< draft-ietf-dnsop-dns-wireformat-http-00.txt		draft-ietf-dnsop-dns-wireformat-http-01.txt >
	Internet Engineering Task Force L. Song		Internet Engineering Task Force L. Song
	Internet-Draft Beijing Internet Institute		Internet-Draft Beijing Internet Institute
	Intended status: Experimental P. Vixie		Intended status: Experimental P. Vixie
	Expires: March 19, 2017 TISF		Expires: September 28, 2017 TISF
	S. Kerr		S. Kerr
	R. Wan		R. Wan
	Beijing Internet Institute		Beijing Internet Institute
	September 15, 2016		March 27, 2017
	DNS wire-format over HTTP		DNS wire-format over HTTP
	draft-ietf-dnsop-dns-wireformat-http-00		draft-ietf-dnsop-dns-wireformat-http-01
	Abstract		Abstract
	This memo introduces a way to tunnel DNS data over HTTP. This may be		This memo introduces a way to tunnel DNS data over HTTP. This may be
	useful in any situation where DNS is not working properly, such as		useful in any situation where DNS is not working properly, such as
	when there is middlebox misbehavior.		when there is middlebox misbehavior.
	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
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	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 March 19, 2017.		This Internet-Draft will expire on September 28, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2017 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Methodology and Configuration . . . . . . . . . . . . . . . . 3		2. Methodology and Configuration . . . . . . . . . . . . . . . . 3
	3. DNS-over-HTTP Message Format . . . . . . . . . . . . . . . . 4		3. DNS-over-HTTP Message Format . . . . . . . . . . . . . . . . 4
	3.1. Request Method . . . . . . . . . . . . . . . . . . . . . 4		3.1. Request Method . . . . . . . . . . . . . . . . . . . . . 5
	3.2. Response Status Code . . . . . . . . . . . . . . . . . . 5		3.2. Response Status Code . . . . . . . . . . . . . . . . . . 5
	3.3. Header Fields . . . . . . . . . . . . . . . . . . . . . . 6		3.3. Header Fields . . . . . . . . . . . . . . . . . . . . . . 6
	3.4. Message Body . . . . . . . . . . . . . . . . . . . . . . 6		3.4. Message Body . . . . . . . . . . . . . . . . . . . . . . 6
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 7		4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 7		5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 7
	6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8		6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	RFC 1035 [RFC1035] specifies the wire format for DNS messages. It		RFC 1035 [RFC1035] specifies the wire format for DNS messages. It
	also specifies DNS transport on UDP and TCP on port 53, which is		also specifies DNS transport on UDP and TCP on port 53, which is
	still used today. However, there are other ways to access DNS		still used today. However, there are other ways to access DNS
	database, for example in a different data format or via alternative		database, for example in a different data format or via alternative
	DNS transport. These approaches are summarized in [draft-shane-		DNS transport. These approaches are summarized in [draft-shane-
	review-DNS-over-http].		review-DNS-over-http].
	skipping to change at page 6, line 41 ¶		skipping to change at page 6, line 45 ¶
	For a stub resolver that connects directly via HTTP to the HTTP		For a stub resolver that connects directly via HTTP to the HTTP
	server proxy then this flag should be set to TCP, as the entire		server proxy then this flag should be set to TCP, as the entire
	response can always be delivered so truncation is never required.		response can always be delivered so truncation is never required.
	The client MUST include this option. If it is missing then it is an		The client MUST include this option. If it is missing then it is an
	error and the server should respond with HTTP code 400 (bad request).		error and the server should respond with HTTP code 400 (bad request).
	3.4. Message Body		3.4. Message Body
	As mentioned, the message body is DNS wire-format data. It is worth		As mentioned, the message body is DNS wire-format data. DNS messages
	mentioning that DNS messages sent over TCP connections is prefixed		sent over TCP connections is prefixed with a two-byte length field
	with a two-byte length field which gives the message length [section		which gives the message length [section 4.2.2 in RFC 1035 [RFC1035]],
	4.2.2 in RFC 1035 [RFC1035]], excluding the two-byte length field.		excluding the two-byte length field. This length field allows the
	This length field allows the low-level processing to assemble a		low-level processing to assemble a complete message before beginning
	complete message before beginning to parse it. In the context of		to parse it. But when HTTP is used, the HTTP protocol itself keeps
	HTTP, there is content-length header field [section 3.3.2 in		track of the length of the message, so there is no need to transmit
	[RFC7230]]in which the field-value is the same with two bytes length		this separately.
	field in DNS over TCP.
	Since this two-byte length field is redundant, when the client proxy		Since the two-byte length field is redundant, when the client proxy
	receives a DNS message over TCP, it MUST NOT include the length field		receives a DNS message over TCP or when the server sends an answer
	in the message sent to the server. The length in the content-length		for a TCP query, it MUST NOT include the length field in the message
	header is only the size of the DNS message itself, and MUST NOT		sent. The length of the message sent by HTTP is only the size of the
	include this two-byte length header.		DNS message itself, and MUST NOT include this two-byte length header.
	4. Security Considerations		4. Security Considerations
	This protocol does not introduce any new security considerations		This protocol does not introduce any new security considerations
	since it is built on the DNS and HTTP protocols.		since it is built on the DNS and HTTP protocols.
	Since this protocol transmits DNS messages, all of the security		Since this protocol transmits DNS messages, all of the security
	concerns that stub resolvers and recursive resolvers have with DNS		concerns that stub resolvers and recursive resolvers have with DNS
	messages apply. However, since HTTP uses TCP as the underlying		messages apply. However, since HTTP uses TCP as the underlying
	protocol, DNS reflection or amplification attacks are not possible.		protocol, DNS reflection or amplification attacks are not possible.
	skipping to change at page 7, line 40 ¶		skipping to change at page 7, line 43 ¶
	example, clients of an open resolver do not require authentication.		example, clients of an open resolver do not require authentication.
	Note that the ability to perform DNS queries in this way may allow		Note that the ability to perform DNS queries in this way may allow
	users to bypass local DNS policy. This is problematic in any		users to bypass local DNS policy. This is problematic in any
	environment where administrators need to enforce specific DNS		environment where administrators need to enforce specific DNS
	behavior, such as an enterprise environment. The protocol outlined		behavior, such as an enterprise environment. The protocol outlined
	here does not introduce any new capabilities in this area, but by		here does not introduce any new capabilities in this area, but by
	creating a more standardized way of doing this it may cause		creating a more standardized way of doing this it may cause
	operational problems for enterprise administrators.		operational problems for enterprise administrators.
	5. IANA considerations		5. Privacy Considerations
			DNS over HTTP involves sending DNS requests, so is subject to most of
			the problems documented in RFC 7626 [RFC7626]. In particular the
			resolver handling the request sees the contents of every query and
			answer, as does any proxy involved on either the client or server
			side.
			Use of TLS encryption will prevent attackers from seeing the plain
			DNS queries on the wire. However, the warnings about privacy in RFC
			7858 [RFC7858] apply: "Even with encrypted messages, a well-
			positioned party may be able to glean certain details from an
			analysis of message timings and sizes."
			If a server requires a client-side certificate or other
			authentication, then this may allow an attacker to identify which
			user is active and when, if they gain access to the server logs.
			The use of DNS over HTTP may act as a strong signal to any
			surviellers that the user is attempting to bypass local DNS policy
			either to get different answers or hide their traffic. Various
			techniques could be used to discover this, such as observing web
			traffic without any corresponding DNS traffic.
			6. IANA considerations
	Registration for a new Media Type: dns-wireformat		Registration for a new Media Type: dns-wireformat
	Registration for a new HTTP header field: Proxy-DNS-Transport		Registration for a new HTTP header field: Proxy-DNS-Transport
	Registration for a new Well-Known URI: "dns-wireformat"		Registration for a new Well-Known URI: "dns-wireformat"
	6. Acknowledgments		7. Acknowledgments
	Thanks to Bob Harold, Paul Hoffman, and Julian Reschke for review.		Thanks to Bob Harold, Paul Hoffman, Julian Reschke, and Erik Kline
			for review.
	7. References		8. References
	[DOTSE] and , "DNSSEC Tests of Consumer Broadband Routers",		[DOTSE] and , "DNSSEC Tests of Consumer Broadband Routers",
	February 2008,		February 2008,
	<http://www.iis.se/docs/Routertester_en.pdf>.		<http://www.iis.se/docs/Routertester_en.pdf>.
	[I-D.bortzmeyer-dns-json]		[I-D.bortzmeyer-dns-json]
	Bortzmeyer, S., "JSON format to represent DNS data",		Bortzmeyer, S., "JSON format to represent DNS data",
	draft-bortzmeyer-dns-json-01 (work in progress), February		draft-bortzmeyer-dns-json-01 (work in progress), February
	2013.		2013.
	skipping to change at page 9, line 15 ¶		skipping to change at page 9, line 38 ¶
	[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,		DOI 10.17487/RFC7231, June 2014,
	<http://www.rfc-editor.org/info/rfc7231>.		<http://www.rfc-editor.org/info/rfc7231>.
	[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext		[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
	Transfer Protocol Version 2 (HTTP/2)", RFC 7540,		Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
	DOI 10.17487/RFC7540, May 2015,		DOI 10.17487/RFC7540, May 2015,
	<http://www.rfc-editor.org/info/rfc7540>.		<http://www.rfc-editor.org/info/rfc7540>.
			[RFC7626] Bortzmeyer, S., "DNS Privacy Considerations", RFC 7626,
			DOI 10.17487/RFC7626, August 2015,
			<http://www.rfc-editor.org/info/rfc7626>.
			[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
			and P. Hoffman, "Specification for DNS over Transport
			Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
			2016, <http://www.rfc-editor.org/info/rfc7858>.
	[SAC035] ICANN Security and Stability Advisory Committee, "DNSSEC		[SAC035] ICANN Security and Stability Advisory Committee, "DNSSEC
	Impact on Broadband Routers and Firewalls", 2008.		Impact on Broadband Routers and Firewalls", 2008.
	Authors' Addresses		Authors' Addresses
	Linjian Song		Linjian Song
	Beijing Internet Institute		Beijing Internet Institute
	2508 Room, 25th Floor, Tower A, Time Fortune		2508 Room, 25th Floor, Tower A, Time Fortune
	Beijing 100028		Beijing 100028
	P. R. China		P. R. China
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