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LuaLDAP - A Lua interface to an LDAP library

Overview

LuaLDAP is a simple interface from Lua to OpenLDAP. It enables a Lua program to:

  • Connect to an LDAP server;
  • Execute any operation (search, add, compare, delete, modify and rename);
  • Retrieve entries and references of the search result.

LuaLDAP is free software and uses the same license as Lua 5.1.

Contributing

Please send any patches or requests to Jason@zx2c4.com.

Credits

LuaLDAP was originally designed by Roberto Ierusalimschy, Andre Carregal and Tomas Guisasola as part of the Kepler Project. It was implemented by Tomas Guisasola and Leonardo Godinho with contributions by Mark Edgar. LuaLDAP development was sponsored by Fabrica Digital and FINEP.

It was abandoned in 2007, and revived in 2015 by Jason Donenfeld.

Manual

Introduction

LuaLDAP defines one single global variable: a table called lualdap. This table holds the functions used to create an LDAP connection object.

A connection object offers methods to perform any operation on the directory such as comparing values, adding new entries, modifying attributes on existing entries, removing entries, and the most common of all: searching. Entries are represented as Lua tables; attributes are its fields. The attribute values can be strings or tables of strings (used to represent multiple values).

Representing attributes

Many LDAP operations manage sets of attributes and values. LuaLDAP provides a uniform way of representing them by using Lua tables. The table attributes can be Lua string, a binary string (a string of bits), or table of n values indexed from 1 to n. Some operations have different approaches that will be explained as necessary.

Here is a simple example:

entry = {
 an_attribute = "a value",
 other_attribute = {
  "first value of other attribute",
  "another value of other attribute",
 },
}

Attribute names cannot contain the '\0' character.

Distinguished names

The distinguished name (DN) is the term used to identify an entry on the directory information tree. It is formed by the relative distinguished name (RDN) of the entry and the distinguished name of its parent. LuaLDAP will always use a string to represent the DN of any entry.

Initialization functions

LuaLDAP provides a single way to connect to an LDAP server:

lualdap.open_simple (connection_info_table)

Initializes a session with an LDAP server, and binds to it. The connection_info_table contains the following entries:

uri

An ldap:// or ldaps:// or similar URI for the requested server.

who

The DN of the user logging in.

password

A password to use in SASL.

starttls

A boolean of whether or not STARTTLS is to be used.

certfile

A path to a client certificate.

keyfile

A path to a client certificate key.

cacertfile

A path to a CA certificate chain.

cacertdir

A path to a CA certificate directory.

Connection objects

A connection object offers methods which implement LDAP operations. Almost all of them need a distinguished name to identify the entry on which the operation will be executed.

These methods execute asynchronous operations and return a function that should be called to obtain the results. The called functions will return true indicating the success of the operation. The only exception is the compare function which can return either true or false (as the result of the comparison) on a successful operation.

There are two types of errors: API errors, such as wrong parameters, absent connection etc.; and LDAP errors, such as malformed DN, unknown attribute etc. API errors will raise a Lua error, while LDAP errors will be reported by the function/method returning nil plus the error message provided by the OpenLDAP client.

A connection object can be created by calling the Initialization function.

Methods

conn:add (distinguished_name, table_of_attributes)

Adds a new entry to the directory with the given attributes and values.

conn:close()

Closes the connection conn.

conn:compare (distinguished_name, attribute, value)

Compares a value to an entry.

conn:delete (distinguished_name)

Deletes an entry from the directory.

conn:modify (distinguished_name, table_of_operations*)

Changes the values of attributes in the given entry. The tables of operations are tables of attributes with the value on index 1 indicating the operation to be performed. The valid operations are:

  • '+' to add the values to the attributes
  • '-' to delete the values of the attributes
  • '=' to replace the values of the attributes

Any number of tables of operations will be used in a single LDAP modify operation.

conn:rename (distinguished_name, new_relative_dn, new_parent)

Changes an entry name (i.e. change its distinguished name).

conn:search (table_of_search_parameters)

Performs a search operation on the directory. The search method will return a search iterator which is a function that requires no arguments. The search iterator is used to get the search result and will return a string representing the distinguished name and a table of attributes as returned by the search request.

The parameters are described below:

attrs

a string or a list of attribute names to be retrieved (default is to retrieve all attributes).

attrsonly

a Boolean value that must be either false (default) if both attribute names and values are to be retrieved, or true if only names are wanted.

base

The distinguished name of the entry at which to start the search.

filter

A string representing the search filter as described in The String Representation of LDAP Search Filters (RFC 2254).

scope

A string indicating the scope of the search. The valid strings are: "base", "onelevel" and "subtree". The empty string ("") and nil will be treated as the default scope.

sizelimit

The maximum number of entries to return (default is no limit).

timeout

The timeout in seconds (default is no timeout). The precision is microseconds.

Example

Here is a some sample code that demonstrate the basic use of the library:

require "lualdap"

ld = assert (lualdap.open_simple { uri = "ldap://ldap.server",
 who = "mydn=manoeljoaquim,ou=people,dc=ldap,dc=world",
 password = "mysecurepassword" })

for dn, attribs in ld:search { base = "ou=people,dc=ldap,dc=world" } do
 io.write (string.format ("\t[%s]\n", dn))
 for name, values in pairs (attribs) do
  io.write ("["..name.."] : ")
  if type (values) == "string" then
   io.write (values)
  elseif type (values) == "table" then
   local n = table.getn(values)
   for i = 1, (n-1) do
    io.write (values[i]..",")
   end
   io.write (values[n])
  end
  io.write ("\n")
 end
end

ld:add ("mydn=newuser,ou=people,dc=ldap,dc=world", {
 objectClass = { "", "", },
 mydn = "newuser",
 abc = "qwerty",
 tel = { "123456758", "98765432", },
 givenName = "New User",
})()

ld:modify {"mydn=newuser,ou=people,dc=ldp,dc=world",
 { '=', givenName = "New", cn = "New", sn = "User", },
 { '+', o = { "University", "College", },
  mail = "newuser@university.edu", },
 { '-', abc = true, tel = "123456758", },
 { '+', tel = "13579113", },
}()

ld:delete ("mydn=newuser,ou=people,dc=ldp,dc=world")()

License

Copyright (c) 2003-2007 The Kepler Project.
Copyright (c) 2015 Jason A. Donenfeld <Jason@zx2c4.com>.

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.