Re: [Twisted-Python] advice on asynchronous LDAP?

14 Nov 2006

      Shimon Rura wrote:
...
Hi folks,
Hello
...
I'm a newbie writing a twisted server that needs to access an LDAP
server.  I started by using python-ldap, which worked fine and is well
documented, but doesn't seem to have support for a callback mechanism
that would make it appropriate for a twisted app.  So I switched to
ldaptor, which fits the twisted model, but doesn't seem to have much
documentation.
I tried to use it but it worked only with twisted 1.3
...
I'm looking for advice from people who have some familiarity with
writing twisted apps that include an LDAP client.  Ideally, I'd like
to find either:
(1) a way to use the standard python-ldap library in a multitasking
twisted server (i.e. without busy wait; polling at timed intervals is
a possibility but also seems bad), or
The way I found was to use python ldap and deferToThread.
This is not really  in the "asynchronous spirit of twisted " but it works.

Here an example I used to make a small sendmail X map lookup:

from twisted.application import internet, service
from twisted.internet import protocol,reactor, defer, threads
from twisted.internet.protocol import Protocol
from twisted.protocols import basic
import ldap

class MapProtocol(Protocol):

    def dataReceived(self, Mel):
        d = threads.deferToThread(self.factory._lire_annuaire_ldap,Mel)
        d.addCallback(self._cb)
        d.addErrback(self._eb)

    def _cb(self, result):
        self.transport.write(result)

    def _eb(self, error):
        print error
        self.transport.loseConnection()

class MapFactory(protocol.ServerFactory):
    protocol = MapProtocol

    def __init__(self, servers,who, cred, mydomains, dictstatus):

        # directory
        self.ldapservers  = ldapservers
        self.who = who
        self.cred = cred
        self.mydomains = mydomains
        self.NOTFOUND = dictstatus['NOTFOUND']
        self.TEMP = dictstatus['PERM']

    def _lire_annuaire_ldap(self,mel):
        """ lookup directory server retourne RHS """

        def _bind2ldap(servers,who="",cred=""):
            """ Trouve une serveur ldap dispo dans la liste qui lui est passé """
            status = False
            for server in servers:
                   urildap = "ldap://" + server
                   l = ldap.initialize(urildap)
                   l.protocol_version=ldap.VERSION3
                   try:
                       resultbind = l.simple_bind_s(who,cred)
                       status = True
                       break
                   except ldap.LDAPError,e :
                       continue
            return(status,l)

        uid = ''
        mailhost = ''
        aretourner = self.NOTFOUND

        statusldap = False # directory server est disponible ?

        # Nom de la map
        # si on en a plusieurs dans le futur

        nommap = mel.split()[0].split(':')[1]

        # map LHS
        mel = mel.split()[1][:-1]

        # our domain or not ?

        try:
                mydomain = mel.split('@')[1]
        except IndexError,e:
                mydomain = 'mydomain'

        if mydomain in self.mydomains:
            statusldap, maconn =  _bind2ldap(self.ldapservers,self.who,self.cred)

            if statusldap:
                marequete = '(|(mail=' + mel + ')(mailalternateaddress=' + mel +')(mailequivalentaddress=' + mel
 + '))'

                result_data = maconn.search_s("dc=...", ldap.SCOPE_SUBTREE, marequete , ['uid', 'mailhost']
)

                if len(result_data) > 0:
                    try:
                       uid  = ''.join(result_data[0][1]['uid'])
                    except KeyError:
                       print 'error clef:%s' % mel
                       uid = mel.split("@")[0]
                    mailhost  = ''.join(result_data[0][1]['mailhost'])
                    status = 'OK '
                    reponse = status + '<' + uid + '@' + mailhost + '>'
                    aretourner = str(len(reponse)) + ":" + reponse + ','
                else:
                   aretourner = self.NOTFOUND
            else:
                aretourner = self.PERM
        else:
            aretourner = self.NOTFOUND

        return (aretourner)

# Status de lookup "fixe"
dictstatus = {'NOTFOUND' : '8:NOTFOUND,', 'PERM' : '4:PERM,'}

# servers/user/pass necessaire au bind
# 

server = ["ldap1","ldap2"]
binddn = ""
passwd = ""
mydomains = ["mydomain"]

application = service.Application('mapsmx', uid=663, gid=663)
factory = MapFactory(server,binddn,passwd,mydomains,dictstatus)
internet.TCPServer(8090, factory).setServiceParent(
    service.IServiceCollection(application))

HTH
jmp

Re: [Twisted-Python] advice on asynchronous LDAP?

jean-marc pouchoulon