< draft-ietf-doh-dns-over-https-01.txt		draft-ietf-doh-dns-over-https-02.txt >
	Network Working Group P. Hoffman		Network Working Group P. Hoffman
	Internet-Draft ICANN		Internet-Draft ICANN
	Intended status: Standards Track P. McManus		Intended status: Standards Track P. McManus
	Expires: May 3, 2018 Mozilla		Expires: June 1, 2018 Mozilla
	October 30, 2017		November 28, 2017
	DNS Queries over HTTPS		DNS Queries over HTTPS
	draft-ietf-doh-dns-over-https-01		draft-ietf-doh-dns-over-https-02
	Abstract		Abstract
	DNS queries sometimes experience problems with end to end		DNS queries sometimes experience problems with end to end
	connectivity at times and places where HTTPS flows freely.		connectivity at times and places where HTTPS flows freely.
	HTTPS provides the most practical mechanism for reliable end to end		HTTPS provides the most practical mechanism for reliable end to end
	communication. Its use of TLS provides integrity and confidentiality		communication. Its use of TLS provides integrity and confidentiality
	guarantees and its use of HTTP allows it to interoperate with		guarantees and its use of HTTP allows it to interoperate with
	proxies, firewalls, and authentication systems where required for		proxies, firewalls, and authentication systems where required for
	transit.		transit.
	This document describes how to run DNS service over HTTP using		This document describes how to run DNS service over HTTP using
	https:// URIs.		https:// URIs.
	[[ There is a repository for this draft at		[[ There is a repository for this draft at https://github.com/dohwg/
	https://github.com/paulehoffman/draft-ietf-doh-dns-over-https ]].		draft-ietf-doh-dns-over-https ]].
	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 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 May 3, 2018.		This Internet-Draft will expire on June 1, 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.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 26 ¶		skipping to change at page 2, line 26 ¶
	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
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3		3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
	4. Protocol Requirements . . . . . . . . . . . . . . . . . . . . 4		4. Protocol Requirements . . . . . . . . . . . . . . . . . . . . 4
	4.1. Non-requirements . . . . . . . . . . . . . . . . . . . . 4		4.1. Non-requirements . . . . . . . . . . . . . . . . . . . . 5
	5. The HTTP Request . . . . . . . . . . . . . . . . . . . . . . 4		5. The HTTP Request . . . . . . . . . . . . . . . . . . . . . . 5
	5.1. DNS Wire Format . . . . . . . . . . . . . . . . . . . . . 5		5.1. DNS Wire Format . . . . . . . . . . . . . . . . . . . . . 6
	5.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 6		5.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 6
	6. The HTTP Response . . . . . . . . . . . . . . . . . . . . . . 6		6. The HTTP Response . . . . . . . . . . . . . . . . . . . . . . 7
	6.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 7		6.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 8
	7. HTTP Integration . . . . . . . . . . . . . . . . . . . . . . 8		7. HTTP Integration . . . . . . . . . . . . . . . . . . . . . . 8
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		7.1. HTTP/2 . . . . . . . . . . . . . . . . . . . . . . . . . 9
	8.1. Registration of Well-Known URI . . . . . . . . . . . . . 8		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
	8.2. Registration of application/dns-udpwireformat Media Type 8		8.1. Registration of Well-Known URI . . . . . . . . . . . . . 9
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 10		8.2. Registration of application/dns-udpwireformat Media Type 9
	10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10		9. Security Considerations . . . . . . . . . . . . . . . . . . . 11
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11		10. Operational Considerations . . . . . . . . . . . . . . . . . 12
	11.1. Normative References . . . . . . . . . . . . . . . . . . 11		11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
	11.2. Informative References . . . . . . . . . . . . . . . . . 11		12. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
	Appendix A. Previous Work on DNS over HTTP or in Other Formats . 12		12.1. Normative References . . . . . . . . . . . . . . . . . . 12
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12		12.2. Informative References . . . . . . . . . . . . . . . . . 13
			Appendix A. Previous Work on DNS over HTTP or in Other Formats . 14
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
	1. Introduction		1. Introduction
	The Internet does not always provide end to end reachability for		The Internet does not always provide end to end reachability for
	native DNS. On-path network devices may spoof DNS responses, block		native DNS. On-path network devices may spoof DNS responses, block
	DNS requests, or just redirect DNS queries to different DNS servers		DNS requests, or just redirect DNS queries to different DNS servers
	that give less-than-honest answers.		that give less-than-honest answers.
	Over time, there have been many proposals for using HTTP and HTTPS as		Over time, there have been many proposals for using HTTP and HTTPS as
	a substrate for DNS queries and responses. To date, none of those		a substrate for DNS queries and responses. To date, none of those
	proposals have made it beyond early discussion, partially due to		proposals have made it beyond early discussion, partially due to
	disagreement about what the appropriate formatting should be and		disagreement about what the appropriate formatting should be and
	partially because they did not follow HTTP best practices.		partially because they did not follow HTTP best practices.
	This document defines a specific protocol for sending DNS [RFC1035]		This document defines a specific protocol for sending DNS [RFC1035]
	queries and getting DNS responses over modern versions of HTTP		queries and getting DNS responses over HTTP [RFC7540] using https://
	[RFC7540] using https:// (and therefore TLS [RFC5246] security for		(and therefore TLS [RFC5246] security for integrity and
	integrity and confidentiality).		confidentiality). Each DNS query-response pair is mapped into a HTTP
			request-response pair.
	The described approach is more than a tunnel over HTTP. It		The described approach is more than a tunnel over HTTP. It
	establishes default media formatting types for requests and responses		establishes default media formatting types for requests and responses
	but uses normal HTTP content negotiation mechanisms for selecting		but uses normal HTTP content negotiation mechanisms for selecting
	alternatives that endpoints may prefer in anticipation of serving new		alternatives that endpoints may prefer in anticipation of serving new
	use cases. In addition to this media type negotiation, it aligns		use cases. In addition to this media type negotiation, it aligns
	itself with HTTP features such as caching, proxying, and compression.		itself with HTTP features such as caching, proxying, and compression.
	The integration with HTTP provides a transport suitable for both		The integration with HTTP provides a transport suitable for both
	traditional DNS clients and native web applications seeking access to		traditional DNS clients and native web applications seeking access to
	skipping to change at page 3, line 38 ¶		skipping to change at page 3, line 42 ¶
	protocol). Similarly, a client that supports this protocol is called		protocol). Similarly, a client that supports this protocol is called
	a "DNS API client".		a "DNS API client".
	In this document, the key words "MUST", "MUST NOT", "REQUIRED",		In this document, the key words "MUST", "MUST NOT", "REQUIRED",
	"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",		"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
	and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119		and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
	[RFC2119].		[RFC2119].
	3. Use Cases		3. Use Cases
	There are two primary use cases for this protocol.		There are two initial use cases for this protocol.
	The primary use case is to prevent on-path network devices from		The primary use case is to prevent on-path network devices from
	interfering with native DNS operations. This interference includes,		interfering with DNS operations. This interference includes, but is
	but is not limited to, spoofing DNS responses, blocking DNS requests,		not limited to, spoofing DNS responses, blocking DNS requests, and
	and tracking. HTTP authentication and proxy friendliness are		tracking.
	expected to make this protocol function in some environments where
	unsecured DNS ([DNS]) or DNS directly on TLS ([RFC7858]) would not.
	A secondary use case is web applications that want to access DNS		In this use, clients - whether operating systems or individual
	information. Standardizing an HTTPS mechanism allows this to be done		applications - will be explicitly configured to use a DOH server as a
	in a way consistent with the cross-origin resource sharing security		recursive resolver by its user (or administrator). They might use
	model of the web [CORS] and also integrate the caching mechanisms of		the DOH server for all queries, or only for a subset of them. The
	DNS with those of HTTP. These applications may be interested in		specific configuration mechanism is out of scope for this document.
	using a different media type than traditional clients.
			A secondary use case is allowing web applications to access DNS
			information, by using existing APIs in browsers to access it over
			HTTP in a safe way consistent with Cross Origin Resource Sharing
			(CORS) [CORS].
			This is technically already possible (since the server controls both
			the HTTP resources it exposes and the use of browser APIs by its
			content), but standardisation might make this easier to accomplish.
			Note that in this second use, the browser does not consult the DOH
			server or use its responses for any DNS lookups outside the scope of
			the application using them; i.e., there is (currently) no API that
			allows a Web site to poison DNS for others.
	[[ This paragraph is to be removed when this document is published as		[[ This paragraph is to be removed when this document is published as
	an RFC ]] Note that these use cases are different than those in a		an RFC ]] Note that these use cases are different than those in a
	similar protocol described at [I-D.ietf-dnsop-dns-wireformat-http].		similar protocol described at [I-D.ietf-dnsop-dns-wireformat-http].
	The use case for that protocol is proxying DNS queries over HTTP		The use case for that protocol is proxying DNS queries over HTTP
	instead of over DNS itself. The use cases in this document all		instead of over DNS itself. The use cases in this document all
	involve query origination instead of proxying.		involve query origination instead of proxying.
	4. Protocol Requirements		4. Protocol Requirements
	skipping to change at page 5, line 13 ¶		skipping to change at page 5, line 31 ¶
	The URI scheme MUST be https.		The URI scheme MUST be https.
	A client can be configured with a DNS API URI, or it can discover the		A client can be configured with a DNS API URI, or it can discover the
	URI. This document defines a well-known URI path of "/.well-known/		URI. This document defines a well-known URI path of "/.well-known/
	dns-query" so that a discovery process that produces a domain name or		dns-query" so that a discovery process that produces a domain name or
	domain name and port can be used to construct the DNS API URI. (See		domain name and port can be used to construct the DNS API URI. (See
	Section 8 for the registration of this in the well-known URI		Section 8 for the registration of this in the well-known URI
	registry.) DNS API servers SHOULD use this well-known path to help		registry.) DNS API servers SHOULD use this well-known path to help
	contextualize DNS Query requests that use server push [RFC7540].		contextualize DNS Query requests that use server push [RFC7540].
	A DNS API Client encodes the DNS query into the HTTP request using		A DNS API Client encodes a single DNS query into the HTTP request
	either the HTTP GET or POST methods.		using either the HTTP GET or POST methods.
	When using the POST method, the DNS query is included as the message		When using the POST method the DNS query is included as the message
	body of the HTTP request and the Content-Type request header		body of the HTTP request and the Content-Type request header
	indicates the media type of the message. POST-ed requests are		indicates the media type of the message. POST-ed requests are
	smaller than their GET equivalents.		smaller than their GET equivalents.
	When using the GET method, the URI path MUST contain a query		When using the GET method the URI path MUST contain a query parameter
	parameter of the form content-type=TTT and another of the form		with the name of ct and a value indicating the media-format used for
	body=BBBB, where "TTT" is the media type of the format used for the		the body parameter. The value may either be an explicit media type
	body parameter, and "BBB" is the content of the body encoded with		(e.g. ct=application/dns-udpwireformat&body=...) or it may be empty.
	base64url [RFC4648]. Using the GET method is friendlier to many HTTP		An empty value indicates the default application/dns-udpwireformat
	cache implementations.		type (e.g. ct&body=...).
			When using the GET method the URI path MUST contain a query parameter
			with the name of body. The value of the parameter is the content of
			the request encoded with base64url [RFC4648]. Using the GET method
			is friendlier to many HTTP cache implementations.
	The DNS API Client SHOULD include an HTTP "Accept:" request header to		The DNS API Client SHOULD include an HTTP "Accept:" request header to
	say what type of content can be understood in response. The client		say what type of content can be understood in response. The client
	MUST be prepared to process "application/dns-udpwireformat"		MUST be prepared to process "application/dns-udpwireformat"
	Section 5.1 responses but MAY process any other type it receives.		Section 5.1 responses but MAY process any other type it receives.
	In order to maximize cache friendliness, DNS API clients using media		In order to maximize cache friendliness, DNS API clients using media
	formats that include DNS ID, such as application/dns-udpwireformat,		formats that include DNS ID, such as application/dns-udpwireformat,
	should use a DNS ID of 0 in every DNS request. HTTP semantics		SHOULD use a DNS ID of 0 in every DNS request. HTTP correlates
	correlate the request and response, thus eliminating the need for the		request and response, thus eliminating the need for the ID in a media
	ID in a media type such as application/dns-udpwireformat.		type such as application/dns-udpwireformat and the use of a varying
			DNS ID can cause semantically equivalent DNS queries to be cached
			separately.
	DNS API clients can use HTTP/2 padding and compression in the same		DNS API clients can use HTTP/2 padding and compression in the same
	way that other HTTP/2 clients use (or don't use) them.		way that other HTTP/2 clients use (or don't use) them.
	5.1. DNS Wire Format		5.1. DNS Wire Format
	The media type is "application/dns-udpwireformat". The body is the		The media type is "application/dns-udpwireformat". The body is the
	DNS on-the-wire format is defined in [RFC1035].		DNS on-the-wire format is defined in [RFC1035].
	When using the GET method, the body MUST be encoded with base64url		When using the GET method, the body MUST be encoded with base64url
	[RFC4648]. Padding characters for base64url MUST NOT be included.		[RFC4648]. Padding characters for base64url MUST NOT be included.
	When using the POST method, the body is not encoded.		When using the POST method, the body is not encoded.
	DNS API clients using the DNS wire format MAY have one or more		DNS API clients using the DNS wire format MAY have one or more
	EDNS(0) extensions [RFC6891] in the request.		EDNS(0) extensions [RFC6891] in the request.
	5.2. Examples		5.2. Examples
	For example, assume a DNS API server is following this specification		These examples use HTTP/2 style formatting from [RFC7540].
	on origin https://dnsserver.example.net/ and the well-known path.
	The DNS API client chooses to send its requests in appliation/dns-
	udpwirefomat but indicates it can parse replies in that format or as
	a JSON-based content type.
	The examples uses HTTP/2 formatting from [RFC7540].
	A query for the IN A records for "www.example.com" with recursion		For this example assume a DNS API server is following this
	turned on using the GET method and a wireformat request would be:		specification on origin https://dnsserver.example.net/ and the well-
			known path. The DNS API client chooses to send its requests in
			application/dns-udpwirefomat but indicates it can parse replies in
			that format or as a hypothetical JSON-based content type. The
			application/simpledns+json type used by this example is currently
			fictitious.
	:method = GET		:method = GET
	:scheme = https		:scheme = https
	:authority = dnsserver.example.net		:authority = dnsserver.example.net
	:path = /.well-known/dns-query? (no CR)		:path = /.well-known/dns-query?ct& (no CR)
	content-type=application/dns-udpwireformat& (no CR)
	body=q80BAAABAAAAAAAAA3d3dwdleGFtcGxlA2NvbQAAAQAB		body=q80BAAABAAAAAAAAA3d3dwdleGFtcGxlA2NvbQAAAQAB
	accept = application/dns-udpwireformat, application/simpledns+json		accept = application/dns-udpwireformat, application/simpledns+json
	The same DNS query, using the POST method would be:		The same DNS query, using the POST method would be:
	:method = POST		:method = POST
	:scheme = https		:scheme = https
	:authority = dnsserver.example.net		:authority = dnsserver.example.net
	:path = /.well-known/dns-query		:path = /.well-known/dns-query
	accept = application/dns-udpwireformat, application/simpledns+json		accept = application/dns-udpwireformat, application/simpledns+json
	skipping to change at page 7, line 18 ¶		skipping to change at page 7, line 39 ¶
	response format will be defined in the future.		response format will be defined in the future.
	The DNS response for "application/dns-udpwireformat" in Section 5.1		The DNS response for "application/dns-udpwireformat" in Section 5.1
	MAY have one or more EDNS(0) extensions, depending on the extension		MAY have one or more EDNS(0) extensions, depending on the extension
	definition of the extensions given in the DNS request.		definition of the extensions given in the DNS request.
	Native HTTP methods are used to correlate requests and responses.		Native HTTP methods are used to correlate requests and responses.
	Responses may be returned in a different temporal order than requests		Responses may be returned in a different temporal order than requests
	were made using the protocols native multi-streaming functionality.		were made using the protocols native multi-streaming functionality.
	In the HTTP responses, the HTTP cache headers SHOULD be set to expire		The Answer section of a DNS response contains one or more RRsets.
	at the same time as the shortest DNS TTL in the response. Because		(RRsets are defined in [RFC7719].) According to [RFC2181], each
	DNS provides only caching but not revalidation semantics, DNS over		resource record in an RRset is supposed to have the Time To Live
	HTTP responses should not carry revalidation response headers (such		(TTL) freshness information. Different RRsets in the Answer section
	as Last-Modified: or Etag:) or return 304 responses.		can have different TTLs, though it is only possible for the HTTP
			response to have a single freshness lifetime. The HTTP response
			freshness lifetime ([RFC7234] Section 4.2) should be coordinated with
			the Resource Record bearing the smallest TTL in the Answer section of
			the response. The HTTP freshness lifetime SHOULD be set to expire at
			the same time any of the DNS Records reach a 0 TTL. The response
			freshness lifetime MUST NOT be greater than that indicated by the DNS
			Record with the smallest TTL in the response.
			A DNS API Client that receives a response without an explicit
			freshness lifetime MUST NOT assign that response a heuristic
			freshness ([RFC7234] Section 4.2.2.) greater than that indicated by
			the DNS Record with the smallest TTL in the response.
	A DNS API Server MUST be able to process application/dns-		A DNS API Server MUST be able to process application/dns-
	udpwireformat request messages.		udpwireformat request messages.
	A DNS API Server SHOULD respond with HTTP status code 415 upon		A DNS API Server SHOULD respond with HTTP status code 415 upon
	receiving a media type it is unable to process.		receiving a media type it is unable to process.
	This document does not change the definition of any HTTP response		This document does not change the definition of any HTTP response
	codes or otherwise proscribe their use.		codes or otherwise proscribe their use.
			HTTP revalidation of cached DNS information may be of limited value
			as revalidation provides only a bandwidth benefit and DNS
			transactions are normally latency bound instead. Furthermore, the
			HTTP response headers that enable revalidation (such as "Last-
			Modified" and "Etag") are often fairly large when compared to the
			overall DNS response size, and have a variable nature that creates
			constant pressure on the HTTP/2 compression dictionary [RFC7541].
			Other types of DNS data, such as zone transfers, may be larger and
			benefit more from revalidation. DNS API servers may wish to consider
			whether providing these optional response headers is worthwhile.
	6.1. Example		6.1. Example
	This is an example response for a query for the IN A records for		This is an example response for a query for the IN A records for
	"www.example.com" with recursion turned on. The response bears one		"www.example.com" with recursion turned on. The response bears one
	record with an address of 93.184.216.34 and a TTL of 128 seconds.		record with an address of 93.184.216.34 and a TTL of 128 seconds.
	:status = 200		:status = 200
	content-type = application/dns-udpwireformat		content-type = application/dns-udpwireformat
	content-length = 64		content-length = 64
	cache-control = max-age=128		cache-control = max-age=128
	skipping to change at page 8, line 9 ¶		skipping to change at page 9, line 5 ¶
	abcd 8180 0001 0001 0000 0000 0377 7777		abcd 8180 0001 0001 0000 0000 0377 7777
	0765 7861 6d70 6c65 0363 6f6d 0000 0100		0765 7861 6d70 6c65 0363 6f6d 0000 0100
	0103 7777 7707 6578 616d 706c 6503 636f		0103 7777 7707 6578 616d 706c 6503 636f
	6d00 0001 0001 0000 0080 0004 5db8 d822		6d00 0001 0001 0000 0080 0004 5db8 d822
	7. HTTP Integration		7. HTTP Integration
	This protocol MUST be used with https scheme URI [RFC7230].		This protocol MUST be used with https scheme URI [RFC7230].
	This protocol MUST use HTTP/2 [RFC7540] or its successors in order to		7.1. HTTP/2
	satisfy the security requirements of DNS over HTTPS. Further, the
	messages in classic UDP based DNS [RFC1035] are inherently unordered		The minimum version of HTTP used by DOH SHOULD be HTTP/2 [RFC7540].
	and have low overhead. A competitive HTTP transport needs to support
	reordering, priority, parallelism, and header compression, all of		The messages in classic UDP based DNS [RFC1035] are inherently
	which are supported by HTTP/2 [RFC7540] or its successors.		unordered and have low overhead. A competitive HTTP transport needs
			to support reordering, parallelism, priority, and header compression
			to acheive similar performance. Those features were introduced to
			HTTP in HTTP/2 [RFC7540]. Earlier versions of HTTP are capable of
			conveying the semantic requirements of DOH but would result in very
			poor performance for many uses cases.
	8. IANA Considerations		8. IANA Considerations
	8.1. Registration of Well-Known URI		8.1. Registration of Well-Known URI
	This specification registers a Well-Known URI [RFC5785]:		This specification registers a Well-Known URI [RFC5785]:
	o URI Suffix: dns-query		o URI Suffix: dns-query
	o Change Controller: IETF		o Change Controller: IETF
	o Specification Document(s): [this specification]		o Specification Document(s): [this specification]
	8.2. Registration of application/dns-udpwireformat Media Type		8.2. Registration of application/dns-udpwireformat Media Type
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of MIME media type		Subject: Registration of MIME media type
	pplication/dns-udpwireformat		application/dns-udpwireformat
	MIME media type name: application		MIME media type name: application
	MIME subtype name: dns-udpwireformat		MIME subtype name: dns-udpwireformat
	Required parameters: n/a		Required parameters: n/a
	Optional parameters: n/a		Optional parameters: n/a
	Encoding considerations: This is a binary format. The contents are a		Encoding considerations: This is a binary format. The contents are a
	skipping to change at page 10, line 8 ¶		skipping to change at page 11, line 8 ¶
	Restrictions on usage: n/a		Restrictions on usage: n/a
	Author: Paul Hoffman, paul.hoffman@icann.org		Author: Paul Hoffman, paul.hoffman@icann.org
	Change controller: IESG		Change controller: IESG
	9. Security Considerations		9. Security Considerations
	Running DNS over HTTPS relies on the security of the underlying HTTP		Running DNS over HTTPS relies on the security of the underlying HTTP
	connection. By requiring at least [RFC7540] levels of support for		transport. Implementations utilizing HTTP/2 benefit from the TLS
	TLS, this protocol expects to use current best practices for secure		profile defined in [RFC7540] Section 9.2.
	transport.
	Session level encryption has well known weaknesses with respect to		Session level encryption has well known weaknesses with respect to
	traffic analysis which might be particularly acute when dealing with		traffic analysis which might be particularly acute when dealing with
	DNS queries. Sections 10.6 (Compression) and 10.7 (Padding) of		DNS queries. Sections 10.6 (Compression) and 10.7 (Padding) of
	[RFC7540] provide some further advice on mitigations within an HTTP/2		[RFC7540] provide some further advice on mitigations within an HTTP/2
	context.		context.
			The HTTPS connection provides transport security for the interaction
			between the DNS API server and client, but does not inherently ensure
			the authenticity of DNS data. A DNS API client may also perform full
			DNSSEC validation of answers received from a DNS API server or it may
			choose to trust answers from a particular DNS API server, much as a
			DNS client might choose to trust answers from its recurvise DNS
			resolver.
	[[ From the WG charter:		[[ From the WG charter:
	The working group will analyze the security and privacy issues that		The working group will analyze the security and privacy issues that
	could arise from accessing DNS over HTTPS. In particular, the		could arise from accessing DNS over HTTPS. In particular, the
	working group will consider the interaction of DNS and HTTP caching.		working group will consider the interaction of DNS and HTTP caching.
	]]		]]
	A server that is acting both as a normal web server and a DNS API		A server that is acting both as a normal web server and a DNS API
	server is in a position to choose which DNS names it forces a client		server is in a position to choose which DNS names it forces a client
	skipping to change at page 10, line 46 ¶		skipping to change at page 12, line 5 ¶
	[[ From the WG charter:		[[ From the WG charter:
	The working group may define mechanisms for discovery of DOH servers		The working group may define mechanisms for discovery of DOH servers
	similar to existing mechanisms for discovering other DNS servers if		similar to existing mechanisms for discovering other DNS servers if
	the chairs determine that there is both sufficient interest and		the chairs determine that there is both sufficient interest and
	working group consensus.		working group consensus.
	]]		]]
	10. Acknowledgments		10. Operational Considerations
			Local policy considerations and similar factors mean different DNS
			servers may provide different results to the same query: for instance
			in split DNS configurations [RFC6950]. It logically follows that the
			server which is queried can influence the end result. Therefore a
			client's choice of DNS server may affect the responses it gets to its
			queries.
			The HTTPS channel used by this specification establishes secure two
			party communication between the DNS API Client and the DNS API
			Server. Filtering or inspection systems that rely on unsecured
			transport of DNS will not function in a DNS over HTTPS environment.
			Many HTTPS implementations perform real time third party checks of
			the revocation status of the certificates being used by TLS. If this
			check is done as part of the DNS API server connection procedure and
			the check itself requires DNS resolution to connect to the third
			party a deadlock can occur. The use of an OCSP [RFC6960] server is
			one example of how this can happen. DNS API servers SHOULD utilize
			OCSP Stapling [RFC6961] to provide the client with certificate
			revocation information that does not require contacting a third
			party.
			11. Acknowledgments
	Joe Hildebrand contributed lots of material for a different iteration		Joe Hildebrand contributed lots of material for a different iteration
	of this document. Helpful early comments were given by Ben Schwartz		of this document. Helpful early comments were given by Ben Schwartz
	and Mark Nottingham.		and Mark Nottingham.
	11. References		12. References
	11.1. Normative References		12.1. Normative References
	[RFC1035] Mockapetris, P., "Domain names - implementation and		[RFC1035] Mockapetris, P., "Domain names - implementation and
	specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,		specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
	November 1987, <https://www.rfc-editor.org/info/rfc1035>.		November 1987, <https://www.rfc-editor.org/info/rfc1035>.
	[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, <https://www.rfc-
	editor.org/info/rfc2119>.		editor.org/info/rfc2119>.
	skipping to change at page 11, line 32 ¶		skipping to change at page 13, line 15 ¶
	[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,		(TLS) Protocol Version 1.2", RFC 5246,
	DOI 10.17487/RFC5246, August 2008, <https://www.rfc-		DOI 10.17487/RFC5246, August 2008, <https://www.rfc-
	editor.org/info/rfc5246>.		editor.org/info/rfc5246>.
	[RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known		[RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known
	Uniform Resource Identifiers (URIs)", RFC 5785,		Uniform Resource Identifiers (URIs)", RFC 5785,
	DOI 10.17487/RFC5785, April 2010, <https://www.rfc-		DOI 10.17487/RFC5785, April 2010, <https://www.rfc-
	editor.org/info/rfc5785>.		editor.org/info/rfc5785>.
			[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A.,
			Galperin, S., and C. Adams, "X.509 Internet Public Key
			Infrastructure Online Certificate Status Protocol - OCSP",
			RFC 6960, DOI 10.17487/RFC6960, June 2013,
			<https://www.rfc-editor.org/info/rfc6960>.
			[RFC6961] Pettersen, Y., "The Transport Layer Security (TLS)
			Multiple Certificate Status Request Extension", RFC 6961,
			DOI 10.17487/RFC6961, June 2013, <https://www.rfc-
			editor.org/info/rfc6961>.
	[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, 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>.
			[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
			Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
			RFC 7234, DOI 10.17487/RFC7234, June 2014,
			<https://www.rfc-editor.org/info/rfc7234>.
	[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, <https://www.rfc-
	editor.org/info/rfc7540>.		editor.org/info/rfc7540>.
	[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,		[RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for
	and P. Hoffman, "Specification for DNS over Transport		HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
	Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May		<https://www.rfc-editor.org/info/rfc7541>.
	2016, <https://www.rfc-editor.org/info/rfc7858>.
	11.2. Informative References
	[CORS] W3C, "Cross-Origin Resource Sharing", 2014,		12.2. Informative References
	<https://www.w3.org/TR/cors/>.
	[DNS] Mockapetris, P., "Domain names - implementation and		[CORS] "Cross-Origin Resource Sharing", n.d.,
	specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,		<https://fetch.spec.whatwg.org/#http-cors-protocol>.
	November 1987, <https://www.rfc-editor.org/info/rfc1035>.
	[I-D.ietf-dnsop-dns-wireformat-http]		[I-D.ietf-dnsop-dns-wireformat-http]
	Song, L., Vixie, P., Kerr, S., and R. Wan, "DNS wire-		Song, L., Vixie, P., Kerr, S., and R. Wan, "DNS wire-
	format over HTTP", draft-ietf-dnsop-dns-wireformat-http-01		format over HTTP", draft-ietf-dnsop-dns-wireformat-http-01
	(work in progress), March 2017.		(work in progress), March 2017.
			[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
			Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997,
			<https://www.rfc-editor.org/info/rfc2181>.
	[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van		[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
	Beijnum, "DNS64: DNS Extensions for Network Address		Beijnum, "DNS64: DNS Extensions for Network Address
	Translation from IPv6 Clients to IPv4 Servers", RFC 6147,		Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
	DOI 10.17487/RFC6147, April 2011, <https://www.rfc-		DOI 10.17487/RFC6147, April 2011, <https://www.rfc-
	editor.org/info/rfc6147>.		editor.org/info/rfc6147>.
	[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms		[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
	for DNS (EDNS(0))", STD 75, RFC 6891,		for DNS (EDNS(0))", STD 75, RFC 6891,
	DOI 10.17487/RFC6891, April 2013, <https://www.rfc-		DOI 10.17487/RFC6891, April 2013, <https://www.rfc-
	editor.org/info/rfc6891>.		editor.org/info/rfc6891>.
			[RFC6950] Peterson, J., Kolkman, O., Tschofenig, H., and B. Aboba,
			"Architectural Considerations on Application Features in
			the DNS", RFC 6950, DOI 10.17487/RFC6950, October 2013,
			<https://www.rfc-editor.org/info/rfc6950>.
			[RFC7719] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
			Terminology", RFC 7719, DOI 10.17487/RFC7719, December
			2015, <https://www.rfc-editor.org/info/rfc7719>.
	Appendix A. Previous Work on DNS over HTTP or in Other Formats		Appendix A. Previous Work on DNS over HTTP or in Other Formats
	The following is an incomplete list of earlier work that related to		The following is an incomplete list of earlier work that related to
	DNS over HTTP/1 or representing DNS data in other formats.		DNS over HTTP/1 or representing DNS data in other formats.
	The list includes links to the tools.ietf.org site (because these		The list includes links to the tools.ietf.org site (because these
	documents are all expired) and web sites of software.		documents are all expired) and web sites of software.
	o https://tools.ietf.org/html/draft-mohan-dns-query-xml		o https://tools.ietf.org/html/draft-mohan-dns-query-xml
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