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RFC 1960

             A String Representation of LDAP Search Filters

1.  Abstract

   The Lightweight Directory Access Protocol (LDAP) [1] defines a
   network representation of a search filter transmitted to an LDAP
   server.  Some applications may find it useful to have a common way of
   representing these search filters in a human-readable form.  This
   document defines a human-readable string format for representing LDAP
   search filters.

2.  LDAP Search Filter Definition

   An LDAP search filter is defined in [1] as 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] AttributeType,
             approxMatch        [8] AttributeValueAssertion
     }

     SubstringFilter ::= SEQUENCE {
             type    AttributeType,
             SEQUENCE OF CHOICE {
                     initial        [0] LDAPString,
                     any            [1] LDAPString,
                     final          [2] LDAPString
             }
     }



Howes                       Standards Track                     [Page 1]

RFC 1960 LDAP Search Filters June 1996 AttributeValueAssertion ::= SEQUENCE { attributeType AttributeType, attributeValue AttributeValue } AttributeType ::= LDAPString AttributeValue ::= OCTET STRING LDAPString ::= OCTET STRING where the LDAPString above is limited to the IA5 character set. The AttributeType is a string representation of the attribute type name and is defined in [1]. The AttributeValue OCTET STRING has the form defined in [2]. The Filter is encoded for transmission over a network using the Basic Encoding Rules defined in [3], with simplifications described in [1]. 3. String Search Filter Definition The string representation of an LDAP search filter is defined by the following grammar. It uses a prefix format. <filter> ::= '(' <filtercomp> ')' <filtercomp> ::= <and> | <or> | <not> | <item> <and> ::= '&' <filterlist> <or> ::= '|' <filterlist> <not> ::= '!' <filter> <filterlist> ::= <filter> | <filter> <filterlist> <item> ::= <simple> | <present> | <substring> <simple> ::= <attr> <filtertype> <value> <filtertype> ::= <equal> | <approx> | <greater> | <less> <equal> ::= '=' <approx> ::= '~=' <greater> ::= '>=' <less> ::= '<=' <present> ::= <attr> '=*' <substring> ::= <attr> '=' <initial> <any> <final> <initial> ::= NULL | <value> <any> ::= '*' <starval> <starval> ::= NULL | <value> '*' <starval> <final> ::= NULL | <value> <attr> is a string representing an AttributeType, and has the format defined in [1]. <value> is a string representing an AttributeValue, or part of one, and has the form defined in [2]. If a <value> must contain one of the characters '*' or '(' or ')', these characters should be escaped by preceding them with the backslash '\' character. Howes Standards Track [Page 2]
RFC 1960 LDAP Search Filters June 1996 Note that although both the <substring> and <present> productions can produce the 'attr=*' construct, this construct is used only to denote a presence filter. 4. Examples This section gives a few examples of search filters written using this notation. (cn=Babs Jensen) (!(cn=Tim Howes)) (&(objectClass=Person)(|(sn=Jensen)(cn=Babs J*))) (o=univ*of*mich*) 5. Security Considerations Security considerations are not discussed in this memo. 6. Bibliography [1] Yeong, W., Howes, T., and S. Kille, "Lightweight Directory Access Protocol", RFC 1777, March 1995. [2] Howes, R., Kille, S., Yeong, W., and C. Robbins, "The String Representation of Standard Attribute Syntaxes", RFC 1778, March 1995. [3] Specification of Basic Encoding Rules for Abstract Syntax Notation One (ASN.1). CCITT Recommendation X.209, 1988.



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