draft-ietf-sip-ipv6-abnf-fix-01.txt   draft-ietf-sip-ipv6-abnf-fix-02.txt 
SIP WG V. Gurbani, Ed. SIP WG V. Gurbani, Ed.
Internet-Draft Bell Laboratories, Alcatel-Lucent Internet-Draft Bell Laboratories, Alcatel-Lucent
Updates: 3261 (if approved) B. Carpenter, Ed. Updates: 3261 (if approved) B. Carpenter, Ed.
Intended status: Standards Track Univ. of Auckland Intended status: Standards Track Univ. of Auckland
Expires: November 6, 2008 B. Tate, Ed. Expires: November 7, 2008 B. Tate, Ed.
BroadSoft BroadSoft
May 5, 2008 May 6, 2008
Essential correction for IPv6 ABNF and URI comparison in RFC3261 Essential correction for IPv6 ABNF and URI comparison in RFC3261
draft-ietf-sip-ipv6-abnf-fix-01 draft-ietf-sip-ipv6-abnf-fix-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware 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 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. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on November 6, 2008. This Internet-Draft will expire on November 7, 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
Abstract Abstract
This memo corrects the Augmented Backus-Naur Form (ABNF) production This memo corrects the Augmented Backus-Naur Form (ABNF) production
rule associated with generating IPv6 literals in RFC3261. It also rule associated with generating IPv6 literals in RFC3261. It also
clarifies the rule for Uniform Resource Identifier (URI) comparison clarifies the rule for Uniform Resource Identifier (URI) comparison
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The ABNF for IPv6 reference is reproduced from RFC3261 below: The ABNF for IPv6 reference is reproduced from RFC3261 below:
IPv6reference = "[" IPv6address "]" IPv6reference = "[" IPv6address "]"
IPv6address = hexpart [ ":" IPv4address ] IPv6address = hexpart [ ":" IPv4address ]
IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
hexpart = hexseq / hexseq "::" [ hexseq ] / "::" [ hexseq ] hexpart = hexseq / hexseq "::" [ hexseq ] / "::" [ hexseq ]
hexseq = hex4 *( ":" hex4) hexseq = hex4 *( ":" hex4)
hex4 = 1*4HEXDIG hex4 = 1*4HEXDIG
Note that the ambiguity occurs in the "IPv6address" production rule Note that the ambiguity occurs in the <IPv6address> production rule
where the "IPv4address" non-terminal is prefixed by ":" token. where the <IPv4address> non-terminal is prefixed by the ":" token.
Because the "hexpart" production rule is defined such that two of its Because the <hexpart> production rule is defined such that two of its
alternatives already include the "::" token, this may yield to the alternatives already include the "::" token, this may yield to the
faulty construction of an IPv6-mapped IPv4 address with an extra faulty construction of an IPv6-mapped IPv4 address with an extra
colon when expanding those alternatives. colon when expanding those alternatives.
2.2. Comparing URIs with textual representation of IP addresses 2.2. Comparing URIs with textual representation of IP addresses
In SIP, URIs are compared for a variety of reasons. Registrars In SIP, URIs are compared for a variety of reasons. Registrars
compare URIs when they receive a binding update request, for compare URIs when they receive a binding update request, for
instance. Section 19.1.4 of RFC3261 [1] provides the rules for instance. Section 19.1.4 of RFC3261 [1] provides the rules for
comparing URIs. Among other rules, it states that: comparing URIs. Among other rules, it states that:
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notation and the need to represent hybrid addresses (like IPv4- notation and the need to represent hybrid addresses (like IPv4-
mapped IPv6 addresses) makes the representation issue more acute. mapped IPv6 addresses) makes the representation issue more acute.
The resolution discussed in Section 3.2 applies to textual The resolution discussed in Section 3.2 applies to textual
representations of both IPv6 and IPv4 addresses. representations of both IPv6 and IPv4 addresses.
3. Resolution 3. Resolution
3.1. Resolution for extra colon in IPv4-mapped IPv6 address 3.1. Resolution for extra colon in IPv4-mapped IPv6 address
The resolution to this ambiguity is simply to use the correct ABNF 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 <IPv6address> production rule from Appendix A of RFC3986 [3].
For the sake of completeness, it is reproduced below: For the sake of completeness, it is reproduced below:
IPv6address = 6( h16 ":" ) ls32 IPv6address = 6( h16 ":" ) ls32
/ "::" 5( h16 ":" ) ls32 / "::" 5( h16 ":" ) ls32
/ [ h16 ] "::" 4( h16 ":" ) ls32 / [ h16 ] "::" 4( h16 ":" ) ls32
/ [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32 / [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
/ [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32 / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
/ [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32 / [ *3( h16 ":" ) h16 ] "::" h16 ":" ls32
/ [ *4( h16 ":" ) h16 ] "::" ls32 / [ *4( h16 ":" ) h16 ] "::" ls32
/ [ *5( h16 ":" ) h16 ] "::" h16 / [ *5( h16 ":" ) h16 ] "::" h16
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h16 = 1*4HEXDIG h16 = 1*4HEXDIG
ls32 = ( h16 ":" h16 ) / IPv4address ls32 = ( h16 ":" h16 ) / IPv4address
IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
dec-octet = DIGIT ; 0-9 dec-octet = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99 / %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199 / "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249 / "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255 / "25" %x30-35 ; 250-255
Accordingly, following the SIP essential corrections process [7], Accordingly, following the SIP essential corrections process [7],
this memo RECOMMENDS that the "IPv6address" and "IPv4address" this memo RECOMMENDS that the <IPv6address> and <IPv4address>
production rules be deleted from RFC3261 and replaced with the production rules be deleted from RFC3261 and replaced with the
production rules of the same name in RFC3986 (and reproduced above.) production rules of the same name in RFC3986 (and reproduced above.)
These changes, when made to RFC3261, will make "hexpart", "hexseq", These changes, when made to RFC3261, will make <hexpart>, <hexseq>,
and "hex4" production rules obsolete. Thus this memo RECOMMENDS that and <hex4> production rules obsolete. Thus this memo RECOMMENDS that
the "hexpart", "hexseq", and "hex4" production rules be deleted from the <hexpart>, <hexseq>, and <hex4> production rules be deleted from
the ABNF of RFC3261. the ABNF of RFC3261.
3.2. Clarification for comparison of URIs with textual representation 3.2. Clarification for comparison of URIs with textual representation
of IP addresses of IP addresses
The resolution to this ambiguity is a simple clarification The resolution to this ambiguity is a simple clarification
acknowledging that the textual representation of an IP addresses acknowledging that the textual representation of an IP addresses
varies, but it is the binary equivalence of the IP address that must varies, but it is the binary equivalence of the IP address that must
be taken into consideration when comparing two URIs that contain be taken into consideration when comparing two URIs that contain
varying textual representation of an IP address. varying textual representations of an IP address.
Accordingly, following the SIP essential corrections process [7], Accordingly, following the SIP essential corrections process [7],
this memo RECOMMENDS that the an existing rule from the bulleted list this memo RECOMMENDS that an existing rule from the bulleted list in
in Section 19.1.4 of RFC3216 be modified as follows: Section 19.1.4 of RFC3216 be modified as follows:
OLD: OLD:
o For two URIs to be equal, the user, password, host, and port o For two URIs to be equal, the user, password, host, and port
components must match. components must match.
NEW: NEW:
o For two URIs to be equal, the user, password, host, and port o For two URIs to be equal, the user, password, host, and port
components must match. If the host component contains textual components must match. If the host component contains a textual
representation of IP addresses, then the representation of those representation of IP addresses, then the representation of those
IP addresses may vary. If so, the host components are considered IP addresses may vary. If so, the host components are considered
to match if the different textual representations yield the same to match if the different textual representations yield the same
binary IP address. binary IP address.
In addition, this memo RECOMMENDS that the text in the following In addition, this memo RECOMMENDS that the text in the following
paragraph be added to the existing list of examples in Section 19.1.4 paragraph be added to the existing list of examples in Section 19.1.4
of RFC3261 in order to demonstrate the intent of the modified rule: of RFC3261 in order to demonstrate the intent of the modified rule:
The following URIs are equivalent because the underlying binary The following URIs are equivalent because the underlying binary
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This document does not include any IANA considerations. This document does not include any IANA considerations.
6. Acknowledgments 6. Acknowledgments
The ABNF for IPv6 was developed by Roy T. Fielding and Andrew Main The ABNF for IPv6 was developed by Roy T. Fielding and Andrew Main
and published in RFC3986. and published in RFC3986.
Jeroen van Bemmel, Peter Blatherwick, Gonzalo Camarillo, Paul Jeroen van Bemmel, Peter Blatherwick, Gonzalo Camarillo, Paul
Kyzivat, Jonathan Rosenberg, Michael Thomas, and Dale Worley provided Kyzivat, Jonathan Rosenberg, Michael Thomas, and Dale Worley provided
invaluable discussion points on the SIP WG mailing list on the URI invaluable discussion points on the SIP WG mailing list on the URI
equivalency problem. equivalency problem. Alfred Hones urged the use of angle brackets
(as specified in Section 2.1 of [4]) to denote productions.
7. References 7. References
7.1. Normative References 7.1. Normative References
[1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002. Session Initiation Protocol", RFC 3261, June 2002.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
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