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DART LDAP Client
An LDAP v3 Client Library for Dart
The Lightweight Directory Access Protocol (LDAP) is a protocol for accessing directories.
An LDAP directory is organised as a hierarchy of entries, where one or more root entries are allowed. Each entry can be identified by a distinguished name, which is an ordered sequence of attribute/value pairs. Each entry contains a set of attributes. Attributes have a name and are associated with a set of one or more values (i.e. attributes can be repeated and are unordered).
This library can be used to query (search for and compare entries) and modify (add, delete and modify) LDAP directories.
This library supports the LDAP v3 protocol, which is defined in IETF RFC 4511.
Breaking changes from previous versions are described at the bottom of this page.
Using dartdap
Examples
To perform operations on an LDAP directory, the basic process is:
- Create an LDAP connection (
LdapConnection
). - Perform LDAP operations (
search
,add
,modify
,modifyDN
,compare
,delete
). - Close the connection (
close
).
The following examples are provided:
- main.dart - A basic sample using the LdapConnection() class
- pool.dart - Connection pool example
- paged_search.dart - demonstrates how to use the paged search control
Note: As of version 0.5.0, An experimental connection pool is also provided. Please read pool.md.
Create an LDAP connection
The first step is to instantiate an LdapConnection
object using its
constructor.
These properties of the connection can be changed from their defaults:
- hostname (defaults to "localhost");
- ssl: false is plain LDAP, true is LDAPS (LDAP over SSL/TLS) (defaults to false);
- port: port number (defaults to standard port for LDAP/LDAPS: 389 or 636);
- bindDN: distinguished name for binding, null means unauthenticated (default is null);
- password: password for binding.
These properties can be set using named parameters to the constructor,
or with the setProtocol
and setAuthentication
methods.
Perform LDAP operations
This example performs a search operation.
The search
method returns a Future to a SearchResult
object, from
which a stream of SearchEntry
objects can be obtained. The results
are obtained by listening to the stream (which in the example is done
using the "await for" syntax).
The SearchEntry
contains the entry's distinguished name and the
attributes returned.
The dn
is a String. The attributes
is a Map
from the name of
the attribute (a String) to an Attribute
.
An Attribute
has a values
member, which returns a Set
of the
values of the attribute. It is a Set because LDAP allows attributes to
have multiple values. It also has a name
member, which is the name
of the attribute as a String.
Close the connection
When finished with the connection, call the close
method.
In the above example, the close is performed in the finally section, to ensure it gets closed even if an exception is thrown.
The close method returns a Future, which completes when the connection is completely closed.
Searching
A search request returns a stream of SearchResults.
There is EXPERIMENTAL support for search result references (referrals)
If SearchResult.referrals[] is not empty, it is an array of strings which are the DNs to repeat the search request. The SDK does not automatically follow referrals.
There are two search methods:
-
ldap.search
takes a dartFilter
object. -
ldap.query
takes an https://tools.ietf.org/html/rfc2254 string to construct the filter
Adding entries
try {
var attrs = {
"objectClass": ["organizationalUnit"],
"description": "Example organizationalUnit entry"
};
await ldap.add("ou=Engineering,dc=example,dc=com", attrs);
} on LdapResultEntryAlreadyExistsException catch (_) {
// cannot add entry because it already exists
} on LdapException catch (e) {
// some other problem
}
Modifying entries
try {
var mod1 = new Modification.replace("description", ["Engineering department"]);
await ldap.modify("ou=Engineering,dc=example,dc=com", [mod1]);
} on LdapResultObjectClassViolationException catch (_) {
// cannot modify entry because it would violate the schema rules
} on LdapException catch (e) {
// some other problem
}
Moving entries
try {
await ldap.modifyDN(oldDN, newDN);
} on LdapException catch (e) {
// some other problem
}
Comparing entries
try {
r = await ldap.compare("ou=Engineering,dc=example,dc=com",
"description", "Engineering Dept");
if (r.resultCode == ResultCode.COMPARE_FALSE) {
} else if (r.resultCode == ResultCode.COMPARE_TRUE) {
} else {
assert(false);
}
} on LdapException catch (e) {
// some other problem
}
Deleting entries
try {
await ldap.delete("ou=Business Development,dc=example,dc=com");
} on LdapResultNoSuchObjectException catch (_) {
// entry did not exist to delete
} on LdapException catch (e) {
// some other problem
}
Connecting and authenticating
The LdapConnection
provides a basic connection to the LdapServer. The caller is
responsible for performing any Bind() operations, handling any disconnects, or
retrying on failure.
As of 0.5.0, a protoype LdapConnectionPool() is provided that handles some of the these tasks. The pool implements the Ldap() interface, and will attempt to bind() with the provided credentials, and will retry a connection if the server is not available.
The Connection pool is still experimental, and provides only basic functionality.
See the documentation of LdapConnection
and LdapConnectionPool
for more details.
Exceptions
Methods in the package throws exceptions which are subclasses
of the LdapException
abstract class.
See the documentaiton of LdapException
for more details.
Logging
This package uses the Dart logging package for logging.
The logging is mainly useful for debugging the package.
Loggers
The following loggers are used:
Logger: ldap.control
- finest = parsing of controls
Logger: ldap.session
- warnings = certificate issues
- fine = connections successfully established, and closing them
- finer = details about attempts to establish a connection
Logger: ldap.send.ldap
for the LDAP messages sent.
- fine = LDAP messages sent.
- finest = details of LDAP message construction
Logger: ldap.send.bytes
for the raw bytes sent to the socket.
Probably only useful when debugging the dartdap package.
- severe = errors/exceptions when sending
- fine = number of raw bytes sent
Logger: ldap.recv.ldap
for the LDAP messages receive
(i.e. received ASN.1 objects processed as LDAP messages).
- fine = LDAP messages received.
- finer = LDAP messages processing.
Logger: ldap.recv.asn1
for the ASN.1 objects received (i.e. parsed
from the raw bytes received). Probably only useful when debugging the
dartdap package.
- fine = ASN.1 messages successfully parsed from the raw bytes
- finest = shows the actual bytes making up the value of the ASN.1 message
Logger: ldap.recv.bytes
for the raw bytes received from the
socket. Probably only useful when debugging the dartdap package.
- fine = number of raw bytes read
- finer = parsing activity of converting the bytes into ASN.1 objects
- finest = shows the actual bytes received and the number in the buffer to parse
Logging Examples
To take advantage of the hierarchy of loggers, enable
hierarchicalLoggingEnabled
and set the logging level on individual
loggers. If the logging level is not explicitly set on a logger,
it is inherited from its parent. The root logger is the ultimate
parent; and its logging level is initally Level.INFO.
For example, to view high level connection and LDAP messages send/received:
import 'package:logging/logging.dart';
...
Logger.root.onRecord.listen((LogRecord rec) {
print('${rec.time}: ${rec.loggerName}: ${rec.level.name}: ${rec.message}');
});
hierarchicalLoggingEnabled = true;
new Logger("ldap.session").level = Level.FINE;
new Logger("ldap.send.ldap").level = Level.FINE;
new Logger("ldap.recv.ldap").level = Level.FINE;
To debug messages received:
new Logger("ldap.recv.ldap").level = Level.ALL;
new Logger("ldap.recv.asn1").level = Level.FINER;
new Logger("ldap.recv.bytes").level = Level.FINE;
Note: in the above examples: SHOUT, SEVERE, WARNING and INFO will still be logged (except for those loggers and their children where the level has been set to Level.OFF). To disable those log messages change the root logger from its default of Level.INFO to Level.OFF.
For example, to suppress all log messages (including suppressing SHOUT, SEVERE, WARNING and INFO):
Logger.root.level = Level.OFF;
Or leave the root level at the default and only disable logging from the package:
new Logger("ldap").level = Level.OFF;
Breaking changes
0.6.2
LdapConnectionPool has been refactored.
0.6.0
- The library user is now responsible for waiting for all LDAP operations to complete before calling connection.close()
0.5.0
There are many breaking changes in 0.5.0. The most signifcant are:
- dartdap is now null safe.
- The
LdapConnection
class no longer handles automatic retry or error handling. A newLdapConnectionPool
has been introduced that will host this functionality.
See the CHANGELOG.md
Version 0.4.0
-
LdapConnection.search
new signature issearch(attributeName,searchExpression)
- A new
LdapConnection.query(attr,searchQuery)
supports rfc2254 query filters.
Version 0.1.x to 0.2.x
-
LdapConnection
changed to support automatic connection/reconnections (and authentication when needed). This allows connections to be safely reused (i.e. kept open for later operations without having to re-open the connection). Previously, there was no guarantee a previously working connection would still be working when an LDAP operation was performed later: it could have been disconnected by intermittent network errors or LDAP server timeouts. Previously, the only safe way to use a connection was to open one for each LDAP operation (which is very inefficient) or to always expect LDAP operations could fail and to open a new connection if it fails (verbose and inelegant code). -
The
search
method returns a Future to aSearchResult
. Previously, it returned the SearchResult synchronously. This change was necessary because (with the introduction of automatic connections) a search could cause the connection to be opened, and bind request to be sent, before the search request is actually sent. -
Renaming of other classes and methods to consistently follow the Dart naming conventions. For example,
LDAPConnection
becomesLdapConnection
,LDAPResult
becomesLdapResult
,LDAPUtil
becomesLdapUtil
. -
Exception raised if a bad certificate is encountered when opening a SSL/TLS connection. Provide a bad certificate handler function, if the application wants to override the default behaviour. Other than for testing, accepting bad certificates is a security risk: so, the default behaviour is the safer option.
-
Internal classes hidden from public interface (e.g.
ConnectionManager
,LDAPUtil
). -
LDAPConfiguration
removed.
Version 0.0.x to 0.1.x
-
Library is now called "dartdap" instead of "ldap_client". There was a disconnect in the naming: package X was imported, but only library Y was imported. That would have been ok if it had multiple libraries, but it currently only contains one publicly visible library. Also, many of the classes could apply an LDAP server too.
-
LDAPException
renamed toLdapException
to follow the Dart naming conventions. -
New exception classed defined for all the LDAP result error conditions. All LDAP operations now throws these new exceptions. Instead of checking the resultCode in the LDAPResult returned by the LDAP operations, catch the new exceptions.
-
SocketException
exceptions are now being internally caught and thrown asLdapSocketException
objects. This make it easier to detect common failure conditions. Instead of catchingSocketException
, catch the newLdapSocketException
or one of its subclasses. -
LDAPConfiguration
is deprecated. Programs should use whatever configuration mechanism they normally use (e.g. databases or configuration files) rather than having to use a special configuration mechanism only for dartdap (and still having to use the other configuration mechanism for the rest of the program). It is also unsafe due to a race condition that could occur if multiple connections are being established. -
Internal organisation of libraries/imports/exports have been cleaned up. This should not be noticable by existing code, unless it was directly referencing those internal libraries or files.
References
https://tools.ietf.org/html/rfc4511