comparison vendor/plugins/ruby-net-ldap-0.0.4/lib/net/ldap.rb @ 0:513646585e45

* Import Redmine trunk SVN rev 3859

+# $Id: ldap.rb 154 2006-08-15 09:35:43Z blackhedd $
+#
+# Net::LDAP for Ruby
+#
+#
+# Copyright (C) 2006 by Francis Cianfrocca. All Rights Reserved.
+#
+# Written and maintained by Francis Cianfrocca, gmail: garbagecat10.
+#
+# This program is free software.
+# You may re-distribute and/or modify this program under the same terms
+# as Ruby itself: Ruby Distribution License or GNU General Public License.
+#
+#
+# See Net::LDAP for documentation and usage samples.
+#
+
+
+require 'socket'
+require 'ostruct'
+
+begin
+  require 'openssl'
+  $net_ldap_openssl_available = true
+rescue LoadError
+end
+
+require 'net/ber'
+require 'net/ldap/pdu'
+require 'net/ldap/filter'
+require 'net/ldap/dataset'
+require 'net/ldap/psw'
+require 'net/ldap/entry'
+
+
+module Net
+
+
+  # == Net::LDAP
+  #
+  # This library provides a pure-Ruby implementation of the
+  # LDAP client protocol, per RFC-2251.
+  # It can be used to access any server which implements the
+  # LDAP protocol.
+  #
+  # Net::LDAP is intended to provide full LDAP functionality
+  # while hiding the more arcane aspects
+  # the LDAP protocol itself, and thus presenting as Ruby-like
+  # a programming interface as possible.
+  # 
+  # == Quick-start for the Impatient
+  # === Quick Example of a user-authentication against an LDAP directory:
+  #
+  #  require 'rubygems'
+  #  require 'net/ldap'
+  #  
+  #  ldap = Net::LDAP.new
+  #  ldap.host = your_server_ip_address
+  #  ldap.port = 389
+  #  ldap.auth "joe_user", "opensesame"
+  #  if ldap.bind
+  #    # authentication succeeded
+  #  else
+  #    # authentication failed
+  #  end
+  #
+  #
+  # === Quick Example of a search against an LDAP directory:
+  #
+  #  require 'rubygems'
+  #  require 'net/ldap'
+  #  
+  #  ldap = Net::LDAP.new :host => server_ip_address,
+  #       :port => 389,
+  #       :auth => {
+  #             :method => :simple,
+  #             :username => "cn=manager,dc=example,dc=com",
+  #             :password => "opensesame"
+  #       }
+  #
+  #  filter = Net::LDAP::Filter.eq( "cn", "George*" )
+  #  treebase = "dc=example,dc=com"
+  #  
+  #  ldap.search( :base => treebase, :filter => filter ) do |entry|
+  #    puts "DN: #{entry.dn}"
+  #    entry.each do |attribute, values|
+  #      puts "   #{attribute}:"
+  #      values.each do |value|
+  #        puts "      --->#{value}"
+  #      end
+  #    end
+  #  end
+  #  
+  #  p ldap.get_operation_result
+  #  
+  #
+  # == A Brief Introduction to LDAP
+  #
+  # We're going to provide a quick, informal introduction to LDAP
+  # terminology and
+  # typical operations. If you're comfortable with this material, skip
+  # ahead to "How to use Net::LDAP." If you want a more rigorous treatment
+  # of this material, we recommend you start with the various IETF and ITU
+  # standards that relate to LDAP.
+  #
+  # === Entities
+  # LDAP is an Internet-standard protocol used to access directory servers.
+  # The basic search unit is the <i>entity,</i> which corresponds to
+  # a person or other domain-specific object.
+  # A directory service which supports the LDAP protocol typically
+  # stores information about a number of entities.
+  #
+  # === Principals
+  # LDAP servers are typically used to access information about people,
+  # but also very often about such items as printers, computers, and other
+  # resources. To reflect this, LDAP uses the term <i>entity,</i> or less
+  # commonly, <i>principal,</i> to denote its basic data-storage unit.
+  # 
+  #
+  # === Distinguished Names
+  # In LDAP's view of the world,
+  # an entity is uniquely identified by a globally-unique text string
+  # called a <i>Distinguished Name,</i> originally defined in the X.400
+  # standards from which LDAP is ultimately derived.
+  # Much like a DNS hostname, a DN is a "flattened" text representation
+  # of a string of tree nodes. Also like DNS (and unlike Java package
+  # names), a DN expresses a chain of tree-nodes written from left to right
+  # in order from the most-resolved node to the most-general one.
+  #
+  # If you know the DN of a person or other entity, then you can query
+  # an LDAP-enabled directory for information (attributes) about the entity.
+  # Alternatively, you can query the directory for a list of DNs matching
+  # a set of criteria that you supply.
+  #
+  # === Attributes
+  #
+  # In the LDAP view of the world, a DN uniquely identifies an entity.
+  # Information about the entity is stored as a set of <i>Attributes.</i>
+  # An attribute is a text string which is associated with zero or more
+  # values. Most LDAP-enabled directories store a well-standardized
+  # range of attributes, and constrain their values according to standard
+  # rules.
+  #
+  # A good example of an attribute is <tt>sn,</tt> which stands for "Surname."
+  # This attribute is generally used to store a person's surname, or last name.
+  # Most directories enforce the standard convention that
+  # an entity's <tt>sn</tt> attribute have <i>exactly one</i> value. In LDAP
+  # jargon, that means that <tt>sn</tt> must be <i>present</i> and
+  # <i>single-valued.</i>
+  #
+  # Another attribute is <tt>mail,</tt> which is used to store email addresses.
+  # (No, there is no attribute called "email," perhaps because X.400 terminology
+  # predates the invention of the term <i>email.</i>) <tt>mail</tt> differs
+  # from <tt>sn</tt> in that most directories permit any number of values for the
+  # <tt>mail</tt> attribute, including zero.
+  #
+  #
+  # === Tree-Base
+  # We said above that X.400 Distinguished Names are <i>globally unique.</i>
+  # In a manner reminiscent of DNS, LDAP supposes that each directory server
+  # contains authoritative attribute data for a set of DNs corresponding
+  # to a specific sub-tree of the (notional) global directory tree.
+  # This subtree is generally configured into a directory server when it is
+  # created. It matters for this discussion because most servers will not
+  # allow you to query them unless you specify a correct tree-base.
+  #
+  # Let's say you work for the engineering department of Big Company, Inc.,
+  # whose internet domain is bigcompany.com. You may find that your departmental
+  # directory is stored in a server with a defined tree-base of
+  #  ou=engineering,dc=bigcompany,dc=com
+  # You will need to supply this string as the <i>tree-base</i> when querying this
+  # directory. (Ou is a very old X.400 term meaning "organizational unit."
+  # Dc is a more recent term meaning "domain component.")
+  #
+  # === LDAP Versions
+  # (stub, discuss v2 and v3)
+  #
+  # === LDAP Operations
+  # The essential operations are: #bind, #search, #add, #modify, #delete, and #rename.
+  # ==== Bind
+  # #bind supplies a user's authentication credentials to a server, which in turn verifies
+  # or rejects them. There is a range of possibilities for credentials, but most directories
+  # support a simple username and password authentication.
+  #
+  # Taken by itself, #bind can be used to authenticate a user against information
+  # stored in a directory, for example to permit or deny access to some other resource.
+  # In terms of the other LDAP operations, most directories require a successful #bind to
+  # be performed before the other operations will be permitted. Some servers permit certain
+  # operations to be performed with an "anonymous" binding, meaning that no credentials are
+  # presented by the user. (We're glossing over a lot of platform-specific detail here.)
+  #
+  # ==== Search
+  # Calling #search against the directory involves specifying a treebase, a set of <i>search filters,</i>
+  # and a list of attribute values.
+  # The filters specify ranges of possible values for particular attributes. Multiple
+  # filters can be joined together with AND, OR, and NOT operators.
+  # A server will respond to a #search by returning a list of matching DNs together with a
+  # set of attribute values for each entity, depending on what attributes the search requested.
+  # 
+  # ==== Add
+  # #add specifies a new DN and an initial set of attribute values. If the operation
+  # succeeds, a new entity with the corresponding DN and attributes is added to the directory.
+  #
+  # ==== Modify
+  # #modify specifies an entity DN, and a list of attribute operations. #modify is used to change
+  # the attribute values stored in the directory for a particular entity.
+  # #modify may add or delete attributes (which are lists of values) or it change attributes by
+  # adding to or deleting from their values.
+  # Net::LDAP provides three easier methods to modify an entry's attribute values:
+  # #add_attribute, #replace_attribute, and #delete_attribute.
+  #
+  # ==== Delete
+  # #delete specifies an entity DN. If it succeeds, the entity and all its attributes
+  # is removed from the directory.
+  #
+  # ==== Rename (or Modify RDN)
+  # #rename (or #modify_rdn) is an operation added to version 3 of the LDAP protocol. It responds to
+  # the often-arising need to change the DN of an entity without discarding its attribute values.
+  # In earlier LDAP versions, the only way to do this was to delete the whole entity and add it
+  # again with a different DN.
+  #
+  # #rename works by taking an "old" DN (the one to change) and a "new RDN," which is the left-most
+  # part of the DN string. If successful, #rename changes the entity DN so that its left-most
+  # node corresponds to the new RDN given in the request. (RDN, or "relative distinguished name,"
+  # denotes a single tree-node as expressed in a DN, which is a chain of tree nodes.)
+  #
+  # == How to use Net::LDAP
+  #
+  # To access Net::LDAP functionality in your Ruby programs, start by requiring
+  # the library:
+  #
+  #  require 'net/ldap'
+  #
+  # If you installed the Gem version of Net::LDAP, and depending on your version of
+  # Ruby and rubygems, you _may_ also need to require rubygems explicitly:
+  #
+  #  require 'rubygems'
+  #  require 'net/ldap'
+  #
+  # Most operations with Net::LDAP start by instantiating a Net::LDAP object.
+  # The constructor for this object takes arguments specifying the network location
+  # (address and port) of the LDAP server, and also the binding (authentication)
+  # credentials, typically a username and password.
+  # Given an object of class Net:LDAP, you can then perform LDAP operations by calling
+  # instance methods on the object. These are documented with usage examples below.
+  #
+  # The Net::LDAP library is designed to be very disciplined about how it makes network
+  # connections to servers. This is different from many of the standard native-code
+  # libraries that are provided on most platforms, which share bloodlines with the
+  # original Netscape/Michigan LDAP client implementations. These libraries sought to
+  # insulate user code from the workings of the network. This is a good idea of course,
+  # but the practical effect has been confusing and many difficult bugs have been caused
+  # by the opacity of the native libraries, and their variable behavior across platforms.
+  #
+  # In general, Net::LDAP instance methods which invoke server operations make a connection
+  # to the server when the method is called. They execute the operation (typically binding first)
+  # and then disconnect from the server. The exception is Net::LDAP#open, which makes a connection
+  # to the server and then keeps it open while it executes a user-supplied block. Net::LDAP#open
+  # closes the connection on completion of the block.
+  #
+
+  class LDAP
+
+    class LdapError < Exception; end
+
+    VERSION = "0.0.4"
+
+
+    SearchScope_BaseObject = 0
+    SearchScope_SingleLevel = 1
+    SearchScope_WholeSubtree = 2
+    SearchScopes = [SearchScope_BaseObject, SearchScope_SingleLevel, SearchScope_WholeSubtree]
+
+    AsnSyntax = {
+      :application => {
+        :constructed => {
+          0 => :array,              # BindRequest
+          1 => :array,              # BindResponse
+          2 => :array,              # UnbindRequest
+          3 => :array,              # SearchRequest
+          4 => :array,              # SearchData
+          5 => :array,              # SearchResult
+          6 => :array,              # ModifyRequest
+          7 => :array,              # ModifyResponse
+          8 => :array,              # AddRequest
+          9 => :array,              # AddResponse
+          10 => :array,             # DelRequest
+          11 => :array,             # DelResponse
+          12 => :array,             # ModifyRdnRequest
+          13 => :array,             # ModifyRdnResponse
+          14 => :array,             # CompareRequest
+          15 => :array,             # CompareResponse
+          16 => :array,             # AbandonRequest
+          19 => :array,             # SearchResultReferral
+          24 => :array,             # Unsolicited Notification
+        }
+      },
+      :context_specific => {
+        :primitive => {
+          0 => :string,             # password
+          1 => :string,             # Kerberos v4
+          2 => :string,             # Kerberos v5
+        },
+        :constructed => {
+          0 => :array,              # RFC-2251 Control
+          3 => :array,              # Seach referral
+        }
+      }
+    }
+
+    DefaultHost = "127.0.0.1"
+    DefaultPort = 389
+    DefaultAuth = {:method => :anonymous}
+    DefaultTreebase = "dc=com"
+
+
+    ResultStrings = {
+      0 => "Success",
+      1 => "Operations Error",
+      2 => "Protocol Error",
+      3 => "Time Limit Exceeded",
+      4 => "Size Limit Exceeded",
+      12 => "Unavailable crtical extension",
+      16 => "No Such Attribute",
+      17 => "Undefined Attribute Type",
+      20 => "Attribute or Value Exists",
+      32 => "No Such Object",
+      34 => "Invalid DN Syntax",
+      48 => "Invalid DN Syntax",
+      48 => "Inappropriate Authentication",
+      49 => "Invalid Credentials",
+      50 => "Insufficient Access Rights",
+      51 => "Busy",
+      52 => "Unavailable",
+      53 => "Unwilling to perform",
+      65 => "Object Class Violation",
+      68 => "Entry Already Exists"
+    }
+
+
+    module LdapControls
+      PagedResults = "1.2.840.113556.1.4.319" # Microsoft evil from RFC 2696
+    end
+
+
+    #
+    # LDAP::result2string
+    #
+    def LDAP::result2string code # :nodoc:
+      ResultStrings[code] || "unknown result (#{code})"
+    end 
+
+
+    attr_accessor :host, :port, :base
+
+
+    # Instantiate an object of type Net::LDAP to perform directory operations.
+    # This constructor takes a Hash containing arguments, all of which are either optional or may be specified later with other methods as described below. The following arguments
+    # are supported:
+    # * :host => the LDAP server's IP-address (default 127.0.0.1)
+    # * :port => the LDAP server's TCP port (default 389)
+    # * :auth => a Hash containing authorization parameters. Currently supported values include:
+    #   {:method => :anonymous} and
+    #   {:method => :simple, :username => your_user_name, :password => your_password }
+    #   The password parameter may be a Proc that returns a String.
+    # * :base => a default treebase parameter for searches performed against the LDAP server. If you don't give this value, then each call to #search must specify a treebase parameter. If you do give this value, then it will be used in subsequent calls to #search that do not specify a treebase. If you give a treebase value in any particular call to #search, that value will override any treebase value you give here.
+    # * :encryption => specifies the encryption to be used in communicating with the LDAP server. The value is either a Hash containing additional parameters, or the Symbol :simple_tls, which is equivalent to specifying the Hash {:method => :simple_tls}. There is a fairly large range of potential values that may be given for this parameter. See #encryption for details.
+    #
+    # Instantiating a Net::LDAP object does <i>not</i> result in network traffic to
+    # the LDAP server. It simply stores the connection and binding parameters in the
+    # object.
+    #
+    def initialize args = {}
+      @host = args[:host] || DefaultHost
+      @port = args[:port] || DefaultPort
+      @verbose = false # Make this configurable with a switch on the class.
+      @auth = args[:auth] || DefaultAuth
+      @base = args[:base] || DefaultTreebase
+      encryption args[:encryption] # may be nil
+
+      if pr = @auth[:password] and pr.respond_to?(:call)
+        @auth[:password] = pr.call
+      end
+
+      # This variable is only set when we are created with LDAP::open.
+      # All of our internal methods will connect using it, or else
+      # they will create their own.
+      @open_connection = nil
+    end
+
+    # Convenience method to specify authentication credentials to the LDAP
+    # server. Currently supports simple authentication requiring
+    # a username and password.
+    #
+    # Observe that on most LDAP servers,
+    # the username is a complete DN. However, with A/D, it's often possible
+    # to give only a user-name rather than a complete DN. In the latter
+    # case, beware that many A/D servers are configured to permit anonymous
+    # (uncredentialled) binding, and will silently accept your binding
+    # as anonymous if you give an unrecognized username. This is not usually
+    # what you want. (See #get_operation_result.)
+    #
+    # <b>Important:</b> The password argument may be a Proc that returns a string.
+    # This makes it possible for you to write client programs that solicit
+    # passwords from users or from other data sources without showing them
+    # in your code or on command lines.
+    #
+    #  require 'net/ldap'
+    #  
+    #  ldap = Net::LDAP.new
+    #  ldap.host = server_ip_address
+    #  ldap.authenticate "cn=Your Username,cn=Users,dc=example,dc=com", "your_psw"
+    #
+    # Alternatively (with a password block):
+    #
+    #  require 'net/ldap'
+    #  
+    #  ldap = Net::LDAP.new
+    #  ldap.host = server_ip_address
+    #  psw = proc { your_psw_function }
+    #  ldap.authenticate "cn=Your Username,cn=Users,dc=example,dc=com", psw
+    #
+    def authenticate username, password
+      password = password.call if password.respond_to?(:call)
+      @auth = {:method => :simple, :username => username, :password => password}
+    end
+
+    alias_method :auth, :authenticate
+
+    # Convenience method to specify encryption characteristics for connections
+    # to LDAP servers. Called implicitly by #new and #open, but may also be called
+    # by user code if desired.
+    # The single argument is generally a Hash (but see below for convenience alternatives).
+    # This implementation is currently a stub, supporting only a few encryption
+    # alternatives. As additional capabilities are added, more configuration values
+    # will be added here.
+    #
+    # Currently, the only supported argument is {:method => :simple_tls}.
+    # (Equivalently, you may pass the symbol :simple_tls all by itself, without
+    # enclosing it in a Hash.)
+    #
+    # The :simple_tls encryption method encrypts <i>all</i> communications with the LDAP
+    # server.
+    # It completely establishes SSL/TLS encryption with the LDAP server 
+    # before any LDAP-protocol data is exchanged.
+    # There is no plaintext negotiation and no special encryption-request controls
+    # are sent to the server. 
+    # <i>The :simple_tls option is the simplest, easiest way to encrypt communications
+    # between Net::LDAP and LDAP servers.</i>
+    # It's intended for cases where you have an implicit level of trust in the authenticity
+    # of the LDAP server. No validation of the LDAP server's SSL certificate is
+    # performed. This means that :simple_tls will not produce errors if the LDAP
+    # server's encryption certificate is not signed by a well-known Certification
+    # Authority.
+    # If you get communications or protocol errors when using this option, check
+    # with your LDAP server administrator. Pay particular attention to the TCP port
+    # you are connecting to. It's impossible for an LDAP server to support plaintext
+    # LDAP communications and <i>simple TLS</i> connections on the same port.
+    # The standard TCP port for unencrypted LDAP connections is 389, but the standard
+    # port for simple-TLS encrypted connections is 636. Be sure you are using the
+    # correct port.
+    #
+    # <i>[Note: a future version of Net::LDAP will support the STARTTLS LDAP control,
+    # which will enable encrypted communications on the same TCP port used for
+    # unencrypted connections.]</i>
+    #
+    def encryption args
+      if args == :simple_tls
+        args = {:method => :simple_tls}
+      end
+      @encryption = args
+    end
+
+
+    # #open takes the same parameters as #new. #open makes a network connection to the
+    # LDAP server and then passes a newly-created Net::LDAP object to the caller-supplied block.
+    # Within the block, you can call any of the instance methods of Net::LDAP to
+    # perform operations against the LDAP directory. #open will perform all the
+    # operations in the user-supplied block on the same network connection, which
+    # will be closed automatically when the block finishes.
+    #
+    #  # (PSEUDOCODE)
+    #  auth = {:method => :simple, :username => username, :password => password}
+    #  Net::LDAP.open( :host => ipaddress, :port => 389, :auth => auth ) do |ldap|
+    #    ldap.search( ... )
+    #    ldap.add( ... )
+    #    ldap.modify( ... )
+    #  end
+    #
+    def LDAP::open args
+      ldap1 = LDAP.new args
+      ldap1.open {|ldap| yield ldap }
+    end
+
+    # Returns a meaningful result any time after
+    # a protocol operation (#bind, #search, #add, #modify, #rename, #delete)
+    # has completed.
+    # It returns an #OpenStruct containing an LDAP result code (0 means success),
+    # and a human-readable string.
+    #  unless ldap.bind
+    #    puts "Result: #{ldap.get_operation_result.code}"
+    #    puts "Message: #{ldap.get_operation_result.message}"
+    #  end
+    #
+    def get_operation_result
+      os = OpenStruct.new
+      if @result
+        os.code = @result
+      else
+        os.code = 0
+      end
+      os.message = LDAP.result2string( os.code )
+      os
+    end
+
+
+    # Opens a network connection to the server and then
+    # passes <tt>self</tt> to the caller-supplied block. The connection is
+    # closed when the block completes. Used for executing multiple
+    # LDAP operations without requiring a separate network connection
+    # (and authentication) for each one.
+    # <i>Note:</i> You do not need to log-in or "bind" to the server. This will
+    # be done for you automatically.
+    # For an even simpler approach, see the class method Net::LDAP#open.
+    #
+    #  # (PSEUDOCODE)
+    #  auth = {:method => :simple, :username => username, :password => password}
+    #  ldap = Net::LDAP.new( :host => ipaddress, :port => 389, :auth => auth )
+    #  ldap.open do |ldap|
+    #    ldap.search( ... )
+    #    ldap.add( ... )
+    #    ldap.modify( ... )
+    #  end
+    #--
+    # First we make a connection and then a binding, but we don't
+    # do anything with the bind results.
+    # We then pass self to the caller's block, where he will execute
+    # his LDAP operations. Of course they will all generate auth failures
+    # if the bind was unsuccessful.
+    def open
+      raise LdapError.new( "open already in progress" ) if @open_connection
+      @open_connection = Connection.new( :host => @host, :port => @port, :encryption => @encryption )
+      @open_connection.bind @auth
+      yield self
+      @open_connection.close
+      @open_connection = nil
+    end
+
+
+    # Searches the LDAP directory for directory entries.
+    # Takes a hash argument with parameters. Supported parameters include:
+    # * :base (a string specifying the tree-base for the search);
+    # * :filter (an object of type Net::LDAP::Filter, defaults to objectclass=*);
+    # * :attributes (a string or array of strings specifying the LDAP attributes to return from the server);
+    # * :return_result (a boolean specifying whether to return a result set).
+    # * :attributes_only (a boolean flag, defaults false)
+    # * :scope (one of: Net::LDAP::SearchScope_BaseObject, Net::LDAP::SearchScope_SingleLevel, Net::LDAP::SearchScope_WholeSubtree. Default is WholeSubtree.)
+    #
+    # #search queries the LDAP server and passes <i>each entry</i> to the
+    # caller-supplied block, as an object of type Net::LDAP::Entry.
+    # If the search returns 1000 entries, the block will
+    # be called 1000 times. If the search returns no entries, the block will
+    # not be called.
+    #
+    #--
+    # ORIGINAL TEXT, replaced 04May06.
+    # #search returns either a result-set or a boolean, depending on the
+    # value of the <tt>:return_result</tt> argument. The default behavior is to return
+    # a result set, which is a hash. Each key in the hash is a string specifying
+    # the DN of an entry. The corresponding value for each key is a Net::LDAP::Entry object.
+    # If you request a result set and #search fails with an error, it will return nil.
+    # Call #get_operation_result to get the error information returned by
+    # the LDAP server.
+    #++
+    # #search returns either a result-set or a boolean, depending on the
+    # value of the <tt>:return_result</tt> argument. The default behavior is to return
+    # a result set, which is an Array of objects of class Net::LDAP::Entry.
+    # If you request a result set and #search fails with an error, it will return nil.
+    # Call #get_operation_result to get the error information returned by
+    # the LDAP server.
+    #
+    # When <tt>:return_result => false,</tt> #search will
+    # return only a Boolean, to indicate whether the operation succeeded. This can improve performance
+    # with very large result sets, because the library can discard each entry from memory after
+    # your block processes it.
+    #
+    #
+    #  treebase = "dc=example,dc=com"
+    #  filter = Net::LDAP::Filter.eq( "mail", "a*.com" )
+    #  attrs = ["mail", "cn", "sn", "objectclass"]
+    #  ldap.search( :base => treebase, :filter => filter, :attributes => attrs, :return_result => false ) do |entry|
+    #    puts "DN: #{entry.dn}"
+    #    entry.each do |attr, values|
+    #      puts ".......#{attr}:"
+    #      values.each do |value|
+    #        puts "          #{value}"
+    #      end
+    #    end
+    #  end
+    #
+    #--
+    # This is a re-implementation of search that replaces the
+    # original one (now renamed searchx and possibly destined to go away).
+    # The difference is that we return a dataset (or nil) from the
+    # call, and pass _each entry_ as it is received from the server
+    # to the caller-supplied block. This will probably make things
+    # far faster as we can do useful work during the network latency
+    # of the search. The downside is that we have no access to the
+    # whole set while processing the blocks, so we can't do stuff
+    # like sort the DNs until after the call completes.
+    # It's also possible that this interacts badly with server timeouts.
+    # We'll have to ensure that something reasonable happens if
+    # the caller has processed half a result set when we throw a timeout
+    # error.
+    # Another important difference is that we return a result set from
+    # this method rather than a T/F indication.
+    # Since this can be very heavy-weight, we define an argument flag
+    # that the caller can set to suppress the return of a result set,
+    # if he's planning to process every entry as it comes from the server.
+    #
+    # REINTERPRETED the result set, 04May06. Originally this was a hash
+    # of entries keyed by DNs. But let's get away from making users
+    # handle DNs. Change it to a plain array. Eventually we may
+    # want to return a Dataset object that delegates to an internal
+    # array, so we can provide sort methods and what-not.
+    #
+    def search args = {}
+      args[:base] ||= @base
+      result_set = (args and args[:return_result] == false) ? nil : []
+
+      if @open_connection
+        @result = @open_connection.search( args ) {|entry|
+          result_set << entry if result_set
+          yield( entry ) if block_given?
+        }
+      else
+        @result = 0
+        conn = Connection.new( :host => @host, :port => @port, :encryption => @encryption )
+        if (@result = conn.bind( args[:auth] || @auth )) == 0
+          @result = conn.search( args ) {|entry|
+            result_set << entry if result_set
+            yield( entry ) if block_given?
+          }
+        end
+        conn.close
+      end
+
+      @result == 0 and result_set
+    end
+
+    # #bind connects to an LDAP server and requests authentication
+    # based on the <tt>:auth</tt> parameter passed to #open or #new.
+    # It takes no parameters.
+    #
+    # User code does not need to call #bind directly. It will be called
+    # implicitly by the library whenever you invoke an LDAP operation,
+    # such as #search or #add.
+    #
+    # It is useful, however, to call #bind in your own code when the
+    # only operation you intend to perform against the directory is
+    # to validate a login credential. #bind returns true or false
+    # to indicate whether the binding was successful. Reasons for
+    # failure include malformed or unrecognized usernames and
+    # incorrect passwords. Use #get_operation_result to find out
+    # what happened in case of failure.
+    #
+    # Here's a typical example using #bind to authenticate a
+    # credential which was (perhaps) solicited from the user of a
+    # web site:
+    #
+    #  require 'net/ldap'
+    #  ldap = Net::LDAP.new
+    #  ldap.host = your_server_ip_address
+    #  ldap.port = 389
+    #  ldap.auth your_user_name, your_user_password
+    #  if ldap.bind
+    #    # authentication succeeded
+    #  else
+    #    # authentication failed
+    #    p ldap.get_operation_result
+    #  end
+    #
+    # You don't have to create a new instance of Net::LDAP every time
+    # you perform a binding in this way. If you prefer, you can cache the Net::LDAP object
+    # and re-use it to perform subsequent bindings, <i>provided</i> you call
+    # #auth to specify a new credential before calling #bind. Otherwise, you'll
+    # just re-authenticate the previous user! (You don't need to re-set
+    # the values of #host and #port.) As noted in the documentation for #auth,
+    # the password parameter can be a Ruby Proc instead of a String.
+    #
+    #--
+    # If there is an @open_connection, then perform the bind
+    # on it. Otherwise, connect, bind, and disconnect.
+    # The latter operation is obviously useful only as an auth check.
+    #
+    def bind auth=@auth
+      if @open_connection
+        @result = @open_connection.bind auth
+      else
+        conn = Connection.new( :host => @host, :port => @port , :encryption => @encryption)
+        @result = conn.bind @auth
+        conn.close
+      end
+
+      @result == 0
+    end
+
+    #
+    # #bind_as is for testing authentication credentials.
+    #
+    # As described under #bind, most LDAP servers require that you supply a complete DN
+    # as a binding-credential, along with an authenticator such as a password.
+    # But for many applications (such as authenticating users to a Rails application),
+    # you often don't have a full DN to identify the user. You usually get a simple
+    # identifier like a username or an email address, along with a password.
+    # #bind_as allows you to authenticate these user-identifiers.
+    #
+    # #bind_as is a combination of a search and an LDAP binding. First, it connects and
+    # binds to the directory as normal. Then it searches the directory for an entry
+    # corresponding to the email address, username, or other string that you supply.
+    # If the entry exists, then #bind_as will <b>re-bind</b> as that user with the
+    # password (or other authenticator) that you supply.
+    #
+    # #bind_as takes the same parameters as #search, <i>with the addition of an
+    # authenticator.</i> Currently, this authenticator must be <tt>:password</tt>.
+    # Its value may be either a String, or a +proc+ that returns a String.
+    # #bind_as returns +false+ on failure. On success, it returns a result set,
+    # just as #search does. This result set is an Array of objects of
+    # type Net::LDAP::Entry. It contains the directory attributes corresponding to
+    # the user. (Just test whether the return value is logically true, if you don't
+    # need this additional information.)
+    #
+    # Here's how you would use #bind_as to authenticate an email address and password:
+    #
+    #  require 'net/ldap'
+    #  
+    #  user,psw = "[e-mail]", "joes_psw"
+    #  
+    #  ldap = Net::LDAP.new
+    #  ldap.host = "192.168.0.100"
+    #  ldap.port = 389
+    #  ldap.auth "cn=manager,dc=yourcompany,dc=com", "topsecret"
+    #  
+    #  result = ldap.bind_as(
+    #    :base => "dc=yourcompany,dc=com",
+    #    :filter => "(mail=#{user})",
+    #    :password => psw
+    #  )
+    #  if result
+    #    puts "Authenticated #{result.first.dn}"
+    #  else
+    #    puts "Authentication FAILED."
+    #  end
+    def bind_as args={}
+      result = false
+      open {|me|
+        rs = search args
+        if rs and rs.first and dn = rs.first.dn
+          password = args[:password]
+          password = password.call if password.respond_to?(:call)
+          result = rs if bind :method => :simple, :username => dn, :password => password
+        end
+      }
+      result
+    end
+
+
+    # Adds a new entry to the remote LDAP server.
+    # Supported arguments:
+    # :dn :: Full DN of the new entry
+    # :attributes :: Attributes of the new entry.
+    #
+    # The attributes argument is supplied as a Hash keyed by Strings or Symbols
+    # giving the attribute name, and mapping to Strings or Arrays of Strings
+    # giving the actual attribute values. Observe that most LDAP directories
+    # enforce schema constraints on the attributes contained in entries.
+    # #add will fail with a server-generated error if your attributes violate
+    # the server-specific constraints.
+    # Here's an example:
+    #
+    #  dn = "cn=George Smith,ou=people,dc=example,dc=com"
+    #  attr = {
+    #    :cn => "George Smith",
+    #    :objectclass => ["top", "inetorgperson"],
+    #    :sn => "Smith",
+    #    :mail => "[e-mail]"
+    #  }
+    #  Net::LDAP.open (:host => host) do |ldap|
+    #    ldap.add( :dn => dn, :attributes => attr )
+    #  end
+    #
+    def add args
+      if @open_connection
+          @result = @open_connection.add( args )
+      else
+        @result = 0
+        conn = Connection.new( :host => @host, :port => @port, :encryption => @encryption)
+        if (@result = conn.bind( args[:auth] || @auth )) == 0
+          @result = conn.add( args )
+        end
+        conn.close
+      end
+      @result == 0
+    end
+
+
+    # Modifies the attribute values of a particular entry on the LDAP directory.
+    # Takes a hash with arguments. Supported arguments are:
+    # :dn :: (the full DN of the entry whose attributes are to be modified)
+    # :operations :: (the modifications to be performed, detailed next)
+    #
+    # This method returns True or False to indicate whether the operation
+    # succeeded or failed, with extended information available by calling
+    # #get_operation_result.
+    #
+    # Also see #add_attribute, #replace_attribute, or #delete_attribute, which
+    # provide simpler interfaces to this functionality.
+    #
+    # The LDAP protocol provides a full and well thought-out set of operations
+    # for changing the values of attributes, but they are necessarily somewhat complex
+    # and not always intuitive. If these instructions are confusing or incomplete,
+    # please send us email or create a bug report on rubyforge.
+    #
+    # The :operations parameter to #modify takes an array of operation-descriptors.
+    # Each individual operation is specified in one element of the array, and
+    # most LDAP servers will attempt to perform the operations in order.
+    #
+    # Each of the operations appearing in the Array must itself be an Array
+    # with exactly three elements:
+    # an operator:: must be :add, :replace, or :delete
+    # an attribute name:: the attribute name (string or symbol) to modify
+    # a value:: either a string or an array of strings.
+    #
+    # The :add operator will, unsurprisingly, add the specified values to
+    # the specified attribute. If the attribute does not already exist,
+    # :add will create it. Most LDAP servers will generate an error if you
+    # try to add a value that already exists.
+    #
+    # :replace will erase the current value(s) for the specified attribute,
+    # if there are any, and replace them with the specified value(s).
+    #
+    # :delete will remove the specified value(s) from the specified attribute.
+    # If you pass nil, an empty string, or an empty array as the value parameter
+    # to a :delete operation, the _entire_ _attribute_ will be deleted, along
+    # with all of its values.
+    #
+    # For example:
+    #
+    #  dn = "mail=[e-mail],ou=people,dc=example,dc=com"
+    #  ops = [
+    #    [:add, :mail, "[e-mail]"],
+    #    [:replace, :mail, ["[e-mail]", "[e-mail]"]],
+    #    [:delete, :sn, nil]
+    #  ]
+    #  ldap.modify :dn => dn, :operations => ops
+    #
+    # <i>(This example is contrived since you probably wouldn't add a mail
+    # value right before replacing the whole attribute, but it shows that order
+    # of execution matters. Also, many LDAP servers won't let you delete SN
+    # because that would be a schema violation.)</i>
+    #
+    # It's essential to keep in mind that if you specify more than one operation in
+    # a call to #modify, most LDAP servers will attempt to perform all of the operations
+    # in the order you gave them.
+    # This matters because you may specify operations on the
+    # same attribute which must be performed in a certain order.
+    #
+    # Most LDAP servers will _stop_ processing your modifications if one of them
+    # causes an error on the server (such as a schema-constraint violation).
+    # If this happens, you will probably get a result code from the server that
+    # reflects only the operation that failed, and you may or may not get extended
+    # information that will tell you which one failed. #modify has no notion
+    # of an atomic transaction. If you specify a chain of modifications in one
+    # call to #modify, and one of them fails, the preceding ones will usually
+    # not be "rolled back," resulting in a partial update. This is a limitation
+    # of the LDAP protocol, not of Net::LDAP.
+    #
+    # The lack of transactional atomicity in LDAP means that you're usually
+    # better off using the convenience methods #add_attribute, #replace_attribute,
+    # and #delete_attribute, which are are wrappers over #modify. However, certain
+    # LDAP servers may provide concurrency semantics, in which the several operations
+    # contained in a single #modify call are not interleaved with other
+    # modification-requests received simultaneously by the server.
+    # It bears repeating that this concurrency does _not_ imply transactional
+    # atomicity, which LDAP does not provide.
+    #
+    def modify args
+      if @open_connection
+          @result = @open_connection.modify( args )
+      else
+        @result = 0
+        conn = Connection.new( :host => @host, :port => @port, :encryption => @encryption )
+        if (@result = conn.bind( args[:auth] || @auth )) == 0
+          @result = conn.modify( args )
+        end
+        conn.close
+      end
+      @result == 0
+    end
+
+
+    # Add a value to an attribute.
+    # Takes the full DN of the entry to modify,
+    # the name (Symbol or String) of the attribute, and the value (String or
+    # Array). If the attribute does not exist (and there are no schema violations),
+    # #add_attribute will create it with the caller-specified values.
+    # If the attribute already exists (and there are no schema violations), the
+    # caller-specified values will be _added_ to the values already present.
+    #
+    # Returns True or False to indicate whether the operation
+    # succeeded or failed, with extended information available by calling
+    # #get_operation_result. See also #replace_attribute and #delete_attribute.
+    #
+    #  dn = "cn=modifyme,dc=example,dc=com"
+    #  ldap.add_attribute dn, :mail, "[e-mail]"
+    #
+    def add_attribute dn, attribute, value
+      modify :dn => dn, :operations => [[:add, attribute, value]]
+    end
+
+    # Replace the value of an attribute.
+    # #replace_attribute can be thought of as equivalent to calling #delete_attribute
+    # followed by #add_attribute. It takes the full DN of the entry to modify,
+    # the name (Symbol or String) of the attribute, and the value (String or
+    # Array). If the attribute does not exist, it will be created with the
+    # caller-specified value(s). If the attribute does exist, its values will be
+    # _discarded_ and replaced with the caller-specified values.
+    #
+    # Returns True or False to indicate whether the operation
+    # succeeded or failed, with extended information available by calling
+    # #get_operation_result. See also #add_attribute and #delete_attribute.
+    #
+    #  dn = "cn=modifyme,dc=example,dc=com"
+    #  ldap.replace_attribute dn, :mail, "[e-mail]"
+    #
+    def replace_attribute dn, attribute, value
+      modify :dn => dn, :operations => [[:replace, attribute, value]]
+    end
+
+    # Delete an attribute and all its values.
+    # Takes the full DN of the entry to modify, and the
+    # name (Symbol or String) of the attribute to delete.
+    #
+    # Returns True or False to indicate whether the operation
+    # succeeded or failed, with extended information available by calling
+    # #get_operation_result. See also #add_attribute and #replace_attribute.
+    #
+    #  dn = "cn=modifyme,dc=example,dc=com"
+    #  ldap.delete_attribute dn, :mail
+    #
+    def delete_attribute dn, attribute
+      modify :dn => dn, :operations => [[:delete, attribute, nil]]
+    end
+
+
+    # Rename an entry on the remote DIS by changing the last RDN of its DN.
+    # _Documentation_ _stub_
+    #
+    def rename args
+      if @open_connection
+          @result = @open_connection.rename( args )
+      else
+        @result = 0
+        conn = Connection.new( :host => @host, :port => @port, :encryption => @encryption )
+        if (@result = conn.bind( args[:auth] || @auth )) == 0
+          @result = conn.rename( args )
+        end
+        conn.close
+      end
+      @result == 0
+    end
+
+    # modify_rdn is an alias for #rename.
+    def modify_rdn args
+      rename args
+    end
+
+    # Delete an entry from the LDAP directory.
+    # Takes a hash of arguments.
+    # The only supported argument is :dn, which must
+    # give the complete DN of the entry to be deleted.
+    # Returns True or False to indicate whether the delete
+    # succeeded. Extended status information is available by
+    # calling #get_operation_result.
+    #
+    #  dn = "mail=[e-mail],ou=people,dc=example,dc=com"
+    #  ldap.delete :dn => dn
+    #
+    def delete args
+      if @open_connection
+          @result = @open_connection.delete( args )
+      else
+        @result = 0
+        conn = Connection.new( :host => @host, :port => @port, :encryption => @encryption )
+        if (@result = conn.bind( args[:auth] || @auth )) == 0
+          @result = conn.delete( args )
+        end
+        conn.close
+      end
+      @result == 0
+    end
+
+  end # class LDAP
+
+
+
+  class LDAP
+  # This is a private class used internally by the library. It should not be called by user code.
+  class Connection # :nodoc:
+
+    LdapVersion = 3
+
+
+    #--
+    # initialize
+    #
+    def initialize server
+      begin
+        @conn = TCPsocket.new( server[:host], server[:port] )
+      rescue
+        raise LdapError.new( "no connection to server" )
+      end
+
+      if server[:encryption]
+        setup_encryption server[:encryption]
+      end
+
+      yield self if block_given?
+    end
+
+
+    #--
+    # Helper method called only from new, and only after we have a successfully-opened
+    # @conn instance variable, which is a TCP connection.
+    # Depending on the received arguments, we establish SSL, potentially replacing
+    # the value of @conn accordingly.
+    # Don't generate any errors here if no encryption is requested.
+    # DO raise LdapError objects if encryption is requested and we have trouble setting
+    # it up. That includes if OpenSSL is not set up on the machine. (Question:
+    # how does the Ruby OpenSSL wrapper react in that case?)
+    # DO NOT filter exceptions raised by the OpenSSL library. Let them pass back
+    # to the user. That should make it easier for us to debug the problem reports.
+    # Presumably (hopefully?) that will also produce recognizable errors if someone
+    # tries to use this on a machine without OpenSSL.
+    #
+    # The simple_tls method is intended as the simplest, stupidest, easiest solution
+    # for people who want nothing more than encrypted comms with the LDAP server.
+    # It doesn't do any server-cert validation and requires nothing in the way
+    # of key files and root-cert files, etc etc.
+    # OBSERVE: WE REPLACE the value of @conn, which is presumed to be a connected
+    # TCPsocket object.
+    #
+    def setup_encryption args
+      case args[:method]
+      when :simple_tls
+        raise LdapError.new("openssl unavailable") unless $net_ldap_openssl_available
+        ctx = OpenSSL::SSL::SSLContext.new
+        @conn = OpenSSL::SSL::SSLSocket.new(@conn, ctx)
+        @conn.connect
+        @conn.sync_close = true
+      # additional branches requiring server validation and peer certs, etc. go here.
+      else
+        raise LdapError.new( "unsupported encryption method #{args[:method]}" )
+      end
+    end
+
+    #--
+    # close
+    # This is provided as a convenience method to make
+    # sure a connection object gets closed without waiting
+    # for a GC to happen. Clients shouldn't have to call it,
+    # but perhaps it will come in handy someday.
+    def close
+      @conn.close
+      @conn = nil
+    end
+
+    #--
+    # next_msgid
+    #
+    def next_msgid
+      @msgid ||= 0
+      @msgid += 1
+    end
+
+
+    #--
+    # bind
+    #
+    def bind auth
+      user,psw = case auth[:method]
+      when :anonymous
+        ["",""]
+      when :simple
+        [auth[:username] || auth[:dn], auth[:password]]
+      end
+      raise LdapError.new( "invalid binding information" ) unless (user && psw)
+
+      msgid = next_msgid.to_ber
+      request = [LdapVersion.to_ber, user.to_ber, psw.to_ber_contextspecific(0)].to_ber_appsequence(0)
+      request_pkt = [msgid, request].to_ber_sequence
+      @conn.write request_pkt
+
+      (be = @conn.read_ber(AsnSyntax) and pdu = Net::LdapPdu.new( be )) or raise LdapError.new( "no bind result" )
+      pdu.result_code
+    end
+
+    #--
+    # search
+    # Alternate implementation, this yields each search entry to the caller
+    # as it are received.
+    # TODO, certain search parameters are hardcoded.
+    # TODO, if we mis-parse the server results or the results are wrong, we can block
+    # forever. That's because we keep reading results until we get a type-5 packet,
+    # which might never come. We need to support the time-limit in the protocol.
+    #--
+    # WARNING: this code substantially recapitulates the searchx method.
+    #
+    # 02May06: Well, I added support for RFC-2696-style paged searches.
+    # This is used on all queries because the extension is marked non-critical.
+    # As far as I know, only A/D uses this, but it's required for A/D. Otherwise
+    # you won't get more than 1000 results back from a query.
+    # This implementation is kindof clunky and should probably be refactored.
+    # Also, is it my imagination, or are A/Ds the slowest directory servers ever???
+    #
+    def search args = {}
+      search_filter = (args && args[:filter]) || Filter.eq( "objectclass", "*" )
+      search_filter = Filter.construct(search_filter) if search_filter.is_a?(String)
+      search_base = (args && args[:base]) || "dc=example,dc=com"
+      search_attributes = ((args && args[:attributes]) || []).map {|attr| attr.to_s.to_ber}
+      return_referrals = args && args[:return_referrals] == true
+
+      attributes_only = (args and args[:attributes_only] == true)
+      scope = args[:scope] || Net::LDAP::SearchScope_WholeSubtree
+      raise LdapError.new( "invalid search scope" ) unless SearchScopes.include?(scope)
+
+      # An interesting value for the size limit would be close to A/D's built-in
+      # page limit of 1000 records, but openLDAP newer than version 2.2.0 chokes
+      # on anything bigger than 126. You get a silent error that is easily visible
+      # by running slapd in debug mode. Go figure.
+      rfc2696_cookie = [126, ""]
+      result_code = 0
+
+      loop {
+        # should collect this into a private helper to clarify the structure
+
+        request = [
+          search_base.to_ber,
+          scope.to_ber_enumerated,
+          0.to_ber_enumerated,
+          0.to_ber,
+          0.to_ber,
+          attributes_only.to_ber,
+          search_filter.to_ber,
+          search_attributes.to_ber_sequence
+        ].to_ber_appsequence(3)
+  
+        controls = [
+          [
+          LdapControls::PagedResults.to_ber,
+          false.to_ber, # criticality MUST be false to interoperate with normal LDAPs.
+          rfc2696_cookie.map{|v| v.to_ber}.to_ber_sequence.to_s.to_ber
+          ].to_ber_sequence
+        ].to_ber_contextspecific(0)
+
+        pkt = [next_msgid.to_ber, request, controls].to_ber_sequence
+        @conn.write pkt
+
+        result_code = 0
+        controls = []
+
+        while (be = @conn.read_ber(AsnSyntax)) && (pdu = LdapPdu.new( be ))
+          case pdu.app_tag
+          when 4 # search-data
+            yield( pdu.search_entry ) if block_given?
+          when 19 # search-referral
+            if return_referrals
+              if block_given?
+                se = Net::LDAP::Entry.new
+                se[:search_referrals] = (pdu.search_referrals || [])
+                yield se
+              end
+            end
+            #p pdu.referrals
+          when 5 # search-result
+            result_code = pdu.result_code
+            controls = pdu.result_controls
+            break
+          else
+            raise LdapError.new( "invalid response-type in search: #{pdu.app_tag}" )
+          end
+        end
+
+        # When we get here, we have seen a type-5 response.
+        # If there is no error AND there is an RFC-2696 cookie,
+        # then query again for the next page of results.
+        # If not, we're done.
+        # Don't screw this up or we'll break every search we do.
+        more_pages = false
+        if result_code == 0 and controls
+          controls.each do |c|
+            if c.oid == LdapControls::PagedResults
+              more_pages = false # just in case some bogus server sends us >1 of these.
+              if c.value and c.value.length > 0
+                cookie = c.value.read_ber[1]
+                if cookie and cookie.length > 0
+                  rfc2696_cookie[1] = cookie
+                  more_pages = true
+                end
+              end
+            end
+          end
+        end
+
+        break unless more_pages
+      } # loop
+
+      result_code
+    end
+
+
+
+
+    #--
+    # modify
+    # TODO, need to support a time limit, in case the server fails to respond.
+    # TODO!!! We're throwing an exception here on empty DN.
+    # Should return a proper error instead, probaby from farther up the chain.
+    # TODO!!! If the user specifies a bogus opcode, we'll throw a
+    # confusing error here ("to_ber_enumerated is not defined on nil").
+    #
+    def modify args
+      modify_dn = args[:dn] or raise "Unable to modify empty DN"
+      modify_ops = []
+      a = args[:operations] and a.each {|op, attr, values|
+        # TODO, fix the following line, which gives a bogus error
+        # if the opcode is invalid.
+        op_1 = {:add => 0, :delete => 1, :replace => 2} [op.to_sym].to_ber_enumerated
+        modify_ops << [op_1, [attr.to_s.to_ber, values.to_a.map {|v| v.to_ber}.to_ber_set].to_ber_sequence].to_ber_sequence
+      }
+
+      request = [modify_dn.to_ber, modify_ops.to_ber_sequence].to_ber_appsequence(6)
+      pkt = [next_msgid.to_ber, request].to_ber_sequence
+      @conn.write pkt
+
+      (be = @conn.read_ber(AsnSyntax)) && (pdu = LdapPdu.new( be )) && (pdu.app_tag == 7) or raise LdapError.new( "response missing or invalid" )
+      pdu.result_code
+    end
+
+
+    #--
+    # add
+    # TODO, need to support a time limit, in case the server fails to respond.
+    #
+    def add args
+      add_dn = args[:dn] or raise LdapError.new("Unable to add empty DN")
+      add_attrs = []
+      a = args[:attributes] and a.each {|k,v|
+        add_attrs << [ k.to_s.to_ber, v.to_a.map {|m| m.to_ber}.to_ber_set ].to_ber_sequence
+      }
+
+      request = [add_dn.to_ber, add_attrs.to_ber_sequence].to_ber_appsequence(8)
+      pkt = [next_msgid.to_ber, request].to_ber_sequence
+      @conn.write pkt
+
+      (be = @conn.read_ber(AsnSyntax)) && (pdu = LdapPdu.new( be )) && (pdu.app_tag == 9) or raise LdapError.new( "response missing or invalid" )
+      pdu.result_code
+    end
+
+
+    #--
+    # rename
+    # TODO, need to support a time limit, in case the server fails to respond.
+    #
+    def rename args
+      old_dn = args[:olddn] or raise "Unable to rename empty DN"
+      new_rdn = args[:newrdn] or raise "Unable to rename to empty RDN"
+      delete_attrs = args[:delete_attributes] ? true : false
+
+      request = [old_dn.to_ber, new_rdn.to_ber, delete_attrs.to_ber].to_ber_appsequence(12)
+      pkt = [next_msgid.to_ber, request].to_ber_sequence
+      @conn.write pkt
+
+      (be = @conn.read_ber(AsnSyntax)) && (pdu = LdapPdu.new( be )) && (pdu.app_tag == 13) or raise LdapError.new( "response missing or invalid" )
+      pdu.result_code
+    end
+
+
+    #--
+    # delete
+    # TODO, need to support a time limit, in case the server fails to respond.
+    #
+    def delete args
+      dn = args[:dn] or raise "Unable to delete empty DN"
+
+      request = dn.to_s.to_ber_application_string(10)
+      pkt = [next_msgid.to_ber, request].to_ber_sequence
+      @conn.write pkt
+
+      (be = @conn.read_ber(AsnSyntax)) && (pdu = LdapPdu.new( be )) && (pdu.app_tag == 11) or raise LdapError.new( "response missing or invalid" )
+      pdu.result_code
+    end
+
+
+  end # class Connection
+  end # class LDAP
+
+
+end # module Net
+
+