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dm-ldap-adapter

Homepage: http://github.com/mkristian/dm-ldap-adapter

Git: git://github.com/mkristian/dm-ldap-adapter.git

Author: Kristian Meier

Copyright: 2008-2009

Note on Patches/Pull Requests

  • Fork the project.

  • Make your feature addition or bug fix.

  • Add tests for it. This is important so I don't break it in a future version unintentionally.

  • Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

  • Send me a pull request.

DESCRIPTION:

usecase

the usecase for that implementation was using an ldap server for user authentication and authorization. the ldap server is configured to have posixAccounts and posixGroups. on the datamapper side these accounts/groups are modeled with many-to-many relationship. further more the model classes should be in such a way that they can be used with another repository as well, i.e. they carry some ldap related configuration but this is only relevant for the ldap-adapter.

low level ldap library

the ldap library which does the actual ldap protocol stuff is [http://rubyforge.org/projects/net-ldap] which is the default. the other ldap library is [http://rubyforge.org/projects/ruby-ldap]. just add a facade parameter when setting up DataMapper

DataMapper.setup(:ldap, {
               :adapter  => 'ldap',
               :facade => :ruby_ldap,
 .... })

or

DataMapper.setup(:ldap, {
               :adapter  => 'ldap',
               :facade => :net_ldap,
 .... })

setup DataMapper

DataMapper.setup(:ldap, {
               :adapter  => 'ldap',
               :host => 'localhost',
               :port => '389',
               :base => "dc=example,dc=com",
               :facade => :ruby_ldap,
               :bind_name => "cn=admin,dc=example,dc=com",
               :password => "behappy"
 })

examples

see 'example/posix.rb' for user/group setup works with default installation of openldap on ubuntu (just change your password as needed in the code)

FEATURES/PROBLEMS:

  • the net-ldap has some issues with not closing the connections when an exception/error got raised, with limit the search result to 126 entries which gets fixed by making consecutives searches and collect the result.

  • error from the ldap server are only logged and do not raise any exceptions (to be changed in next release) with one exception: when creating a new ldap entry a duplicated entry will raise DataMapper::PersistenceError

SYNOPSIS:

distinguished name (DN) of a model

there are three parts which makes the DN of a model, the base from the ldap conncetion, the treebase of the model and dn_prefix of an instance.

class User
  include DataMapper::Resource
  property :id, Serial, :field => "uidNumber"
  dn_prefix { |user| "uid=#{user.login}"}
  treebase "ou=people"
end

with a base dc=example,dc=com we get a DN like the user 'admin'

uid=admin,ou=people,dc=example,dc=com

ldap entities are bigger than the model

for example the ldap posixGroup has more attributes than the model class, it needs the objectclass attribute set to posixGroup.

class Group
  include DataMapper::Resource
  property :id, Serial, :field => "gidNumber"
  property :name,     String, :field => "cn"
  dn_prefix { |group| "cn=#{group.name}" }
  treebase "ou=groups"
  ldap_properties {{ :objectclass => "posixGroup"}}
end

so with the help of the ldap_properties you can define a block which returns an hash with extra attributes. with such block you can make some calculations if needed, i.e. :homedirectory => "/home/#{login}" for the posixAccount.

authentication

this uses the underlying bind of a ldap connection. so on any model where you have the dn_prefix and the treebase configured, you can call the method authenticate(password). this will forward the request to the ldap server.

queries

conditions in ldap depend on the attributes definition in the ldap schema. here is the list of what is working with that ldap adapter side and the usual AND between the conditions:

  • :eql
  • :not
  • :like
  • :in
  • Range

not working are :lt, :lte, :gt, :gte

note: sql handles NULL different from values, i.e.

 select * from users where name = 'sd';

and

 select * from users where name != 'sd';

gives the same result when all names are NULL !!!

OR conditions

or-conditions can be done with :conditions option but only of the form "<property_name> [or <property_name> ]*" where the comparator is one of "=", "like". it can be also combined with extra ANDs like this example

Contact.all(:name.like => "A%", :conditions => ["phone like '+49%' or mobile like '+49%'"])

multiple repositories

most probably you have to work with ldap as one repository and a database as a second repository. for me it worked best to define the default_repository for each model in the model itself:

class User
  . . .
  def self.default_repository_name
    :ldap
  end
end

class Config
  . . .
  def self.default_repository_name
    :db
  end
end

if you want to benefit from the advantages of the identidy maps you need to wrap your actions for merb see http://www.datamapper.org/doku.php?id=docs:identity_map or for rails put an around_filter inside application.rb

 around_filter :repositories

 def repositories
   DataMapper.repository(:ldap) do
     DataMapper.repository(:db) do
       yield
     end
   end
 end

and to let the ldap resources use the ldap respository it is best to bind it to that repository like this

class User . . . def self.repository_name :ldap end end

transactions

the adapter offers a noop transaction, i.e. you can wrap everything into a transaction but the ldap part has no functionality.

note: the ldap protocol does not know transactions

many-to-many associations

staying with posix example there the groups has a memberuid attribute BUT unlike with relational databases it can have multiple values. to achieve a relationship with these values the underlying adapter needs to know that this specific attribute needs to be handled differently. for this multivalue_field comes into play. the ldap adapter clones the model and places the each memberuid in its own clone.

class GroupUser
  include DataMapper::Resource
  property :memberUid, String, :key => true
  property :gidNumber, Integer, :key => true
  dn_prefix { |group_user| "cn=#{group_user.group.name}" }
  treebase "ou=groups"
  ldap_properties do |group_user|
    {:cn=>"#{group_user.group.name}",  :objectclass => "posixGroup"}
  end

  multivalue_field :memberuid

end

ldap attributes with many values

let's say your LDAP has multiple email values for a users then you can define your resource class like that using the type LdapArray for such multivalue fields

class User
  include DataMapper::Resource
  property :id,        Serial, :field => "uidNumber"
  property :login,     String, :field => "uid", :unique_index => true
  property :mail,      LdapArray

  dn_prefix { |user| "uid=#{user.login}"}
  treebase "ou=people"
  ldap_properties do |user|
    properties = { :objectclass => ["inetOrgPerson", "posixAccount", "shadowAccount"], :loginshell => "/bin/bash", :gidNumber => "10000" }
   properties
  end
end

REQUIREMENTS:

  • slf4r the logging facade
  • net-ldap pure ruby ldap library
  • ruby-ldap (optional) ruby with native ldap code
  • logging (optional) if logging via logging is desired
  • log4r (optional) if logging via log4r is desired

INSTALL:

  • sudo gem install dm-ldap-adapter

LICENSE:

(The MIT License)

Copyright (c) 2009 Kristian Meier

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.