ldap-filter

Python LDAP Filter ·

Build, generate, and validate LDAP filters

A Python 3 utility library for working with Lightweight Directory Access Protocol (LDAP) filters.

This project is a Python port of the node-ldap-filters project. The filters produced by the library are based on RFC 4515.

Note: This project is currently only compatible with Python 3.4 or higher.

Usage

Installation

Install via pip:

pip install ldap-filter

Building a Filter

This library exposes a number of APIs that allow you to build filters programmatically. The logical and attribute methods of the Filter object can be combined in a number of ways to generate filters ranging from very simple to very complex.

The following is a quick example of how you might build a filter programmatically:

from ldap_filter import Filter

output = Filter.AND([
    Filter.attribute('name').equal_to('bob'),
    Filter.attribute('mail').ends_with('@example.com'),
    Filter.OR([
        Filter.attribute('dept').equal_to('accounting'),
        Filter.attribute('dept').equal_to('operations')
    ])
])

print(output.to_string())  # (&(name=bob)(mail=*@example.com)(|(dept=accounting)(dept=operations)))

Attribute Methods

Attribute methods are used to create LDAP attribute filter strings. The Filter.attribute(name) method returns an Attribute object that the following filter methods can be applied to.

output = Filter.attribute('name').equal_to('bob')  # (name=bob)

Methods:

• Attribute.present() - Tests if an attribute is present.

  • Output: (attribute=*)

• Attribute.equal_to(value) - Tests if an attribute is equal to the provided value.

  • Output: (attribute=value)

• Attribute.contains(value) - Tests if an attribute contains the provided value.

  • Output: (attribute=*value*)

• Attribute.starts_with(value) - Tests if an attribute starts with the provided value.

  • Output: (attribute=value*)

• Attribute.ends_with(value) - Tests if an attribute ends with the provided value.

  • Output: (attribute=*value)

• Attribute.approx(value) - Tests if an attribute is an approximate match to the provided value.

  • Output: (attribute~=value)

• Attribute.gte(value) - Tests if an attribute is greater than or equal to the provided value.

  • Output: (attribute>=value)

• Attribute.lte(value) - Tests if an attribute is less than or equal to the provided value.

  • Output: (attribute<=value)

• Attribute.raw(value) - Allows for a custom filter with escaped value output.

  • Output: (attribute=value)

Logical Methods

Logical methods are used to aggregate simple attribute filters. You can nest as many logical methods as needed to produce complex filters.

output = Filter.OR([
    Filter.attribute('name').equal_to('bob'),
    Filter.attribute('name').equal_to('bill')
])

print(output)  # (|(name=bob)(name=bill))

Methods:

• Filter.AND(filt) - Accepts a list of Filter, Attribute, or Group objects.

  • Output: (&(filt=1)(filt=2)..)

• Filter.OR(filt) - Accepts a list of Filter, Attribute, or Group objects.

  • Output: (|(filt=1)(filt=2)..)

• Filter.NOT(filt) - Accepts a single Attribute object.

  • Output: (!(filt=1))

Filter Parsing

The Filter.parse(input) method can be used to create a Filter object from an existing LDAP filter. This method can also be used to determine if a string is a valid LDAP filter or not.

input = '(|(name=bob)(name=bill))'

Filter.parse(input)

If an invalid LDAP filter string is passed a ParseError exception will be thrown.

from ldap_filter import Filter, ParseError


input = '(|(name=bob)name=bill))'

try:
    Filter.parse(input)
except ParseError as e:
    print(e)

Error Output:

Line 1: expected [\x20], [\x09], "\r\n", "\n", '(', ')'
(|(name=bob)name=bill)
            ^

Simplifying Filters

The Filter.simplify() method can be used to eliminate unnecessary AND/OR filters that only have one child node.

input = '(&(name=bob))'
complex = Filter.parse(input)

print(complex.simplify())  # (name=bob)

Filter Output

There are a few options for getting a string output from your Filter object with optional custom formatting.

Simple String

You can get simple filter string by calling the Filter.to_string() method. The Filter class also implements Python's __str__ method, allowing you to type cast the Filter object directly to a string or concatenate with other strings.

output = Filter.AND([
    Filter.attribute('name').equal_to('bob'),
    Filter.attribute('mail').ends_with('@example.com'),
])

# Filter.to_string() output.
print(output.to_string())  # (&(name=bob)(mail=*@example.com))

# Typecast output.
print(str(output)) # (&(name=bob)(mail=*@example.com))

# String concatenate output
print('LDAP Filter: ' + output) # LDAP Filter: (&(name=bob)(mail=*@example.com))

Beautified String

The Filter.to_string() method provides additional formatting options to produce beautified filter strings.

You can get the default beautified format by passing True to the Filter.to_string(indent) method

output = Filter.AND([
    Filter.attribute('name').equal_to('bob'),
    Filter.attribute('mail').ends_with('@example.com'),
    Filter.OR([
        Filter.attribute('dept').equal_to('accounting'),
        Filter.attribute('dept').equal_to('operations')
    ])
])

print(output.to_string(True))

Default Beautified Output:

(&
    (name=bob)
    (mail=*@example.com)
    (|
        (dept=accounting)
        (dept=operations)
    )
)

or you can customize the output by passing the indent and/or indt_char parameters to Filter.to_string(indent, indt_char). The indent parameter accepts an integer value while the indt_char parameter accepts any string or character value.

output = Filter.AND([
    Filter.attribute('name').equal_to('bob'),
    Filter.attribute('mail').ends_with('@example.com'),
    Filter.OR([
        Filter.attribute('dept').equal_to('accounting'),
        Filter.attribute('dept').equal_to('operations')
    ])
])

print(output.to_string(2, '.'))

Custom Beautified Output:

(&
..(name=bob)
..(mail=*@example.com)
..(|
....(dept=accounting)
....(dept=operations)
..)
)

Filter Matching

The Filter.match(data) method allows you to evaluate a Python dictionary with attributes against an LDAP filter. The method will return True if a match is found or False if there is no match (or if an attribute matches a NOT exclusion).

filt = Filter.AND([
    Filter.attribute('department').equal_to('accounting'),
    Filter.NOT(
        Filter.attribute('status').equal_to('terminated')
    )
])

employee1 = {
    'name': 'Bob Smith',
    'department': 'Accounting',
    'status': 'Active'
}

print(filt.match(employee1))  # True

employee2 = {
    'name': 'Jane Brown',
    'department': 'Accounting',
    'status': 'Terminated'
}

print(filt.match(employee2))  # False

employee3 = {
    'name': 'Bob Smith',
    'department': 'Marketing',
    'status': 'Active'
}

print(filt.match(employee3))  # False

Unit Tests

In order to run the test suite the pytest library is required. You can install pytest by running:

pip install pytest

To run the unit tests simply type pytest in the projects root directory

Home Page

Project home page is https://github.com/SteveEwell/python-ldap-filter

License

The Python LDAP Filter project is open source software released under the MIT licence. Copyright 2024 Stephen Ewell