rfc4518.txt

samba最新软件


RFC 4518       LDAP: Internationalized String Preparation      June 2006


   no combining marks and a space is defined to be the SPACE (U+0020)
   code point followed by no combining marks.

   All hyphens and spaces are considered insignificant and are to be
   removed.

   For example, removal of hyphens and spaces from the Form KC string:
       "<SPACE><HYPHEN>123<SPACE><SPACE>456<SPACE><HYPHEN>"
   would result in the output string:
       "123456"
   and the Form KC string:
       "<HYPHEN><HYPHEN><HYPHEN>"
   would result in the (empty) output string:
       "".

3.  Security Considerations

   "Preparation of Internationalized Strings ("stringprep")" [RFC3454]
   security considerations generally apply to the algorithms described
   here.

4.  Acknowledgements

   The approach used in this document is based upon design principles
   and algorithms described in "Preparation of Internationalized Strings
   ('stringprep')" [RFC3454] by Paul Hoffman and Marc Blanchet.  Some
   additional guidance was drawn from Unicode Technical Standards,
   Technical Reports, and Notes.

   This document is a product of the IETF LDAP Revision (LDAPBIS)
   Working Group.

5.  References

5.1.  Normative References

   [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3454]     Hoffman, P. and M. Blanchet, "Preparation of
                 Internationalized Strings ("stringprep")", RFC 3454,
                 December 2002.

   [RFC4510]     Zeilenga, K., "Lightweight Directory Access Protocol
                 (LDAP): Technical Specification Road Map", RFC 4510,
                 June 2006.





Zeilenga                    Standards Track                     [Page 8]

RFC 4518       LDAP: Internationalized String Preparation      June 2006


   [RFC4517]     Legg, S., Ed., "Lightweight Directory Access Protocol
                 (LDAP): Syntaxes and Matching Rules", RFC 4517, June
                 2006.

   [Unicode]     The Unicode Consortium, "The Unicode Standard, Version
                 3.2.0" is defined by "The Unicode Standard, Version
                 3.0" (Reading, MA, Addison-Wesley, 2000.  ISBN 0-201-
                 61633-5), as amended by the "Unicode Standard Annex
                 #27: Unicode 3.1"
                 (http://www.unicode.org/reports/tr27/) and by the
                 "Unicode Standard Annex #28: Unicode 3.2"
                 (http://www.unicode.org/reports/tr28/).

   [UAX15]       Davis, M. and M. Duerst, "Unicode Standard Annex #15:
                 Unicode Normalization Forms, Version 3.2.0".
                 <http://www.unicode.org/unicode/reports/tr15/tr15-
                 22.html>, March 2002.

   [X.680]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "Abstract
                 Syntax Notation One (ASN.1) - Specification of Basic
                 Notation", X.680(2002) (also ISO/IEC 8824-1:2002).

5.2.  Informative References

   [X.500]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "The
                 Directory -- Overview of concepts, models and
                 services," X.500(1993) (also ISO/IEC 9594-1:1994).

   [X.501]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "The
                 Directory -- Models," X.501(1993) (also ISO/IEC 9594-
                 2:1994).

   [X.520]       International Telecommunication Union -
                 Telecommunication Standardization Sector, "The
                 Directory: Selected Attribute Types", X.520(1993) (also
                 ISO/IEC 9594-6:1994).

   [Glossary]    The Unicode Consortium, "Unicode Glossary",
                 <http://www.unicode.org/glossary/>.

   [CharModel]   Whistler, K. and M. Davis, "Unicode Technical Report
                 #17, Character Encoding Model", UTR17,
                 <http://www.unicode.org/unicode/reports/tr17/>, August
                 2000.




Zeilenga                    Standards Track                     [Page 9]

RFC 4518       LDAP: Internationalized String Preparation      June 2006


   [RFC3377]     Hodges, J. and R. Morgan, "Lightweight Directory Access
                 Protocol (v3): Technical Specification", RFC 3377,
                 September 2002.

   [RFC4515]     Smith, M., Ed. and T. Howes, "Lightweight Directory
                 Access Protocol (LDAP): String Representation of Search
                 Filters", RFC 4515, June 2006.

   [XMATCH]      Zeilenga, K., "Internationalized String Matching Rules
                 for X.500", Work in Progress.









































Zeilenga                    Standards Track                    [Page 10]

RFC 4518       LDAP: Internationalized String Preparation      June 2006


Appendix A.  Combining Marks

   This appendix is normative.

   This table was derived from Unicode [Unicode] data files; it lists
   all code points with the Mn, Mc, or Me properties.  This table is to
   be considered definitive for the purposes of implementation of this
   specification.

         0300-034F 0360-036F 0483-0486 0488-0489 0591-05A1
         05A3-05B9 05BB-05BC 05BF 05C1-05C2 05C4 064B-0655 0670
         06D6-06DC 06DE-06E4 06E7-06E8 06EA-06ED 0711 0730-074A
         07A6-07B0 0901-0903 093C 093E-094F 0951-0954 0962-0963
         0981-0983 09BC 09BE-09C4 09C7-09C8 09CB-09CD 09D7
         09E2-09E3 0A02 0A3C 0A3E-0A42 0A47-0A48 0A4B-0A4D
         0A70-0A71 0A81-0A83 0ABC 0ABE-0AC5 0AC7-0AC9 0ACB-0ACD
         0B01-0B03 0B3C 0B3E-0B43 0B47-0B48 0B4B-0B4D 0B56-0B57
         0B82 0BBE-0BC2 0BC6-0BC8 0BCA-0BCD 0BD7 0C01-0C03
         0C3E-0C44 0C46-0C48 0C4A-0C4D 0C55-0C56 0C82-0C83
         0CBE-0CC4 0CC6-0CC8 0CCA-0CCD 0CD5-0CD6 0D02-0D03
         0D3E-0D43 0D46-0D48 0D4A-0D4D 0D57 0D82-0D83 0DCA
         0DCF-0DD4 0DD6 0DD8-0DDF 0DF2-0DF3 0E31 0E34-0E3A
         0E47-0E4E 0EB1 0EB4-0EB9 0EBB-0EBC 0EC8-0ECD 0F18-0F19
         0F35 0F37 0F39 0F3E-0F3F 0F71-0F84 0F86-0F87 0F90-0F97
         0F99-0FBC 0FC6 102C-1032 1036-1039 1056-1059 1712-1714
         1732-1734 1752-1753 1772-1773 17B4-17D3 180B-180D 18A9
         20D0-20EA 302A-302F 3099-309A FB1E FE00-FE0F FE20-FE23
         1D165-1D169 1D16D-1D172 1D17B-1D182 1D185-1D18B
         1D1AA-1D1AD

Appendix B.  Substrings Matching

   This appendix is non-normative.

   In the absence of substrings matching, the insignificant space
   handling for case ignore/exact matching could be simplified.
   Specifically, the handling could be to require that all sequences of
   one or more spaces be replaced with one space and, if the string
   contains non-space characters, removal of all leading spaces and
   trailing spaces.

   In the presence of substrings matching, this simplified space
   handling would lead to unexpected and undesirable matching behavior.
   For instance:

   1) (CN=foo\20*\20bar) would match the CN value "foobar";





Zeilenga                    Standards Track                    [Page 11]

RFC 4518       LDAP: Internationalized String Preparation      June 2006


   2) (CN=*\20foobar\20*) would match "foobar", but
      (CN=*\20*foobar*\20*) would not.

   Note to readers not familiar with LDAP substrings matching: the LDAP
   filter [RFC4515] assertion (CN=A*B*C) says to "match any value (of
   the attribute CN) that begins with A, contains B after A, ends with C
   where C is also after B."

   The first case illustrates that this simplified space handling would
   cause leading and trailing spaces in substrings of the string to be
   regarded as insignificant.  However, only leading and trailing (as
   well as multiple consecutive spaces) of the string (as a whole) are
   insignificant.

   The second case illustrates that this simplified space handling would
   cause sub-partitioning failures.  That is, if a prepared any
   substring matches a partition of the attribute value, then an
   assertion constructed by subdividing that substring into multiple
   substrings should also match.

   In designing an appropriate approach for space handling for
   substrings matching, one must study key aspects of X.500 case
   exact/ignore matching.  X.520 [X.520] says:

      The [substrings] rule returns TRUE if there is a partitioning of
      the attribute value (into portions) such that:

         -  the specified substrings (initial, any, final) match
            different portions of the value in the order of the strings
            sequence;

         -  initial, if present, matches the first portion of the value;

         -  final, if present, matches the last portion of the value;

         -  any, if present, matches some arbitrary portion of the
            value.

   That is, the substrings assertion (CN=foo\20*\20bar) matches the
   attribute value "foo<SPACE><SPACE>bar" as the value can be
   partitioned into the portions "foo<SPACE>" and "<SPACE>bar" meeting
   the above requirements.









Zeilenga                    Standards Track                    [Page 12]

RFC 4518       LDAP: Internationalized String Preparation      June 2006


   X.520 also says:

      [T]he following spaces are regarded as not significant:

         -  leading spaces (i.e., those preceding the first character
            that is not a space);

         -  trailing spaces (i.e., those following the last character
            that is not a space);

         -  multiple consecutive spaces (these are taken as equivalent
            to a single space character).

   This statement applies to the assertion values and attribute values
   as whole strings, and not individually to substrings of an assertion
   value.  In particular, the statements should be taken to mean that if
   an assertion value and attribute value match without any
   consideration to insignificant characters, then that assertion value
   should also match any attribute value that differs only by inclusion
   nor removal of insignificant characters.

   Hence the assertion (CN=foo\20*\20bar) matches
   "foo<SPACE><SPACE><SPACE>bar" and "foo<SPACE>bar" as these values
   only differ from "foo<SPACE><SPACE>bar" by the inclusion or removal
   of insignificant spaces.

   Astute readers of this text will also note that there are special
   cases where the specified space handling does not ignore spaces that
   could be considered insignificant.  For instance, the assertion
   (CN=\20*\20*\20) does not match "<SPACE><SPACE><SPACE>"
   (insignificant spaces present in value) or " " (insignificant spaces
   not present in value).  However, as these cases have no practical
   application that cannot be met by simple assertions, e.g., (cn=\20),
   and this minor anomaly can only be fully addressed by a preparation
   algorithm to be used in conjunction with character-by-character
   partitioning and matching, the anomaly is considered acceptable.

Author's Address

   Kurt D. Zeilenga
   OpenLDAP Foundation

   EMail: [e-mail]








Zeilenga                    Standards Track                    [Page 13]

RFC 4518       LDAP: Internationalized String Preparation      June 2006


Full Copyright Statement

   Copyright (C) The Internet Society (2006).

   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 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.

Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   [e-mail].

Acknowledgement

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).







Zeilenga                    Standards Track                    [Page 14]