As per Relevance of the word matching, we have this rfc below:
Network Working Group T.
Request for Comments: 2254 Netscape Communications Corp
Category: Standards Track December 1997
The String Representation of LDAP Search
1. Status of this
This document specifies an Internet standards track protocol for
Internet community, and requests discussion and suggestions
improvements. Please refer to the current edition of the "
Official Protocol Standards" (STD 1) for the standardization
and status of this protocol. Distribution of this memo is unlimited
Copyright
Copyright (C) The Internet Society (1997). All Rights Reserved
IESG
This document describes a directory access protocol that
both read and update access. Update access requires
authentication, but this document does not mandate implementation
any satisfactory authentication mechanisms
In accordance with RFC 2026, section 4.4.1, this specification
being approved by IESG as a Proposed Standard despite
limitation, for the following reasons
a. to encourage implementation and interoperability testing
these protocols (with or without update access) before
are deployed,
b. to encourage deployment and use of these protocols in read-
applications. (e.g. applications where LDAPv3 is used
a query language for directories which are updated by
secure mechanism other than LDAP),
c. to avoid delaying the advancement and deployment of other
standards-track protocols which require the ability to query,
not update, LDAPv3 directory servers
Howes Standards Track [Page 1]
RFC 2254 String Representation of LDAP December 1997
Readers are hereby warned that until mandatory
mechanisms are standardized, clients and servers written according
this specification which make use of update functionality
UNLIKELY TO INTEROPERATE, or MAY INTEROPERATE ONLY IF
IS REDUCED TO AN UNACCEPTABLY WEAK LEVEL
Implementors are hereby discouraged from deploying LDAPv3 clients
servers which implement the update functionality, until a
Standard for mandatory authentication in LDAPv3 has been approved
published as an RFC
2.
The Lightweight Directory Access Protocol (LDAP) [1] defines
network representation of a search filter transmitted to an
server. Some applications may find it useful to have a common way
representing these search filters in a human-readable form.
document defines a human-readable string format for representing
search filters
This document replaces RFC 1960, extending the string LDAP
definition to include support for LDAP version 3 extended
filters, and including support for representing the full range
possible LDAP search filters
Howes Standards Track [Page 2]
RFC 2254 String Representation of LDAP December 1997
3. LDAP Search Filter
An LDAPv3 search filter is defined in Section 4.5.1 of [1]
follows
Filter ::= CHOICE {
and [0] SET OF Filter
or [1] SET OF Filter
not [2] Filter
equalityMatch [3] AttributeValueAssertion
substrings [4] SubstringFilter
greaterOrEqual [5] AttributeValueAssertion
lessOrEqual [6] AttributeValueAssertion
present [7] AttributeDescription
approxMatch [8] AttributeValueAssertion
extensibleMatch [9]
}
SubstringFilter ::= SEQUENCE {
type AttributeDescription
SEQUENCE OF CHOICE {
initial [0] LDAPString
any [1] LDAPString
final [2]
}
}
AttributeValueAssertion ::= SEQUENCE {
attributeDesc AttributeDescription
attributeValue
}
MatchingRuleAssertion ::= SEQUENCE {
matchingRule [1] MatchingRuleID OPTIONAL
type [2] AttributeDescription OPTIONAL
matchValue [3] AssertionValue
dnAttributes [4] BOOLEAN DEFAULT
}
AttributeDescription ::=
AttributeValue ::= OCTET
MatchingRuleID ::=
AssertionValue ::= OCTET
LDAPString ::= OCTET
Howes Standards Track [Page 3]
RFC 2254 String Representation of LDAP December 1997
where the LDAPString above is limited to the UTF-8 encoding of
ISO 10646 character set [4]. The AttributeDescription is a
representation of the attribute description and is defined in [1].
The AttributeValue and AssertionValue OCTET STRING have the
defined in [2]. The Filter is encoded for transmission over
network using the Basic Encoding Rules defined in [3],
simplifications described in [1].
4. String Search Filter
The string representation of an LDAP search filter is defined by
following grammar, following the ABNF notation defined in [5].
filter format uses a prefix notation
filter = "(" filtercomp ")"
filtercomp = and / or / not /
and = "&"
or = "|"
not = "!"
filterlist = 1*
item = simple / present / substring /
simple = attr filtertype
filtertype = equal / approx / greater /
equal = "="
approx = "~="
greater = ">="
less = "<="
extensible = attr [":dn"] [":" matchingrule] ":="
/ [":dn"] ":" matchingrule ":="
present = attr "=*"
substring = attr "=" [initial] any [final
initial =
any = "*" *(value "*")
final =
attr = AttributeDescription from Section 4.1.5 of [1]
matchingrule = MatchingRuleId from Section 4.1.9 of [1]
value = AttributeValue from Section 4.1.6 of [1]
The attr, matchingrule, and value constructs are as described in
corresponding section of [1] given above
Howes Standards Track [Page 4]
RFC 2254 String Representation of LDAP December 1997
If a value should contain any of the following
Character ASCII
---------------------------
* 0x2
( 0x28
) 0x29
\ 0x5
NUL 0x00
the character must be encoded as the backslash '\' character (
0x5c) followed by the two hexadecimal digits representing the
value of the encoded character. The case of the two
digits is not significant
This simple escaping mechanism eliminates filter-parsing
and allows any filter that can be represented in LDAP to
represented as a NUL-terminated string. Other characters besides
ones listed above may be escaped using this mechanism, for example
non-printing characters
For example, the filter checking whether the "cn" attribute
a value with the character "*" anywhere in it would be represented
"(cn=*\2a*)".
Note that although both the substring and present productions in
grammar above can produce the "attr=*" construct, this construct
used only to denote a presence filter
5.
This section gives a few examples of search filters written
this notation
(cn=Babs Jensen
(!(cn=Tim Howes))
(&(objectClass=Person)(|(sn=Jensen)(cn=Babs J*)))
(o=univ*of*mich*)
The following examples illustrate the use of extensible matching
(cn:1.2.3.4.5:=Fred Flintstone
(sn:dn:2.4.6.8.10:=Barney Rubble
(o:dn:=Ace Industry
(:dn:2.4.6.8.10:=Dino
Howes Standards Track [Page 5]
RFC 2254 String Representation of LDAP December 1997
The second example illustrates the use of the ":dn" notation
indicate that matching rule "2.4.6.8.10" should be used when
comparisons, and that the attributes of an entry's distinguished
should be considered part of the entry when evaluating the match
The third example denotes an equality match, except that
components should be considered part of the entry when doing
match
The fourth example is a filter that should be applied to
attribute supporting the matching rule given (since the attr has
left off). Attributes supporting the matching rule contained in
DN should also be considered
The following examples illustrate the use of the escaping mechanism
(o=Parens R Us \28for all your parenthetical needs\29)
(cn=*\2A*)
(filename=C:\5cMyFile
(bin=\00\00\00\04)
(sn=Lu\c4\8di\c4\87)
The first example shows the use of the escaping mechanism
represent parenthesis characters. The second shows how to represent
"*" in a value, preventing it from being interpreted as a
indicator. The third illustrates the escaping of the
character
The fourth example shows a filter searching for the four-byte
0x00000004, illustrating the use of the escaping mechanism
represent arbitrary data, including NUL characters
The final example illustrates the use of the escaping mechanism
represent various non-ASCII UTF-8 characters
6. Security
This memo describes a string representation of LDAP search filters
While the representation itself has no known security implications
LDAP search filters do. They are interpreted by LDAP servers
select entries from which data is retrieved. LDAP servers
take care to protect the data they maintain from unauthorized access
Howes Standards Track [Page 6]
RFC 2254 String Representation of LDAP December 1997
7.
[1] Wahl, M., Howes, T., and S. Kille, "Lightweight Directory
Protocol (v3)", RFC 2251, December 1997.
[2] Wahl, M., Coulbeck, A., Howes, T., and S. Kille, "
Directory Access Protocol (v3): Attribute Syntax Definitions",
2252, December 1997.
[3] Specification of ASN.1 encoding rules: Basic, Canonical,
Distinguished Encoding Rules, ITU-T Recommendation X.690, 1994.
[4] Yergeau, F., "UTF-8, a transformation format of Unicode and
10646", RFC 2044, October 1996.
[5] Crocker, D., "Standard for the Format of ARPA Internet
Messages", STD 11, RFC 822, August 1982.
8. Author's
Tim
Netscape Communications Corp
501 E. Middlefield
Mountain View, CA 94043
Phone: +1 415 937-3419
EMail: howes@netscape.
Howes Standards Track [Page 7]
RFC 2254 String Representation of LDAP December 1997
9. Full Copyright
Copyright (C) The Internet Society (1997). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
and distributed, in whole or in part, without restriction of
kind, provided that the above copyright notice and this paragraph
included on all such copies and derivative works. However,
document itself may not be modified in any way, such as by
the copyright notice or references to the Internet Society or
Internet organizations, except as needed for the purpose
developing Internet standards in which case the procedures
copyrights defined in the Internet Standards process must
followed, or as required to translate it into languages other
English
The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns
This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
Howes Standards Track [Page 8]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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