the alternative. Likewise, the Host header field ([RFC7230], Section
	5.4) is still derived from the origin, not the alternative service		5.4) is still derived from the origin, not the alternative service
	(just as it would if a CNAME were being used).		(just as it would if a CNAME were being used).
	The changes MAY, however, be made visible in debugging tools,		The changes MAY, however, be made visible in debugging tools,
	consoles, etc.		consoles, etc.
	Formally, an alternative service is identified by the combination of:		Formally, an alternative service is identified by the combination of:
	o An Application Layer Protocol Negotiation (ALPN) protocol, as per		o An Application Layer Protocol Negotiation (ALPN) protocol, as per
	[RFC7301]		[RFC7301]
	skipping to change at page 8, line 32 ¶		skipping to change at page 8, line 39 ¶
	3. The Alt-Svc HTTP Header Field		3. The Alt-Svc HTTP Header Field
	An HTTP(S) origin server can advertise the availability of		An HTTP(S) origin server can advertise the availability of
	alternative services to clients by adding an Alt-Svc header field to		alternative services to clients by adding an Alt-Svc header field to
	responses.		responses.
	Alt-Svc = 1#( alternative *( OWS ";" OWS parameter ) )		Alt-Svc = 1#( alternative *( OWS ";" OWS parameter ) )
	alternative = protocol-id "=" alt-authority		alternative = protocol-id "=" alt-authority
	protocol-id = token ; percent-encoded ALPN protocol identifier		protocol-id = token ; percent-encoded ALPN protocol identifier
	alt-authority = quoted-string ; containing [ uri-host ] ":" port		alt-authority = quoted-string ; containing [ uri-host ] ":" port
			parameter = token "=" ( token / quoted-string )
	ALPN protocol names are octet sequences with no additional		ALPN protocol names are octet sequences with no additional
	constraints on format. Octets not allowed in tokens ([RFC7230],		constraints on format. Octets not allowed in tokens ([RFC7230],
	Section 3.2.6) MUST be percent-encoded as per Section 2.1 of		Section 3.2.6) MUST be percent-encoded as per Section 2.1 of
	[RFC3986]. Consequently, the octet representing the percent		[RFC3986]. Consequently, the octet representing the percent
	character "%" (hex 25) MUST be percent-encoded as well.		character "%" (hex 25) MUST be percent-encoded as well.
	In order to have precisely one way to represent any ALPN protocol		In order to have precisely one way to represent any ALPN protocol
	name, the following additional constraints apply:		name, the following additional constraints apply:
	skipping to change at page 9, line 9 ¶		skipping to change at page 9, line 18 ¶
	to match protocol identifiers.		to match protocol identifiers.
	The "alt-authority" component consists of an OPTIONAL uri-host		The "alt-authority" component consists of an OPTIONAL uri-host
	("host" in Section 3.2.2 of [RFC3986]), a colon (":"), and a port		("host" in Section 3.2.2 of [RFC3986]), a colon (":"), and a port
	number.		number.
	For example:		For example:
	Alt-Svc: h2=":8000"		Alt-Svc: h2=":8000"
	This indicates the "h2" protocol ([HTTP2]) on the same host using the		This indicates the "h2" protocol ([RFC7540]) on the same host using
	indicated port 8000.		the indicated port 8000.
	An example involving a change of host:		An example involving a change of host:
	Alt-Svc: h2="new.example.org:80"		Alt-Svc: h2="new.example.org:80"
	This indicates the "h2" protocol on the host "new.example.org",		This indicates the "h2" protocol on the host "new.example.org",
	running on port 80. Note that the "quoted-string" syntax needs to be		running on port 80. Note that the "quoted-string" syntax needs to be
	used because ":" is not an allowed character in "token".		used because ":" is not an allowed character in "token".
	Examples for protocol name escaping:		Examples for protocol name escaping:
	skipping to change at page 9, line 43 ¶		skipping to change at page 9, line 52 ¶
	status code.		status code.
	The Alt-Svc field value can have multiple values:		The Alt-Svc field value can have multiple values:
	Alt-Svc: h2c=":8000", h2=":443"		Alt-Svc: h2c=":8000", h2=":443"
	The value(s) advertised by Alt-Svc can be used by clients to open a		The value(s) advertised by Alt-Svc can be used by clients to open a
	new connection to one or more alternative services immediately, or		new connection to one or more alternative services immediately, or
	simultaneously with subsequent requests on the same connection.		simultaneously with subsequent requests on the same connection.
	When using HTTP/2 ([HTTP2]), servers SHOULD instead send an ALTSVC		When using HTTP/2 ([RFC7540]), servers SHOULD instead send an ALTSVC
	frame (Section 4). A single ALTSVC frame can be sent for a		frame (Section 4). A single ALTSVC frame can be sent for a
	connection; a new frame is not needed for every request.		connection; a new frame is not needed for every request.
	Note that all field elements that allow "quoted-string" syntax MUST		Note that all field elements that allow "quoted-string" syntax MUST
	be processed as per Section 3.2.6 of [RFC7230].		be processed as per Section 3.2.6 of [RFC7230].
	3.1. Caching Alt-Svc Header Field Values		3.1. Caching Alt-Svc Header Field Values
	When an alternative service is advertised using Alt-Svc, it is		When an alternative service is advertised using Alt-Svc, it is
	considered fresh for 24 hours from generation of the message. This		considered fresh for 24 hours from generation of the message. This
	can be modified with the 'ma' (max-age) parameter;		can be modified with the 'ma' (max-age) parameter:
	Alt-Svc: h2=":443"; ma=3600		Alt-Svc: h2=":443"; ma=3600
	which indicates the number of seconds since the response was		which indicates the number of seconds since the response was
	generated the alternative service is considered fresh for.		generated the alternative service is considered fresh for.
	ma = delta-seconds		ma = delta-seconds
	See Section 4.2.3 of [RFC7234] for details of determining response		See Section 4.2.3 of [RFC7234] for details of determining response
	age.		age.
	skipping to change at page 10, line 47 ¶		skipping to change at page 11, line 7 ¶
	When an Alt-Svc response header field is received from an origin, its		When an Alt-Svc response header field is received from an origin, its
	value invalidates and replaces all cached alternative services for		value invalidates and replaces all cached alternative services for
	that origin.		that origin.
	See Section 2.2 for general requirements on caching alternative		See Section 2.2 for general requirements on caching alternative
	services.		services.
	4. The ALTSVC HTTP/2 Frame		4. The ALTSVC HTTP/2 Frame
	The ALTSVC HTTP/2 frame ([HTTP2], Section 4) advertises the		The ALTSVC HTTP/2 frame ([RFC7540], Section 4) advertises the
	availability of an alternative service to an HTTP/2 client.		availability of an alternative service to an HTTP/2 client.
	The ALTSVC frame is a non-critical extension to HTTP/2. Endpoints		The ALTSVC frame is a non-critical extension to HTTP/2. Endpoints
	that do not support this frame can safely ignore it.		that do not support this frame can safely ignore it.
	An ALTSVC frame from a server to a client on a client-initiated		An ALTSVC frame from a server to a client on a stream other than
	stream indicates that the conveyed alternative service is associated		stream 0 indicates that the conveyed alternative service is
	with the origin of that stream.		associated with the origin of that stream.
	An ALTSVC frame from a server to a client on stream 0 indicates that		An ALTSVC frame from a server to a client on stream 0 indicates that
	the conveyed alternative service is associated with the origin		the conveyed alternative service is associated with the origin
	contained in the Origin field of the frame. An association with an		contained in the Origin field of the frame. An association with an
	origin that the client does not consider authoritative for the		origin that the client does not consider authoritative for the
	current connection MUST be ignored.		current connection MUST be ignored.
	The ALTSVC frame type is 0xa (decimal 10).		The ALTSVC frame type is 0xa (decimal 10).
	+-------------------------------+-------------------------------+		+-------------------------------+-------------------------------+
	skipping to change at page 11, line 45 ¶		skipping to change at page 12, line 5 ¶
	subtracting the length of all preceding fields from the frame		subtracting the length of all preceding fields from the frame
	length) containing a value identical to the Alt-Svc field value		length) containing a value identical to the Alt-Svc field value
	defined in Section 3 (ABNF production "Alt-Svc").		defined in Section 3 (ABNF production "Alt-Svc").
	The ALTSVC frame does not define any flags.		The ALTSVC frame does not define any flags.
	The ALTSVC frame is intended for receipt by clients; a server that		The ALTSVC frame is intended for receipt by clients; a server that
	receives an ALTSVC frame MUST treat it as a connection error of type		receives an ALTSVC frame MUST treat it as a connection error of type
	PROTOCOL_ERROR.		PROTOCOL_ERROR.
	An ALTSVC frame on a client-initiated stream containing non-empty		An ALTSVC frame on stream 0 with empty (length 0) "Origin"
	"Origin" information is invalid and MUST be ignored. Likewise, an		information is invalid and MUST be ignored. An ALTSVC frame on a
	ALTSVC frame on stream 0 with empty (length 0) "Origin" information		stream other than stream 0 containing non-empty "Origin" information
	is invalid and MUST be ignored.		is invalid and MUST be ignored.
	The ALTSVC frame is processed hop-by-hop. An intermediary MUST NOT		The ALTSVC frame is processed hop-by-hop. An intermediary MUST NOT
	forward ALTSVC frames, though it can use the information contained in		forward ALTSVC frames, though it can use the information contained in
	ALTSVC frames in forming new ALTSVC frames to send to its own		ALTSVC frames in forming new ALTSVC frames to send to its own
	clients.		clients.
	5. The Alt-Used HTTP Header Field		5. The Alt-Used HTTP Header Field
	The Alt-Used header field is used in requests to indicate the		The Alt-Used header field is used in requests to indicate the
	skipping to change at page 12, line 41 ¶		skipping to change at page 12, line 50 ¶
	Host: origin.example.com		Host: origin.example.com
	Alt-Used: alternate.example.net		Alt-Used: alternate.example.net
	The extension parameters (ext-param) are reserved for future use;		The extension parameters (ext-param) are reserved for future use;
	specifications that want to define an extension will need to update		specifications that want to define an extension will need to update
	this document (and ought to introduce an extension registry).		this document (and ought to introduce an extension registry).
	6. The 421 Misdirected Request HTTP Status Code		6. The 421 Misdirected Request HTTP Status Code
	The 421 (Misdirected Request) status code is defined in Section 9.1.2		The 421 (Misdirected Request) status code is defined in Section 9.1.2
	of [HTTP2] to indicate that the current server instance is not		of [RFC7540] to indicate that the current server instance is not
	authoritative for the requested resource. This can be used to		authoritative for the requested resource. This can be used to
	indicate that an alternative service is not authoritative; see		indicate that an alternative service is not authoritative; see
	Section 2).		Section 2).
	Clients receiving 421 (Misdirected Request) from an alternative		Clients receiving 421 (Misdirected Request) from an alternative
	service MUST remove the corresponding entry from its alternative		service MUST remove the corresponding entry from its alternative
	service cache (see Section 2.2) for that origin. Regardless of the		service cache (see Section 2.2) for that origin. Regardless of the
	idempotency of the request method, they MAY retry the request, either		idempotency of the request method, they MAY retry the request, either
	at another alternative server, or at the origin.		at another alternative server, or at the origin.
	skipping to change at page 13, line 33 ¶		skipping to change at page 13, line 40 ¶
	| Alt-Svc | http | standard | Section 3 |		| Alt-Svc | http | standard | Section 3 |
	| Alt-Used | http | standard | Section 5 |		| Alt-Used | http | standard | Section 5 |
	+-------------------+----------+----------+-----------+		+-------------------+----------+----------+-----------+
	The change controller is: "IETF (iesg@ietf.org) - Internet		The change controller is: "IETF (iesg@ietf.org) - Internet
	Engineering Task Force".		Engineering Task Force".
	7.2. The ALTSVC HTTP/2 Frame Type		7.2. The ALTSVC HTTP/2 Frame Type
	This document registers the ALTSVC frame type in the HTTP/2 Frame		This document registers the ALTSVC frame type in the HTTP/2 Frame
	Types registry ([HTTP2], Section 11.2).		Types registry ([RFC7540], Section 11.2).
	Frame Type: ALTSVC		Frame Type: ALTSVC
	Code: 0xa		Code: 0xa
	Specification: Section 4 of this document		Specification: Section 4 of this document
	8. Internationalization Considerations		8. Internationalization Considerations
	An internationalized domain name that appears in either the header		An internationalized domain name that appears in either the header
	skipping to change at page 15, line 6 ¶		skipping to change at page 15, line 19 ¶
	agent still directs traffic to the attacker even when not using the		agent still directs traffic to the attacker even when not using the
	intermediary.		intermediary.
	9.3. Changing Protocols		9.3. Changing Protocols
	When the ALPN protocol is changed due to the use of an alternative		When the ALPN protocol is changed due to the use of an alternative
	service, the security properties of the new connection to the origin		service, the security properties of the new connection to the origin
	can be different from that of the "normal" connection to the origin,		can be different from that of the "normal" connection to the origin,
	because the protocol identifier itself implies this.		because the protocol identifier itself implies this.
	For example, if a "https://" URI had a protocol advertised that does		For example, if a "https://" URI has a protocol advertised that does
	not use some form of end-to-end encryption (most likely, TLS), it		not use some form of end-to-end encryption (most likely, TLS), it
	violates the expectations for security that the URI scheme implies.		violates the expectations for security that the URI scheme implies.
	Therefore, clients cannot blindly use alternative services, but		Therefore, clients cannot blindly use alternative services, but
	instead evaluate the option(s) presented to assure that security		instead evaluate the option(s) presented to assure that security
	requirements and expectations (of specifications, implementations and		requirements and expectations (of specifications, implementations and
	end users) are met.		end users) are met.
	9.4. Tracking Clients Using Alternative Services		9.4. Tracking Clients Using Alternative Services
	Choosing an alternative service implies connecting to a new, server-		Choosing an alternative service implies connecting to a new, server-
	supplied host name. By using many different (potentially unique)		supplied host name. By using many different (potentially unique)
	host names, servers could conceivably track client requests.		host names, servers could conceivably track client requests.
	Clients concerned by the additional fingerprinting can choose to		Clients concerned by the additional fingerprinting can choose to
	ignore alternative service advertisements.		ignore alternative service advertisements.
	In a browser, any alternative service information MUST be removed		In a user agent, any alternative service information MUST be removed
	when origin-specific data is cleared (for instance, when cookies are		when origin-specific data is cleared (for instance, when cookies are
	cleared).		cleared).
	10. Acknowledgements		9.5. Confusion Regarding Request Scheme
	Thanks to Adam Langley, Bence Beky, Eliot Lear, Erik Nygren, Guy
	Podjarny, Herve Ruellan, Martin Thomson, Matthew Kerwin, Paul
	Hoffman, Richard Barnes, Stephen Farrell, Stephen Ludin, and Will
	Chan for their feedback and suggestions.
	The Alt-Svc header field was influenced by the design of the
	Alternate-Protocol header field in SPDY.
	11. References		Alternative Services MUST NOT be advertised for a protocol that is
			not designed to carry the scheme. In particular, HTTP/1.1 over TLS
			cannot carry safely requests for http resources.
	11.1. Normative References		10. References
	[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext		10.1. Normative References
	Transfer Protocol version 2", draft-ietf-httpbis-http2-16
	(work in progress), November 2014.
	[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, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997,
			<http://www.rfc-editor.org/info/rfc2119>.
	[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform		[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
	Resource Identifier (URI): Generic Syntax", STD 66,		Resource Identifier (URI): Generic Syntax", STD 66,
	RFC 3986, January 2005.		RFC 3986, January 2005,
			<http://www.rfc-editor.org/info/rfc3986>.
	[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234, January 2008.		Specifications: ABNF", STD 68, RFC 5234, January 2008,
			<http://www.rfc-editor.org/info/rfc5234>.
	[RFC5890] Klensin, J., "Internationalized Domain Names for		[RFC5890] Klensin, J., "Internationalized Domain Names for
	Applications (IDNA): Definitions and Document Framework",		Applications (IDNA): Definitions and Document Framework",
	RFC 5890, August 2010.		RFC 5890, August 2010,
			<http://www.rfc-editor.org/info/rfc5890>.
	[RFC6066] Eastlake, D., "Transport Layer Security (TLS) Extensions:		[RFC6066] Eastlake, D., "Transport Layer Security (TLS) Extensions:
	Extension Definitions", RFC 6066, January 2011.		Extension Definitions", RFC 6066, 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,
	December 2011.		December 2011, <http://www.rfc-editor.org/info/rfc6454>.
	[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer		[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	Protocol (HTTP/1.1): Message Syntax and Routing",		Protocol (HTTP/1.1): Message Syntax and Routing",
	RFC 7230, June 2014.		RFC 7230, June 2014,
			<http://www.rfc-editor.org/info/rfc7230>.
	[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,		[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",		Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
	RFC 7234, June 2014.		RFC 7234, June 2014,
			<http://www.rfc-editor.org/info/rfc7234>.
	[RFC7301] Friedl, S., Popov, A., Langley, A., and S. Emile,		[RFC7301] Friedl, S., Popov, A., Langley, A., and S. Emile,
	"Transport Layer Security (TLS) Application-Layer Protocol		"Transport Layer Security (TLS) Application-Layer Protocol
	Negotiation Extension", RFC 7301, July 2014.		Negotiation Extension", RFC 7301, July 2014,
			<http://www.rfc-editor.org/info/rfc7301>.
	11.2. Informative References		[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
			Transfer Protocol version 2", RFC 7540, May 2015,
			<http://www.rfc-editor.org/info/rfc7540>.
			10.2. Informative References
	[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration		[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
	Procedures for Message Header Fields", BCP 90, RFC 3864,		Procedures for Message Header Fields", BCP 90, RFC 3864,
	September 2004.		September 2004, <http://www.rfc-editor.org/info/rfc3864>.
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.2", RFC 5246, August 2008.		(TLS) Protocol Version 1.2", RFC 5246, August 2008,
			<http://www.rfc-editor.org/info/rfc5246>.
	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. Since draft-nottingham-httpbis-alt-svc-05		A.1. Since draft-nottingham-httpbis-alt-svc-05
	This is the first version after adoption of		This is the first version after adoption of
	draft-nottingham-httpbis-alt-svc-05 as Working Group work item. It		draft-nottingham-httpbis-alt-svc-05 as Working Group work item. It
	only contains editorial changes.		only contains editorial changes.
	A.2. Since draft-ietf-httpbis-alt-svc-00		A.2. Since draft-ietf-httpbis-alt-svc-00
	skipping to change at page 18, line 13 ¶		skipping to change at page 18, line 30 ¶
	(<https://github.com/httpwg/http-extensions/issues/37>).		(<https://github.com/httpwg/http-extensions/issues/37>).
	A.7. Since draft-ietf-httpbis-alt-svc-05		A.7. Since draft-ietf-httpbis-alt-svc-05
	Go back to specifying the origin in Alt-Used, but make it a "SHOULD"		Go back to specifying the origin in Alt-Used, but make it a "SHOULD"
	(<https://github.com/httpwg/http-extensions/issues/34>).		(<https://github.com/httpwg/http-extensions/issues/34>).
	Restore Origin field in ALT-SVC frame		Restore Origin field in ALT-SVC frame
	(<https://github.com/httpwg/http-extensions/issues/38>).		(<https://github.com/httpwg/http-extensions/issues/38>).
			A.8. Since draft-ietf-httpbis-alt-svc-06
			Disallow use of alternative services when the protocol might not
			carry the scheme
			(<https://github.com/httpwg/http-extensions/issues/12>).
			Align opp-sec and alt-svc
			(<https://github.com/httpwg/http-extensions/issues/33>).
			alt svc frame on pushed (even and non-0) frame
			(<https://github.com/httpwg/http-extensions/issues/44>).
			"browser" -> "user agent"
			(<https://github.com/httpwg/http-extensions/pull/61>).
			ABNF for "parameter"
			(<https://github.com/httpwg/http-extensions/issues/65>).
			Updated HTTP/2 reference.
			Appendix B. Acknowledgements
			Thanks to Adam Langley, Bence Beky, Eliot Lear, Erik Nygren, Guy
			Podjarny, Herve Ruellan, Martin Thomson, Matthew Kerwin, Paul
			Hoffman, Richard Barnes, Stephen Farrell, Stephen Ludin, and Will
			Chan for their feedback and suggestions.
			The Alt-Svc header field was influenced by the design of the
			Alternate-Protocol header field in SPDY.
	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/
	Patrick McManus		Patrick McManus
	Mozilla		Mozilla
End of changes. 44 change blocks.
	68 lines changed or deleted		114 lines changed or added
This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/