Class: Net::LDAP::Filter

Inherits:
Object
  • Object
show all
Defined in:
lib/net/ldap/filter.rb

Overview

Class Net::LDAP::Filter is used to constrain LDAP searches. An object of this class is passed to Net::LDAP#search in the parameter :filter.

Net::LDAP::Filter supports the complete set of search filters available in LDAP, including conjunction, disjunction and negation (AND, OR, and NOT). This class supplants the (infamous) RFC 2254 standard notation for specifying LDAP search filters. – NOTE: This wording needs to change as we will be supporting LDAPv3 search filter strings (RFC 4515). ++

Here’s how to code the familiar “objectclass is present” filter:

f = Net::LDAP::Filter.present("objectclass")

The object returned by this code can be passed directly to the :filter parameter of Net::LDAP#search.

See the individual class and instance methods below for more examples.

Defined Under Namespace

Classes: FilterParser

Constant Summary collapse

FilterTypes =

Known filter types.

[ :ne, :eq, :ge, :le, :and, :or, :not, :ex ]

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(op, left, right) ⇒ Filter

:nodoc:



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# File 'lib/net/ldap/filter.rb', line 48

def initialize(op, left, right) #:nodoc:
  unless FilterTypes.include?(op)
    raise Net::LDAP::LdapError, "Invalid or unsupported operator #{op.inspect} in LDAP Filter."
  end
  @op = op
  @left = left
  @right = right
end

Class Method Details

.construct(ldap_filter_string) ⇒ Object Also known as: from_rfc2254, from_rfc4515

Converts an LDAP filter-string (in the prefix syntax specified in RFC-2254) to a Net::LDAP::Filter.



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# File 'lib/net/ldap/filter.rb', line 284

def construct(ldap_filter_string)
  FilterParser.parse(ldap_filter_string)
end

.eq(attribute, value) ⇒ Object

Creates a Filter object indicating that the value of a particular attribute must either be present or match a particular string.

Specifying that an attribute is ‘present’ means only directory entries which contain a value for the particular attribute will be selected by the filter. This is useful in case of optional attributes such as mail. Presence is indicated by giving the value “*” in the second parameter to #eq. This example selects only entries that have one or more values for sAMAccountName:

f = Net::LDAP::Filter.eq("sAMAccountName", "*")

To match a particular range of values, pass a string as the second parameter to #eq. The string may contain one or more “*” characters as wildcards: these match zero or more occurrences of any character. Full regular-expressions are not supported due to limitations in the underlying LDAP protocol. This example selects any entry with a mail value containing the substring “anderson”:

f = Net::LDAP::Filter.eq("mail", "*anderson*")



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# File 'lib/net/ldap/filter.rb', line 82

def eq(attribute, value)
  new(:eq, attribute, value)
end

.ex(attribute, value) ⇒ Object

Creates a Filter object indicating extensible comparison. This Filter object is currently considered EXPERIMENTAL.

sample_attributes = ['cn:fr', 'cn:fr.eq',
  'cn:1.3.6.1.4.1.42.2.27.9.4.49.1.3', 'cn:dn:fr', 'cn:dn:fr.eq']
attr = sample_attributes.first # Pick an extensible attribute
value = 'roberts'

filter = "#{attr}:=#{value}" # Basic String Filter
filter = Net::LDAP::Filter.ex(attr, value) # Net::LDAP::Filter

# Perform a search with the Extensible Match Filter
Net::LDAP.search(:filter => filter)

– The LDIF required to support the above examples on the OpenDS LDAP server:

version: 1

dn: dc=example,dc=com
objectClass: domain
objectClass: top
dc: example

dn: ou=People,dc=example,dc=com
objectClass: organizationalUnit
objectClass: top
ou: People

dn: uid=1,ou=People,dc=example,dc=com
objectClass: person
objectClass: organizationalPerson
objectClass: inetOrgPerson
objectClass: top
cn:: csO0YsOpcnRz
sn:: YsO0YiByw7Riw6lydHM=
givenName:: YsO0Yg==
uid: 1

Refs:

++



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# File 'lib/net/ldap/filter.rb', line 131

def ex(attribute, value)
  new(:ex, attribute, value)
end

.ge(attribute, value) ⇒ Object

Creates a Filter object indicating that a particular attribute value is greater than or equal to the specified value.



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# File 'lib/net/ldap/filter.rb', line 146

def ge(attribute, value)
  new(:ge, attribute, value)
end

.intersect(left, right) ⇒ Object

Creates a disjoint comparison between two or more filters. Selects entries where either the left or right side are true. Calling Filter.intersect(left, right) is the same as left | right.

# Selects only entries that have an <tt>objectclass</tt> attribute.
x = Net::LDAP::Filter.present("objectclass")
# Selects only entries that have a <tt>mail</tt> attribute that begins
# with "George".
y = Net::LDAP::Filter.eq("mail", "George*")
# Selects only entries that meet either condition above.
z = x | y



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# File 'lib/net/ldap/filter.rb', line 186

def intersect(left, right)
  new(:or, left, right)
end

.join(left, right) ⇒ Object

Joins two or more filters so that all conditions must be true. Calling Filter.join(left, right) is the same as left & right.

# Selects only entries that have an <tt>objectclass</tt> attribute.
x = Net::LDAP::Filter.present("objectclass")
# Selects only entries that have a <tt>mail</tt> attribute that begins
# with "George".
y = Net::LDAP::Filter.eq("mail", "George*")
# Selects only entries that meet both conditions above.
z = Net::LDAP::Filter.join(x, y)



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# File 'lib/net/ldap/filter.rb', line 169

def join(left, right)
  new(:and, left, right)
end

.le(attribute, value) ⇒ Object

Creates a Filter object indicating that a particular attribute value is less than or equal to the specified value.



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# File 'lib/net/ldap/filter.rb', line 153

def le(attribute, value)
  new(:le, attribute, value)
end

.ne(attribute, value) ⇒ Object

Creates a Filter object indicating that a particular attribute value is either not present or does not match a particular string; see Filter::eq for more information.



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# File 'lib/net/ldap/filter.rb', line 139

def ne(attribute, value)
  new(:ne, attribute, value)
end

.negate(filter) ⇒ Object

Negates a filter. Calling Fitler.negate(filter) i s the same as ~filter.

# Selects only entries that do not have an <tt>objectclass</tt>
# attribute.
x = ~Net::LDAP::Filter.present("objectclass")



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# File 'lib/net/ldap/filter.rb', line 197

def negate(filter)
  new(:not, filter, nil)
end

.parse_ber(ber) ⇒ Object

Converts an LDAP search filter in BER format to an Net::LDAP::Filter object. The incoming BER object most likely came to us by parsing an LDAP searchRequest PDU. See also the comments under #to_ber, including the grammar snippet from the RFC. – We’re hardcoding the BER constants from the RFC. These should be broken out insto constants.



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# File 'lib/net/ldap/filter.rb', line 218

def parse_ber(ber)
  case ber.ber_identifier
  when 0xa0 # context-specific constructed 0, "and"
    ber.map { |b| parse_ber(b) }.inject { |memo, obj| memo & obj }
  when 0xa1 # context-specific constructed 1, "or"
    ber.map { |b| parse_ber(b) }.inject { |memo, obj| memo | obj }
  when 0xa2 # context-specific constructed 2, "not"
    ~parse_ber(ber.first)
  when 0xa3 # context-specific constructed 3, "equalityMatch"
    if ber.last == "*"
    else
      eq(ber.first, ber.last)
    end
  when 0xa4 # context-specific constructed 4, "substring"
    str = ""
    final = false
    ber.last.each { |b|
      case b.ber_identifier
      when 0x80 # context-specific primitive 0, SubstringFilter "initial"
        raise Net::LDAP::LdapError, "Unrecognized substring filter; bad initial value." if str.length > 0
        str += b
      when 0x81 # context-specific primitive 0, SubstringFilter "any"
        str += "*#{b}"
      when 0x82 # context-specific primitive 0, SubstringFilter "final"
        str += "*#{b}"
        final = true
      end
    }
    str += "*" unless final
    eq(ber.first.to_s, str)
  when 0xa5 # context-specific constructed 5, "greaterOrEqual"
    ge(ber.first.to_s, ber.last.to_s)
  when 0xa6 # context-specific constructed 6, "lessOrEqual"
    le(ber.first.to_s, ber.last.to_s)
  when 0x87 # context-specific primitive 7, "present"
    # call to_s to get rid of the BER-identifiedness of the incoming string.
    present?(ber.to_s)
  when 0xa9 # context-specific constructed 9, "extensible comparison"
    raise Net::LDAP::LdapError, "Invalid extensible search filter, should be at least two elements" if ber.size<2
    
    # Reassembles the extensible filter parts 
    # (["sn", "2.4.6.8.10", "Barbara Jones", '1'])
    type = value = dn = rule = nil
    ber.each do |element|
      case element.ber_identifier
        when 0x81 then rule=element
        when 0x82 then type=element
        when 0x83 then value=element
        when 0x84 then dn='dn'
      end
    end

    attribute = ''
    attribute << type if type
    attribute << ":#{dn}" if dn
    attribute << ":#{rule}" if rule
    
    ex(attribute, value)
  else
    raise Net::LDAP::LdapError, "Invalid BER tag-value (#{ber.ber_identifier}) in search filter."
  end
end

.parse_ldap_filter(obj) ⇒ Object

Convert an RFC-1777 LDAP/BER “Filter” object to a Net::LDAP::Filter object. – TODO, we’re hardcoding the RFC-1777 BER-encodings of the various filter types. Could pull them out into a constant. ++



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# File 'lib/net/ldap/filter.rb', line 297

def parse_ldap_filter(obj)
  case obj.ber_identifier
  when 0x87 # present. context-specific primitive 7.
    eq(obj.to_s, "*")
  when 0xa3 # equalityMatch. context-specific constructed 3.
    eq(obj[0], obj[1])
  else
    raise Net::LDAP::LdapError, "Unknown LDAP search-filter type: #{obj.ber_identifier}"
  end
end

.present?(attribute) ⇒ Boolean Also known as: present, pres

This is a synonym for #eq(attribute, “*”). Also known as #present and #pres.

Returns:

  • (Boolean) 


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# File 'lib/net/ldap/filter.rb', line 204

def present?(attribute)
  eq(attribute, "*")
end

Instance Method Details

#&(filter) ⇒ Object

Joins two or more filters so that all conditions must be true.

# Selects only entries that have an <tt>objectclass</tt> attribute.
x = Net::LDAP::Filter.present("objectclass")
# Selects only entries that have a <tt>mail</tt> attribute that begins
# with "George".
y = Net::LDAP::Filter.eq("mail", "George*")
# Selects only entries that meet both conditions above.
z = x & y



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# File 'lib/net/ldap/filter.rb', line 319

def &(filter)
  self.class.join(self, filter)
end

#==(filter) ⇒ Object

Equality operator for filters, useful primarily for constructing unit tests.



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# File 'lib/net/ldap/filter.rb', line 350

def ==(filter)
  # 20100320 AZ: We need to come up with a better way of doing this. This
  # is just nasty.
  str = "[@op,@left,@right]"
  self.instance_eval(str) == filter.instance_eval(str)
end

#coalesce(operator) ⇒ Object

This is a private helper method for dealing with chains of ANDs and ORs that are longer than two. If BOTH of our branches are of the specified type of joining operator, then return both of them as an array (calling coalesce recursively). If they’re not, then return an array consisting only of self.



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# File 'lib/net/ldap/filter.rb', line 560

def coalesce(operator) #:nodoc:
  if @op == operator
    [@left.coalesce(operator), @right.coalesce(operator)]
  else
    [self]
  end
end

#execute(&block) ⇒ Object

Perform filter operations against a user-supplied block. This is useful when implementing an LDAP directory server. The caller’s block will be called with two arguments: first, a symbol denoting the “operation” of the filter; and second, an array consisting of arguments to the operation. The user-supplied block (which is MANDATORY) should perform some desired application-defined processing, and may return a locally-meaningful object that will appear as a parameter in the :and, :or and :not operations detailed below.

A typical object to return from the user-supplied block is an array of Net::LDAP::Filter objects.

These are the possible values that may be passed to the user-supplied block:

* :equalityMatch (the arguments will be an attribute name and a value
  to be matched);
* :substrings (two arguments: an attribute name and a value containing
  one or more "*" characters);
* :present (one argument: an attribute name);
* :greaterOrEqual (two arguments: an attribute name and a value to be
  compared against);
* :lessOrEqual (two arguments: an attribute name and a value to be
  compared against);
* :and (two or more arguments, each of which is an object returned
  from a recursive call to #execute, with the same block;
* :or (two or more arguments, each of which is an object returned from
  a recursive call to #execute, with the same block; and
* :not (one argument, which is an object returned from a recursive
  call to #execute with the the same block.



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# File 'lib/net/ldap/filter.rb', line 533

def execute(&block)
  case @op
  when :eq
    if @right == "*"
      yield :present, @left
    elsif @right.index '*'
      yield :substrings, @left, @right
    else
      yield :equalityMatch, @left, @right
    end
  when :ge
    yield :greaterOrEqual, @left, @right
  when :le
    yield :lessOrEqual, @left, @right
  when :or, :and
    yield @op, (@left.execute(&block)), (@right.execute(&block))
  when :not
    yield @op, (@left.execute(&block))
  end || []
end

#match(entry) ⇒ Object

– We got a hash of attribute values. Do we match the attributes? Return T/F, and call match recursively as necessary. ++



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# File 'lib/net/ldap/filter.rb', line 574

def match(entry)
  case @op
  when :eq
    if @right == "*"
      l = entry[@left] and l.length > 0
    else
      l = entry[@left] and l = Array(l) and l.index(@right)
    end
  else
    raise Net::LDAP::LdapError, "Unknown filter type in match: #{@op}"
  end
end

#to_ber ⇒ Object

Converts the filter to BER format. – 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,
    extensibleMatch [9] MatchingRuleAssertion
}

SubstringFilter ::=

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

MatchingRuleAssertion ::=

SEQUENCE {
  matchingRule    [1] MatchingRuleId OPTIONAL,
  type            [2] AttributeDescription OPTIONAL,
  matchValue      [3] AssertionValue,
  dnAttributes    [4] BOOLEAN DEFAULT FALSE
}

Matching Rule Suffixes

Less than   [.1] or .[lt]
Less than or equal to  [.2] or [.lte]
Equality  [.3] or  [.eq] (default)
Greater than or equal to  [.4] or [.gte]
Greater than  [.5] or [.gt]
Substring  [.6] or  [.sub]

++



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# File 'lib/net/ldap/filter.rb', line 432

def to_ber
  case @op
  when :eq
    if @right == "*" # presence test
      @left.to_s.to_ber_contextspecific(7)
    elsif @right =~ /[*]/ # substring
      # Parsing substrings is a little tricky. We use String#split to
      # break a string into substrings delimited by the * (star)
      # character. But we also need to know whether there is a star at the
      # head and tail of the string, so we use a limit parameter value of
      # -1: "If negative, there is no limit to the number of fields
      # returned, and trailing null fields are not suppressed."
      #
      # 20100320 AZ: This is much simpler than the previous verison. Also,
      # unnecessary regex escaping has been removed.

      ary = @right.split(/[*]+/, -1)

      if ary.first.empty?
        first = nil
        ary.shift
      else
        first = ary.shift.to_ber_contextspecific(0)
      end

      if ary.last.empty?
        last = nil
        ary.pop
      else
        last = ary.pop.to_ber_contextspecific(2)
      end

      seq = ary.map { |e| e.to_ber_contextspecific(1) }
      seq.unshift first if first
      seq.push last if last

      [@left.to_s.to_ber, seq.to_ber].to_ber_contextspecific(4)
    else # equality
      [@left.to_s.to_ber, unescape(@right).to_ber].to_ber_contextspecific(3)
    end
  when :ex
    seq = []

    unless @left =~ /^([-;\d\w]*)(:dn)?(:(\w+|[.\d\w]+))?$/
      raise Net::LDAP::LdapError, "Bad attribute #{@left}"
    end
    type, dn, rule = $1, $2, $4

    seq << rule.to_ber_contextspecific(1) unless rule.to_s.empty? # matchingRule
    seq << type.to_ber_contextspecific(2) unless type.to_s.empty? # type
    seq << unescape(@right).to_ber_contextspecific(3) # matchingValue
    seq << "1".to_ber_contextspecific(4) unless dn.to_s.empty? # dnAttributes

    seq.to_ber_contextspecific(9)
  when :ge
    [@left.to_s.to_ber, unescape(@right).to_ber].to_ber_contextspecific(5)
  when :le
    [@left.to_s.to_ber, unescape(@right).to_ber].to_ber_contextspecific(6)
  when :ne
    [self.class.eq(@left, @right).to_ber].to_ber_contextspecific(2)
  when :and
    ary = [@left.coalesce(:and), @right.coalesce(:and)].flatten
    ary.map {|a| a.to_ber}.to_ber_contextspecific(0)
  when :or
    ary = [@left.coalesce(:or), @right.coalesce(:or)].flatten
    ary.map {|a| a.to_ber}.to_ber_contextspecific(1)
  when :not
    [@left.to_ber].to_ber_contextspecific(2)
  end
end

#to_raw_rfc2254 ⇒ Object 



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# File 'lib/net/ldap/filter.rb', line 357

def to_raw_rfc2254
  case @op
  when :ne
    "!(#{@left}=#{@right})"
  when :eq
    "#{@left}=#{@right}"
  when :ex
    "#{@left}:=#{@right}"
  when :ge
    "#{@left}>=#{@right}"
  when :le
    "#{@left}<=#{@right}"
  when :and
    "&(#{@left.to_raw_rfc2254})(#{@right.to_raw_rfc2254})"
  when :or
    "|(#{@left.to_raw_rfc2254})(#{@right.to_raw_rfc2254})"
  when :not
    "!(#{@left.to_raw_rfc2254})"
  end
end

#to_rfc2254 ⇒ Object

Converts the Filter object to an RFC 2254-compatible text format.



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# File 'lib/net/ldap/filter.rb', line 380

def to_rfc2254
  "(#{to_raw_rfc2254})"
end

#to_s ⇒ Object 



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# File 'lib/net/ldap/filter.rb', line 384

def to_s
  to_rfc2254
end

#|(filter) ⇒ Object

Creates a disjoint comparison between two or more filters. Selects entries where either the left or right side are true.

# Selects only entries that have an <tt>objectclass</tt> attribute.
x = Net::LDAP::Filter.present("objectclass")
# Selects only entries that have a <tt>mail</tt> attribute that begins
# with "George".
y = Net::LDAP::Filter.eq("mail", "George*")
# Selects only entries that meet either condition above.
z = x | y



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# File 'lib/net/ldap/filter.rb', line 334

def |(filter)
  self.class.intersect(self, filter)
end

#~@ ⇒ Object

Negates a filter.

# Selects only entries that do not have an <tt>objectclass</tt>
# attribute.
x = ~Net::LDAP::Filter.present("objectclass")



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# File 'lib/net/ldap/filter.rb', line 344

def ~@
  self.class.negate(self)
end