# copyright 2003-2016 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 ldap feed source"""

from datetime import datetime

import ldap3

from logilab.common.configuration import merge_options

from cubicweb import ValidationError, AuthenticationError, Binary

from cubicweb.server import utils

from cubicweb.server.sources import datafeed

from cubicweb import _

# search scopes

# map ldap protocol to their standard port

PROTO_PORT = {'ldap': 389,

              'ldaps': 636,

              'ldapi': None,

              }

def replace_filter(s):

    s = s.replace('*', '\\2A')

    s = s.replace('(', '\\28')

    s = s.replace(')', '\\29')

    s = s.replace('\\', '\\5c')

    s = s.replace('\0', '\\00')

    return s

class LDAPFeedSource(datafeed.DataFeedSource):

    """LDAP feed source: unlike ldapuser source, this source is copy based and

    will import ldap content (beside passwords for authentication) into the

    system source.

    """

    support_entities = {'CWUser': False}

    use_cwuri_as_url = False

    options = (

        ('auth-mode',

         {'type': 'choice',

          'default': 'simple',

          'choices': ('simple', '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': '',

          'help': 'base DN to lookup for users; disable user importation mechanism if unset',

          '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'},

          '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,

          }),

        ('group-base-dn',

         {'type': 'string',

          'default': '',

          'help': 'base DN to lookup for groups; disable group importation mechanism if unset',

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

          }),

        ('group-scope',

         {'type': 'choice',

          'default': 'ONELEVEL',

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

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

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

          }),

        ('group-classes',

         {'type': 'csv',

          'default': ('top', 'posixGroup'),

          'help': 'classes of group',

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

          }),

        ('group-filter',

         {'type': 'string',

          'default': '',

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

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

          }),

        ('group-attrs-map',

         {'type': 'named',

          'default': {'cn': 'name', 'memberUid': 'member'},

          'help': 'map from ldap group attributes to cubicweb attributes',

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

          }),

    )

    options = merge_options(datafeed.DataFeedSource.options + options,

                            optgroup='ldap-source',)

    _conn = None

    def check_urls(self, source_entity):

        urls = super(LDAPFeedSource, self).check_urls(source_entity)

        if len(urls) > 1:

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

        try:

            protocol, hostport = 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')})

        return urls

    def init(self, source_entity):

        super(LDAPFeedSource, self).init(source_entity)

        typedconfig = self.config

        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_login_attr = typedconfig['user-login-attr']

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

        self.user_attrs = {'dn': 'eid', 'modifyTimestamp': 'modification_date'}

        self.user_attrs.update(typedconfig['user-attrs-map'])

        self.user_rev_attrs = dict((v, k) for k, v in self.user_attrs.items())

        self.base_filters = ['(objectclass=%s)' % replace_filter(o)

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

        if typedconfig['user-filter']:

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

        self.group_base_dn = str(typedconfig['group-base-dn'])

        self.group_base_scope = LDAP_SCOPES[typedconfig['group-scope']]

        self.group_attrs = typedconfig['group-attrs-map']

        self.group_attrs = {'dn': 'eid', 'modifyTimestamp': 'modification_date'}

        self.group_attrs.update(typedconfig['group-attrs-map'])

        self.group_rev_attrs = dict((v, k) for k, v in self.group_attrs.items())

        self.group_base_filters = ['(objectClass=%s)' % replace_filter(o)

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

        if typedconfig['group-filter']:

            self.group_base_filters.append(typedconfig['group-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 ':' in hostport:

            host, port = hostport.rsplit(':', 1)

        else:

            host, port = hostport, PROTO_PORT[protocol]

        return protocol, host, port

    def authenticate(self, cnx, 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 = ['(%s=%s)' % (replace_filter(self.user_login_attr), replace_filter(login))]

        searchfilter.extend(self.base_filters)

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

        # first search the user

        try:

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

                                self.user_base_scope, searchstr)[0]

        except IndexError:

            # no such user

            raise AuthenticationError()

        # check password by establishing a (unused) connection

        try:

            self._connect(user, password)

        except ldap3.LDAPException as ex:

            # 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()

        rset = cnx.execute('Any X,SN WHERE X cwuri %(extid)s, X is CWUser, '

                           'X cw_source S, S name SN', {'extid': user['dn']})

        if not rset or rset[0][1] != self.uri:

            # user is not known or has been moved away from this source

            raise AuthenticationError()

        return rset[0][0]

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

        protocol, host, port = self.connection_info()

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

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

        server = ldap3.Server(host, port=int(port))

        conn = ldap3.Connection(

            server, user=user and user['dn'],

            client_strategy=ldap3.STRATEGY_SYNC_RESTARTABLE,

            auto_referrals=False)

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

        if user is None:

            # XXX always use simple bind for data connection

            if not self.cnx_dn:

                conn.bind()

            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

            if not self._authenticate(conn, user, userpwd):

                raise AuthenticationError()

        return conn

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

        conn.authentication = ldap3.AUTH_SIMPLE

        conn.user = user['dn']

        conn.password = userpwd

        return conn.bind()

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

        conn.authentication = ldap3.AUTH_SASL

        conn.sasl_mechanism = 'DIGEST-MD5'

        # realm, user, password, authz-id

        conn.sasl_credentials = (None, user['dn'], userpwd, None)

        return conn.bind()

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

        conn.authentication = ldap3.AUTH_SASL

        conn.sasl_mechanism = 'GSSAPI'

        return conn.bind()

    def _search(self, cnx, 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))

        if self._conn is None:

            self._conn = self._connect()

        ldapcnx = self._conn

        if not ldapcnx.search(base, searchstr, search_scope=scope, attributes=attrs):

            return []

        result = []

        for rec in ldapcnx.response:

            if rec['type'] != 'searchResEntry':

                continue

            items = rec['attributes'].items()

            itemdict = self._process_ldap_item(rec['dn'], items)

            result.append(itemdict)

        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(b'{SSHA}'):

                    value = utils.crypt_password(value)

                itemdict[key] = Binary(value)

            elif self.user_attrs.get(key) == 'modification_date':

                itemdict[key] = datetime.strptime(value[0], '%Y%m%d%H%M%SZ')

            else:

                if len(value) == 1:

                    itemdict[key] = value = value[0]

                else:

                    itemdict[key] = value

        # we expect memberUid to be a list of user ids, make sure of it

        member = self.group_rev_attrs['member']

        if isinstance(itemdict.get(member), str):

            itemdict[member] = [itemdict[member]]

        return itemdict

    def _process_no_such_object(self, cnx, 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.

        """