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HTTP Working Group                                              S. Sahib
Internet-Draft                                          October 27, 2017
Intended status: Informational
Expires: April 30, 2018


             New protocol elements for HTTP Status Code 451
                   draft-451-new-protocol-elements-01

Abstract

   This draft recommends protocol updates to Hypertext Transfer Protocol
   (HTTP) status code 451 (defined by RFC7725) based on an examination
   of how the new status code is being used by parties involved in
   denial of Internet resources because of legal demands.

   Discussion of this draft is at https://www.irtf.org/mailman/listinfo/
   hrpc and https://lists.ghserv.net/mailman/listinfo/statuscode451.

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-
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 30, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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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
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Existing Protocol Elements  . . . . . . . . . . . . . . . . .   2
   4.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [RFC7725] was standardized by the IETF in February 2016.  It defined
   HTTP status code 451 - to be used when a "a server operator has
   received a legal demand to deny access to a resource or to a set of
   resources that includes the requested resource".  The intention was
   to provide a uniform mechanism to indicate online censorship.

   Subsequently, an effort was made to investigate usage of 451 status
   code and evaluate if it fulfills its mandate of providing
   "transparency in circumstances where issues of law or public policy
   affect server operations" [IMPL_REPORT_DRAFT].  This draft attempts
   to explicate the protocol recommendations arising out of that
   investigation.

2.  Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  Existing Protocol Elements

   The status code as standardized by the IETF specifies the following
   elements [RFC7725] -

   -  A server can return status code 451 to indicate that it is denying
      access to a resource or multiple resources on account of a legal
      demand.

   -  Responses using the status code SHOULD include an explanation in
      the response body of the details of the legal demand.





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   -  Responses SHOULD include a "Link" HTTP header field [RFC8288]
      whose value is a URI reference [RFC3986] identifying itself.  The
      "Link" header field MUST have a "rel" parameter whose value is
      "blocked-by".  The intent is that the header be used to identify
      the entity actually implementing blockage, not any other entity
      mandating it.

4.  Recommendations

   -  In addition to the "blocked-by" header, an HTTP response with
      status code 451 SHOULD include another "Link" HTTP header field
      which has a "rel" parameter whose value is "blocking-authority".
      It's important to distinguish between the implementer of the
      block, and the authority that mandated the block in the first
      place.  This is because these two organizations might not be the
      same - a government (the blocking authority) could force an
      Internet Service Provider (the implementer of the block) to deny
      access to a certain resource.

   -  HTTP status code 451 is increasingly being used to deny access to
      resources based on geographical IP.  The scope of this denial is
      sometimes as finely scoped as a city or a province.  The response
      SHOULD contain a provisional header with geographical scope of
      block.

5.  Security Considerations

   This document does not add additional security considerations to
   [RFC7725].

6.  IANA Considerations

   The Link Relation Type Registry should be updated with the following
   entry [TBD]:

   -  Relation Name: blocking-authority

   -  Description: Identifies the authority that has issued the block.

   -  Reference: This document

   In addition, IANA should be updated with the following provisional
   header [TBD]:

   -  Header field name: geo-scope-block

   -  Applicable protocol: http




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   -  Status: provisional

   -  Specification document(s): this document

7.  Normative References

   [IMPL_REPORT_DRAFT]
              Abraham, S., Canales, MP., Hall, J., Khrustaleva, O., ten
              Oever, N., Runnegar, C., and S. Sahib, "Implementation
              Report for HTTP Status Code 451", 2017,
              <https://tools.ietf.org/html/draft-451-imp-report-00>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
              editor.org/info/rfc2119>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC7725]  Bray, T., "An HTTP Status Code to Report Legal Obstacles",
              RFC 7725, DOI 10.17487/RFC7725, February 2016,
              <https://www.rfc-editor.org/info/rfc7725>.

   [RFC8288]  Nottingham, M., "Web Linking", RFC 8288,
              DOI 10.17487/RFC8288, October 2017, <https://www.rfc-
              editor.org/info/rfc8288>.

Author's Address

   Shivan Kaul Sahib

   EMail: shivankaulsahib@gmail.com
















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