< draft-ietf-dnsop-extended-error-02.txt		draft-ietf-dnsop-extended-error-03.txt >
	Network Working Group W. Kumari		Network Working Group W. Kumari
	Internet-Draft Google		Internet-Draft Google
	Intended status: Standards Track E. Hunt		Intended status: Standards Track E. Hunt
	Expires: March 25, 2019 ISC		Expires: June 23, 2019 ISC
	R. Arends		R. Arends
	ICANN		ICANN
	W. Hardaker		W. Hardaker
	USC/ISI		USC/ISI
	D. Lawrence		D. Lawrence
	Oracle + Dyn		Oracle + Dyn
	September 21, 2018		December 20, 2018
	Extended DNS Errors		Extended DNS Errors
	draft-ietf-dnsop-extended-error-02		draft-ietf-dnsop-extended-error-03
	Abstract		Abstract
	This document defines an extensible method to return additional		This document defines an extensible method to return additional
	information about the cause of DNS errors. The primary use case is		information about the cause of DNS errors. Though created primarily
	to extend SERVFAIL to provide additional information about the cause		to extend SERVFAIL to provide additional information about the cause
	of DNS and DNSSEC failures.		of DNS and DNSSEC failures, the Extended DNS Errors option defined in
			this document allows all response types to contain extended error
			information.
	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 https://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 25, 2019.		This Internet-Draft will expire on June 23, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 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
	(https://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 and background . . . . . . . . . . . . . . . . . 2		1. Introduction and background . . . . . . . . . . . . . . . . . 3
	1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3		1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
	2. Extended Error EDNS0 option format . . . . . . . . . . . . . 3		2. Extended Error EDNS0 option format . . . . . . . . . . . . . 3
	3. Use of the Extended DNS Error option . . . . . . . . . . . . 5		3. Use of the Extended DNS Error option . . . . . . . . . . . . 4
			3.1. The R (Retry) flag . . . . . . . . . . . . . . . . . . . 5
			3.2. The RESPONSE-CODE field . . . . . . . . . . . . . . . . . 5
			3.3. The INFO-CODE field . . . . . . . . . . . . . . . . . . . 5
			3.4. The EXTRA-TEXT field . . . . . . . . . . . . . . . . . . 5
	4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5		4. Defined Extended DNS Errors . . . . . . . . . . . . . . . . . 5
	4.1. SERVFAIL(2) extended information codes . . . . . . . . . 5		4.1. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2) . . . 6
	4.1.1. Extended DNS Error Code 1 - DNSSEC Bogus . . . . . . 6		4.1.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus . . 6
	4.1.2. Extended DNS Error Code 2 - DNSSEC Indeterminate . . 6		4.1.2. SERVFAIL Extended DNS Error Code 2 - DNSSEC
	4.1.3. Extended DNS Error Code 3 - Signature Expired . . . . 6		Indeterminate . . . . . . . . . . . . . . . . . . . . 6
	4.1.4. Extended DNS Error Code 4 - Signature Not Yet Valid . 6		4.1.3. SERVFAIL Extended DNS Error Code 3 - Signature
	4.1.5. Extended DNS Error Code 5 - Unsupported		Expired . . . . . . . . . . . . . . . . . . . . . . . 6
			4.1.4. SERVFAIL Extended DNS Error Code 4 - Signature Not
			Yet Valid . . . . . . . . . . . . . . . . . . . . . . 6
			4.1.5. SERVFAIL Extended DNS Error Code 5 - Unsupported
	DNSKEY Algorithm . . . . . . . . . . . . . . . . . . 6		DNSKEY Algorithm . . . . . . . . . . . . . . . . . . 6
	4.1.6. Extended DNS Error Code 6 - Unsupported		4.1.6. SERVFAIL Extended DNS Error Code 6 - Unsupported
	DS Algorithm . . . . . . . . . . . . . . . . . . . . 6		DS Algorithm . . . . . . . . . . . . . . . . . . . . 6
	4.1.7. Extended DNS Error Code 7 - DNSKEY missing . . . . . 6		4.1.7. SERVFAIL Extended DNS Error Code 7 - DNSKEY missing . 6
	4.1.8. Extended DNS Error Code 8 - RRSIGs missing . . . . . 6		4.1.8. SERVFAIL Extended DNS Error Code 8 - RRSIGs missing . 7
	4.1.9. Extended DNS Error Code 9 - No Zone Key Bit Set . . . 6		4.1.9. SERVFAIL Extended DNS Error Code 9 - No Zone Key Bit
	4.2. REFUSED(5) extended information codes . . . . . . . . . . 7		Set . . . . . . . . . . . . . . . . . . . . . . . . . 7
	4.2.1. Extended DNS Error Code 1 - Lame . . . . . . . . . . 7		4.2. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5) . . . . 7
	4.2.2. Extended DNS Error Code 2 - Prohibited . . . . . . . 7		4.2.1. REFUSED Extended DNS Error Code 1 - Lame . . . . . . 7
	4.3. NXDOMAIN(3) extended information codes . . . . . . . . . 7		4.2.2. REFUSED Extended DNS Error Code 2 - Prohibited . . . 7
	4.3.1. Extended DNS Error Code 1 - Blocked . . . . . . . . . 7		4.3. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3) . . . 7
			4.3.1. NXDOMAIN Extended DNS Error Code 1 - Blocked . . . . 7
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	5.1. new Extended Error Code EDNS Option . . . . . . . . . . . 7		5.1. new Extended Error Code EDNS Option . . . . . . . . . . . 7
	5.2. new Extended Error Code EDNS Option . . . . . . . . . . . 7		5.2. New Extended Error Code EDNS Option . . . . . . . . . . . 8
	6. Open questions . . . . . . . . . . . . . . . . . . . . . . . 8		6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 8		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9		8.1. Normative References . . . . . . . . . . . . . . . . . . 10
	9.1. Normative References . . . . . . . . . . . . . . . . . . 9		8.2. Informative References . . . . . . . . . . . . . . . . . 10
	9.2. Informative References . . . . . . . . . . . . . . . . . 9		Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 11
	Appendix A. Changes / Author Notes. . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction and background		1. Introduction and background
	There are many reasons that a DNS query may fail, some of them		There are many reasons that a DNS query may fail, some of them
	transient, some permanent; some can be resolved by querying another		transient, some permanent; some can be resolved by querying another
	server, some are likely best handled by stopping resolution.		server, some are likely best handled by stopping resolution.
	Unfortunately, the error signals that a DNS server can return are		Unfortunately, the error signals that a DNS server can return are
	very limited, and are not very expressive. This means that		very limited, and are not very expressive. This means that
	applications and resolvers often have to "guess" at what the issue is		applications and resolvers often have to "guess" at what the issue is
	- e.g the answer was marked REFUSED because of a lame delegation, or		- e.g. was the answer marked REFUSED because of a lame delegation, or
	because of a lame delegation or because the nameserver is still		because the nameserver is still starting up and loading zones? Is a
	starting up and loading zones? Is a SERVFAIL a DNSSEC validation		SERVFAIL a DNSSEC validation issue, or is the nameserver experiencing
	issue, or is the nameserver experiencing a bad hair day?		a bad hair day?
	A good example of issues that would benefit by additional error		A good example of issues that would benefit by additional error
	information is an error caused by a DNSSEC validation issue. When a		information are errors caused by DNSSEC validation issues. When a
	stub resolver queries a DNSSEC bogus name (using a validating		stub resolver queries a DNSSEC bogus name (using a validating
	resolver), the stub resolver receives only a SERVFAIL in response.		resolver), the stub resolver receives only a SERVFAIL in response.
	Unfortunately, SERVFAIL is used to signal many sorts of DNS errors,		Unfortunately, SERVFAIL is used to signal many sorts of DNS errors,
	and so the stub resolver simply asks the next configured DNS		and so the stub resolver simply asks the next configured DNS
	resolver. The result of trying the next resolver is one of two		resolver. The result of trying the next resolver is one of two
	outcomes: either the next resolver also validates, a SERVFAIL is		outcomes: either the next resolver also validates, a SERVFAIL is
	returned again, and the user gets an (largely) incomprehensible error		returned again, and the user gets an (largely) incomprehensible error
	message; or the next resolver is not a validating resolver, and the		message; or the next resolver is not a validating resolver, and the
	user is returned a potentially harmful result.		user is returned a potentially harmful result.
	This document specifies a mechanism to extend (or annotate) DNS		This document specifies a mechanism to extend (or annotate) DNS
	errors to provide additional information about the cause of the		errors to provide additional information about the cause of the
	error. This information can be used by the resolver to make a		error. When properly authenticated, this information can be used by
	decision regarding whether or not to retry, or by technical users		the resolver to make a decision regarding whether or not to retry or
	attempting to debug issues.		it can be used or by technical users attempting to debug issues.
	Here is a reference to an "external" (non-RFC / draft) thing:
	([IANA.AS_Numbers]). And this is a link to an
	ID:[I-D.ietf-sidr-iana-objects].
	1.1. Requirements notation		1.1. Requirements notation
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	2. Extended Error EDNS0 option format		2. Extended Error EDNS0 option format
	This draft uses an EDNS0 ([RFC2671]) option to include extended error		This draft uses an EDNS0 ([RFC2671]) option to include Extended DNS
	(ExtError) information in DNS messages. The option is structured as		Error (EDE) information in DNS messages. The option is structured as
	follows:		follows:
	1 1 1 1 1 1		1 1 1 1 1 1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	0: | OPTION-CODE |		0: | OPTION-CODE |
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	2: | OPTION-LENGTH |		2: | OPTION-LENGTH |
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	4: | R | RESERVED |		4: | R | RESERVED |
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	6: | RESPONSE-CODE |		6: | RESPONSE-CODE | INFO-CODE |
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	8: | INFO-CODE |
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	A: | EXTRA-TEXT |		8: | EXTRA-TEXT |
	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
	o OPTION-CODE, 2 octets (defined in [RFC6891]), for ExtError is TBD.		Field definition details:
			o OPTION-CODE, 2 octets (defined in [RFC6891]), for EDE is TBD.
			[RFC Editor: change TBD to the proper code once assigned by IANA.]
	o OPTION-LENGTH, 2 octets ((defined in [RFC6891]) contains the		o OPTION-LENGTH, 2 octets ((defined in [RFC6891]) contains the
	length of the payload (everything after OPTION-LENGTH) in octets		length of the payload (everything after OPTION-LENGTH) in octets
	and should be 4.		and should be 4 plus the length of the EXTRA-TEXT section (which
			may be a zero-length string).
			o The RETRY flag, 1 bit; the RETRY bit (R) indicates a flag defined
			for use in this specification.
			o The RESERVED bits, 15 bits: these bits are reserved for future
			use, potentially as additional flags. The RESERVED bits MUST be
			set to 0 by the sender and SHOULD be ignored by the receiver.
			o RESPONSE-CODE, 4 bits.
			o INFO-CODE, 12-bits.
			o EXTRA-TEXT, a variable length, ASCII encoded, text field that may
			hold additional textual information.
	o RESERVED, 2 octets; the first bit (R) indicates a flag defined in		3. Use of the Extended DNS Error option
	this specification. The remaining bits are reserved for future
	use, potentially as additional flags.
	o RESPONSE-CODE, 2 octets: this SHOULD be a copy of the RCODE from		The Extended DNS Error (EDE) is an EDNS option. It can be included
	the primary DNS packet. When including multiple extended error		in any response (SERVFAIL, NXDOMAIN, REFUSED, etc) to a query that
	EDNS0 records in a response in order to provide additional error		includes an EDNS option. This document includes a set of initial
	information, the RESPONSE-CODE MAY be a different RCODE.		codepoints (and requests to the IANA to add them to the registry),
			but is extensible via the IANA registry to allow additional error and
			information codes to be defined in the future.
	o INFO-CODE, 2 octets.		The fields of the Extended DNS Error option are defined further in
			the following sub-sections.
	o A variable length EXTRA-TEXT field holding additional textual		3.1. The R (Retry) flag
	information. It may be zero length when no additional textual
	information is included.
	Currently the only defined flag is the R flag.		The R (Retry) flag provides a hint as to what the receiver may want
			to do with this annotated error. Specifically, the R (or Retry) flag
			provides a hint to the receiver that it should retry the query to
			another server. If the R bit is set (1), the sender believes that
			retrying the query may provide a successful answer next time; if the
			R bit is clear (0), the sender believes that the resolver should not
			ask another server.
	R - Retry The R (or Retry) flag provides a hint to the receiver that		The mechanism is specifically designed to be extensible, and so
	it should retry the query, probably by querying another server.		implementations may receive EDE codes that it does not understand.
	If the R bit is set (1), the sender believes that retrying the		The R flag allows implementations to make a decision as to what to do
	query may provide a successful answer next time; if the R bit is		if it receives a response with an unknown code - retry or drop the
	clear (0), the sender believes that it should not ask another		query. Note that this flag is only a suggestion. Unless a
	server.		protective transport mechanism (like TSIG [RFC2845] or TLS [RFC8094])
			is used, the bit's value could have have been altered by a person-in-
			the-middle. Receivers can choose to ignore this hint. See the
			security considerations for additional considerations.
	The remaining bits in the RESERVED field are reserved for future use		3.2. The RESPONSE-CODE field
	and MUST be set to 0 by the sender and SHOULD be ignored by the
	receiver.
	INFO-CODE: A code point that, when combined with the RCODE from the		This 4-bit value SHOULD be a copy of the RCODE from the primary DNS
	DNS packet, serve as a joint-index into the IANA "Extended DNS		packet. Multiple EDNS0/EDE records may be included in the response.
	Errors" registry.		When including multiple EDNS0/EDE records in a response in order to
			provide additional error information, other RESPONSE-CODEs MAY use a
			different RCODE.
	3. Use of the Extended DNS Error option		3.3. The INFO-CODE field
	The Extended DNS Error (EDE) is an EDNS option. It can be included		This 12-bit value provides the additional context for the RESPONSE-
	in any error response (SERVFAIL, NXDOMAIN, REFUSED, etc) to a query		CODE value. This combination of the RESPONSE-CODE and the INFO-CODE
	that includes an EDNS option. This document includes a set of		serve as a joint-index into the IANA "Extended DNS Errors" registry.
	initial codepoints (and requests to the IANA to add them to the
	registry), but is extensible via the IANA registry to allow
	additional error and information codes to be defined in the future.
	The R (Retry) flag provides a hint (or suggestion) as to what the		3.4. The EXTRA-TEXT field
	receiver may want to do with this annotated error. The mechanism is
	specifically designed to be extensible, and so implementations may
	receive EDE codes that it does not understand. The R flag allows
	implementations to make a decision as to what to do if it receives a
	response with an unknown code - retry or drop the query. Note that
	this flag is only a suggestion or hint. Receivers can choose to
	ignore this hint.
	The EXTRA-INFO textual field may be zero-length, or may hold		The ASCII-encoded, EXTRA-TEXT field may be zero-length, or may hold
	additional information useful to network operators.		additional information useful to network operators.
	4. Defined Extended DNS Errors		4. Defined Extended DNS Errors
	This document defines some initial EDE codes. The mechanism is		This document defines some initial EDE codes. The mechanism is
	intended to be extensible, and additional codepoints will be		intended to be extensible, and additional code-points can be
	registered in the "Extended DNS Errors" registry. This document		registered in the "Extended DNS Errors" registry. This document
	provides suggestions for the R flag, but the originating server may		provides suggestions for the R flag, but the originating server may
	ignore these recommendations if it knows better.		ignore these recommendations if it knows better.
	The RESPONSE-CODE and the INFO-CODE from the EDE EDNS option is used		The RESPONSE-CODE and the INFO-CODE from the EDE EDNS option is used
	to serve as a double index into the "Extended DNS Error codes" IANA		to serve as a double index into the "Extended DNS Error codes" IANA
	registry, the initial values for which are defined in the following		registry, the initial values for which are defined in the following
	sub-sections.		sub-sections.
	4.1. SERVFAIL(2) extended information codes		4.1. INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2)
	4.1.1. Extended DNS Error Code 1 - DNSSEC Bogus
			4.1.1. SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus
	The resolver attempted to perform DNSSEC validation, but validation		The resolver attempted to perform DNSSEC validation, but validation
	ended in the Bogus state. The R flag should not be set.		ended in the Bogus state. The R flag should not be set.
	4.1.2. Extended DNS Error Code 2 - DNSSEC Indeterminate		4.1.2. SERVFAIL Extended DNS Error Code 2 - DNSSEC Indeterminate
	The resolver attempted to perform DNSSEC validation, but validation		The resolver attempted to perform DNSSEC validation, but validation
	ended in the Indeterminate state. The R flag should not be set.		ended in the Indeterminate state. The R flag should not be set.
	4.1.3. Extended DNS Error Code 3 - Signature Expired		4.1.3. SERVFAIL Extended DNS Error Code 3 - Signature Expired
	The resolver attempted to perform DNSSEC validation, but the		The resolver attempted to perform DNSSEC validation, but the
	signature was expired. The R flag should not be set.		signature was expired. The R flag should not be set.
	4.1.4. Extended DNS Error Code 4 - Signature Not Yet Valid		4.1.4. SERVFAIL Extended DNS Error Code 4 - Signature Not Yet Valid
	The resolver attempted to perform DNSSEC validation, but the		The resolver attempted to perform DNSSEC validation, but the
	signatures received were not yet valid. The R flag should not be		signatures received were not yet valid. The R flag should not be
	set.		set.
	4.1.5. Extended DNS Error Code 5 - Unsupported DNSKEY Algorithm		4.1.5. SERVFAIL Extended DNS Error Code 5 - Unsupported DNSKEY
			Algorithm
	The resolver attempted to perform DNSSEC validation, but a DNSKEY		The resolver attempted to perform DNSSEC validation, but a DNSKEY
	RRSET contained only unknown algorithms. The R flag should not be		RRSET contained only unknown algorithms. The R flag should be set.
	set.
	4.1.6. Extended DNS Error Code 6 - Unsupported DS Algorithm		4.1.6. SERVFAIL Extended DNS Error Code 6 - Unsupported DS Algorithm
	The resolver attempted to perform DNSSEC validation, but a DS RRSET		The resolver attempted to perform DNSSEC validation, but a DS RRSET
	contained only unknown algorithms. The R flag should not be set.		contained only unknown algorithms. The R flag should be set.
	4.1.7. Extended DNS Error Code 7 - DNSKEY missing		4.1.7. SERVFAIL Extended DNS Error Code 7 - DNSKEY missing
	A DS record existed at a parent, but no DNSKEY record could be found		A DS record existed at a parent, but no DNSKEY record could be found
	for the child. The R flag should not be set.		for the child. The R flag should not be set.
	4.1.8. Extended DNS Error Code 8 - RRSIGs missing		4.1.8. SERVFAIL Extended DNS Error Code 8 - RRSIGs missing
	The resolver attempted to perform DNSSEC validation, but no RRSIGs		The resolver attempted to perform DNSSEC validation, but no RRSIGs
	could be found for at least one RRset where RRSIGs were expected.		could be found for at least one RRset where RRSIGs were expected.
	4.1.9. Extended DNS Error Code 9 - No Zone Key Bit Set		4.1.9. SERVFAIL Extended DNS Error Code 9 - No Zone Key Bit Set
	The resolver attempted to perform DNSSEC validation, but no Zone Key		The resolver attempted to perform DNSSEC validation, but no Zone Key
	Bit was set in a DNSKEY.		Bit was set in a DNSKEY.
	4.2. REFUSED(5) extended information codes		4.2. INFO-CODEs for use with RESPONSE-CODE: REFUSED(5)
	4.2.1. Extended DNS Error Code 1 - Lame		4.2.1. REFUSED Extended DNS Error Code 1 - Lame
	An authoritative resolver that receives a query (with the RD bit		An authoritative resolver that receives a query (with the RD bit
	clear) for a domain for which it is not authoritative SHOULD include		clear) for a domain for which it is not authoritative SHOULD include
	this EDE code in the REFUSED response. Implementations should set		this EDE code in the REFUSED response. Implementations should set
	the R flag in this case (another nameserver might not be lame).		the R flag in this case (another nameserver might not be lame).
	4.2.2. Extended DNS Error Code 2 - Prohibited		4.2.2. REFUSED Extended DNS Error Code 2 - Prohibited
	An authoritative or recursive resolver that receives a query from an		An authoritative or recursive resolver that receives a query from an
	"unauthorized" client can annotate its REFUSED message with this		"unauthorized" client can annotate its REFUSED message with this
	code. Examples of "unauthorized" clients are recursive queries from		code. Examples of "unauthorized" clients are recursive queries from
	IP addresses outside the network, blacklisted IP addresses, local		IP addresses outside the network, blacklisted IP addresses, local
	policy, etc.		policy, etc.
	Implementations SHOULD allow operators to define what to set the R		Implementations SHOULD allow operators to define what to set the R
	flag to in this case.		flag to in this case.
	4.3. NXDOMAIN(3) extended information codes		4.3. INFO-CODEs for use with RESPONSE-CODE: NXDOMAIN(3)
	4.3.1. Extended DNS Error Code 1 - Blocked		4.3.1. NXDOMAIN Extended DNS Error Code 1 - Blocked
	The resolver attempted to perfom a DNS query but the domain is		The resolver attempted to perfom a DNS query but the domain is
	blacklisted due to a security policy. The R flag should not be set.		blacklisted due to a security policy. The R flag should not be set.
	5. IANA Considerations		5. IANA Considerations
	[This section under construction, beware. ]
	5.1. new Extended Error Code EDNS Option		5.1. new Extended Error Code EDNS Option
	This document defines a new EDNS(0) option, entitled "Extended DNS		This document defines a new EDNS(0) option, entitled "Extended DNS
	Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes		Error", assigned a value of TBD1 from the "DNS EDNS0 Option Codes
	(OPT)" registry [to be removed upon publication:		(OPT)" registry [to be removed upon publication:
	[http://www.iana.org/assignments/dns-parameters/dns-		[http://www.iana.org/assignments/dns-parameters/dns-
	parameters.xhtml#dns-parameters-11]		parameters.xhtml#dns-parameters-11]
	Value Name Status Reference		Value Name Status Reference
	----- ---------------- ------ ------------------		----- ---------------- ------ ------------------
	TBD Extended DNS Error TBD [ This document ]		TBD Extended DNS Error TBD [ This document ]
	5.2. new Extended Error Code EDNS Option		5.2. New Extended Error Code EDNS Option
	This document defines a new double-index IANA registry table, where		This document defines a new double-index IANA registry table, where
	the first index value is the RCODE value and the second index value		the first index value is the RCODE value and the second index value
	is the INFO-CODE from the Extended DNS Error EDNS option defined in		is the INFO-CODE from the Extended DNS Error EDNS option defined in
	this document. The IANA is requested to create and maintain this		this document. The IANA is requested to create and maintain this
	"Extended DNS Error codes" registry. The codepoint space for each		"Extended DNS Error codes" registry. The codepoint space for each
	RCODE index is to be broken into 3 ranges:		INFO-CODE index is to be broken into 3 ranges:
	o 1 - 16384: Specification required.		o 0 - 3583: Specification required.
			o 3584 - 3839: First Come First Served.
			o 3840 - 4095: Experimental / Private use
	o 16385 - 65000: First Come First Served		A starting set of entries, based on the contents of this document, is
			as follows:
	o 65000 - 65534: Experimental / Private use		RESPONSE-CODE: 2 (SERVFAIL)
			INFO-CODE: 1
			Purpose: DNSSEC Bogus
			Reference: Section 4.1.1
	The codepoints 0, 65535 are reserved.		RESPONSE-CODE: 2 (SERVFAIL)
			INFO-CODE: 2
			Purpose: DNSSEC Indeterminate
			Reference: Section 4.1.2
	A starting table, based on the contents of this document, is as		RESPONSE-CODE: 2 (SERVFAIL)
	follows:		INFO-CODE: 3
			Purpose: Signature Expired
			Reference: Section 4.1.3
	| RCODE | EDE-INFO-CODE | Meaning | Ref |		RESPONSE-CODE: 2 (SERVFAIL)
	|-------------+-------------------------+---------------------------------------------+------------------------------------------|		INFO-CODE: 4
	| SERVFAIL(2) | DNSSEC_BOGUS(1) | DNSSEC Validation resulted in Bogus | section <xref target="errbogus" /> |		Purpose: Signature Not Yet Valid
	| SERVFAIL(2) | DNSSEC_INDETERMINATE(2) | DNSSEC Validation resulted in Indeterminate | section <xref target="errindeterminate" /> |		Reference: Section 4.1.4
	[incomplete]		RESPONSE-CODE: 2 (SERVFAIL)
			INFO-CODE: 5
			Purpose: Unsupported DNSKEY
			Reference: Section 4.1.5
	6. Open questions		RESPONSE-CODE: 2 (SERVFAIL)
			INFO-CODE: 6
			Purpose: Unsupported DS Algorithm
			Reference: Section 4.1.6
	1 Can this be included in *any* response or only responses to		RESPONSE-CODE: 2 (SERVFAIL)
	requests that included an EDNS option? Resolvers are supposed to		INFO-CODE: 7
	ignore additional. EDNS capable ones are supposed to simply		Purpose: DNSKEY missing
	ignore unknown options. I know the spec says you can only include		Reference: Section 4.1.7
	EDNS0 in a response if in a request -- it is time to reevaluate
	this?
	7. Security Considerations		RESPONSE-CODE: 2 (SERVFAIL)
			INFO-CODE: 8
			Purpose: RRSIGs missing
			Reference: Section 4.1.8
	DNSSEC is being deployed - unfortunately a significant number of		RESPONSE-CODE: 2 (SERVFAIL)
	clients (~11% according to [GeoffValidation]), when receiving a		INFO-CODE: 9
	SERVFAIL from a validating resolver because of a DNSSEC validaion		Purpose: No Zone Key Bit Set
	issue simply ask the next (non-validating) resolver in their list,		Reference: Section 4.1.9
	and don't get any of the protections which DNSSEC should provide.
	This is very similar to a kid asking his mother if he can have
	another cookie. When the mother says "No, it will ruin your
	dinner!", going off and asking his (more permissive) father and
	getting a "Yes, sure, cookie!".
	8. Acknowledgements		RESPONSE-CODE: 3 (NXDOMAIN)
			INFO-CODE: 1
			Purpose: Blocked
			Reference: Section 4.3.1
	The authors wish to thank Geoff Huston and Bob Harold, Carlos M.		RESPONSE-CODE: 5 (REFUSED)
	Martinez, Peter DeVries, George Michelson, Mark Andrews, Ondrej Sury,		INFO-CODE: 1
	Edward Lewis, Paul Vixie, Shane Kerr, Loganaden Velvindron. They		Purpose: Lame
	also vaguely remember discussing this with a number of people over		Reference: Section 4.2.1
	the years, but have forgotten who all they were -- if you were one of
			RESPONSE-CODE: 5 (REFUSED)
			INFO-CODE: 2
			Purpose: Prohibited
			Reference: Section 4.2.2
			6. Security Considerations
			Though DNSSEC continues to be deployed, unfortunately a significant
			number of clients (~11% according to [GeoffValidation]) that receive
			a SERVFAIL from a validating resolver because of a DNSSEC validaion
			issue will simply ask the next (potentially non-validating) resolver
			in their list, and thus don't get any of the protections which DNSSEC
			should provide. This is very similar to a kid asking his mother if
			he can have another cookie. When the mother says "No, it will ruin
			your dinner!", going off and asking his (more permissive) father and
			getting a "Yes, sure, have a cookie!".
			This information is unauthenticated information, and an attacker (e.g
			MITM or malicious recursive server) could insert an extended error
			response into already untrusted data -- ideally clients and resolvers
			would not trust any unauthenticated information, but until we live in
			an era where all DNS answers are authenticated via DNSSEC or other
			mechanisms, there are some tradeoffs. As an example, an attacker who
			is able to insert the DNSSEC Bogus Extended Error into a packet could
			instead simply reply with a fictitious address (A or AAAA) record.
			The R bit hint and extended error information are informational -
			implementations can choose how much to trust this information and
			validating resolvers / stubs may choose to put a different weight on
			it.
			7. Acknowledgements
			The authors wish to thank Joe Abley, Mark Andrews, Peter DeVries,
			Peter van Dijk, Donald Eastlake, Bob Harold, Evan Hunt, Geoff Huston,
			Shane Kerr, Edward Lewis, Carlos M. Martinez, George Michelson, Petr
			Spacek, Ondrej Sury, Loganaden Velvindron, and Paul Vixie. They also
			vaguely remember discussing this with a number of people over the
			years, but have forgotten who all they were -- if you were one of
	them, and are not listed, please let us know and we'll acknowledge		them, and are not listed, please let us know and we'll acknowledge
	you.		you.
	I also want to thank the band "Infected Mushroom" for providing a		I also want to thank the band "Infected Mushroom" for providing a
	good background soundtrack (and to see if I can get away with this!)		good background soundtrack (and to see if I can get away with this!)
	Another author would like to thank the band "Mushroom Infectors".		Another author would like to thank the band "Mushroom Infectors".
	This was funny at the time we wrote it, but I cannot remember why...		This was funny at the time we wrote it, but I cannot remember why...
	We would like to especially thank Peter van Dijk, who sent GitHub		8. References
	pull requests.
	9. References
	9.1. Normative References
	[IANA.AS_Numbers]		8.1. Normative References
	IANA, "Autonomous System (AS) Numbers",
	<http://www.iana.org/assignments/as-numbers>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
	<https://www.rfc-editor.org/info/rfc2119>.		editor.org/info/rfc2119>.
	9.2. Informative References		8.2. Informative References
	[GeoffValidation]		[GeoffValidation]
	IANA, "A quick review of DNSSEC Validation in today's		IANA, "A quick review of DNSSEC Validation in today's
	Internet", June 2016, <http://www.potaroo.net/		Internet", June 2016, <http://www.potaroo.net/
	presentations/2016-06-27-dnssec.pdf>.		presentations/2016-06-27-dnssec.pdf>.
	[I-D.ietf-sidr-iana-objects]		[RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
	Manderson, T., Vegoda, L., and S. Kent, "RPKI Objects		Wellington, "Secret Key Transaction Authentication for DNS
	issued by IANA", draft-ietf-sidr-iana-objects-03 (work in		(TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000,
	progress), May 2011.		<https://www.rfc-editor.org/info/rfc2845>.
			[RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram
			Transport Layer Security (DTLS)", RFC 8094,
			DOI 10.17487/RFC8094, February 2017, <https://www.rfc-
			editor.org/info/rfc8094>.
	Appendix A. Changes / Author Notes.		Appendix A. Changes / Author Notes.
	[RFC Editor: Please remove this section before publication ]		[RFC Editor: Please remove this section before publication ]
	From -00 to -01:		From -00 to -01:
	o Address comments from IETF meeting.		o Address comments from IETF meeting.
	o document copying the response code		o document copying the response code
	o mention zero length fields are ok		o mention zero length fields are ok
	o clarify lookup procedure		o clarify lookup procedure
	o mention that table isn't done		o mention that table isn't done
	From -03 to -IETF 00:		From -03 to -IETF 00:
	o Renamed to draft-ietf-dnsop-extended-error		o Renamed to draft-ietf-dnsop-extended-error
	From -02 to -03:		From -02 to -03:
	o Added David Lawrence -- I somehow missed that in last version.		o Added David Lawrence -- I somehow missed that in last version.
End of changes. 79 change blocks.
	173 lines changed or deleted		231 lines changed or added
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