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Network Working Group                                        R. Van Rein
Internet-Draft                                          InternetWide.org
Intended status: Standards Track                        January 23, 2020
Expires: July 26, 2020

                   User Names for HTTP Resource Views


   Most protocols support users under domain names, but HTTP does not.
   Usage patterns in the wild do suggest a desire to have this
   facilitated.  This specification defines a header for this purpose,
   orthogonal to any authentication or authorisation concerns.

Status of This Memo

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

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   This Internet-Draft will expire on July 26, 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  The HTTP User-View Header . . . . . . . . . . . . . . . . . .   2
   3.  Protocol Handling of HTTP User-View . . . . . . . . . . . . .   3
   4.  Caching Behaviour . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Appendix A.  HTTP User-View Environment Variable  . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Most protocols support Network Access Identifiers [RFC7542] like
   john@example.com to identify users like john within domains such as
   example.com.  The URI format for HTTP can express [Section 2.7.1 of
   [RFC7230]] such authority sections, and many online applications seem
   to want to address individual users, but HTTP lacks the customary
   representation for user names.  This specification therefore
   introduces a new header field, similar to the "Host" header field.

   Historically, user names have been coupled to (Basic and Digest)
   authentication.  This is not generally correct; the user name in the
   URI represents a resource, not an (authenticating) visitor.  By using
   a new header field, this specification allows authentication to be
   orthogonal to resource selection.

   Browsers have supported (Basic and Digest) authentication with a
   scheme of "user:password" in the authority section of URIs.  This has
   now been deprecated [Section 3.2.1 of [RFC3986]] but the form with
   just "user" and no ":password" is still open to use.  Various HTTP
   clients have different handling of this form, sometimes flagging it
   incorrectly as a security hazard, which is another reason to specify
   what to do.

   TODO: Erratum #5964 against RFC 7230, https://www.rfc-

   The purpose of this specification is to provide a clear meaning to a
   URI with a user name portion, and treat it similar to the host name.

2.  The HTTP User-View Header

   The "User-View" header field provides the user name as part of the
   authority that selects a name scope.  The value usually is taken from
   the authority section [Section 3.2 of [RFC3986]] which MUST NOT
   include a colon and/or a password.  An empty header value is valid;

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   it indicates absense of a user name, and additionally signals support
   for the User-View header.

   The User-View header value holds precisely one value with the
   following ABNF grammar:

   User-View = 0*( unreserved / pct-encoded / sub-delims )

   The referenced non-terminals are as for URIs [RFC3986].  Zeal in use
   of the "pct-encoded" non-terminal for plain characters that have a
   direct representation MAY be considered an attempted attack.

   The User-View header MAY occur in requests and responses, but MUST
   NOT be included in trailers [Section 4.1 of [RFC7230]].  It is normal
   for HTTP to ignore unrecognised headers [Section 3.2.1 of [RFC7230]].
   Intermediate such as proxies and caches MUST NOT add, remove or
   modify the User-View header.

3.  Protocol Handling of HTTP User-View

   User agents SHOULD render user names in authority sections whenever
   they render host names, though it is helpful if it stands out
   graphically [Section 7.6 of [RFC3986]].  User agents SHOULD NOT
   remove user names from the URI except when a response indicates a new
   value.  User agents MAY remove the "@" (U+0040) symbol from a URI
   when the preceding user name is empty.  User agents SHOULD refuse
   URIs with the deprecated form "user:password" but MUST NOT complain
   about a user name that does not hold a ":" (U+003A) symbol.

   When the User-View header is included in a response, it declares a
   reference point for relative references [Section 4.2 of [RFC3986]],
   but this information MUST be ignored by any reference that mentions
   an authority component, with or without a userinfo sub-component.
   However, when constructing an absolute URI from a relative URI such
   as in an HTTP redirect [Section 6.4 of [RFC7231]], without an
   authority component, a User-View header in a response MUST be
   considered the source of a user name to include in the newly formed
   URI.  Likewise, in the same situation MUST the absense of a User-View
   header field cause the removal of the user name from the newly formed
   URI.  Other than this, the User-View header field is not
   automatically copied from a redirection response to a follow-up

   HTTP servers MAY redirect a request to a location that encodes the
   same or another user name in the path of the URI, while setting the
   User-View header to a new value.  This enables HTTP servers to define
   a local path syntax for user names, even when users and tools can
   approach them without knowing about this local convention.

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4.  Caching Behaviour

   The privacy or security of an HTTP resource is not impacted by the
   use of a User-View header.  This is because User-View is about
   resource location.  Its value has no bearing on authentication or

   HTTP caches [RFC7234] need to distinguish responses when they are
   requested with different User-View header values.  Given a User-View
   header in a request, the Vary header [Section 7.1.4 of [RFC7231]]
   MUST be present, and MUST either be valued "*" or list the "user-
   view" name, as part of any response that has been influenced by the
   User-View header.  Software or configurations that ignore the User-
   View header are not subjected to this requirement.

5.  IANA Considerations

   IANA adds the following entry to the Message Headers registry:

   Header Field Name   Template   Protocol   Status    Reference
   ------------------  ---------  ---------  -------   ----------
   User-View                      http       TBD       TBD:THIS_SPEC

6.  Security Considerations

   The User-View header field as defined herein is orthogonal to issues
   of authentication or authorisation, and so it implies no security

7.  Normative References

   [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,

   [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,

   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,

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   [RFC7234]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
              RFC 7234, DOI 10.17487/RFC7234, June 2014,

   [RFC7542]  DeKok, A., "The Network Access Identifier", RFC 7542,
              DOI 10.17487/RFC7542, May 2015,

Appendix A.  HTTP User-View Environment Variable

   We define a variable that SHOULD be passed from an HTTP stack to
   applications run on top of it.  The intention of defining this is to
   obtain maximum interoperability between these layers of software.

   The following variable MAY be included in the environment available
   passed to active HTTP server components:

   HTTP_USERVIEW  reports the User-View header value after percent-
         decoding.  The value is not authenticated, but HTTP server
         configuration MAY have applied access controls.

Author's Address

   Rick van Rein
   Haarlebrink 5
   Enschede, Overijssel  7544 WP
   The Netherlands

   Email: rick@openfortress.nl

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