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.
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
).
import 'dart:async';
import 'package:dartdap/dartdap.dart';
Future example() async {
// Create an LDAP connection object
var host = "localhost";
var ssl = false; // true = use LDAPS (i.e. LDAP over SSL/TLS)
var port = null; // null = use standard LDAP/LDAPS port
var bindDN = "cn=Manager,dc=example,dc=com"; // null=unauthenticated
var password = "p@ssw0rd";
var connection = new LdapConnection(host: host);
connection.setProtocol(ssl, port);
connection.setAuthentication(bindDN, password);
try {
// Perform search operation
var base = "dc=example,dc=com";
var filter = Filter.present("objectClass");
var attrs = ["dc", "objectClass"];
var count = 0;
var searchResult = await connection.search(base, filter, attrs);
await for (var entry in searchResult.stream) {
// Processing stream of SearchEntry
count++;
print("dn: ${entry.dn}");
// Getting all attributes returned
for (var attr in entry.attributes.values) {
for (var value in attr.values) { // attr.values is a Set
print(" ${attr.name}: $value");
}
}
// Getting a particular attribute
assert(entry.attributes["dc"].values.length == 1);
var dc = entry.attributes["dc"].values.first;
print("# dc=$dc");
}
print("# Number of entries: ${count}");
} catch (e) {
print("Exception: $e");
} finally {
// Close the connection when finished with it
await connection.close();
}
}
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.
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.
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.
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
}
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
}
try {
await ldap.modifyDN(oldDN, newDN);
} on LdapException catch (e) {
// some other problem
}
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
}
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
}
The LdapConnection
can operate in automatic or manual modes. The
mode can be set when it is created, or by using the setAutomaticMode
method.
In automatic mode (the default), it is not necessary to explicitly connect or send LDAP BIND requests.
In automatic mode, the connection to the LDAP directory will be established whenever it is needed. This will occur when the first LDAP operation is performed. If it becomes disconnected (e.g. LDAP server timeout), it will also re-establish the connection when the next LDAP operation is performed.
In automatic mode, LDAP BIND requests will be made when necessary. For
example, if a bindDN and password has been set (via the constructor,
or the setAuthentication
and setAnonymous
methods), an LDAP BIND
request will be sent when the first LDAP operation is performed:
obviously, after the connection has been established and before the
operation's request.
There are open
and bind
methods to explicitly cause the connection
to be made and LDAP BIND request to be sent. But since these are
performed automatically, using them is optional in automatic
mode. However, an application might want to explicitly use them to
check the connection/authentication parameters; rather than have the
errors detected later when an LDAP operation is performed.
In manual mode, opening the connection and sending LDAP BIND requests must be explicitly performed by the application. Exceptions will be raised if the application fails to do this (e.g. attempting to perform a search with a closed connection). In manual mode, if a disconnection occurs subsequent LDAP operations will fail unless the application re-opens the connection.
It is expected that most applications will use automatic mode.
The state
property indicates what state the connection is in.
See the documentation of LdapConnection
for more details.
Methods in the package throws exceptions which are subclasses
of the LdapException
abstract class.
See the documentaiton of LdapException
for more details.
This package uses the Dart logging package for logging.
The logging is mainly useful for debugging the package.
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
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;
-
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.
-
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.