LDAP

v1.2.1

Published

2 years ago

LDAP Binding for node.js

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jeremycx

node-LDAP 1.2.0

OpenLDAP client bindings for Node.js. Requires libraries from http://www.openldap.org installed.

This latest version implements proper reconnects to a lost LDAP server.

Of note in this release is access to LDAP Syncrepl. With this API, you can subscribe to changes to the LDAP database, and be notified (and fire a callback) when anything is changed in LDAP. Use Syncrepl to completely mirror an LDAP database, or use it to implement triggers that perform an action when LDAP is modified.

The API is finally stable, and (somewhat) sane.

Contributing

Any and all patches and pull requests are certainly welcome.

Thanks to:

Petr Běhan
YANG Xudong
Victor Powell

Dependencies

Node >= 0.8

Install

You must ensure you have the latest OpenLDAP client libraries installed from http://www.openldap.org

To install the latest release from npm:

npm install LDAP

If this fails, please ensure you have uuid.h available (on Ubuntu, install the uuid-dev package).

You will also require the LDAP Development Libraries (on Ubuntu, sudo apt-get install libldap2-dev)

API

new LDAP(options);

Options are provided as a JS object:

var options = {
    uri: 'ldap://my.ldap.server', // string
    version: 3, // integer, default is 3,
    starttls: false, // boolean, default is false
    connecttimeout: -1, // seconds, default is -1 (infinite timeout), connect timeout
    timeout: 5000, // milliseconds, default is 5000 (infinite timeout is unsupported), operation timeout
    reconnect: true // boolean, default is true,
    backoffmax: 32 // seconds, default is 32, reconnect timeout
};

ldap.open()

ldap.open(function(err));

Now that you have an instance, you can open a connection. This will automatically reconnect until you close():

ldap.open(function(err) {
    if (err) {
       throw new Error('Can not connect');
    }
    // connection is ready.

});

You can disable the automatic reconnect by setting the reconnect option to false.

ldap.simplebind()

Calling open automatically does an anonymous bind to check to make sure the connection is actually open. If you call simplebind(), you will upgrade the existing anonymous bind.

ldap.simplebind(bind_options, function(err));

Options are binddn and password:

bind_options = {
    binddn: '',
    password: ''
}

ldap.search()

ldap.search(search_options, function(err, data));

Options are provided as a JS object:

search_options = {
    base: '',
    scope: '',
    filter: '',
    attrs: '' // default is '*'
}

Scopes are specified as one of the following integers:

Connection.BASE = 0;
Connection.ONELEVEL = 1;
Connection.SUBTREE = 2;
Connection.SUBORDINATE = 3;
Connection.DEFAULT = -1;

List of attributes you want is passed as simple string - join their names with space if you need more ('objectGUID sAMAccountName cname' is example of valid attrs filter). '*' is also accepted.

Results are returned as an array of zero or more objects. Each object has attributes named after the LDAP attributes in the found record(s). Each attribute contains an array of values for that attribute (even if the attribute is single-valued - having to check typeof() before you can act on /anything/ is a pet peeve of mine). The exception to this rule is the 'dn' attribute - this is always a single-valued string.

Example of search result:

[ { gidNumber: [ '2000' ],
  objectClass: [ 'posixAccount', 'top', 'account' ],
  uidNumber: [ '3214' ],
  uid: [ 'fred' ],
  homeDirectory: [ '/home/fred' ],
  cn: [ 'fred' ],
  dn: 'cn=fred,dc=ssimicro,dc=com' } ]

Attributes themselves are usually returned as strings. There is a list of known binary attribute names hardcoded in C++ binding sources. Those are always returned as Buffers, but the list is incomplete so far. You can take advantage of RFC4522 and specify attribute names in the form '<name>;binary' - such attributes are returned as Buffers too. There is currently no known way to do this for '*' wildcard - patches are welcome (see discussion in issue #44 and pull #58 for some ideas).

LDAP servers are usually limited in how many items they are willing to return - 1024 or 4096 are some typical values. For larger LDAP directories, you need to either partition your results with filter, or use paged search. To get a paged search, add the following attributes to your search request:

search_options = {
    base: '',
    scope: '',
    filter: '',
    attrs: '',
    pagesize: n
}

The callback will be called with a new parameter: cookie. Pass this cookie back in subsequent searches to get the next page of results:

search_options = {
    base: '',
    scope: '',
    filter: '',
    attrs: '',
    pagesize: n,
    cookie: cookie
}

As of version 1.2.0 you can also read the rootDSE entry of an ldap server. To do so, simply issue a read request with base set to an empty string:

search_options = {
  base: '',
  scope: Connection.BASE,  // 0
  // ... other options as necessary
}

ldap.findandbind()

A convenience function that is in here only to encourage developers to do LDAP authentication "the right way" if possible.

ldap.findandbind(fb_options, function(err, data))

Options are exactly like the search options, with the addition of a "password" attribute:

fb_options = {
    base: '',
    filter: '',
    scope: '',
    attrs: '',
    password: ''
}

Calls the callback with the record it authenticated against.

Note: since findandbind leaves the connection in an authenticated state, you probably don't want to do a findandbind with a general purpose instance of this library, as you would be sending one user's queries on the authenticated connection of the last user to log in. Depending on your configuration, this may not even be an issue, but you should be aware.

Did someone say that asyncronous programming wasn't perilous?

There are three obvious solutions to this problem:

Use two instances of this library (and thus two TCP connections) - one for authenication binds, and the other for general purpose use (which may be pre-bound as admin or some other suitably priveleged user). You are then completely in charge of authorization (can this user edit that user?).
Create a new instance for each authenticated user, and reconnect that user to their own instance with each page load. The advantage of this strategy is you can then rely on LDAP's authorization systems (slapd then decides what each user can and can't do).
Create, bind, and close a connection for each user's initial visit, and use cookies and session trickery for subsequent visits.

ldap.add()

ldap.add(dn, [attrs], function(err))

dn is the full DN of the record you want to add, attrs to be provided as follows:

var attrs = [
    { attr: 'objectClass',  vals: [ 'organizationalPerson', 'person', 'top' ] },
    { attr: 'sn',           vals: [ 'Smith' ] },
    { attr: 'badattr',      vals: [ 'Fried' ] }
]

ldap.modify()

ldap.modify(dn, [ changes ], function(err))

Modifies the provided dn as per the changes array provided. Ops are one of "add", "delete" or "replace".

var changes = [
    { op: 'add',
      attr: 'title',
      vals: [ 'King of Callbacks' ]
    }
]

ldap.rename()

ldap.rename(dn, newrdn, function(err))

Will rename the entry to the new RDN provided.

Example:

ldap.rename('cn=name,dc=example,dc=com', 'cn=newname')

ldap.remove()

ldap.remove(dn, function(err))

Deletes an entry.

Example:

ldap.remove('cn=name,dc=example,dc=com', function(err) {
  if (err) {
    // Could not delete entry
  }
});

Schema

To instantiate:

var LDAP = require('LDAP');
var schema = new LDAP.Schema({
    init_attr: function(attr),
    init_obj: function(obj),
    ready: function()
})

init_attr is called as each attribute is added so you can augment the attributes as they are loaded (add friendly labels, for instance). Similarly, init_obj is called as each objectClass is loaded so you can add your own properties to objectClasses.

ready is called when the schema has been completely loaded from the server.

Once the schema are loaded, you can get an objectClass like this:

schema.getObjectClass('person')

Get a specific attribute:

schema.getAttribute('cn');

Given a LDAP search, result, get all the possible attributes associated with it:

schema.getAttributesForRec(searchres);

SYNCREPL API

If you are connecting to an LDAP server with syncrepl overlay enabled, you can be notified of updates to the LDAP tree. Begin by connecting, then issue the ldap.sync() command:

ldap.sync(options)

The options are as follows:

{
    base: '',
    scope: ldap.SUBTREE,
    filter: '(objectClass=*)',
    attrs: '* +',
    rid: '000',
    cookie: '',
    syncentry: function(data),
    syncintermediate: function(data),
    syncresult: function(data)
}

The cookie attribute is used to send a cookie to the server to ensure sync continues where you last left off.

The rid attribute is required, and should be set to a unique value for the server you are syncing to.

The function callbacks are called upon initial refresh, and as new data is available.

syncentry(data)

When this callback fires, you should call ldap.getcookie() to record the current cookie and save it somewhere. You can provide this cookie to the ldap.sync() call when your process restarts.

syncintermediate()

TBD.

syncresult(data)