Registration Protocols Extensions                            M. Loffredo
Internet-Draft                                             M. Martinelli
Intended status: Standards Track                     IIT-CNR/
Expires: April 19, 2019                                 October 16, 2018

  Registration Data Access Protocol (RDAP) Reverse search capabilities


   The Registration Data Access Protocol (RDAP) does not include query
   capabilities to find the list of domains related to a set of entities
   matching a given search pattern.  Even if such capabilities, commonly
   referred to as reverse search, respond to some needs not yet readily
   fulfilled by the current Whois protocol, they have raised concern
   from two perspectives: server processing impact and data privacy.
   Anyway, the impact of the reverse queries on RDAP servers processing
   is the same of the standard searches and it can be reduced by
   implementing policies to deal with big result sets, while data
   privacy risks can be mitigated by RDAP access control
   functionalities.  This document describes RDAP query extensions that
   allows clients to request a reverse search based on the domains-
   entities relationship.

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
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   This Internet-Draft will expire on April 19, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
   2.  RDAP Path Segment Specification . . . . . . . . . . . . . . .   3
   3.  Implementation Considerations . . . . . . . . . . . . . . . .   5
     3.1.  JSON in URLs  . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Implementation Status . . . . . . . . . . . . . . . . . . . .   6
     4.1.  IIT-CNR/ . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Reverse Whois is a service provided by many web applications that
   allows users to find domain names owned by an individual person or
   company starting from the owner details (like name, email).  Even if
   the availability of this service might raise some objections due to
   potential privacy risks, ICANN itself, in its report about Next-Gen
   Registration Directory Service (RDS) [ICANN-RDS], states that it is
   allowed when driven by some permissible purposes (e.g. legal actions,
   criminal investigations) and if it provides adequate policies to
   enforce the requestor accreditation, authentication, authorization,
   and terms and conditions of data use.

   It is well known that such policies are not implemented in Whois
   [RFC3912], while they are in RDAP.  In fact, RDAP relies on security
   features, available in the HTTP protocol, to support access control
   based on local policy [RFC7481].

   Another objection to the implementation of Reverse Whois is connected
   with its impact on server processing.  Since RDAP supports search

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   queries, the impact of both standard and reverse searches can be
   mitigated by servers adopting ad hoc strategies.  Furthermore,
   reverse search is almost always performed by specifying an entity
   role (e.g. registrant, technical contact) and this can contribute to
   restrict the result set.

   Reverse searches, such as finding the list of domain names associated
   to contacts, nameservers or DNSSEC keys, may be useful to registrars
   as well.  Usually, registries adopt out-of-band mechanisms to provide
   results to registrars asking for reverse searches on their domains.
   Possible reasons of such requests are:

   o  the loss of synchronization between the registrar database and the
      registry database;

   o  the need of such data to perform massive EPP updates (i.e.
      changing the contacts of a set of domains, etc.).

   Currently, RDAP does not provide any way for a client to search for
   the collection of domains associated to an entity [RFC7482].  A query
   (lookup or search) on domains can return the array of entities
   related to a domain with different roles (registrant, registrar,
   administrative, technical, reseller, etc.), but the reverse operation
   is not allowed.  Only reverse searches to find the collection of
   domains related to a nameserver (ldhName or ip) can be requested.
   Since entities can be in relationship with all RDAP objects
   [RFC7483], the availability of a reverse search can be common to all
   RDAP query paths.

   The protocol described in this specification aims to extend the RDAP
   query capabilities to enable reverse search based on the domains-
   entities relationship (the classic Reverse Whois scenario).  The
   extension is implemented by adding new path segments (i.e. search
   paths) and using a RESTful web service [REST].  The service is
   implemented using the Hypertext Transfer Protocol (HTTP) [RFC7230]
   and the conventions described in RFC 7480 [RFC7480].

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2.  RDAP Path Segment Specification

   The new search paths are OPTIONAL extensions of path segments defined
   in RFC 7482 [RFC7482].  The search paths are:

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      Syntax: domains?entityHandle=<reverse search pattern>

      Syntax: domains?entityFn=<reverse search pattern>

      Syntax: domains?entityEmail=<reverse search pattern>

      Syntax: domains?entityAddr=<reverse search pattern>

   The reverse search pattern is a JSON [RFC8259] object including two
   members: "value" and "role".  The "value" member represents the
   search pattern to be applied to the corresponding entity field and
   can be a JSON type primitive or object.  The "role" member is a
   string whose possible values are those detailed in Section 10.2.4 of
   RFC 7483 [RFC7483].  The former is REQUIRED while the latter is
   OPTIONAL to allow RDAP servers to provide reverse search capabilities
   without specifying any role.

   The search patterns corresponding to the "value" in the first two
   cases are the same as specified in paragraph Section 3.2.3 of RFC
   7482 [RFC7482] (Figure 1).



    Figure 1: Examples of RDAP queries to find all domains related to a
    registrant whose handle matches "CID-40*" and whose formatted name
                             matches "Bobby*"

   The last two reverse searches are considered by ICANN very useful to
   improve searchability capabilities of the Registry Directory Services

   Searches for domains by related entity email are specified using this


   where XXXX is a search pattern representing an email address as
   defined in RFC 5322 [RFC5322].

   Searches for domains by related entity postal address are specified
   using this form:


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   where YYYY is a JSON object containing the information described in
   Section 2.4 of RFC 5733 [RFC5733], respectively: "street", "city",
   "sp", "pc" and "cc" (Figure 2).  All the members of the postal
   address object are OPTIONAL but at least one is REQUIRED.  The
   constraints on the members are implicitly joined by AND.


    Figure 2: Example of a RDAP query to find all domains related to a
    registrant whose postal address contains the country code equals to
                   "CA" and the city equals to "Sydney"

3.  Implementation Considerations

   The implementation of the proposed extension is technically feasible.
   The search paths "handle" and "fn" are used as standard paths to
   search for entities.  With regards to the last two reverse searches,
   both email and postal address information are usually required by the
   registries but, while the former is usually mapped on a DBMS indexed
   field, the latter is mapped on a combination of non-indexed fields.
   As a consequence while the former should not significantly decrease
   the performance, the latter might have an impact on server
   processing.  Anyway, this impact is evaluated to be the same as other
   query capabilities already presented in RDAP (e.g. wildcard prefixed
   search pattern) so the risks to generate huge result sets are the
   same existing for the other standard searches and can be mitigated by
   adopting the same policies (e.g. restricting search functionalities,
   limiting the rate of search requests according to the user profile,
   truncating and paging the results, returning partial responses).

3.1.  JSON in URLs

   Many web services, including RDAP, rely on the HTTP GET method to
   take advantage from some of its features:

   o  GET requests can be cached;
   o  GET requests remain in the browser history;
   o  GET requests can be bookmarked.

   Sometimes it happens that such advantages should be combined with the
   requirement to pass objects and arrays in the query string.  JSON is
   the best candidate as data interchange format but it contains some
   characters that are forbidden from appearing in a URL.  Anyway,
   escaping the invalid characters is not an issue because, on client
   side, modern browsers automatically encode URLs and, on server side,
   a lot of URL encoding/decoding libraries for all web development
   programming languages are available.  The downside of URL encoding is

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   that it can make a URL rather long which, depending on the initial
   length and the number of invalid characters, might exceed the
   practical limit of web browsers (i.e. 2,000 characters).

   Other solutions to pass a JSON expression in a URL could be:

   o  converting JSON to Base64 ([RFC4648]) but binary data are

   o  using a JSON variation that complies with URL specifications and
      mantains readability like Rison ([RISON]), URLON ([URLON]) or
      JSURL ([JSURL]).

   The extensions proposed in this document rely on URL encoding because
   it is widely supported and the risk to exceed the maximum URL length
   is considered to be very unlikely in RDAP.

4.  Implementation Status

   NOTE: Please remove this section and the reference to RFC 7942 prior
   to publication as an RFC.

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in RFC 7942
   [RFC7942].  The description of implementations in this section is
   intended to assist the IETF in its decision processes in progressing
   drafts to RFCs.  Please note that the listing of any individual
   implementation here does not imply endorsement by the IETF.
   Furthermore, no effort has been spent to verify the information
   presented here that was supplied by IETF contributors.  This is not
   intended as, and must not be construed to be, a catalog of available
   implementations or their features.  Readers are advised to note that
   other implementations may exist.

   According to RFC 7942, "this will allow reviewers and working groups
   to assign due consideration to documents that have the benefit of
   running code, which may serve as evidence of valuable experimentation
   and feedback that have made the implemented protocols more mature.
   It is up to the individual working groups to use this information as
   they see fit".

4.1.  IIT-CNR/

      Responsible Organization: Institute of Informatics and Telematics
      of National Research Council (IIT-CNR)/

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      Description: This implementation includes support for RDAP queries
      using data from the public test environment of .it ccTLD.  The
      RDAP server does not implement any security policy because data
      returned by this server are only for experimental testing
      Level of Maturity: This is a "proof of concept" research
      Coverage: This implementation includes all of the features
      described in this specification.
      Contact Information: Mario Loffredo,

5.  Security Considerations

   Security services for the operations specified in this document are
   described in RFC 7481 [RFC7481].  It is quite easy to imagine that,
   in order to be compliant with ICANN recommendations about its use,
   RDAP servers will provide reverse search, like other query
   capabilities, only to restricted communities.  One realistic scenario
   for servers is to provide reverse search only for registrars
   searching for their own domains.  Another one is to prevent users to
   start a reverse search from a registrant detail, by removing
   "registrant" from the possible "role" values.

6.  IANA Considerations

   This document has no actions for IANA.

7.  Acknowledgements

   The authors would like to acknowledge Scott Hollenbeck, Francisco
   Arias, Gustavo Lozano and Eduardo Alvarez for their contribution to
   this document.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC3912]  Daigle, L., "WHOIS Protocol Specification", RFC 3912,
              DOI 10.17487/RFC3912, September 2004,

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   [RFC5733]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)
              Contact Mapping", STD 69, RFC 5733, DOI 10.17487/RFC5733,
              August 2009, <>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,

   [RFC7480]  Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the
              Registration Data Access Protocol (RDAP)", RFC 7480,
              DOI 10.17487/RFC7480, March 2015,

   [RFC7481]  Hollenbeck, S. and N. Kong, "Security Services for the
              Registration Data Access Protocol (RDAP)", RFC 7481,
              DOI 10.17487/RFC7481, March 2015,

   [RFC7482]  Newton, A. and S. Hollenbeck, "Registration Data Access
              Protocol (RDAP) Query Format", RFC 7482,
              DOI 10.17487/RFC7482, March 2015,

   [RFC7483]  Newton, A. and S. Hollenbeck, "JSON Responses for the
              Registration Data Access Protocol (RDAP)", RFC 7483,
              DOI 10.17487/RFC7483, March 2015,

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,

8.2.  Informative References

              Internet Corporation For Assigned Names and Numbers,
              "Registry Agreement", July 2017,

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              Internet Corporation For Assigned Names and Numbers,
              "Final Report from the Expert Working Group on gTLD
              Directory Services: A Next-Generation Registration
              Directory Service (RDS)", June 2014,

   [JSURL]    "JSURL", 2016, <>.

   [REST]     Fielding, R., "Architectural Styles and the Design of
              Network-based Software Architectures", 2000,

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,

   [RISON]    "Rison - Compact Data in URIs", 2017,

   [URLON]    "URL Object Notation", 2017,

Appendix A.  Change Log

   00:  Initial version.
   01:  Revised some sentences and references.
   02:  Added "entityEmail" and "entityAddr" path segments.  Removed
      "entityRole" path segment.  Revised "Acknowledgements" section
   03:  Added "JSON in URLs" section

Authors' Addresses

   Mario Loffredo
   Via Moruzzi,1
   Pisa  56124


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   Maurizio Martinelli
   Via Moruzzi,1
   Pisa  56124


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