Clarifications for when to use the name-addr production in SIP messages
draft-ietf-sipcore-name-addr-guidance-00

Document Type Active Internet-Draft (sipcore WG)
Last updated 2017-02-28
Replaces draft-sparks-sipcore-name-addr-guidance
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Network Working Group                                          R. Sparks
Internet-Draft                                                    Oracle
Updates: 3261, 3325, 3515, 3892, 4508,                 February 28, 2017
         5002, 5318, 5360, 5502 (if
         approved)
Intended status: Standards Track
Expires: September 1, 2017

Clarifications for when to use the name-addr production in SIP messages
                draft-ietf-sipcore-name-addr-guidance-00

Abstract

   RFC3261 constrained several SIP header fields whose grammar contains
   the "name-addr / addr-spec" alternative to use name-addr when certain
   characters appear.  Unfortunately it expressed the constraints with
   prose copied into each header field definition, and at least one
   header field was missed.  Further, the constraint has not been copied
   into documents defining extension headers whose grammar contains the
   alternative.

   This document updates RFC3261 to state the constraint generically,
   and clarifies that the constraint applies to all SIP header fields
   where there is a choice between using name-addr or addr-spec.  It
   also updates those extension SIP header fields that use the
   alternative to clarify that the constraint applies (RFCs 3325, 3515,
   3892, 4508, 5002, 5318, 5360, and 5502).

Status of This Memo

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   This Internet-Draft will expire on September 1, 2017.

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Internet-Draft          Name-addr Clarifications           February 2017

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Updates to RFC3261  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Updates to RFCs defining SIP Extension header fields  . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Instructions to the RFC Editor  . . . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC3261] defines several header fields that contain URIs to allow
   both a form that contains the bare URI (addr-spec) and one that
   provides a name and the URI (name-addr).  This subset, taken from the
   ABNF [RFC5234] specified in [RFC3261] shows the relevant part of the
   definition of the syntax of the "From" header field:

     From        =  ( "From" / "f" ) HCOLON from-spec
     from-spec   =  ( name-addr / addr-spec )
                    *( SEMI from-param )
     name-addr      =  [ display-name ] LAQUOT addr-spec RAQUOT
     addr-spec      =  SIP-URI / SIPS-URI / absoluteURI

   The prose in section 20.20 of [RFC3261], which discusses the "From"
   header field, constrains how the production may be used by saying:

      Even if the "display-name" is empty, the "name-addr" form
      MUST be used if the "addr-spec" contains a comma, question
      mark, or semicolon.

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   Section 20.39, which discusses the "To" header field contains no such
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