dnsop D. Crocker
Internet-Draft Brandenburg InternetWorking
Updates: 2782, 3263, 3404, 3529, 3620, May 11, 2018
3832, 3887, 3958, 4120, 4227,
4386, 4387, 4976, 5026, 5328,
5389, 5415, 5555, 5679, 5766,
5780, 5804, 6011, 6120, 6186,
6733 (if approved)
Intended status: Best Current Practice
Expires: November 12, 2018

DNS Attrleaf Changes: Fixing Specifications with _Underscored Node Name Use
draft-ietf-dnsop-attrleaf-fix-00

Abstract

Original uses of an _underscore character as a domain node name prefix, which creates a space for constrained interpretation of resource records, were specified without the benefit of an IANA registry. This produced an entirely uncoordinated set of name-creation activities, all drawing from the same namespace. A registry now has been defined. However the existing specifications that use _underscore naming need to be modified, to be in line with the new registry. This document specifies those changes. The changes preserve existing software and operational practice, while adapting the specifications for those practices to the newer _underscore registry model.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on November 12, 2018.

Copyright Notice

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Table of Contents

1. Introduction

Original uses of an _underscore character as a domain node name prefix, which creates a space for constrained interpretation of resource records, were specified without the benefit of an [IANA-reg] registry. This produced an entirely uncoordinated set of name-creation activities, all drawing from the same namespace. A registry has been now defined, and that document discusses the background for _underscore domain name use [Attrleaf].

The basic model for underscored name registration, as specified in [Attrleaf], is to have each registry entry be unique in terms of the combination of a resource record type and a 'global' (ie, right-most) underscore name.

The existing uses of _underscore naming have specifications that do not reflect the existence of this integrated registry. For the new reader or the new editor of one of those documents, there is currently nothing signaling that the underscore name(s) defined in the document are now processed through an IANA registry. This document remedies that, by marking such a published document with an update, indicating the nature of the change.

The documents that define the SRV and URI DNS resource records provide a meta-template for underscore assignments, partially based on separate registries [RFC6335]. For the portion that selects the global (right-most) underscore name, this perpetuates uncoordinated assignment activities by separate technical specifications, out of the same name space. This document remedies that by providing detail for revisions to the SRV and URI specifications, to bring their use in line with the single, integrated global underscore registry.

The result of these changes preserves existing software and operations practices, while adapting the technical specifications to the newer _underscore registry model.

2. RRset Use in Specifications

2.1. TXT RRset Use

This section provides a generic approach for changes to existing specifications that define straightforward use of _underscored node names, when scoping the use of a TXT RR. The approach provides the information needed for adapting such specifications to the use of the IANA DNS Underscore Global Scoped Entry Registry. Hence the approach is meant both as an update to these existing specifications, and as guidance for changes when those documents are revised.

For any document that specifies the use of a TXT RRset under an underscored name, that name is expected to be registered in the IANA DNS Underscore Global Scoped Entry Registry. An effort has been made to locate existing drafts that do this, register the global underscored name, and list them in this document.

If a specification that defines use of a TXT record within an underscore-scoped name is revised, it SHOULD add an entry to the global underscored name registry, if one does not already exist.

Here is a template of suggested text for this to appear in the IANA Considerations section of the specification:

Underscore Global Registry Entry
RR Type _NODE NAME REFERENCE
TXT _{DNS node name} {citation for the document making the addition.}

2.2. SRV RRset Use

Specification for the SRV resource record provides a template for use of underscored node names. The global (right-most) name, is characterised as naming the 'protocol' that is associated with SRV RR usage.

This section provides a generic approach for changes to existing specifications that define the use of an SRV RR. The approach provides the information needed for adapting such specifications to the use of the IANA DNS Underscore Global Scoped Entry Registry. Hence the approach is meant both as an update to these existing specifications, and as guidance for changes when those documents are revised.

For any document that specifies the use of a SRV RRset, the global ('protocol', right-most) underscored name is expected to be registered in the IANA DNS Underscore Global Scoped Entry Registry. An effort has been made to locate existing drafts that do this, register the global underscored name, and list them in this document.

If a specification that defines use of an SRV record is revised, and the right-most underscored name above the record is not already registered, an entry for the name SHOULD be added to the global underscored name registry.

Here is a template of suggested text for this to appear in the IANA Considerations section of the specification:

Underscore Global Registry Entry
RR Type _NODE NAME REFERENCE
SRV _{DNS 'protocol' node name} {citation for the document making the addition.}

2.3. URI RRset Use

Specification for the URI resource record provides a template for use of underscored node names. The global (right-most) name, is characterised as naming the 'protocol' that is associated with URI RR usage or by reversing an Enumservice sequence.

This section provides a generic approach for changes to existing specifications that define use of a URI RRset. The approach provides the information needed for adapting such specifications to the use of the IANA DNS Underscore Global Scoped Entry Registry. Hence the approach is meant both as an update to these existing specifications, and as guidance for changes when those documents are revised.

For any RFC that specifies the use of a URI RR, the global ('protocol' or right-most enumservice) underscored name is expected to be registered in the IANA DNS Underscore Global Scoped Entry Registry. An effort has been made to locate existing drafts that do this and register the associated 'protocol' name.

If a specification that defines use of a URI record is revised, when the right-most underscored name used by it is not already registered, an entry for the name SHOULD be added to the global underscored name registry.

Here is a template of suggested text for this to appear in the IANA Considerations section of the specification:

Underscore Global Registry Entry
RR Type _NODE NAME REFERENCE
URI _{DNS 'protocol' or Enumservice node name} {citation for the document making the addition.}

3. Underscored Template Specifications

3.1. SRV Specification Changes

The specification for a domain name under which an SRV resource record appears provides a template for use of underscored node names. The global (right-most) underscored name, is characterised as indicating the 'protocol' that is associated with SRV RR usage.

The format of the SRV RR

 Here is the format of the SRV RR, whose DNS type code is 33:
       _Service._Proto.Name TTL Class SRV Priority Weight Port Target
 ...
 Proto
      The symbolic name of the desired protocol, with an underscore
      (_) prepended to prevent collisions with DNS labels that occur
      in nature.  _TCP and _UDP are at present the most useful values
      for this field, though any name defined by Assigned Numbers or
      locally may be used (as for Service).  The Proto is case
      insensitive.

The text of that specification is hereby updated from:

3.2. URI Specification Changes

Specification for the domain name under which a URI resource record occurs is similar to that for the SRV resource record, although the text refers only to 'service' name, rather than distinguishing 'service' from 'protocol'. Further, the URI RR specification permits alternative underscored naming schemes:

4.1.  Owner Name, Class, and Type

The URI owner name is subject to special conventions.

Just like the SRV RR [RFC2782], the URI RR has service information
encoded in its owner name.  In order to encode the service for a
specific owner name, one uses service parameters.  Valid service
parameters are those registered by IANA in the "Service Name and
Transport Protocol Port Number Registry" [RFC6335] or as "Enumservice
---
Registrations [RFC6117].  The Enumservice Registration parameters are
reversed (i.e., subtype(s) before type), prepended with an underscore
(_), and prepended to the owner name in separate labels.  The
underscore is prepended to the service parameters to avoid collisions
with DNS labels that occur in nature, and the order is reversed to
make it possible to do delegations, if needed, to different zones
(and therefore providers of DNS).

For example, suppose we are looking for the URI for a service with
ENUM Service Parameter "A:B:C" for host example.com.  Then we would
query for (QNAME,QTYPE)=("_C._B._A.example.com","URI").
 
As another example, suppose we are looking for the URI for a service
with Service Name "A" and Transport Protocol "B" for host
example.com.  Then we would query for
(QNAME,QTYPE)=("_A._B.example.com","URI").

The text to be updated is:

4. IANA Considerations

Although this document makes reference to IANA registries, it introduces no new IANA registries or procedures.

5. Security Considerations

This memo raises no security issues.

6. References

6.1. Normative References

[Attrleaf] Crocker, D., "DNS Scoped Data Through '_Underscore' Naming of Attribute Leaves", 2018.
[RFC6117] Hoeneisen, B., Mayrhofer, A. and J. Livingood, "IANA Registration of Enumservices: Guide, Template, and IANA Considerations", RFC 6117, March 2011.
[RFC6335] Cotton, M., Eggert, L., Tpuch, J., Westerlund, M. and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", RFC 6335, Aug 2011.
[RFC7553] Falstrom, P. and O. Kolkman, "The Uniform Resource Identifier (URI) DNS Resource Record", RFC 7553, ISSN 2070-1721, June 2015.

6.2. References -- Informative

[IANA-reg] "Protocol Registries", URL https://www.iana.org/protocols, 2018.
[RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987.
[RFC2782] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000.
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP): Locating SIP Servers", RFC 3263, June 2002.
[RFC3404] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI) Resolution Application", RFC 3404, October 2002.
[RFC3529] Harold, W., "Using Extensible Markup Language-Remote Procedure Calling (XML-RPC) in Blocks Extensible Exchange Protocol (BEEP)", RFC 3529, April 2003.
[RFC3620] New, D., "The TUNNEL Profile", RFC 3620, October 2003.
[RFC3832] , , , and , "Remote Service Discovery in the Service Location Protocol (SLP) via DNS SRV", RFC 3832, July 2004.
[RFC3861] Peterson, J., "Address Resolution for Instant Messaging and Presence", RFC 3861, August 2004.
[RFC3887] "Message Tracking Query Protocol", RFC 3887, September 2007.
[RFC3958] Daigle, L. and A. Newton, "Domain-Based Application Service Location Using SRV RRs and the Dynamic Delegation Discovery Service (DDDS)", RFC 3958, January 2005.
[RFC4120] , , and , "The Kerberos Network Authentication Service (V5)", RFC 4120, July 2005.
[RFC4227] O'Tuathail, E. and M. Rose, "Using the Simple Object Access Protocol (SOAP) in Blocks Extensible Exchange Protocol (BEEP)", RFC 4227, January 2006.
[RFC4386] Boeyen, S. and P. Hallam-Baker, "Internet X.509 Public Key Infrastructure: Repository Locator Service", RFC 4386, February 2006.
[RFC4387] Gutmann, P., "Internet X.509 Public Key Infrastructure Operational Protocols: Certificate Store Access via HTTP", RFC 4387, February 2006.
[RFC4976] Jennings, C., Mahy, R. and Roach, "Relay Extensions for the Message Session Relay Protocol (MSRP)", RFC 4976, September 2007.
[RFC5026] Giaretta, G., Kempf, J. and V. Devarapalli, "Mobile IPv6 Bootstrapping in Split Scenario", RFC 5026, October 2007.
[RFC5328] Adolf, A. and P. MacAvock, "A Uniform Resource Name (URN) Namespace for the Digital Video Broadcasting Project (DVB)", RFC 5328, September 2008.
[RFC5389] Rosenberg, Mahy, Matthews and Wing, "Session Traversal Utilities for NAT (STUN)", RFC 5389, October 2008.
[RFC5415] Calhoun, P., Montemurro, M. and D. Stanley, "Control And Provisioning of Wireless Access Points (CAPWAP) Protocol Specification", RFC 5415, March 2009.
[RFC5507] Faltstrom, P. and R. Austein, "Design Choices When Expanding the DNS", RFC 5507, April 2009.
[RFC5509] Loreto, S., "Internet Assigned Numbers Authority (IANA) Registration of Instant Messaging and Presence DNS SRV RRs for the Session Initiation Protocol (SIP)", RFC 5509, April 2009.
[RFC5518] Hoffman, P., Levine, J. and A. Hathcock, "Vouch By Reference", RFC 5518, April 2009.
[RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and Routers", RFC 5555, June 2009.
[RFC5617] , , and , "DomainKeys Identified Mail (DKIM) Author Domain Signing Practices (ADSP)", RFC 5617, August 2009.
[RFC5679] Bajko, G., "Locating IEEE 802.21 Mobility Services Using DNS", RFC 5679, December 2009.
[RFC5766] Mahy, R., Matthews, P. and J. Rosenberg, "Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.
[RFC5780] MacDonald, D. and B. Lowekamp, "NAT Behavior Discovery Using Session Traversal Utilities for NAT (STUN)", RFC 5780, May 2010.
[RFC5804] Melnikov, A. and T. Martin, "A Protocol for Remotely Managing Sieve Scripts", RFC 5804, July 2010.
[RFC5864] Allbery, R., "NS SRV Resource Records for AFS", RFC 5864, April 2010.
[RFC5928] Petit-Huguenin, M., "Traversal Using Relays around NAT (TURN) Resolution Mechanism", RFC 5928, August 2010.
[RFC6011] Lawrence, S. and J. Elwell, "Session Initiation Protocol (SIP) User Agent Configuration", RFC 6011, October 2010.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Core", RFC 6120, March 2011.
[RFC6186] Daboo, C., "Use of SRV Records for Locating Email Submission/Access Services", RFC 6186, March 2011.
[RFC6376] Crocker, D., Hansen, T. and M. Kucherawy, "DomainKeys Identified Mail (DKIM) Signatures", RFC 6376, Sept 2011.
[RFC6733] Fajardo, V., Arkko, J., Loughney, J. and G. Zorn, "Diameter Base Protocol", RFC 6733, October 2012.
[RFC7208] Kitterman, S., "Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, Version 1", RFC 7208, April 2014.
[RFC7489] Kucherawy, M. and E. Zwicky, "Domain-based Message Authentication, Reporting, and Conformance (DMARC)", RFC 7489, March 2015.

Appendix A. Acknowledgements

Thanks go to Bill Fenner, Tony Hansen, Peter Koch, Olaf Kolkman, and Andrew Sullivan for diligent review of the (much) earlier drafts. For the later enhancements, thanks to: Tim Wicinski, John Levine, Bob Harold, Joel Jaeggli, Ondřej Surý and Paul Wouters.

Special thanks to Ray Bellis for more than 10 years of persistent encouragement to continue this effort, as well as the suggestion for an essential simplification to the registration model.

Author's Address

Dave Crocker Brandenburg InternetWorking 675 Spruce Dr. Sunnyvale, CA 94086 USA Phone: +1.408.246.8253 EMail: dcrocker@bbiw.net URI: http://bbiw.net/