SIP WG V. Gurbani, Ed. Internet-Draft Bell Laboratories, Alcatel-Lucent Updates: 3261 (if approved) B. Carpenter, Ed. Intended status: Standards Track Univ. of Auckland Expires: May 8, 2008 November 5, 2007 Essential correction for IPv6 ABNF in RFC3261 draft-gurbani-sip-ipv6-abnf-fix-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 8, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This memo corrects the Augmented Backus-Naur Form (ABNF) production rule associated with generating IPv6 literals in RFC3261 Gurbani & Carpenter Expires May 8, 2008 [Page 1] Internet-Draft SIP IPv6 ABNF November 2007 Table of Contents 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem statement . . . . . . . . . . . . . . . . . . . . . . . 3 3. Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Gurbani & Carpenter Expires May 8, 2008 [Page 2] Internet-Draft SIP IPv6 ABNF November 2007 1. Terminology 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 RFC 2119 [2]. 2. Problem statement The ABNF [4] for generating IPv6 literals in RFC3261 [1] is incorrect. When generating IPv4-mapped IPv6 addresses, the production rule may actually generate the following construct: [2001:db8:::192.0.2.1] - Note the extra colon before the IPv4 address. The correct construct, of course, would only include two colons before the IPv4 address. Historically, the ABNF pertaining to IPv6 references in RFC3261 was derived from Appendix B of RFC 2373 [6], which was flawed to begin with (see also RFC2373 errata at http://www.rfc-editor.org/cgi-bin/errataSearch.pl?rfc=2373.) RFC2373 has been subsequently obsoleted by RFC 4291 [5]. The ABNF for IPv6 reference is reproduced from RFC3261 below: IPv6reference = "[" IPv6address "]" IPv6address = hexpart [ ":" IPv4address ] IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT hexpart = hexseq / hexseq "::" [ hexseq ] / "::" [ hexseq ] hexseq = hex4 *( ":" hex4) hex4 = 1*4HEXDIG Note that the ambiguity occurs in the "IPv6address" production rule where the "IPv4address" non-terminal is prefixed by ":" token. Because the "hexpart" production rule is defined such that two of its alternatives already include the "::" token, this may yield to the faulty construction of an IPv6-mapped IPv4 address with an extra colon when expanding those alternatives. 3. Resolution The resolution to this ambiguity is simply to use the correct ABNF for the "IPv6address" production rule from Appendix A of RFC3986 [3]. For the sake of completeness, it is reproduced below: Gurbani & Carpenter Expires May 8, 2008 [Page 3] Internet-Draft SIP IPv6 ABNF November 2007 IPv6address = 6( h16 ":" ) ls32 / "::" 5( h16 ":" ) ls32 / [ h16 ] "::" 4( h16 ":" ) ls32 / [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32 / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32 / [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32 / [ *4( h16 ":" ) h16 ] "::" ls32 / [ *5( h16 ":" ) h16 ] "::" h16 / [ *6( h16 ":" ) h16 ] "::" h16 = 1*4HEXDIG ls32 = ( h16 ":" h16 ) / IPv4address IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet dec-octet = DIGIT ; 0-9 / %x31-39 DIGIT ; 10-99 / "1" 2DIGIT ; 100-199 / "2" %x30-34 DIGIT ; 200-249 / "25" %x30-35 ; 250-255 Accordingly, following the SIP essential corrections process [7], this memo RECOMMENDS that the "IPv6address" and "IPv4address" production rules be deleted from RFC3261 and replaced with the production rules of the same name in RFC3986 (and reproduced above.) These changes, when made to RFC3261, will make "hexpart", "hexseq", and "hex4" production rules obsolete. Thus this memo RECOMMENDS that the "hexpart", "hexseq", and "hex4" production rules be deleted from the ABNF of RFC3261. 4. Security Considerations This document does not introduce any new security considerations. 5. IANA Considerations This document does not include any IANA considerations. 6. Acknowledgments The correct ABNF for IPv6 was developed by Andrew Main (draft-main-ipaddr-text-rep) in 2005 and published in RFC3986. 7. References Gurbani & Carpenter Expires May 8, 2008 [Page 4] Internet-Draft SIP IPv6 ABNF November 2007 7.1. Normative References [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [4] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. 7.2. Informative References [5] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. [6] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 2373, July 1998. [7] Drage, K., "A Process for Handling Essential Corrections to the Session Initiation Protocol (SIP)", draft-drage-sip-essential-correction-01 (work in progress), March 2007. Authors' Addresses Vijay K. Gurbani (editor) Bell Laboratories, Alcatel-Lucent 2701 Lucent Lane Room 9F-546 Lisle, IL 60532 USA Phone: +1 630 224-0216 Email: vkg at bell hyphen labs dot com Gurbani & Carpenter Expires May 8, 2008 [Page 5] Internet-Draft SIP IPv6 ABNF November 2007 Brian E. Carpenter (editor) Department of Computer Science University of Auckland PB 92019 Auckland, 1142 New Zealand Email: brian.e.carpenter@gmail.com Gurbani & Carpenter Expires May 8, 2008 [Page 6] Internet-Draft SIP IPv6 ABNF November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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