# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""cubicweb utilities for ldap sources

Part of the code is coming form Zope's LDAPUserFolder

Copyright (c) 2004 Jens Vagelpohl.

All Rights Reserved.

This software is subject to the provisions of the Zope Public License,

Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.

THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED

WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS

FOR A PARTICULAR PURPOSE.

"""

from __future__ import division # XXX why?

import ldap

from ldap.ldapobject import ReconnectLDAPObject

from ldap.filter import filter_format

from ldapurl import LDAPUrl

from cubicweb import ValidationError, AuthenticationError, Binary

from cubicweb.server import utils

from cubicweb.server.sources import ConnectionWrapper

_ = unicode

# search scopes

BASE = ldap.SCOPE_BASE

ONELEVEL = ldap.SCOPE_ONELEVEL

SUBTREE = ldap.SCOPE_SUBTREE

# map ldap protocol to their standard port

PROTO_PORT = {'ldap': 389,

              'ldaps': 636,

              'ldapi': None,

              }

class LDAPSourceMixIn(object):

    """a mix-in for LDAP based source"""

    options = (

        ('auth-mode',

         {'type' : 'choice',

          'default': 'simple',

          'choices': ('simple', 'cram_md5', 'digest_md5', 'gssapi'),

          'help': 'authentication mode used to authenticate user to the ldap.',

          'group': 'ldap-source', 'level': 3,

          }),

        ('auth-realm',

         {'type' : 'string',

          'default': None,

          'help': 'realm to use when using gssapi/kerberos authentication.',

          'group': 'ldap-source', 'level': 3,

          }),

        ('data-cnx-dn',

         {'type' : 'string',

          'default': '',

          'help': 'user dn to use to open data connection to the ldap (eg used \

to respond to rql queries). Leave empty for anonymous bind',

          'group': 'ldap-source', 'level': 1,

          }),

        ('data-cnx-password',

         {'type' : 'string',

          'default': '',

          'help': 'password to use to open data connection to the ldap (eg used to respond to rql queries). Leave empty for anonymous bind.',

          'group': 'ldap-source', 'level': 1,

          }),

        ('user-base-dn',

         {'type' : 'string',

          'default': 'ou=People,dc=logilab,dc=fr',

          'help': 'base DN to lookup for users',

          'group': 'ldap-source', 'level': 1,

          }),

        ('user-scope',

         {'type' : 'choice',

          'default': 'ONELEVEL',

          'choices': ('BASE', 'ONELEVEL', 'SUBTREE'),

          'help': 'user search scope (valid values: "BASE", "ONELEVEL", "SUBTREE")',

          'group': 'ldap-source', 'level': 1,

          }),

        ('user-classes',

         {'type' : 'csv',

          'default': ('top', 'posixAccount'),

          'help': 'classes of user (with Active Directory, you want to say "user" here)',

          'group': 'ldap-source', 'level': 1,

          }),

        ('user-filter',

         {'type': 'string',

          'default': '',

          'help': 'additional filters to be set in the ldap query to find valid users',

          'group': 'ldap-source', 'level': 2,

          }),

        ('user-login-attr',

         {'type' : 'string',

          'default': 'uid',

          'help': 'attribute used as login on authentication (with Active Directory, you want to use "sAMAccountName" here)',

          'group': 'ldap-source', 'level': 1,

          }),

        ('user-default-group',

         {'type' : 'csv',

          'default': ('users',),

          'help': 'name of a group in which ldap users will be by default. \

You can set multiple groups by separating them by a comma.',

          'group': 'ldap-source', 'level': 1,

          }),

        ('user-attrs-map',

         {'type' : 'named',

          'default': {'uid': 'login', 'gecos': 'email', 'userPassword': 'upassword'},

          'help': 'map from ldap user attributes to cubicweb attributes (with Active Directory, you want to use sAMAccountName:login,mail:email,givenName:firstname,sn:surname)',

          'group': 'ldap-source', 'level': 1,

          }),

    )

    _conn = None

    def _entity_update(self, source_entity):

        super(LDAPSourceMixIn, self)._entity_update(source_entity)

        if self.urls:

            if len(self.urls) > 1:

                raise ValidationError(source_entity.eid, {'url': _('can only have one url')})

            try:

                protocol, hostport = self.urls[0].split('://')

            except ValueError:

                raise ValidationError(source_entity.eid, {'url': _('badly formatted url')})

            if protocol not in PROTO_PORT:

                raise ValidationError(source_entity.eid, {'url': _('unsupported protocol')})

    def update_config(self, source_entity, typedconfig):

        """update configuration from source entity. `typedconfig` is config

        properly typed with defaults set

        """

        super(LDAPSourceMixIn, self).update_config(source_entity, typedconfig)

        self.authmode = typedconfig['auth-mode']

        self._authenticate = getattr(self, '_auth_%s' % self.authmode)

        self.cnx_dn = typedconfig['data-cnx-dn']

        self.cnx_pwd = typedconfig['data-cnx-password']

        self.user_base_dn = str(typedconfig['user-base-dn'])

        self.user_base_scope = globals()[typedconfig['user-scope']]

        self.user_login_attr = typedconfig['user-login-attr']

        self.user_default_groups = typedconfig['user-default-group']

        self.user_attrs = typedconfig['user-attrs-map']

        self.user_rev_attrs = {'eid': 'dn'}

        for ldapattr, cwattr in self.user_attrs.items():

            self.user_rev_attrs[cwattr] = ldapattr

        self.base_filters = [filter_format('(%s=%s)', ('objectClass', o))

                             for o in typedconfig['user-classes']]

        if typedconfig['user-filter']:

            self.base_filters.append(typedconfig['user-filter'])

        self._conn = None

    def connection_info(self):

        assert len(self.urls) == 1, self.urls

        protocol, hostport = self.urls[0].split('://')

        if protocol != 'ldapi' and not ':' in hostport:

            hostport = '%s:%s' % (hostport, PROTO_PORT[protocol])

        return protocol, hostport

    def get_connection(self):

        """open and return a connection to the source"""

        if self._conn is None:

            try:

                self._connect()

            except Exception:

                self.exception('unable to connect to ldap')

        return ConnectionWrapper(self._conn)

    def authenticate(self, session, login, password=None, **kwargs):

        """return CWUser eid for the given login/password if this account is

        defined in this source, else raise `AuthenticationError`

        two queries are needed since passwords are stored crypted, so we have

        to fetch the salt first

        """

        self.info('ldap authenticate %s', login)

        if not password:

            # On Windows + ADAM this would have succeeded (!!!)

            # You get Authenticated as: 'NT AUTHORITY\ANONYMOUS LOGON'.

            # we really really don't want that

            raise AuthenticationError()

        searchfilter = [filter_format('(%s=%s)', (self.user_login_attr, login))]

        searchfilter.extend(self.base_filters)

        searchstr = '(&%s)' % ''.join(searchfilter)

        # first search the user

        try:

            user = self._search(session, self.user_base_dn,

                                self.user_base_scope, searchstr)[0]

        except (IndexError, ldap.SERVER_DOWN):

            # no such user

            raise AuthenticationError()

        # check password by establishing a (unused) connection

        try:

            self._connect(user, password)

            # Something went wrong, most likely bad credentials

            self.info('while trying to authenticate %s: %s', user, ex)

            raise AuthenticationError()

        except Exception:

            self.error('while trying to authenticate %s', user, exc_info=True)

            raise AuthenticationError()

        eid = self.repo.extid2eid(self, user['dn'], 'CWUser', session, {})

        if eid < 0:

            # user has been moved away from this source

            raise AuthenticationError()

        return eid

    def _connect(self, user=None, userpwd=None):

        protocol, hostport = self.connection_info()

        self.info('connecting %s://%s as %s', protocol, hostport,

                  user and user['dn'] or 'anonymous')

        # don't require server certificate when using ldaps (will

        # enable self signed certs)

        ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)

        url = LDAPUrl(urlscheme=protocol, hostport=hostport)

        conn = ReconnectLDAPObject(url.initializeUrl())

        # Set the protocol version - version 3 is preferred

        try:

            conn.set_option(ldap.OPT_PROTOCOL_VERSION, ldap.VERSION3)

        except ldap.LDAPError: # Invalid protocol version, fall back safely

            conn.set_option(ldap.OPT_PROTOCOL_VERSION, ldap.VERSION2)

        # Deny auto-chasing of referrals to be safe, we handle them instead

        # Required for AD

        try:

           conn.set_option(ldap.OPT_REFERRALS, 0)

        except ldap.LDAPError: # Cannot set referrals, so do nothing

           pass

        #conn.set_option(ldap.OPT_NETWORK_TIMEOUT, conn_timeout)

        #conn.timeout = op_timeout

        # Now bind with the credentials given. Let exceptions propagate out.

        if user is None:

            # no user specified, we want to initialize the 'data' connection,

            assert self._conn is None

            self._conn = conn

            # XXX always use simple bind for data connection

            if not self.cnx_dn:

                conn.simple_bind_s(self.cnx_dn, self.cnx_pwd)

            else:

                self._authenticate(conn, {'dn': self.cnx_dn}, self.cnx_pwd)

        else:

            # user specified, we want to check user/password, no need to return

            # the connection which will be thrown out

            self._authenticate(conn, user, userpwd)

        return conn

    def _auth_simple(self, conn, user, userpwd):

        conn.simple_bind_s(user['dn'], userpwd)

    def _auth_cram_md5(self, conn, user, userpwd):

        from ldap import sasl

        auth_token = sasl.cram_md5(user['dn'], userpwd)

        conn.sasl_interactive_bind_s('', auth_token)

    def _auth_digest_md5(self, conn, user, userpwd):

        from ldap import sasl

        auth_token = sasl.digest_md5(user['dn'], userpwd)

        conn.sasl_interactive_bind_s('', auth_token)

    def _auth_gssapi(self, conn, user, userpwd):

        # print XXX not proper sasl/gssapi

        import kerberos

        if not kerberos.checkPassword(user[self.user_login_attr], userpwd):

            raise Exception('BAD login / mdp')

        #from ldap import sasl

        #conn.sasl_interactive_bind_s('', sasl.gssapi())

    def _search(self, session, base, scope,

                searchstr='(objectClass=*)', attrs=()):

        """make an ldap query"""

        self.debug('ldap search %s %s %s %s %s', self.uri, base, scope,

                   searchstr, list(attrs))

        # XXX for now, we do not have connections set support for LDAP, so

        # this is always self._conn

        cnx = self.get_connection().cnx #session.cnxset.connection(self.uri).cnx

        if cnx is None:

            # cant connect to server

            msg = session._("can't connect to source %s, some data may be missing")

            session.set_shared_data('sources_error', msg % self.uri, txdata=True)

            return []

        try:

            res = cnx.search_s(base, scope, searchstr, attrs)

        except ldap.PARTIAL_RESULTS:

            res = cnx.result(all=0)[1]

        except ldap.NO_SUCH_OBJECT:

            self.info('ldap NO SUCH OBJECT %s %s %s', base, scope, searchstr)

            self._process_no_such_object(session, base)

            return []

        #     cnx = self.handle_referral(e)

        #     try:

        #         res = cnx.search_s(base, scope, searchstr, attrs)

        #     except ldap.PARTIAL_RESULTS:

        #         res_type, res = cnx.result(all=0)

        result = []

        for rec_dn, rec_dict in res:

            # When used against Active Directory, "rec_dict" may not be

            # be a dictionary in some cases (instead, it can be a list)

            #

            # An example of a useless "res" entry that can be ignored

            # from AD is

            # (None, ['ldap://ForestDnsZones.PORTAL.LOCAL/DC=ForestDnsZones,DC=PORTAL,DC=LOCAL'])

            # This appears to be some sort of internal referral, but

            # we can't handle it, so we need to skip over it.

            try:

                items = rec_dict.iteritems()

            except AttributeError:

                continue

            else:

                itemdict = self._process_ldap_item(rec_dn, items)

                result.append(itemdict)

        #print '--->', result

        self.debug('ldap built results %s', len(result))

        return result

    def _process_ldap_item(self, dn, iterator):

        """Turn an ldap received item into a proper dict."""

        itemdict = {'dn': dn}

        for key, value in iterator:

            if self.user_attrs.get(key) == 'upassword': # XXx better password detection

                value = value[0].encode('utf-8')

                # we only support ldap_salted_sha1 for ldap sources, see: server/utils.py

                if not value.startswith('{SSHA}'):

                    value = utils.crypt_password(value)

                itemdict[key] = Binary(value)

            else:

                for i, val in enumerate(value):

                    value[i] = unicode(val, 'utf-8', 'replace')

                if isinstance(value, list) and len(value) == 1:

                    itemdict[key] = value = value[0]

        return itemdict

    def _process_no_such_object(self, session, dn):

        """Some search return NO_SUCH_OBJECT error, handle this (usually because

        an object whose dn is no more existent in ldap as been encountered).

        Do nothing by default, let sub-classes handle that.

        """