Network Working Group T. Howes Request for Comments: 1960 University of Michigan Obsoletes: 1558 June 1996 Category: Standards Track
A String Representation of LDAP Search Filters
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
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 } }
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.
<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.
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.
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