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doc/draft/draft-ietf-dnsext-unknown-rrs-04.txt → doc/draft/draft-ietf-dnsext-unknown-rrs-05.txt
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INTERNET-DRAFT Andreas Gustafsson
draft-ietf-dnsext-unknown-rrs-04.txt Nominum Inc.
September 2002
draft-ietf-dnsext-unknown-rrs-05.txt Nominum Inc.
March 2003
Updates: RFC 1034, RFC 2163, RFC 2535
Handling of Unknown DNS RR Types
Handling of Unknown DNS Resource Record Types
Status of this Memo
@ -31,7 +33,7 @@ Status of this Memo
Abstract
Extending the Domain Name System with new Resource Record types
Extending the Domain Name System with new Resource Record (RR) types
currently requires changes to name server software. This document
specifies the changes necessary to allow future DNS implementations
to handle new RR types transparently.
@ -46,16 +48,15 @@ Abstract
slave servers for the zone containing it, and in some cases also at
caching name servers and forwarders used by the client.
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Because the deployment of new server software is slow and expensive,
the potential of the DNS in supporting new services has never been
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fully realized. This memo proposes changes to name servers and to
procedures for defining new RR types aimed at simplifying the future
deployment of new RR types.
@ -103,20 +104,26 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
which now contains unrelated data. This would cause the compressed
name to be corrupted.
To avoid such corruption, servers MUST NOT compress domain names
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To avoid such corruption, servers MUST NOT compress domain names
embedded in the RDATA of types that are class-specific or not well-
known. This requirement was stated in RFC1123 without defining the
term "well-known"; it is hereby specified that only the RR types
defined in RFC1035 are to be considered "well-known".
The specifications of a few existing RR types have explicitly allowed
compression contrary to this specification: RFC2163 specified that
compression applies to the PX RR, and RFC2535 allowed compression in
SIG RRs and NXT RRs records. Since this specification disallows
compression in these cases, it is an update to RFC2163 (section 4)
and RFC2535 (sections 4.1.7 and 5.2).
Receiving servers MUST decompress domain names in RRs of well-known
type, and SHOULD also decompress RRs of type RP, AFSDB, RT, SIG, PX,
NXT, NAPTR, and SRV (although the current specification of the SRV RR
@ -153,6 +160,13 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
herein rather than a traditional type-specific
encoding.
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An unsigned decimal integer specifying the
RDATA length in octets.
@ -160,14 +174,6 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
the actual RDATA field, each containing an even
number of hexadecimal digits.
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If the RDATA is of zero length, the text representation contains only
the \# token and the single zero representing the length.
@ -209,6 +215,14 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
This implies that embedded domain names, being included in the
overall bitwise comparison, are compared in a case-sensitive manner.
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As a result, when a new RR type contains one or more embedded domain
names, it is possible to have multiple RRs owned by the same name
that differ only in the character case of the embedded domain
@ -216,35 +230,54 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
records differing only in character case, and not expected to cause
any problems in practice.
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7. DNSSEC Canonical Form and Ordering
DNSSEC [RFC2535] defines a canonical form and ordering for RRs. In
the canonical form, domain names embedded in the RDATA are converted
to lower case.
DNSSEC defines a canonical form and ordering for RRs [RFC2535,
section 8.1]. In that canonical form, domain names embedded in the
RDATA are converted to lower case.
To ensure backwards compatibility, this canonical form remains
unchanged for any RR types defined in RFC2931 or earlier. That is,
the domain names embedded in RRs of type NS, MD, MF, CNAME, SOA, MB,
MG, MR, PTR, HINFO, MINFO, MX, HINFO, RP, AFSDB, RT, SIG, PX, NXT,
NAPTR, KX, SRV, DNAME, and A6 are converted to lower case according
to the DNS rules for character comparisons.
The downcasing is necessary to ensure the correctness of DNSSEC
signatures when case distinctions in domain names are lost due to
compression, but since it requires knowledge of the presence and
position of embedded domain names, it cannot be applied to unknown
types.
For all other RR types, the canonical form is hereby changed such
that no downcasing of embedded domain names takes place. The owner
name is always set to lower case according to the DNS rules for
character comparisons, regardless of the RR type.
To ensure continued consistency of the canonical form of RR types
where compression is allowed, and for continued interoperability with
existing implementations that already implement the RFC2535 canonical
form and apply it to their known RR types, the canonical form remains
unchanged for all RR types whose whose initial publication as an RFC
was prior to the initial publication of this specification as an RFC
(RFC TBD).
As a courtesy to implementors, it is hereby noted that the complete
set of such previously published RR types that contain embedded
domain names, and whose DNSSEC canonical form therefore involves
downcasing according to the DNS rules for character comparisons,
consists of the RR types NS, MD, MF, CNAME, SOA, MB, MG, MR, PTR,
HINFO, MINFO, MX, HINFO, RP, AFSDB, RT, SIG, PX, NXT, NAPTR, KX, SRV,
DNAME, and A6.
This document specifies that for all other RR types (whether treated
as unknown types or treated as known types according to an RR type
definition RFC more recent than than RFC TBD), the canonical form is
such that no downcasing of embedded domain names takes place, and
otherwise identical to the canonical form specified in RFC2535
section 8.1.
Note that the owner name is always set to lower case according to the
DNS rules for character comparisons, regardless of the RR type.
The DNSSEC canonical RR ordering is as specified in RFC2535 section
8.3, where the octet sequence is the canonical form as revised by
this specification.
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The canonical ordering is as specified in RFC2535 section 8.3, where
the octet sequence is the canonical form as revised by this
specification.
8. Additional Section Processing
@ -265,7 +298,7 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
This specification is not believed to cause any new security
problems, nor to solve any existing ones.
References
Normative References
[RFC1034] - Domain Names - Concepts and Facilities, P. Mockapetris,
November 1987.
@ -273,37 +306,43 @@ References
[RFC1035] - Domain Names - Implementation and Specifications, P.
Mockapetris, November 1987.
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[RFC1123] - Requirements for Internet Hosts -- Application and
Support, R. Braden, Editor, October 1989.
[RFC2119] - Key words for use in RFCs to Indicate Requirement Levels,
S. Bradner, BCP 14, March 1997.
[RFC2535] - Domain Name System Security Extensions. D. Eastlake,
March 1999.
[RFC2613] - Using the Internet DNS to Distribute MIXER Conformant
Global Address Mapping (MCGAM), C. Allocchio, January 1998.
[RFC2929] - Domain Name System (DNS) IANA Considerations, D.
Eastlake, E. Brunner-Williams, B. Manning, September 2000.
Non-normative References
[RFC1876] - A Means for Expressing Location Information in the Domain
Name System, C. Davis, P. Vixie, T. Goodwin, I. Dickinson, January
1996.
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[RFC2052] - A DNS RR for specifying the location of services (DNS
SRV), A. Gulbrandsen, P. Vixie, October 1996. Obsoleted by RFC2782.
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2136] - Dynamic Updates in the Domain Name System (DNS UPDATE).
[RFC2136] - Dynamic Updates in the Domain Name System (DNS UPDATE),
P. Vixie, Ed., S. Thomson, Y. Rekhter, J. Bound, April 1997.
[RFC2535] - Domain Name System Security Extensions. D. Eastlake,
March 1999.
[RFC2782] - A DNS RR for specifying the location of services (DNS
SRV). A. Gulbrandsen, P. Vixie, L. Esibov, February 2000.
[RFC2929] - Domain Name System (DNS) IANA Considerations. D.
Eastlake, E. Brunner-Williams, B. Manning, September 2000.
SRV), A. Gulbrandsen, P. Vixie, L. Esibov, February 2000.
Author's Address
@ -328,14 +367,6 @@ Full Copyright Statement
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
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document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
@ -352,8 +383,37 @@ draft-ietf-dnsext-unknown-rrs-04.txt September 2002
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to pertain
to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; neither does it represent that it has made any
effort to identify any such rights. Information on the IETF's
procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such proprietary
rights by implementors or users of this specification can be obtained
from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
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