ruby-net-ldap/lib/net/ldap.rb
2006-04-24 21:58:14 +00:00

678 lines
23 KiB
Ruby

# $Id$
#
# 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'
require 'net/ber'
require 'net/ldap/pdu'
require 'net/ldap/filter'
require 'net/ldap/dataset'
require 'net/ldap/psw'
module Net
# == Net::LDAP
#
# This library provides a pure-Ruby implementation of the
# LDAP client protocol, per RFC-1777.
# 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
# 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 |result|
# result.each do |dn, attrs|
# puts "DN: #{dn}"
# attrs.each do |attr, values|
# puts "***Attr: #{attr}"
# values.each do |value|
# puts " #{value}"
# end
# end
# end
# end
#
# p ldap.get_operation_result
#
#
# == Quick introduction to LDAP
#
# We're going to provide a quick and highly 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 control 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>cn,</tt> which stands for "Common Name."
# In many directories, this attribute is used to store a string consisting of
# a person's first and last names. Most directories enforce the convention that
# an entity's <tt>cn</tt> attribute have <i>exactly one</i> value. In LDAP
# jargon, that means that <tt>cn</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>cn</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: <i>bind, search, add, modify, delete, and rename.</i>
# ==== 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, the bind operation 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
# Searching 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
# An add operation 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.
#
# ==== Delete
# The delete operation 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
#
# This is how to access Net::LDAP functionality in your Ruby programs
# (note that at present, Net::LDAP is provided as a gem):
#
# 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, and that 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
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
}
},
:context_specific => {
:primitive => {
0 => :string, # password
1 => :string, # Kerberos v4
2 => :string, # Kerberos v5
}
}
}
DefaultHost = "127.0.0.1"
DefaultPort = 389
DefaultAuth = {:method => :anonymous}
ResultStrings = {
0 => "Success",
1 => "Operations Error",
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"
}
#
# LDAP::result2string
#
def LDAP::result2string code
ResultStrings[code] || "unknown result (#{code})"
end
#
# initialize
#
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
# 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
#
# open
#
def LDAP::open args
ldap = LDAP.new args
ldap.open {|ldap1| yield ldap1 }
end
# This method will return 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
# This method opens a network connection to the server and then
# passes self to the caller-supplied block. The connection is
# closed when the block completes. It's for executing multiple
# LDAP operations without requiring a separate network connection
# (and authentication) for each one.
#--
# 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 )
@open_connection.bind @auth
yield self
@open_connection.close
end
#
# search
#--
# If an open call is in progress (@open_connection will be non-nil),
# then ASSUME a bind has been performed and accepted, and just
# execute the search.
# If @open_connection is nil, then we have to connect, bind,
# search, and then disconnect. (The disconnect is not strictly
# necessary but it's friendlier to the network to do it here
# rather than waiting for Ruby's GC.)
# Note that in the standalone case, we're permitting the caller
# to modify the auth parms.
#
def search args
if @open_connection
@result = @open_connection.search( args ) {|values|
block_given? and yield( values )
}
else
@result = 0
conn = Connection.new( :host => @host, :port => @port )
if (@result = conn.bind( args[:auth] || @auth )) == 0
@result = conn.search( args ) {|values|
block_given? and yield( values )
}
end
conn.close
end
@result == 0
end
#
# bind
# Bind and unbind.
# Can serve as a connectivity test as well as an auth test.
#--
# 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
if @open_connection
@result = @open_connection.bind @auth
else
conn = Connection.new( :host => @host, :port => @port )
@result = conn.bind @auth
conn.close
end
@result == 0
end
#
# bind_as
# This is for testing authentication credentials.
# Most likely a "standard" name (like a CN or an email
# address) will be presented along with a password.
# We'll bind with the main credential given in the
# constructor, query the full DN of the user given
# to us as a parameter, then unbind and rebind as the
# new user.
#
def bind_as
end
#
# add
# Add a full RDN to the remote DIS.
#
def add args
if @open_connection
@result = @open_connection.add( args )
else
@result = 0
conn = Connection.new( :host => @host, :port => @port )
if (@result = conn.bind( args[:auth] || @auth )) == 0
@result = conn.add( args )
end
conn.close
end
@result == 0
end
#
# modify
# Modify the attributes of an entry on the remote DIS.
#
def modify args
if @open_connection
@result = @open_connection.modify( args )
else
@result = 0
conn = Connection.new( :host => @host, :port => @port )
if (@result = conn.bind( args[:auth] || @auth )) == 0
@result = conn.modify( args )
end
conn.close
end
@result == 0
end
#
# rename
# Rename an entry on the remote DIS by changing the last RDN of its DN.
#
def rename args
if @open_connection
@result = @open_connection.rename( args )
else
@result = 0
conn = Connection.new( :host => @host, :port => @port )
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
end # class LDAP
class LDAP
class Connection
LdapVersion = 3
#
# initialize
#
def initialize server
begin
@conn = TCPsocket.new( server[:host], server[:port] )
rescue
raise LdapError.new( "no connection to server" )
end
block_given? and yield self
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
# 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.
#
def search args
search_filter = (args && args[:filter]) || Filter.eq( "objectclass", "*" )
search_base = (args && args[:base]) || "dc=example,dc=com"
search_attributes = ((args && args[:attributes]) || []).map {|attr| attr.to_s.to_ber}
request = [
search_base.to_ber,
2.to_ber_enumerated,
0.to_ber_enumerated,
0.to_ber,
0.to_ber,
false.to_ber,
search_filter.to_ber,
search_attributes.to_ber_sequence
].to_ber_appsequence(3)
pkt = [next_msgid.to_ber, request].to_ber_sequence
@conn.write pkt
search_results = {}
result_code = 0
while (be = @conn.read_ber(AsnSyntax)) && (pdu = LdapPdu.new( be ))
case pdu.app_tag
when 4 # search-data
search_results [pdu.search_dn] = pdu.search_attributes
when 5 # search-result
result_code = pdu.result_code
block_given? and yield( search_results )
break
else
raise LdapError.new( "invalid response-type in search: #{pdu.app_tag}" )
end
end
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
end # class Connection
end # class LDAP
end # module Net
#------------------------------------------------------
if __FILE__ == $0
puts "No default action"
end