< draft-ietf-httpbis-replay-00.txt		draft-ietf-httpbis-replay-01.txt >
	httpbis Working Group M. Thomson		httpbis Working Group M. Thomson
	Internet-Draft Mozilla		Internet-Draft Mozilla
	Intended status: Standards Track M. Nottingham		Intended status: Standards Track M. Nottingham
	Expires: March 10, 2018 true		Expires: April 23, 2018 Fastly
	W. Tarreau		W. Tarreau
	HAProxy Technologies		HAProxy Technologies
	September 06, 2017		October 20, 2017
	Using Early Data in HTTP		Using Early Data in HTTP
	draft-ietf-httpbis-replay-00		draft-ietf-httpbis-replay-01
	Abstract		Abstract
	This document explains the risks of using early data for HTTP and		This document explains the risks of using early data for HTTP and
	describes techniques for reducing them. In particular, it defines a		describes techniques for reducing them. In particular, it defines a
	mechanism that enables clients to communicate with servers about		mechanism that enables clients to communicate with servers about
	early data, to assure correct operation.		early data, to assure correct operation.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 https://datatracker.ietf.org/drafts/current/.
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	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on March 10, 2018.		This Internet-Draft will expire on April 23, 2018.
	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.
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	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
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	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. Conventions and Definitions . . . . . . . . . . . . . . . 3		1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3
	2. Early Data in HTTP . . . . . . . . . . . . . . . . . . . . . 3		2. Early Data in HTTP . . . . . . . . . . . . . . . . . . . . . 3
	3. Supporting Early Data in HTTP Servers . . . . . . . . . . . . 3		3. Supporting Early Data in HTTP Servers . . . . . . . . . . . . 3
	4. Using Early Data in HTTP Clients . . . . . . . . . . . . . . 5		4. Using Early Data in HTTP Clients . . . . . . . . . . . . . . 5
	5. Extensions for Early Data in HTTP . . . . . . . . . . . . . . 6		5. Extensions for Early Data in HTTP . . . . . . . . . . . . . . 6
	5.1. The Early-Data Header Field . . . . . . . . . . . . . . . 6		5.1. The Early-Data Header Field . . . . . . . . . . . . . . . 6
	5.2. The 4NN (Too Early) Status Code . . . . . . . . . . . . . 7		5.2. The 425 (Too Early) Status Code . . . . . . . . . . . . . 7
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 8		6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	6.1. Gateways and Early Data . . . . . . . . . . . . . . . . . 8		6.1. Gateways and Early Data . . . . . . . . . . . . . . . . . 8
	6.2. Consistent Handling of Early Data . . . . . . . . . . . . 8		6.2. Consistent Handling of Early Data . . . . . . . . . . . . 8
	6.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 8		6.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 8
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		6.4. Out of Order Delivery . . . . . . . . . . . . . . . . . . 9
			7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
	8.1. Normative References . . . . . . . . . . . . . . . . . . 9		8.1. Normative References . . . . . . . . . . . . . . . . . . 9
	8.2. Informative References . . . . . . . . . . . . . . . . . 10		8.2. Informative References . . . . . . . . . . . . . . . . . 10
	Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 10		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	TLS 1.3 [TLS13] introduces the concept of early data (also known as		TLS 1.3 [TLS13] introduces the concept of early data (also known as
	zero round trip data or 0-RTT data). Early data allows a client to		zero round trip data or 0-RTT data). Early data allows a client to
	send data to a server in the first round trip of a connection,		send data to a server in the first round trip of a connection,
	without waiting for the TLS handshake to complete if the client has		without waiting for the TLS handshake to complete if the client has
	spoken to the same server recently.		spoken to the same server recently.
	skipping to change at page 3, line 49 ¶		skipping to change at page 3, line 49 ¶
	1. TLS [TLS13] mandates the use of replay detection strategies that		1. TLS [TLS13] mandates the use of replay detection strategies that
	reduce the ability of an attacker to successfully replay early		reduce the ability of an attacker to successfully replay early
	data. These anti-replay techniques reduce but don't completely		data. These anti-replay techniques reduce but don't completely
	eliminate the chance of data being replayed and ensure a fixed		eliminate the chance of data being replayed and ensure a fixed
	upper limit to the number of replays.		upper limit to the number of replays.
	2. The server can choose whether it will process early data before		2. The server can choose whether it will process early data before
	the TLS handshake completes. By deferring processing, it can		the TLS handshake completes. By deferring processing, it can
	ensure that only a successfully completed connection is used for		ensure that only a successfully completed connection is used for
	the request(s) therein. Assuming that a replayed ClientHello		the request(s) therein. This provides the server with some
	will not result in additional connections being made by the		assurance that the early data was not replayed.
	client, this provides the server with some assurance that the
	early data was not replayed.
	3. If the server receives multiple requests in early data, it can		3. If the server receives multiple requests in early data, it can
	determine whether to defer HTTP processing on a per-request		determine whether to defer HTTP processing on a per-request
	basis. This may require buffering the responses to preserve		basis. This may require buffering the responses to preserve
	ordering in HTTP/1.1.		ordering in HTTP/1.1.
	4. The server can cause a client to retry a request and not use		4. The server can cause a client to retry a request and not use
	early data by responding with the 4NN (Too Early) status code		early data by responding with the 425 (Too Early) status code
	(Section 5.2), in cases where the risk of replay is judged too		(Section 5.2), in cases where the risk of replay is judged too
	great.		great.
	For a given request, the level of tolerance to replay risk is		For a given request, the level of tolerance to replay risk is
	specific to the resource it operates upon (and therefore only known		specific to the resource it operates upon (and therefore only known
	to the origin server). In general, if processing a request does not		to the origin server). In general, if processing a request does not
	have state-changing side effects, the consequences of replay are not		have state-changing side effects, the consequences of replay are not
	significant.		significant.
	The request method's safety ([RFC7231], Section 4.2.1) is one way to		The request method's safety ([RFC7231], Section 4.2.1) is one way to
	skipping to change at page 5, line 5 ¶		skipping to change at page 5, line 5 ¶
	Intermediary servers do not have sufficient information to make this		Intermediary servers do not have sufficient information to make this
	determination, so Section 5.2 describes a way for the origin to		determination, so Section 5.2 describes a way for the origin to
	signal to them that a particular request isn't appropriate for early		signal to them that a particular request isn't appropriate for early
	data. Intermediaries that accept early data MUST implement that		data. Intermediaries that accept early data MUST implement that
	mechanism.		mechanism.
	Note that a server cannot choose to selectively reject early data at		Note that a server cannot choose to selectively reject early data at
	the TLS layer. TLS only permits a server to accept all early data,		the TLS layer. TLS only permits a server to accept all early data,
	or none of it. Once a server has decided to accept early data, it		or none of it. Once a server has decided to accept early data, it
	MUST process all requests in early data, even if the server rejects		MUST process all requests in early data, even if the server rejects
	the request by sending a 4NN (Too Early) response.		the request by sending a 425 (Too Early) response.
	A server can limit the amount of early data with the		A server can limit the amount of early data with the
	"max_early_data_size" field of the "early_data" TLS extension. This		"max_early_data_size" field of the "early_data" TLS extension. This
	can be used to avoid committing an arbitrary amount of memory for		can be used to avoid committing an arbitrary amount of memory for
	deferred requests. A server SHOULD ensure that when it accepts early		deferred requests. A server SHOULD ensure that when it accepts early
	data, it can defer processing of requests until after the TLS		data, it can defer processing of requests until after the TLS
	handshake completes.		handshake completes.
	4. Using Early Data in HTTP Clients		4. Using Early Data in HTTP Clients
	skipping to change at page 5, line 37 ¶		skipping to change at page 5, line 37 ¶
	start sending again as though the connection was new. For HTTP/2,		start sending again as though the connection was new. For HTTP/2,
	this means re-sending the connection preface. Any requests sent in		this means re-sending the connection preface. Any requests sent in
	early data MUST be sent again, unless the client decides to abandon		early data MUST be sent again, unless the client decides to abandon
	those requests.		those requests.
	This automatic retry exposes the request to a potential replay		This automatic retry exposes the request to a potential replay
	attack. An attacker sends early data to one server instance that		attack. An attacker sends early data to one server instance that
	accepts and processes the early data, but allows that connection to		accepts and processes the early data, but allows that connection to
	proceed no further. The attacker then forwards the same messages		proceed no further. The attacker then forwards the same messages
	from the client to another server instance that will reject early		from the client to another server instance that will reject early
	data. The client the retries the request, resulting in the request		data. The client then retries the request, resulting in the request
	being processed twice. Replays are also possible if there are		being processed twice. Replays are also possible if there are
	multiple server instances that will accept early data, or if the same		multiple server instances that will accept early data, or if the same
	server accepts early data multiple times (though this would be in		server accepts early data multiple times (though this would be in
	violation of requirements in TLS).		violation of requirements in TLS).
	Clients that use early data MUST retry requests upon receipt of a 4NN		Clients that use early data MUST retry requests upon receipt of a 425
	(Too Early) status code; see Section 5.2.		(Too Early) status code; see Section 5.2.
	An intermediary MUST NOT use early data when forwarding a request		An intermediary MUST NOT use early data when forwarding a request
	unless early data was used on a previous hop, or it knows that the		unless early data was used on a previous hop, or it knows that the
	request can be retried safely without consequences (typically, using		request can be retried safely without consequences (typically, using
	out-of-band configuration). Absent better information, that means		out-of-band configuration). Absent better information, that means
	that an intermediary can only use early data if the request either		that an intermediary can only use early data if the request either
	arrived in early data or arrived with the "Early-Data" header field		arrived in early data or arrived with the "Early-Data" header field
	set to "1".		set to "1" (see Section 5.1).
	5. Extensions for Early Data in HTTP		5. Extensions for Early Data in HTTP
	Because HTTP requests can span multiple "hops", it is necessary to		Because HTTP requests can span multiple "hops", it is necessary to
	explicitly communicate whether a request has been sent in early data		explicitly communicate whether a request has been sent in early data
	on a previous connection. Likewise, some means of explicitly		on a previous connection. Likewise, some means of explicitly
	triggering a retry when early data is not desirable is necessary.		triggering a retry when early data is not desirable is necessary.
	Finally, it is necessary to know whether the client will actually		Finally, it is necessary to know whether the client will actually
	perform such a retry.		perform such a retry.
	To meet these needs, two signalling mechanisms are defined:		To meet these needs, two signalling mechanisms are defined:
	o The "Early-Data" header field is included in requests that are		o The "Early-Data" header field is included in requests that are
	received in early data.		received in early data.
	o The 4NN (Too Early) status code is defined for a server to		o The 425 (Too Early) status code is defined for a server to
	indicate that a request could not be processed due to the		indicate that a request could not be processed due to the
	consequences of a possible replay attack.		consequences of a possible replay attack.
	They are designed to enable better coordination of the use of early		They are designed to enable better coordination of the use of early
	data between the user agent and origin server, and also when a		data between the user agent and origin server, and also when a
	gateway (also "reverse proxy", "Content Delivery Network", or		gateway (also "reverse proxy", "Content Delivery Network", or
	"surrogate") is present.		"surrogate") is present.
	Gateways typically don't have specific information about whether a		Gateways typically don't have specific information about whether a
	given request can be processed safely when it is sent in early data.		given request can be processed safely when it is sent in early data.
	In many cases, only the origin server has the necessary information		In many cases, only the origin server has the necessary information
	to decide whether the risk of replay is acceptable. These extensions		to decide whether the risk of replay is acceptable. These extensions
	allow coordination between a gateway and its origin server.		allow coordination between a gateway and its origin server.
	5.1. The Early-Data Header Field		5.1. The Early-Data Header Field
	The "Early-Data" request header field indicates that the request has		The "Early-Data" request header field indicates that the request has
	been conveyed in early data, and additionally indicates that a client		been conveyed in early data, and additionally indicates that a client
	understands the 4NN (Too Early) status code.		understands the 425 (Too Early) status code.
	It has just one valid value: "1". Its syntax is defined by the		It has just one valid value: "1". Its syntax is defined by the
	following ABNF [ABNF]:		following ABNF [ABNF]:
	Early-Data = "1"		Early-Data = "1"
	For example:		For example:
	GET /resource HTTP/1.0		GET /resource HTTP/1.0
	Host: example.com		Host: example.com
	Early-Data: 1		Early-Data: 1
	An intermediary that forwards a request received in TLS early data
	MUST send it with the "Early-Data" header field set to "1" (i.e., it		An intermediary that forwards a request prior to the completion of
	adds it if not present in the request).		the TLS handshake MUST send it with the "Early-Data" header field set
			to "1" (i.e., it adds it if not present in the request). An
			intermediary MUST use the "Early-Data" header field if it might have
			forwarded the request prior to handshake completion (see Section 6.2
			for details).
	An intermediary MUST NOT remove this header field if it is present in		An intermediary MUST NOT remove this header field if it is present in
	a request.		a request.
	The "Early-Data" header field is not intended for use by user agents		The "Early-Data" header field is not intended for use by user agents
	(that is, the original initiator of a request). Sending a request in		(that is, the original initiator of a request). Sending a request in
	early data implies that the client understands this specification and		early data implies that the client understands this specification and
	is willing to retry a request in response to a 4NN (Too Early) status		is willing to retry a request in response to a 425 (Too Early) status
	code. A user agent that sends a request in early data does not need		code. A user agent that sends a request in early data does not need
	to include the "Early-Data" header field.		to include the "Early-Data" header field.
	A server cannot make a request that contains the Early-Data header		A server cannot make a request that contains the Early-Data header
	field safe for processing by waiting for the handshake to complete.		field safe for processing by waiting for the handshake to complete.
	A request that is marked with Early-Data was sent in early data on a		A request that is marked with Early-Data was sent in early data on a
	previous hop. Requests that contain the Early-Data field and cannot		previous hop. Requests that contain the Early-Data field and cannot
	be safely processed MUST be rejected using the 4NN (Too Early) status		be safely processed MUST be rejected using the 425 (Too Early) status
	code.		code.
	5.2. The 4NN (Too Early) Status Code		5.2. The 425 (Too Early) Status Code
	A 4NN (Too Early) status code indicates that the server is unwilling		A 425 (Too Early) status code indicates that the server is unwilling
	to risk processing a request that might be replayed.		to risk processing a request that might be replayed.
	Clients (user-agents and intermediaries) that sent the request in		Clients (user-agents and intermediaries) that sent the request in
	early data MUST automatically retry the request when receiving a 4NN		early data MUST automatically retry the request when receiving a 425
	(Too Early) response status code. Such retries MUST NOT be sent in		(Too Early) response status code. Such retries MUST NOT be sent in
	early data, and SHOULD NOT be sent if the TLS handshake on the		early data.
	original connection does not successfully complete.
	Intermediaries that receive a 4NN (Too Early) status code MAY		Intermediaries that receive a 425 (Too Early) status code MAY
	automatically retry requests after allowing the handshake to complete		automatically retry requests after allowing the handshake to complete
	unless the original request contained the "Early-Data" header field		unless the original request contained the "Early-Data" header field
	when it was received. Otherwise, an intermediary MUST forward the		when it was received. Otherwise, an intermediary MUST forward the
	4NN (Too Early) status code.		425 (Too Early) status code.
	The server cannot assume that a client is able to retry a request		The server cannot assume that a client is able to retry a request
	unless the request is received in early data or the "Early-Data"		unless the request is received in early data or the "Early-Data"
	header field is set to "1". A server SHOULD NOT emit the 4NN status		header field is set to "1". A server SHOULD NOT emit the 425 status
	code unless one of these conditions is met.		code unless one of these conditions is met.
	The 4NN (Too Early) status code is not cacheable by default. Its		The 425 (Too Early) status code is not cacheable by default. Its
	payload is not the representation of any identified resource.		payload is not the representation of any identified resource.
	6. Security Considerations		6. Security Considerations
	Using early data exposes a client to the risk that their request is		Using early data exposes a client to the risk that their request is
	replayed. A retried or replayed request can produce different side		replayed. A retried or replayed request can produce different side
	effects on the server. In addition to those side effects, replays		effects on the server. In addition to those side effects, replays
	and retries might be used for traffic analysis to recover information		and retries might be used for traffic analysis to recover information
	about requests or the resources those requests target.		about requests or the resources those requests target.
	6.1. Gateways and Early Data		6.1. Gateways and Early Data
	A gateway that forwards requests that were received in early data		A gateway that forwards requests that were received in early data
	MUST only do so if it knows that the server that receives those		MUST only do so if it knows that the origin server that receives
	requests understands the "Early-Data" header field and will correctly		those requests understands the "Early-Data" header field and will
	generate a 4NN (Too Early) status code. A gateway that isn't certain		correctly generate a 425 (Too Early) status code. A gateway that
	about server support SHOULD either delay forwarding the request until		isn't certain about origin server support SHOULD either delay
	the TLS handshake completes, or send a 4NN (Too Early) status code in		forwarding the request until the TLS handshake with its client
	response. A gateway that is uncertain about whether an origin server		completes, or send a 425 (Too Early) status code in response. A
	supports the "Early-Data" header field SHOULD disable early data.		gateway that is uncertain about whether an origin server supports the
			"Early-Data" header field SHOULD disable early data.
	6.2. Consistent Handling of Early Data		6.2. Consistent Handling of Early Data
	Consistent treatment of a request that arrives in - or partially in -		Consistent treatment of a request that arrives in - or partially in -
	early data is critical to avoiding inappropriate processing of		early data is critical to avoiding inappropriate processing of
	replayed requests. If a request is not safe to process before the		replayed requests. If a request is not safe to process before the
	TLS handshake completes, then all instances of the server need to		TLS handshake completes, then all instances of the server (including
	agree and either reject the request or delay processing.		gateways) need to agree and either reject the request or delay
			processing.
			A server MUST NOT act on early data before the handshake completes if
			it and any other server instance could make a different decision
			about how to handle the same data.
	6.3. Denial of Service		6.3. Denial of Service
	Accepting early data exposes a server to potential denial of service		Accepting early data exposes a server to potential denial of service
	through the replay of requests that are expensive to handle. A		through the replay of requests that are expensive to handle. A
	server that is under load SHOULD prefer rejecting TLS early data as a		server that is under load SHOULD prefer rejecting TLS early data as a
	whole rather than accepting early data and selectively processing		whole rather than accepting early data and selectively processing
	requests. Generating a 503 (Service Unavailable) or 4NN (Too Early)		requests. Generating a 503 (Service Unavailable) or 425 (Too Early)
	status code often leads to clients retrying requests, which could		status code often leads to clients retrying requests, which could
	result in increased load.		result in increased load.
			6.4. Out of Order Delivery
			In protocols that deliver data out of order (such as QUIC [HQ]) early
			data can arrive after the handshake completes. This leads to
			potential ambiguity about the status of requests and could lead to
			inconsistent treatment (see Section 6.2). Implementations MUST
			either ensure that any early data that is delivered late is either
			discarded or consistently identified and processed.
	7. IANA Considerations		7. IANA Considerations
	This document registers the "Early-Data" header field in the "Message		This document registers the "Early-Data" header field in the "Message
	Headers" registry [HEADERS].		Headers" registry [HEADERS].
	Header field name: Early-Data		Header field name: Early-Data
	Applicable protocol: http		Applicable protocol: http
	Status: standard		Status: standard
	skipping to change at page 9, line 4 ¶		skipping to change at page 9, line 24 ¶
	7. IANA Considerations		7. IANA Considerations
	This document registers the "Early-Data" header field in the "Message		This document registers the "Early-Data" header field in the "Message
	Headers" registry [HEADERS].		Headers" registry [HEADERS].
	Header field name: Early-Data		Header field name: Early-Data
	Applicable protocol: http		Applicable protocol: http
	Status: standard		Status: standard
	Author/Change controller: IETF		Author/Change controller: IETF
	Specification document(s): This document		Specification document(s): This document
	Related information: (empty)		Related information: (empty)
	This document registers the 4NN (Too Early) status code in the		This document registers the 425 (Too Early) status code in the
	"Hypertext Transfer Protocol (HTTP) Status Code" registry established		"Hypertext Transfer Protocol (HTTP) Status Code" registry established
	in [RFC7231].		in [RFC7231].
	Value: 4NN		Value: 425
	Description: Too Early		Description: Too Early
	Reference: This document		Reference: This document
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234,		Specifications: ABNF", STD 68, RFC 5234,
	DOI 10.17487/RFC5234, January 2008, <https://www.rfc-		DOI 10.17487/RFC5234, January 2008,
	editor.org/info/rfc5234>.		<https://www.rfc-editor.org/info/rfc5234>.
	[HEADERS] Klyne, G., Nottingham, M., and J. Mogul, "Registration		[HEADERS] 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,
	DOI 10.17487/RFC3864, September 2004, <https://www.rfc-		DOI 10.17487/RFC3864, September 2004,
	editor.org/info/rfc3864>.		<https://www.rfc-editor.org/info/rfc3864>.
	[HTTP] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer		[HTTP] 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, DOI 10.17487/RFC7230, June 2014,		RFC 7230, DOI 10.17487/RFC7230, June 2014,
	<https://www.rfc-editor.org/info/rfc7230>.		<https://www.rfc-editor.org/info/rfc7230>.
	[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, <https://www.rfc-		DOI 10.17487/RFC2119, March 1997,
	editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer		[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	Protocol (HTTP/1.1): Semantics and Content", RFC 7231,		Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
	DOI 10.17487/RFC7231, June 2014, <https://www.rfc-		DOI 10.17487/RFC7231, June 2014,
	editor.org/info/rfc7231>.		<https://www.rfc-editor.org/info/rfc7231>.
	[TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol		[TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol
	Version 1.3", draft-ietf-tls-tls13-21 (work in progress),		Version 1.3", draft-ietf-tls-tls13-21 (work in progress),
	July 2017.		July 2017.
	8.2. Informative References		8.2. Informative References
	[HQ] Bishop, M., "Hypertext Transfer Protocol (HTTP) over		[HQ] Bishop, M., "Hypertext Transfer Protocol (HTTP) over
	QUIC", draft-ietf-quic-http-05 (work in progress), August		QUIC", draft-ietf-quic-http-07 (work in progress), October
	2017.		2017.
	[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, <https://www.rfc-		DOI 10.17487/RFC7540, May 2015,
	editor.org/info/rfc7540>.		<https://www.rfc-editor.org/info/rfc7540>.
	Appendix A. Acknowledgments		Acknowledgments
	This document was not easy to produce. The following people made		This document was not easy to produce. The following people made
	substantial contributions to the quality and completeness of the		substantial contributions to the quality and completeness of the
	document: Subodh Iyengar, Benjamin Kaduk, Ilari Liusavaara, Kazuho		document: Subodh Iyengar, Benjamin Kaduk, Ilari Liusavaara, Kazuho
	Oku, and Victor Vasiliev.		Oku, Kyle Rose, and Victor Vasiliev.
	Authors' Addresses		Authors' Addresses
	Martin Thomson		Martin Thomson
	Mozilla		Mozilla
	Email: martin.thomson@gmail.com		Email: martin.thomson@gmail.com
	Mark Nottingham		Mark Nottingham
	true		Fastly
	Email: mnot@mnot.net		Email: mnot@mnot.net
	Willy Tarreau		Willy Tarreau
	HAProxy Technologies		HAProxy Technologies
	Email: willy@haproxy.org		Email: willy@haproxy.org
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