path: root/keystone-moon/keystone/common/ldap/core.py

# Copyright 2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import abc
import codecs
import functools
import os.path
import re
import sys
import weakref

import ldap.filter
import ldappool
from oslo_log import log
import six
from six.moves import map, zip

from keystone import exception
from keystone.i18n import _
from keystone.i18n import _LW


LOG = log.getLogger(__name__)

LDAP_VALUES = {'TRUE': True, 'FALSE': False}
CONTROL_TREEDELETE = '1.2.840.113556.1.4.805'
LDAP_SCOPES = {'one': ldap.SCOPE_ONELEVEL,
               'sub': ldap.SCOPE_SUBTREE}
LDAP_DEREF = {'always': ldap.DEREF_ALWAYS,
              'default': None,
              'finding': ldap.DEREF_FINDING,
              'never': ldap.DEREF_NEVER,
              'searching': ldap.DEREF_SEARCHING}
LDAP_TLS_CERTS = {'never': ldap.OPT_X_TLS_NEVER,
                  'demand': ldap.OPT_X_TLS_DEMAND,
                  'allow': ldap.OPT_X_TLS_ALLOW}


# RFC 4511 (The LDAP Protocol) defines a list containing only the OID '1.1' to
# indicate that no attributes should be returned besides the DN.
DN_ONLY = ['1.1']

_utf8_encoder = codecs.getencoder('utf-8')


def utf8_encode(value):
    """Encode a basestring to UTF-8.

    If the string is unicode encode it to UTF-8, if the string is
    str then assume it's already encoded. Otherwise raise a TypeError.

    :param value: A basestring
    :returns: UTF-8 encoded version of value
    :raises: TypeError if value is not basestring
    """
    if isinstance(value, six.text_type):
        return _utf8_encoder(value)[0]
    elif isinstance(value, six.binary_type):
        return value
    else:
        raise TypeError("value must be basestring, "
                        "not %s" % value.__class__.__name__)

_utf8_decoder = codecs.getdecoder('utf-8')


def utf8_decode(value):
    """Decode a from UTF-8 into unicode.

    If the value is a binary string assume it's UTF-8 encoded and decode
    it into a unicode string. Otherwise convert the value from its
    type into a unicode string.

    :param value: value to be returned as unicode
    :returns: value as unicode
    :raises: UnicodeDecodeError for invalid UTF-8 encoding
    """
    if isinstance(value, six.binary_type):
        return _utf8_decoder(value)[0]
    return six.text_type(value)


def py2ldap(val):
    """Type convert a Python value to a type accepted by LDAP (unicode).

    The LDAP API only accepts strings for values therefore convert
    the value's type to a unicode string. A subsequent type conversion
    will encode the unicode as UTF-8 as required by the python-ldap API,
    but for now we just want a string representation of the value.

    :param val: The value to convert to a LDAP string representation
    :returns: unicode string representation of value.
    """
    if isinstance(val, bool):
        return u'TRUE' if val else u'FALSE'
    else:
        return six.text_type(val)


def enabled2py(val):
    """Similar to ldap2py, only useful for the enabled attribute."""

    try:
        return LDAP_VALUES[val]
    except KeyError:
        pass
    try:
        return int(val)
    except ValueError:
        pass
    return utf8_decode(val)


def ldap2py(val):
    """Convert an LDAP formatted value to Python type used by OpenStack.

    Virtually all LDAP values are stored as UTF-8 encoded strings.
    OpenStack prefers values which are unicode friendly.

    :param val: LDAP formatted value
    :returns: val converted to preferred Python type
    """
    return utf8_decode(val)


def convert_ldap_result(ldap_result):
    """Convert LDAP search result to Python types used by OpenStack.

    Each result tuple is of the form (dn, attrs), where dn is a string
    containing the DN (distinguished name) of the entry, and attrs is
    a dictionary containing the attributes associated with the
    entry. The keys of attrs are strings, and the associated values
    are lists of strings.

    OpenStack wants to use Python types of its choosing. Strings will
    be unicode, truth values boolean, whole numbers int's, etc. DN's will
    also be decoded from UTF-8 to unicode.

    :param ldap_result: LDAP search result
    :returns: list of 2-tuples containing (dn, attrs) where dn is unicode
              and attrs is a dict whose values are type converted to
              OpenStack preferred types.
    """
    py_result = []
    at_least_one_referral = False
    for dn, attrs in ldap_result:
        ldap_attrs = {}
        if dn is None:
            # this is a Referral object, rather than an Entry object
            at_least_one_referral = True
            continue

        for kind, values in attrs.items():
            try:
                val2py = enabled2py if kind == 'enabled' else ldap2py
                ldap_attrs[kind] = [val2py(x) for x in values]
            except UnicodeDecodeError:
                LOG.debug('Unable to decode value for attribute %s', kind)

        py_result.append((utf8_decode(dn), ldap_attrs))
    if at_least_one_referral:
        LOG.debug(('Referrals were returned and ignored. Enable referral '
                   'chasing in keystone.conf via [ldap] chase_referrals'))

    return py_result


def safe_iter(attrs):
    if attrs is None:
        return
    elif isinstance(attrs, list):
        for e in attrs:
            yield e
    else:
        yield attrs


def parse_deref(opt):
    try:
        return LDAP_DEREF[opt]
    except KeyError:
        raise ValueError(_('Invalid LDAP deref option: %(option)s. '
                           'Choose one of: %(options)s') %
                         {'option': opt,
                          'options': ', '.join(LDAP_DEREF.keys()), })


def parse_tls_cert(opt):
    try:
        return LDAP_TLS_CERTS[opt]
    except KeyError:
        raise ValueError(_(
            'Invalid LDAP TLS certs option: %(option)s. '
            'Choose one of: %(options)s') % {
                'option': opt,
                'options': ', '.join(LDAP_TLS_CERTS.keys())})


def ldap_scope(scope):
    try:
        return LDAP_SCOPES[scope]
    except KeyError:
        raise ValueError(
            _('Invalid LDAP scope: %(scope)s. Choose one of: %(options)s') % {
                'scope': scope,
                'options': ', '.join(LDAP_SCOPES.keys())})


def prep_case_insensitive(value):
    """Prepare a string for case-insensitive comparison.

    This is defined in RFC4518. For simplicity, all this function does is
    lowercase all the characters, strip leading and trailing whitespace,
    and compress sequences of spaces to a single space.
    """
    value = re.sub(r'\s+', ' ', value.strip().lower())
    return value


def is_ava_value_equal(attribute_type, val1, val2):
    """Returns True if and only if the AVAs are equal.

    When comparing AVAs, the equality matching rule for the attribute type
    should be taken into consideration. For simplicity, this implementation
    does a case-insensitive comparison.

    Note that this function uses prep_case_insenstive so the limitations of
    that function apply here.

    """

    return prep_case_insensitive(val1) == prep_case_insensitive(val2)


def is_rdn_equal(rdn1, rdn2):
    """Returns True if and only if the RDNs are equal.

    * RDNs must have the same number of AVAs.
    * Each AVA of the RDNs must be the equal for the same attribute type. The
      order isn't significant. Note that an attribute type will only be in one
      AVA in an RDN, otherwise the DN wouldn't be valid.
    * Attribute types aren't case sensitive. Note that attribute type
      comparison is more complicated than implemented. This function only
      compares case-insentive. The code should handle multiple names for an
      attribute type (e.g., cn, commonName, and 2.5.4.3 are the same).

    Note that this function uses is_ava_value_equal to compare AVAs so the
    limitations of that function apply here.

    """

    if len(rdn1) != len(rdn2):
        return False

    for attr_type_1, val1, dummy in rdn1:
        found = False
        for attr_type_2, val2, dummy in rdn2:
            if attr_type_1.lower() != attr_type_2.lower():
                continue

            found = True
            if not is_ava_value_equal(attr_type_1, val1, val2):
                return False
            break
        if not found:
            return False

    return True


def is_dn_equal(dn1, dn2):
    """Returns True if and only if the DNs are equal.

    Two DNs are equal if they've got the same number of RDNs and if the RDNs
    are the same at each position. See RFC4517.

    Note that this function uses is_rdn_equal to compare RDNs so the
    limitations of that function apply here.

    :param dn1: Either a string DN or a DN parsed by ldap.dn.str2dn.
    :param dn2: Either a string DN or a DN parsed by ldap.dn.str2dn.

    """

    if not isinstance(dn1, list):
        dn1 = ldap.dn.str2dn(utf8_encode(dn1))
    if not isinstance(dn2, list):
        dn2 = ldap.dn.str2dn(utf8_encode(dn2))

    if len(dn1) != len(dn2):
        return False

    for rdn1, rdn2 in zip(dn1, dn2):
        if not is_rdn_equal(rdn1, rdn2):
            return False
    return True


def dn_startswith(descendant_dn, dn):
    """Returns True if and only if the descendant_dn is under the dn.

    :param descendant_dn: Either a string DN or a DN parsed by ldap.dn.str2dn.
    :param dn: Either a string DN or a DN parsed by ldap.dn.str2dn.

    """

    if not isinstance(descendant_dn, list):
        descendant_dn = ldap.dn.str2dn(utf8_encode(descendant_dn))
    if not isinstance(dn, list):
        dn = ldap.dn.str2dn(utf8_encode(dn))

    if len(descendant_dn) <= len(dn):
        return False

    # Use the last len(dn) RDNs.
    return is_dn_equal(descendant_dn[-len(dn):], dn)


@six.add_metaclass(abc.ABCMeta)
class LDAPHandler(object):
    """Abstract class which defines methods for a LDAP API provider.

    Native Keystone values cannot be passed directly into and from the
    python-ldap API. Type conversion must occur at the LDAP API
    boudary, examples of type conversions are:

        * booleans map to the strings 'TRUE' and 'FALSE'

        * integer values map to their string representation.

        * unicode strings are encoded in UTF-8

    In addition to handling type conversions at the API boundary we
    have the requirement to support more than one LDAP API
    provider. Currently we have:

        * python-ldap, this is the standard LDAP API for Python, it
          requires access to a live LDAP server.

        * Fake LDAP which emulates python-ldap. This is used for
          testing without requiring a live LDAP server.

    To support these requirements we need a layer that performs type
    conversions and then calls another LDAP API which is configurable
    (e.g. either python-ldap or the fake emulation).

    We have an additional constraint at the time of this writing due to
    limitations in the logging module. The logging module is not
    capable of accepting UTF-8 encoded strings, it will throw an
    encoding exception. Therefore all logging MUST be performed prior
    to UTF-8 conversion. This means no logging can be performed in the
    ldap APIs that implement the python-ldap API because those APIs
    are defined to accept only UTF-8 strings. Thus the layer which
    performs type conversions must also do the logging. We do the type
    conversions in two steps, once to convert all Python types to
    unicode strings, then log, then convert the unicode strings to
    UTF-8.

    There are a variety of ways one could accomplish this, we elect to
    use a chaining technique whereby instances of this class simply
    call the next member in the chain via the "conn" attribute. The
    chain is constructed by passing in an existing instance of this
    class as the conn attribute when the class is instantiated.

    Here is a brief explanation of why other possible approaches were
    not used:

        subclassing

            To perform the wrapping operations in the correct order
            the type convesion class would have to subclass each of
            the API providers. This is awkward, doubles the number of
            classes, and does not scale well. It requires the type
            conversion class to be aware of all possible API
            providers.

        decorators

            Decorators provide an elegant solution to wrap methods and
            would be an ideal way to perform type conversions before
            calling the wrapped function and then converting the
            values returned from the wrapped function. However
            decorators need to be aware of the method signature, it
            has to know what input parameters need conversion and how
            to convert the result. For an API like python-ldap which
            has a large number of different method signatures it would
            require a large number of specialized
            decorators. Experience has shown it's very easy to apply
            the wrong decorator due to the inherent complexity and
            tendency to cut-n-paste code. Another option is to
            parameterize the decorator to make it "smart". Experience
            has shown such decorators become insanely complicated and
            difficult to understand and debug. Also decorators tend to
            hide what's really going on when a method is called, the
            operations being performed are not visible when looking at
            the implemation of a decorated method, this too experience
            has shown leads to mistakes.

    Chaining simplifies both wrapping to perform type conversion as
    well as the substitution of alternative API providers. One simply
    creates a new instance of the API interface and insert it at the
    front of the chain. Type conversions are explicit and obvious.

    If a new method needs to be added to the API interface one adds it
    to the abstract class definition. Should one miss adding the new
    method to any derivations of the abstract class the code will fail
    to load and run making it impossible to forget updating all the
    derived classes.

    """
    @abc.abstractmethod
    def __init__(self, conn=None):
        self.conn = conn

    @abc.abstractmethod
    def connect(self, url, page_size=0, alias_dereferencing=None,
                use_tls=False, tls_cacertfile=None, tls_cacertdir=None,
                tls_req_cert='demand', chase_referrals=None, debug_level=None,
                use_pool=None, pool_size=None, pool_retry_max=None,
                pool_retry_delay=None, pool_conn_timeout=None,
                pool_conn_lifetime=None):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def set_option(self, option, invalue):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def get_option(self, option):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def simple_bind_s(self, who='', cred='',
                      serverctrls=None, clientctrls=None):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def unbind_s(self):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def add_s(self, dn, modlist):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def search_s(self, base, scope,
                 filterstr='(objectClass=*)', attrlist=None, attrsonly=0):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def search_ext(self, base, scope,
                   filterstr='(objectClass=*)', attrlist=None, attrsonly=0,
                   serverctrls=None, clientctrls=None,
                   timeout=-1, sizelimit=0):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def result3(self, msgid=ldap.RES_ANY, all=1, timeout=None,
                resp_ctrl_classes=None):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def modify_s(self, dn, modlist):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def delete_s(self, dn):
        raise exception.NotImplemented()  # pragma: no cover

    @abc.abstractmethod
    def delete_ext_s(self, dn, serverctrls=None, clientctrls=None):
        raise exception.NotImplemented()  # pragma: no cover


class PythonLDAPHandler(LDAPHandler):
    """LDAPHandler implementation which calls the python-ldap API.

    Note, the python-ldap API requires all string values to be UTF-8 encoded.
    The KeystoneLDAPHandler enforces this prior to invoking the methods in this
    class.

    """

    def __init__(self, conn=None):
        super(PythonLDAPHandler, self).__init__(conn=conn)

    def connect(self, url, page_size=0, alias_dereferencing=None,
                use_tls=False, tls_cacertfile=None, tls_cacertdir=None,
                tls_req_cert='demand', chase_referrals=None, debug_level=None,
                use_pool=None, pool_size=None, pool_retry_max=None,
                pool_retry_delay=None, pool_conn_timeout=None,
                pool_conn_lifetime=None):

        _common_ldap_initialization(url=url,
                                    use_tls=use_tls,
                                    tls_cacertfile=tls_cacertfile,
                                    tls_cacertdir=tls_cacertdir,
                                    tls_req_cert=tls_req_cert,
                                    debug_level=debug_level)

        self.conn = ldap.initialize(url)
        self.conn.protocol_version = ldap.VERSION3

        if alias_dereferencing is not None:
            self.conn.set_option(ldap.OPT_DEREF, alias_dereferencing)
        self.page_size = page_size

        if use_tls:
            self.conn.start_tls_s()

        if chase_referrals is not None:
            self.conn.set_option(ldap.OPT_REFERRALS, int(chase_referrals))

    def set_option(self, option, invalue):
        return self.conn.set_option(option, invalue)

    def get_option(self, option):
        return self.conn.get_option(option)

    def simple_bind_s(self, who='', cred='',
                      serverctrls=None, clientctrls=None):
        return self.conn.simple_bind_s(who, cred, serverctrls, clientctrls)

    def unbind_s(self):
        return self.conn.unbind_s()

    def add_s(self, dn, modlist):
        return self.conn.add_s(dn, modlist)

    def search_s(self, base, scope,
                 filterstr='(objectClass=*)', attrlist=None, attrsonly=0):
        return self.conn.search_s(base, scope, filterstr,
                                  attrlist, attrsonly)

    def search_ext(self, base, scope,
                   filterstr='(objectClass=*)', attrlist=None, attrsonly=0,
                   serverctrls=None, clientctrls=None,
                   timeout=-1, sizelimit=0):
        return self.conn.search_ext(base, scope,
                                    filterstr, attrlist, attrsonly,
                                    serverctrls, clientctrls,
                                    timeout, sizelimit)

    def result3(self, msgid=ldap.RES_ANY, all=1, timeout=None,
                resp_ctrl_classes=None):
        # The resp_ctrl_classes parameter is a recent addition to the
        # API. It defaults to None. We do not anticipate using it.
        # To run with older versions of python-ldap we do not pass it.
        return self.conn.result3(msgid, all, timeout)

    def modify_s(self, dn, modlist):
        return self.conn.modify_s(dn, modlist)

    def delete_s(self, dn):
        return self.conn.delete_s(dn)

    def delete_ext_s(self, dn, serverctrls=None, clientctrls=None):
        return self.conn.delete_ext_s(dn, serverctrls, clientctrls)


def _common_ldap_initialization(url, use_tls=False, tls_cacertfile=None,
                                tls_cacertdir=None, tls_req_cert=None,
                                debug_level=None):
    """LDAP initialization for PythonLDAPHandler and PooledLDAPHandler."""
    LOG.debug("LDAP init: url=%s", url)
    LOG.debug('LDAP init: use_tls=%s tls_cacertfile=%s tls_cacertdir=%s '
              'tls_req_cert=%s tls_avail=%s',
              use_tls, tls_cacertfile, tls_cacertdir,
              tls_req_cert, ldap.TLS_AVAIL)

    if debug_level is not None:
        ldap.set_option(ldap.OPT_DEBUG_LEVEL, debug_level)

    using_ldaps = url.lower().startswith("ldaps")

    if use_tls and using_ldaps:
        raise AssertionError(_('Invalid TLS / LDAPS combination'))

    # The certificate trust options apply for both LDAPS and TLS.
    if use_tls or using_ldaps:
        if not ldap.TLS_AVAIL:
            raise ValueError(_('Invalid LDAP TLS_AVAIL option: %s. TLS '
                               'not available') % ldap.TLS_AVAIL)
        if tls_cacertfile:
            # NOTE(topol)
            # python ldap TLS does not verify CACERTFILE or CACERTDIR
            # so we add some extra simple sanity check verification
            # Also, setting these values globally (i.e. on the ldap object)
            # works but these values are ignored when setting them on the
            # connection
            if not os.path.isfile(tls_cacertfile):
                raise IOError(_("tls_cacertfile %s not found "
                                "or is not a file") %
                              tls_cacertfile)
            ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, tls_cacertfile)
        elif tls_cacertdir:
            # NOTE(topol)
            # python ldap TLS does not verify CACERTFILE or CACERTDIR
            # so we add some extra simple sanity check verification
            # Also, setting these values globally (i.e. on the ldap object)
            # works but these values are ignored when setting them on the
            # connection
            if not os.path.isdir(tls_cacertdir):
                raise IOError(_("tls_cacertdir %s not found "
                                "or is not a directory") %
                              tls_cacertdir)
            ldap.set_option(ldap.OPT_X_TLS_CACERTDIR, tls_cacertdir)
        if tls_req_cert in list(LDAP_TLS_CERTS.values()):
            ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, tls_req_cert)
        else:
            LOG.debug("LDAP TLS: invalid TLS_REQUIRE_CERT Option=%s",
                      tls_req_cert)


class MsgId(list):
    """Wrapper class to hold connection and msgid."""
    pass


def use_conn_pool(func):
    """Use this only for connection pool specific ldap API.

    This adds connection object to decorated API as next argument after self.

    """
    def wrapper(self, *args, **kwargs):
        # assert isinstance(self, PooledLDAPHandler)
        with self._get_pool_connection() as conn:
            self._apply_options(conn)
            return func(self, conn, *args, **kwargs)
    return wrapper


class PooledLDAPHandler(LDAPHandler):
    """LDAPHandler implementation which uses pooled connection manager.

    Pool specific configuration is defined in [ldap] section.
    All other LDAP configuration is still used from [ldap] section

    Keystone LDAP authentication logic authenticates an end user using its DN
    and password via LDAP bind to establish supplied password is correct.
    This can fill up the pool quickly (as pool re-uses existing connection
    based on its bind data) and would not leave space in pool for connection
    re-use for other LDAP operations.
    Now a separate pool can be established for those requests when related flag
    'use_auth_pool' is enabled. That pool can have its own size and
    connection lifetime. Other pool attributes are shared between those pools.
    If 'use_pool' is disabled, then 'use_auth_pool' does not matter.
    If 'use_auth_pool' is not enabled, then connection pooling is not used for
    those LDAP operations.

    Note, the python-ldap API requires all string values to be UTF-8
    encoded. The KeystoneLDAPHandler enforces this prior to invoking
    the methods in this class.

    """
    # Added here to allow override for testing
    Connector = ldappool.StateConnector
    auth_pool_prefix = 'auth_pool_'

    connection_pools = {}  # static connector pool dict

    def __init__(self, conn=None, use_auth_pool=False):
        super(PooledLDAPHandler, self).__init__(conn=conn)
        self.who = ''
        self.cred = ''
        self.conn_options = {}  # connection specific options
        self.page_size = None
        self.use_auth_pool = use_auth_pool
        self.conn_pool = None

    def connect(self, url, page_size=0, alias_dereferencing=None,
                use_tls=False, tls_cacertfile=None, tls_cacertdir=None,
                tls_req_cert='demand', chase_referrals=None, debug_level=None,
                use_pool=None, pool_size=None, pool_retry_max=None,
                pool_retry_delay=None, pool_conn_timeout=None,
                pool_conn_lifetime=None):

        _common_ldap_initialization(url=url,
                                    use_tls=use_tls,
                                    tls_cacertfile=tls_cacertfile,
                                    tls_cacertdir=tls_cacertdir,
                                    tls_req_cert=tls_req_cert,
                                    debug_level=debug_level)

        self.page_size = page_size

        # Following two options are not added in common initialization as they
        # need to follow a sequence in PythonLDAPHandler code.
        if alias_dereferencing is not None:
            self.set_option(ldap.OPT_DEREF, alias_dereferencing)
        if chase_referrals is not None:
            self.set_option(ldap.OPT_REFERRALS, int(chase_referrals))

        if self.use_auth_pool:  # separate pool when use_auth_pool enabled
            pool_url = self.auth_pool_prefix + url
        else:
            pool_url = url
        try:
            self.conn_pool = self.connection_pools[pool_url]
        except KeyError:
            self.conn_pool = ldappool.ConnectionManager(
                url,
                size=pool_size,
                retry_max=pool_retry_max,
                retry_delay=pool_retry_delay,
                timeout=pool_conn_timeout,
                connector_cls=self.Connector,
                use_tls=use_tls,
                max_lifetime=pool_conn_lifetime)
            self.connection_pools[pool_url] = self.conn_pool

    def set_option(self, option, invalue):
        self.conn_options[option] = invalue

    def get_option(self, option):
        value = self.conn_options.get(option)
        # if option was not specified explicitly, then use connection default
        # value for that option if there.
        if value is None:
            with self._get_pool_connection() as conn:
                value = conn.get_option(option)
        return value

    def _apply_options(self, conn):
        # if connection has a lifetime, then it already has options specified
        if conn.get_lifetime() > 30:
            return
        for option, invalue in self.conn_options.items():
            conn.set_option(option, invalue)

    def _get_pool_connection(self):
        return self.conn_pool.connection(self.who, self.cred)

    def simple_bind_s(self, who='', cred='',
                      serverctrls=None, clientctrls=None):
        # Not using use_conn_pool decorator here as this API takes cred as
        # input.
        self.who = who
        self.cred = cred
        with self._get_pool_connection() as conn:
            self._apply_options(conn)

    def unbind_s(self):
        # After connection generator is done `with` statement execution block
        # connection is always released via finally block in ldappool.
        # So this unbind is a no op.
        pass

    @use_conn_pool
    def add_s(self, conn, dn, modlist):
        return conn.add_s(dn, modlist)

    @use_conn_pool
    def search_s(self, conn, base, scope,
                 filterstr='(objectClass=*)', attrlist=None, attrsonly=0):
        return conn.search_s(base, scope, filterstr, attrlist,
                             attrsonly)

    def search_ext(self, base, scope,
                   filterstr='(objectClass=*)', attrlist=None, attrsonly=0,
                   serverctrls=None, clientctrls=None,
                   timeout=-1, sizelimit=0):
        """Asynchronous API to return a ``MsgId`` instance.

        The ``MsgId`` instance can be safely used in a call to ``result3()``.

        To work with ``result3()`` API in predictable manner, the same LDAP
        connection is needed which originally provided the ``msgid``. So, this
        method wraps the existing connection and ``msgid`` in a new ``MsgId``
        instance. The connection associated with ``search_ext`` is released
        once last hard reference to the ``MsgId`` instance is freed.

        """
        conn_ctxt = self._get_pool_connection()
        conn = conn_ctxt.__enter__()
        try:
            msgid = conn.search_ext(base, scope,
                                    filterstr, attrlist, attrsonly,
                                    serverctrls, clientctrls,
                                    timeout, sizelimit)
        except Exception:
            conn_ctxt.__exit__(*sys.exc_info())
            raise
        res = MsgId((conn, msgid))
        weakref.ref(res, functools.partial(conn_ctxt.__exit__,
                                           None, None, None))
        return res

    def result3(self, msgid, all=1, timeout=None,
                resp_ctrl_classes=None):
        """This method is used to wait for and return result.

        This method returns the result of an operation previously initiated by
        one of the LDAP asynchronous operation routines (eg search_ext()). It
        returned an invocation identifier (a message id) upon successful
        initiation of their operation.

        Input msgid is expected to be instance of class MsgId which has LDAP
        session/connection used to execute search_ext and message idenfier.

        The connection associated with search_ext is released once last hard
        reference to MsgId object is freed. This will happen when function
        which requested msgId and used it in result3 exits.

        """

        conn, msg_id = msgid
        return conn.result3(msg_id, all, timeout)

    @use_conn_pool
    def modify_s(self, conn, dn, modlist):
        return conn.modify_s(dn, modlist)

    @use_conn_pool
    def delete_s(self, conn, dn):
        return conn.delete_s(dn)

    @use_conn_pool
    def delete_ext_s(self, conn, dn, serverctrls=None, clientctrls=None):
        return conn.delete_ext_s(dn, serverctrls, clientctrls)


class KeystoneLDAPHandler(LDAPHandler):
    """Convert data types and perform logging.

    This LDAP inteface wraps the python-ldap based interfaces. The
    python-ldap interfaces require string values encoded in UTF-8. The
    OpenStack logging framework at the time of this writing is not
    capable of accepting strings encoded in UTF-8, the log functions
    will throw decoding errors if a non-ascii character appears in a
    string.

    Prior to the call Python data types are converted to a string
    representation as required by the LDAP APIs.

    Then logging is performed so we can track what is being
    sent/received from LDAP. Also the logging filters security
    sensitive items (i.e. passwords).

    Then the string values are encoded into UTF-8.

    Then the LDAP API entry point is invoked.

    Data returned from the LDAP call is converted back from UTF-8
    encoded strings into the Python data type used internally in
    OpenStack.

    """

    def __init__(self, conn=None):
        super(KeystoneLDAPHandler, self).__init__(conn=conn)
        self.page_size = 0

    def __enter__(self):
        return self

    def _disable_paging(self):
        # Disable the pagination from now on
        self.page_size = 0

    def connect(self, url, page_size=0, alias_dereferencing=None,
                use_tls=False, tls_cacertfile=None, tls_cacertdir=None,
                tls_req_cert='demand', chase_referrals=None, debug_level=None,
                use_pool=None, pool_size=None,
                pool_retry_max=None, pool_retry_delay=None,
                pool_conn_timeout=None, pool_conn_lifetime=None):
        self.page_size = page_size
        return self.conn.connect(url, page_size, alias_dereferencing,
                                 use_tls, tls_cacertfile, tls_cacertdir,
                                 tls_req_cert, chase_referrals,
                                 debug_level=debug_level,
                                 use_pool=use_pool,
                                 pool_size=pool_size,
                                 pool_retry_max=pool_retry_max,
                                 pool_retry_delay=pool_retry_delay,
                                 pool_conn_timeout=pool_conn_timeout,
                                 pool_conn_lifetime=pool_conn_lifetime)

    def set_option(self, option, invalue):
        return self.conn.set_option(option, invalue)

    def get_option(self, option):
        return self.conn.get_option(option)

    def simple_bind_s(self, who='', cred='',
                      serverctrls=None, clientctrls=None):
        LOG.debug("LDAP bind: who=%s", who)
        who_utf8 = utf8_encode(who)
        cred_utf8 = utf8_encode(cred)
        return self.conn.simple_bind_s(who_utf8, cred_utf8,
                                       serverctrls=serverctrls,
                                       clientctrls=clientctrls)

    def unbind_s(self):
        LOG.debug("LDAP unbind")
        return self.conn.unbind_s()

    def add_s(self, dn, modlist):
        ldap_attrs = [(kind, [py2ldap(x) for x in safe_iter(values)])
                      for kind, values in modlist]
        logging_attrs = [(kind, values
                         if kind != 'userPassword'
                         else ['****'])
                         for kind, values in ldap_attrs]
        LOG.debug('LDAP add: dn=%s attrs=%s',
                  dn, logging_attrs)
        dn_utf8 = utf8_encode(dn)
        ldap_attrs_utf8 = [(kind, [utf8_encode(x) for x in safe_iter(values)])
                           for kind, values in ldap_attrs]
        return self.conn.add_s(dn_utf8, ldap_attrs_utf8)

    def search_s(self, base, scope,
                 filterstr='(objectClass=*)', attrlist=None, attrsonly=0):
        # NOTE(morganfainberg): Remove "None" singletons from this list, which
        # allows us to set mapped attributes to "None" as defaults in config.
        # Without this filtering, the ldap query would raise a TypeError since
        # attrlist is expected to be an iterable of strings.
        if attrlist is not None:
            attrlist = [attr for attr in attrlist if attr is not None]
        LOG.debug('LDAP search: base=%s scope=%s filterstr=%s '
                  'attrs=%s attrsonly=%s',
                  base, scope, filterstr, attrlist, attrsonly)
        if self.page_size:
            ldap_result = self._paged_search_s(base, scope,
                                               filterstr, attrlist)
        else:
            base_utf8 = utf8_encode(base)
            filterstr_utf8 = utf8_encode(filterstr)
            if attrlist is None:
                attrlist_utf8 = None
            else:
                attrlist_utf8 = list(map(utf8_encode, attrlist))
            ldap_result = self.conn.search_s(base_utf8, scope,
                                             filterstr_utf8,
                                             attrlist_utf8, attrsonly)

        py_result = convert_ldap_result(ldap_result)

        return py_result

    def search_ext(self, base, scope,
                   filterstr='(objectClass=*)', attrlist=None, attrsonly=0,
                   serverctrls=None, clientctrls=None,
                   timeout=-1, sizelimit=0):
        if attrlist is not None:
            attrlist = [attr for attr in attrlist if attr is not None]
        LOG.debug('LDAP search_ext: base=%s scope=%s filterstr=%s '
                  'attrs=%s attrsonly=%s'
                  'serverctrls=%s clientctrls=%s timeout=%s sizelimit=%s',
                  base, scope, filterstr, attrlist, attrsonly,
                  serverctrls, clientctrls, timeout, sizelimit)
        return self.conn.search_ext(base, scope,
                                    filterstr, attrlist, attrsonly,
                                    serverctrls, clientctrls,
                                    timeout, sizelimit)

    def _paged_search_s(self, base, scope, filterstr, attrlist=None):
        res = []
        use_old_paging_api = False
        # The API for the simple paged results control changed between
        # python-ldap 2.3 and 2.4.  We need to detect the capabilities
        # of the python-ldap version we are using.
        if hasattr(ldap, 'LDAP_CONTROL_PAGE_OID'):
            use_old_paging_api = True
            lc = ldap.controls.SimplePagedResultsControl(
                controlType=ldap.LDAP_CONTROL_PAGE_OID,
                criticality=True,
                controlValue=(self.page_size, ''))
            page_ctrl_oid = ldap.LDAP_CONTROL_PAGE_OID
        else:
            lc = ldap.controls.libldap.SimplePagedResultsControl(
                criticality=True,
                size=self.page_size,
                cookie='')
            page_ctrl_oid = ldap.controls.SimplePagedResultsControl.controlType

        base_utf8 = utf8_encode(base)
        filterstr_utf8 = utf8_encode(filterstr)
        if attrlist is None:
            attrlist_utf8 = None
        else:
            attrlist = [attr for attr in attrlist if attr is not None]
            attrlist_utf8 = list(map(utf8_encode, attrlist))
        msgid = self.conn.search_ext(base_utf8,
                                     scope,
                                     filterstr_utf8,
                                     attrlist_utf8,
                                     serverctrls=[lc])
        # Endless loop request pages on ldap server until it has no data
        while True:
            # Request to the ldap server a page with 'page_size' entries
            rtype, rdata, rmsgid, serverctrls = self.conn.result3(msgid)
            # Receive the data
            res.extend(rdata)
            pctrls = [c for c in serverctrls
                      if c.controlType == page_ctrl_oid]
            if pctrls:
                # LDAP server supports pagination
                if use_old_paging_api:
                    est, cookie = pctrls[0].controlValue
                    lc.controlValue = (self.page_size, cookie)
                else:
                    cookie = lc.cookie = pctrls[0].cookie

                if cookie:
                    # There is more data still on the server
                    # so we request another page
                    msgid = self.conn.search_ext(base_utf8,
                                                 scope,
                                                 filterstr_utf8,
                                                 attrlist_utf8,
                                                 serverctrls=[lc])
                else:
                    # Exit condition no more data on server
                    break
            else:
                LOG.warning(_LW('LDAP Server does not support paging. '
                                'Disable paging in keystone.conf to '
                                'avoid this message.'))
                self._disable_paging()
                break
        return res

    def result3(self, msgid=ldap.RES_ANY, all=1, timeout=None,
                resp_ctrl_classes=None):
        ldap_result = self.conn.result3(msgid, all, timeout, resp_ctrl_classes)

        LOG.debug('LDAP result3: msgid=%s all=%s timeout=%s '
                  'resp_ctrl_classes=%s ldap_result=%s',
                  msgid, all, timeout, resp_ctrl_classes, ldap_result)

        py_result = convert_ldap_result(ldap_result)
        return py_result

    def modify_s(self, dn, modlist):
        ldap_modlist = [
            (op, kind, (None if values is None
                        else [py2ldap(x) for x in safe_iter(values)]))
            for op, kind, values in modlist]

        logging_modlist = [(op, kind, (values if kind != 'userPassword'
                           else ['****']))
                           for op, kind, values in ldap_modlist]
        LOG.debug('LDAP modify: dn=%s modlist=%s',
                  dn, logging_modlist)

        dn_utf8 = utf8_encode(dn)
        ldap_modlist_utf8 = [
            (op, kind, (None if values is None
                        else [utf8_encode(x) for x in safe_iter(values)]))
            for op, kind, values in ldap_modlist]
        return self.conn.modify_s(dn_utf8, ldap_modlist_utf8)

    def delete_s(self, dn):
        LOG.debug("LDAP delete: dn=%s", dn)
        dn_utf8 = utf8_encode(dn)
        return self.conn.delete_s(dn_utf8)

    def delete_ext_s(self, dn, serverctrls=None, clientctrls=None):
        LOG.debug('LDAP delete_ext: dn=%s serverctrls=%s clientctrls=%s',
                  dn, serverctrls, clientctrls)
        dn_utf8 = utf8_encode(dn)
        return self.conn.delete_ext_s(dn_utf8, serverctrls, clientctrls)

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.unbind_s()


_HANDLERS = {}


def register_handler(prefix, handler):
    _HANDLERS[prefix] = handler


def _get_connection(conn_url, use_pool=False, use_auth_pool=False):
    for prefix, handler in _HANDLERS.items():
        if conn_url.startswith(prefix):
            return handler()

    if use_pool:
        return PooledLDAPHandler(use_auth_pool=use_auth_pool)
    else:
        return PythonLDAPHandler()


def filter_entity(entity_ref):
    """Filter out private items in an entity dict.

    :param entity_ref:  the entity dictionary. The 'dn' field will be removed.
        'dn' is used in LDAP, but should not be returned to the user.  This
        value may be modified.

    :returns: entity_ref

    """
    if entity_ref:
        entity_ref.pop('dn', None)
    return entity_ref


class BaseLdap(object):
    DEFAULT_OU = None
    DEFAULT_STRUCTURAL_CLASSES = None
    DEFAULT_ID_ATTR = 'cn'
    DEFAULT_OBJECTCLASS = None
    DEFAULT_FILTER = None
    DEFAULT_EXTRA_ATTR_MAPPING = []
    DUMB_MEMBER_DN = 'cn=dumb,dc=nonexistent'
    NotFound = None
    notfound_arg = None
    options_name = None
    model = None
    attribute_options_names = {}
    immutable_attrs = []
    attribute_ignore = []
    tree_dn = None

    def __init__(self, conf):
        self.LDAP_URL = conf.ldap.url
        self.LDAP_USER = conf.ldap.user
        self.LDAP_PASSWORD = conf.ldap.password
        self.LDAP_SCOPE = ldap_scope(conf.ldap.query_scope)
        self.alias_dereferencing = parse_deref(conf.ldap.alias_dereferencing)
        self.page_size = conf.ldap.page_size
        self.use_tls = conf.ldap.use_tls
        self.tls_cacertfile = conf.ldap.tls_cacertfile
        self.tls_cacertdir = conf.ldap.tls_cacertdir
        self.tls_req_cert = parse_tls_cert(conf.ldap.tls_req_cert)
        self.attribute_mapping = {}
        self.chase_referrals = conf.ldap.chase_referrals
        self.debug_level = conf.ldap.debug_level

        # LDAP Pool specific attribute
        self.use_pool = conf.ldap.use_pool
        self.pool_size = conf.ldap.pool_size
        self.pool_retry_max = conf.ldap.pool_retry_max
        self.pool_retry_delay = conf.ldap.pool_retry_delay
        self.pool_conn_timeout = conf.ldap.pool_connection_timeout
        self.pool_conn_lifetime = conf.ldap.pool_connection_lifetime

        # End user authentication pool specific config attributes
        self.use_auth_pool = self.use_pool and conf.ldap.use_auth_pool
        self.auth_pool_size = conf.ldap.auth_pool_size
        self.auth_pool_conn_lifetime = conf.ldap.auth_pool_connection_lifetime

        if self.options_name is not None:
            self.suffix = conf.ldap.suffix
            dn = '%s_tree_dn' % self.options_name
            self.tree_dn = (getattr(conf.ldap, dn)
                            or '%s,%s' % (self.DEFAULT_OU, self.suffix))

            idatt = '%s_id_attribute' % self.options_name
            self.id_attr = getattr(conf.ldap, idatt) or self.DEFAULT_ID_ATTR

            objclass = '%s_objectclass' % self.options_name
            self.object_class = (getattr(conf.ldap, objclass)
                                 or self.DEFAULT_OBJECTCLASS)

            for k, v in self.attribute_options_names.items():
                v = '%s_%s_attribute' % (self.options_name, v)
                self.attribute_mapping[k] = getattr(conf.ldap, v)

            attr_mapping_opt = ('%s_additional_attribute_mapping' %
                                self.options_name)
            attr_mapping = (getattr(conf.ldap, attr_mapping_opt)
                            or self.DEFAULT_EXTRA_ATTR_MAPPING)
            self.extra_attr_mapping = self._parse_extra_attrs(attr_mapping)

            ldap_filter = '%s_filter' % self.options_name
            self.ldap_filter = getattr(conf.ldap,
                                       ldap_filter) or self.DEFAULT_FILTER

            allow_create = '%s_allow_create' % self.options_name
            self.allow_create = getattr(conf.ldap, allow_create)

            allow_update = '%s_allow_update' % self.options_name
            self.allow_update = getattr(conf.ldap, allow_update)

            allow_delete = '%s_allow_delete' % self.options_name
            self.allow_delete = getattr(conf.ldap, allow_delete)

            member_attribute = '%s_member_attribute' % self.options_name
            self.member_attribute = getattr(conf.ldap, member_attribute, None)

            self.structural_classes = self.DEFAULT_STRUCTURAL_CLASSES

            if self.notfound_arg is None:
                self.notfound_arg = self.options_name + '_id'

            attribute_ignore = '%s_attribute_ignore' % self.options_name
            self.attribute_ignore = getattr(conf.ldap, attribute_ignore)

        self.use_dumb_member = conf.ldap.use_dumb_member
        self.dumb_member = (conf.ldap.dumb_member or
                            self.DUMB_MEMBER_DN)

        self.subtree_delete_enabled = conf.ldap.allow_subtree_delete

    def _not_found(self, object_id):
        if self.NotFound is None:
            return exception.NotFound(target=object_id)
        else:
            return self.NotFound(**{self.notfound_arg: object_id})

    def _parse_extra_attrs(self, option_list):
        mapping = {}
        for item in option_list:
            try:
                ldap_attr, attr_map = item.split(':')
            except Exception:
                LOG.warn(_LW(
                    'Invalid additional attribute mapping: "%s". '
                    'Format must be <ldap_attribute>:<keystone_attribute>'),
                    item)
                continue
            mapping[ldap_attr] = attr_map
        return mapping

    def _is_dumb_member(self, member_dn):
        """Checks that member is a dumb member.

        :param member_dn: DN of member to be checked.
        """
        return (self.use_dumb_member
                and is_dn_equal(member_dn, self.dumb_member))

    def get_connection(self, user=None, password=None, end_user_auth=False):
        use_pool = self.use_pool
        pool_size = self.pool_size
        pool_conn_lifetime = self.pool_conn_lifetime

        if end_user_auth:
            if not self.use_auth_pool:
                use_pool = False
            else:
                pool_size = self.auth_pool_size
                pool_conn_lifetime = self.auth_pool_conn_lifetime

        conn = _get_connection(self.LDAP_URL, use_pool,
                               use_auth_pool=end_user_auth)

        conn = KeystoneLDAPHandler(conn=conn)

        conn.connect(self.LDAP_URL,
                     page_size=self.page_size,
                     alias_dereferencing=self.alias_dereferencing,
                     use_tls=self.use_tls,
                     tls_cacertfile=self.tls_cacertfile,
                     tls_cacertdir=self.tls_cacertdir,
                     tls_req_cert=self.tls_req_cert,
                     chase_referrals=self.chase_referrals,
                     debug_level=self.debug_level,
                     use_pool=use_pool,
                     pool_size=pool_size,
                     pool_retry_max=self.pool_retry_max,
                     pool_retry_delay=self.pool_retry_delay,
                     pool_conn_timeout=self.pool_conn_timeout,
                     pool_conn_lifetime=pool_conn_lifetime
                     )

        if user is None:
            user = self.LDAP_USER

        if password is None:
            password = self.LDAP_PASSWORD

        # not all LDAP servers require authentication, so we don't bind
        # if we don't have any user/pass
        if user and password:
            conn.simple_bind_s(user, password)

        return conn

    def _id_to_dn_string(self, object_id):
        return u'%s=%s,%s' % (self.id_attr,
                              ldap.dn.escape_dn_chars(
                                  six.text_type(object_id)),
                              self.tree_dn)

    def _id_to_dn(self, object_id):
        if self.LDAP_SCOPE == ldap.SCOPE_ONELEVEL:
            return self._id_to_dn_string(object_id)
        with self.get_connection() as conn:
            search_result = conn.search_s(
                self.tree_dn, self.LDAP_SCOPE,
                u'(&(%(id_attr)s=%(id)s)(objectclass=%(objclass)s))' %
                {'id_attr': self.id_attr,
                 'id': ldap.filter.escape_filter_chars(
                     six.text_type(object_id)),
                 'objclass': self.object_class},
                attrlist=DN_ONLY)
        if search_result:
            dn, attrs = search_result[0]
            return dn
        else:
            return self._id_to_dn_string(object_id)

    @staticmethod
    def _dn_to_id(dn):
        return utf8_decode(ldap.dn.str2dn(utf8_encode(dn))[0][0][1])

    def _ldap_res_to_model(self, res):
        # LDAP attribute names may be returned in a different case than
        # they are defined in the mapping, so we need to check for keys
        # in a case-insensitive way.  We use the case specified in the
        # mapping for the model to ensure we have a predictable way of
        # retrieving values later.
        lower_res = {k.lower(): v for k, v in res[1].items()}

        id_attrs = lower_res.get(self.id_attr.lower())
        if not id_attrs:
            message = _('ID attribute %(id_attr)s not found in LDAP '
                        'object %(dn)s') % ({'id_attr': self.id_attr,
                                             'dn': res[0]})
            raise exception.NotFound(message=message)
        if len(id_attrs) > 1:
            # FIXME(gyee): if this is a multi-value attribute and it has
            # multiple values, we can't use it as ID. Retain the dn_to_id
            # logic here so it does not potentially break existing
            # deployments. We need to fix our read-write LDAP logic so
            # it does not get the ID from DN.
            message = _LW('ID attribute %(id_attr)s for LDAP object %(dn)s '
                          'has multiple values and therefore cannot be used '
                          'as an ID. Will get the ID from DN instead') % (
                              {'id_attr': self.id_attr,
                               'dn': res[0]})
            LOG.warn(message)
            id_val = self._dn_to_id(res[0])
        else:
            id_val = id_attrs[0]
        obj = self.model(id=id_val)

        for k in obj.known_keys:
            if k in self.attribute_ignore:
                continue

            try:
                map_attr = self.attribute_mapping.get(k, k)
                if map_attr is None:
                    # Ignore attributes that are mapped to None.
                    continue

                v = lower_res[map_attr.lower()]
            except KeyError:
                pass
            else:
                try:
                    obj[k] = v[0]
                except IndexError:
                    obj[k] = None

        return obj

    def check_allow_create(self):
        if not self.allow_create:
            action = _('LDAP %s create') % self.options_name
            raise exception.ForbiddenAction(action=action)

    def check_allow_update(self):
        if not self.allow_update:
            action = _('LDAP %s update') % self.options_name
            raise exception.ForbiddenAction(action=action)

    def check_allow_delete(self):
        if not self.allow_delete:
            action = _('LDAP %s delete') % self.options_name
            raise exception.ForbiddenAction(action=action)

    def affirm_unique(self, values):
        if values.get('name') is not None:
            try:
                self.get_by_name(values['name'])
            except exception.NotFound:
                pass
            else:
                raise exception.Conflict(type=self.options_name,
                                         details=_('Duplicate name, %s.') %
                                         values['name'])

        if values.get('id') is not None:
            try:
                self.get(values['id'])
            except exception.NotFound:
                pass
            else:
                raise exception.Conflict(type=self.options_name,
                                         details=_('Duplicate ID, %s.') %
                                         values['id'])

    def create(self, values):
        self.affirm_unique(values)
        object_classes = self.structural_classes + [self.object_class]
        attrs = [('objectClass', object_classes)]
        for k, v in values.items():
            if k in self.attribute_ignore:
                continue
            if k == 'id':
                # no need to check if v is None as 'id' will always have
                # a value
                attrs.append((self.id_attr, [v]))
            elif v is not None:
                attr_type = self.attribute_mapping.get(k, k)
                if attr_type is not None:
                    attrs.append((attr_type, [v]))
                extra_attrs = [attr for attr, name
                               in self.extra_attr_mapping.items()
                               if name == k]
                for attr in extra_attrs:
                    attrs.append((attr, [v]))

        if 'groupOfNames' in object_classes and self.use_dumb_member:
            attrs.append(('member', [self.dumb_member]))
        with self.get_connection() as conn:
            conn.add_s(self._id_to_dn(values['id']), attrs)
        return values

    def _ldap_get(self, object_id, ldap_filter=None):
        query = (u'(&(%(id_attr)s=%(id)s)'
                 u'%(filter)s'
                 u'(objectClass=%(object_class)s))'
                 % {'id_attr': self.id_attr,
                    'id': ldap.filter.escape_filter_chars(
                        six.text_type(object_id)),
                    'filter': (ldap_filter or self.ldap_filter or ''),
                    'object_class': self.object_class})
        with self.get_connection() as conn:
            try:
                attrs = list(set(([self.id_attr] +
                                  list(self.attribute_mapping.values()) +
                                  list(self.extra_attr_mapping.keys()))))
                res = conn.search_s(self.tree_dn,
                                    self.LDAP_SCOPE,
                                    query,
                                    attrs)
            except ldap.NO_SUCH_OBJECT:
                return None
        try:
            return res[0]
        except IndexError:
            return None

    def _ldap_get_all(self, ldap_filter=None):
        query = u'(&%s(objectClass=%s)(%s=*))' % (
            ldap_filter or self.ldap_filter or '',
            self.object_class,
            self.id_attr)
        with self.get_connection() as conn:
            try:
                attrs = list(set(([self.id_attr] +
                                  list(self.attribute_mapping.values()) +
                                  list(self.extra_attr_mapping.keys()))))
                return conn.search_s(self.tree_dn,
                                     self.LDAP_SCOPE,
                                     query,
                                     attrs)
            except ldap.NO_SUCH_OBJECT:
                return []

    def _ldap_get_list(self, search_base, scope, query_params=None,
                       attrlist=None):
        query = u'(objectClass=%s)' % self.object_class
        if query_params:

            def calc_filter(attrname, value):
                val_esc = ldap.filter.escape_filter_chars(value)
                return '(%s=%s)' % (attrname, val_esc)

            query = (u'(&%s%s)' %
                     (query, ''.join([calc_filter(k, v) for k, v in
                                      query_params.items()])))
        with self.get_connection() as conn:
            return conn.search_s(search_base, scope, query, attrlist)

    def get(self, object_id, ldap_filter=None):
        res = self._ldap_get(object_id, ldap_filter)
        if res is None:
            raise self._not_found(object_id)
        else:
            return self._ldap_res_to_model(res)

    def get_by_name(self, name, ldap_filter=None):
        query = (u'(%s=%s)' % (self.attribute_mapping['name'],
                               ldap.filter.escape_filter_chars(
                                   six.text_type(name))))
        res = self.get_all(query)
        try:
            return res[0]
        except IndexError:
            raise self._not_found(name)

    def get_all(self, ldap_filter=None):
        return [self._ldap_res_to_model(x)
                for x in self._ldap_get_all(ldap_filter)]

    def update(self, object_id, values, old_obj=None):
        if old_obj is None:
            old_obj = self.get(object_id)

        modlist = []
        for k, v in values.items():
            if k == 'id':
                # id can't be modified.
                continue

            if k in self.attribute_ignore:

                # Handle 'enabled' specially since can't disable if ignored.
                if k == 'enabled' and (not v):
                    action = _("Disabling an entity where the 'enable' "
                               "attribute is ignored by configuration.")
                    raise exception.ForbiddenAction(action=action)

                continue

            # attribute value has not changed
            if k in old_obj and old_obj[k] == v:
                continue

            if k in self.immutable_attrs:
                msg = (_("Cannot change %(option_name)s %(attr)s") %
                       {'option_name': self.options_name, 'attr': k})
                raise exception.ValidationError(msg)

            if v is None:
                if old_obj.get(k) is not None:
                    modlist.append((ldap.MOD_DELETE,
                                    self.attribute_mapping.get(k, k),
                                    None))
                continue

            current_value = old_obj.get(k)
            if current_value is None:
                op = ldap.MOD_ADD
                modlist.append((op, self.attribute_mapping.get(k, k), [v]))
            elif current_value != v:
                op = ldap.MOD_REPLACE
                modlist.append((op, self.attribute_mapping.get(k, k), [v]))

        if modlist:
            with self.get_connection() as conn:
                try:
                    conn.modify_s(self._id_to_dn(object_id), modlist)
                except ldap.NO_SUCH_OBJECT:
                    raise self._not_found(object_id)

        return self.get(object_id)

    def delete(self, object_id):
        with self.get_connection() as conn:
            try:
                conn.delete_s(self._id_to_dn(object_id))
            except ldap.NO_SUCH_OBJECT:
                raise self._not_found(object_id)

    def deleteTree(self, object_id):
        tree_delete_control = ldap.controls.LDAPControl(CONTROL_TREEDELETE,
                                                        0,
                                                        None)
        with self.get_connection() as conn:
            try:
                conn.delete_ext_s(self._id_to_dn(object_id),
                                  serverctrls=[tree_delete_control])
            except ldap.NO_SUCH_OBJECT:
                raise self._not_found(object_id)
            except ldap.NOT_ALLOWED_ON_NONLEAF:
                # Most LDAP servers do not support the tree_delete_control.
                # In these servers, the usual idiom is to first perform a
                # search to get the entries to delete, then delete them in
                # in order of child to parent, since LDAP forbids the
                # deletion of a parent entry before deleting the children
                # of that parent.  The simplest way to do that is to delete
                # the entries in order of the length of the DN, from longest
                # to shortest DN.
                dn = self._id_to_dn(object_id)
                scope = ldap.SCOPE_SUBTREE
                # With some directory servers, an entry with objectclass
                # ldapsubentry will not be returned unless it is explicitly
                # requested, by specifying the objectclass in the search
                # filter.  We must specify this, with objectclass=*, in an
                # LDAP filter OR clause, in order to return all entries
                filt = '(|(objectclass=*)(objectclass=ldapsubentry))'
                # We only need the DNs of the entries.  Since no attributes
                # will be returned, we do not have to specify attrsonly=1.
                entries = conn.search_s(dn, scope, filt, attrlist=DN_ONLY)
                if entries:
                    for dn in sorted((e[0] for e in entries),
                                     key=len, reverse=True):
                        conn.delete_s(dn)
                else:
                    LOG.debug('No entries in LDAP subtree %s', dn)

    def add_member(self, member_dn, member_list_dn):
        """Add member to the member list.

        :param member_dn: DN of member to be added.
        :param member_list_dn: DN of group to which the
                               member will be added.

        :raises: exception.Conflict: If the user was already a member.
                 self.NotFound: If the group entry didn't exist.
        """
        with self.get_connection() as conn:
            try:
                mod = (ldap.MOD_ADD, self.member_attribute, member_dn)
                conn.modify_s(member_list_dn, [mod])
            except ldap.TYPE_OR_VALUE_EXISTS:
                raise exception.Conflict(_('Member %(member)s '
                                           'is already a member'
                                           ' of group %(group)s') % {
                                         'member': member_dn,
                                         'group': member_list_dn})
            except ldap.NO_SUCH_OBJECT:
                raise self._not_found(member_list_dn)

    def remove_member(self, member_dn, member_list_dn):
        """Remove member from the member list.

        :param member_dn: DN of member to be removed.
        :param member_list_dn: DN of group from which the
                               member will be removed.

        :raises: self.NotFound: If the group entry didn't exist.
                 ldap.NO_SUCH_ATTRIBUTE: If the user wasn't a member.
        """
        with self.get_connection() as conn:
            try:
                mod = (ldap.MOD_DELETE, self.member_attribute, member_dn)
                conn.modify_s(member_list_dn, [mod])
            except ldap.NO_SUCH_OBJECT:
                raise self._not_found(member_list_dn)

    def _delete_tree_nodes(self, search_base, scope, query_params=None):
        query = u'(objectClass=%s)' % self.object_class
        if query_params:
            query = (u'(&%s%s)' %
                     (query, ''.join(['(%s=%s)'
                                      % (k, ldap.filter.escape_filter_chars(v))
                                      for k, v in
                                      query_params.items()])))
        not_deleted_nodes = []
        with self.get_connection() as conn:
            try:
                nodes = conn.search_s(search_base, scope, query,
                                      attrlist=DN_ONLY)
            except ldap.NO_SUCH_OBJECT:
                LOG.debug('Could not find entry with dn=%s', search_base)
                raise self._not_found(self._dn_to_id(search_base))
            else:
                for node_dn, _t in nodes:
                    try:
                        conn.delete_s(node_dn)
                    except ldap.NO_SUCH_OBJECT:
                        not_deleted_nodes.append(node_dn)

        if not_deleted_nodes:
            LOG.warn(_LW("When deleting entries for %(search_base)s, could not"
                         " delete nonexistent entries %(entries)s%(dots)s"),
                     {'search_base': search_base,
                      'entries': not_deleted_nodes[:3],
                      'dots': '...' if len(not_deleted_nodes) > 3 else ''})

    def filter_query(self, hints, query=None):
        """Applies filtering to a query.

        :param hints: contains the list of filters, which may be None,
                      indicating that there are no filters to be applied.
                      If it's not None, then any filters satisfied here will be
                      removed so that the caller will know if any filters
                      remain to be applied.
        :param query: LDAP query into which to include filters

        :returns query: LDAP query, updated with any filters satisfied

        """
        def build_filter(filter_, hints):
            """Build a filter for the query.

            :param filter_: the dict that describes this filter
            :param hints: contains the list of filters yet to be satisfied.

            :returns query: LDAP query term to be added

            """
            ldap_attr = self.attribute_mapping[filter_['name']]
            val_esc = ldap.filter.escape_filter_chars(filter_['value'])

            if filter_['case_sensitive']:
                # NOTE(henry-nash): Although dependent on the schema being
                # used, most LDAP attributes are configured with case
                # insensitive matching rules, so we'll leave this to the
                # controller to filter.
                return

            if filter_['name'] == 'enabled':
                # NOTE(henry-nash): Due to the different options for storing
                # the enabled attribute (e,g, emulated or not), for now we
                # don't try and filter this at the driver level - we simply
                # leave the filter to be handled by the controller. It seems
                # unlikley that this will cause a signifcant performance
                # issue.
                return

            # TODO(henry-nash): Currently there are no booleans (other than
            # 'enabled' that is handled above) on which you can filter. If
            # there were, we would need to add special handling here to
            # convert the booleans values to 'TRUE' and 'FALSE'. To do that
            # we would also need to know which filter keys were actually
            # booleans (this is related to bug #1411478).

            if filter_['comparator'] == 'equals':
                query_term = (u'(%(attr)s=%(val)s)'
                              % {'attr': ldap_attr, 'val': val_esc})
            elif filter_['comparator'] == 'contains':
                query_term = (u'(%(attr)s=*%(val)s*)'
                              % {'attr': ldap_attr, 'val': val_esc})
            elif filter_['comparator'] == 'startswith':
                query_term = (u'(%(attr)s=%(val)s*)'
                              % {'attr': ldap_attr, 'val': val_esc})
            elif filter_['comparator'] == 'endswith':
                query_term = (u'(%(attr)s=*%(val)s)'
                              % {'attr': ldap_attr, 'val': val_esc})
            else:
                # It's a filter we don't understand, so let the caller
                # work out if they need to do something with it.
                return

            return query_term

        if query is None:
            # make sure query is a string so the ldap filter is properly
            # constructed from filter_list later
            query = ''

        if hints is None:
            return query

        filter_list = []
        satisfied_filters = []

        for filter_ in hints.filters:
            if filter_['name'] not in self.attribute_mapping:
                continue
            new_filter = build_filter(filter_, hints)
            if new_filter is not None:
                filter_list.append(new_filter)
                satisfied_filters.append(filter_)

        if filter_list:
            query = u'(&%s%s)' % (query, ''.join(filter_list))

        # Remove satisfied filters, then the caller will know remaining filters
        for filter_ in satisfied_filters:
            hints.filters.remove(filter_)

        return query


class EnabledEmuMixIn(BaseLdap):
    """Emulates boolean 'enabled' attribute if turned on.

    Creates groupOfNames holding all enabled objects of this class, all missing
    objects are considered disabled.

    Options:

    * $name_enabled_emulation - boolean, on/off
    * $name_enabled_emulation_dn - DN of that groupOfNames, default is
      cn=enabled_${name}s,${tree_dn}

    Where ${name}s is the plural of self.options_name ('users' or 'tenants'),
    ${tree_dn} is self.tree_dn.
    """

    def __init__(self, conf):
        super(EnabledEmuMixIn, self).__init__(conf)
        enabled_emulation = '%s_enabled_emulation' % self.options_name
        self.enabled_emulation = getattr(conf.ldap, enabled_emulation)

        enabled_emulation_dn = '%s_enabled_emulation_dn' % self.options_name
        self.enabled_emulation_dn = getattr(conf.ldap, enabled_emulation_dn)
        if not self.enabled_emulation_dn:
            naming_attr_name = 'cn'
            naming_attr_value = 'enabled_%ss' % self.options_name
            sub_vals = (naming_attr_name, naming_attr_value, self.tree_dn)
            self.enabled_emulation_dn = '%s=%s,%s' % sub_vals
            naming_attr = (naming_attr_name, [naming_attr_value])
        else:
            # Extract the attribute name and value from the configured DN.
            naming_dn = ldap.dn.str2dn(utf8_encode(self.enabled_emulation_dn))
            naming_rdn = naming_dn[0][0]
            naming_attr = (utf8_decode(naming_rdn[0]),
                           utf8_decode(naming_rdn[1]))
        self.enabled_emulation_naming_attr = naming_attr

    def _get_enabled(self, object_id, conn):
        dn = self._id_to_dn(object_id)
        query = '(member=%s)' % dn
        try:
            enabled_value = conn.search_s(self.enabled_emulation_dn,
                                          ldap.SCOPE_BASE,
                                          query, attrlist=DN_ONLY)
        except ldap.NO_SUCH_OBJECT:
            return False
        else:
            return bool(enabled_value)

    def _add_enabled(self, object_id):
        with self.get_connection() as conn:
            if not self._get_enabled(object_id, conn):
                modlist = [(ldap.MOD_ADD,
                            'member',
                            [self._id_to_dn(object_id)])]
                try:
                    conn.modify_s(self.enabled_emulation_dn, modlist)
                except ldap.NO_SUCH_OBJECT:
                    attr_list = [('objectClass', ['groupOfNames']),
                                 ('member', [self._id_to_dn(object_id)]),
                                 self.enabled_emulation_naming_attr]
                    if self.use_dumb_member:
                        attr_list[1][1].append(self.dumb_member)
                    conn.add_s(self.enabled_emulation_dn, attr_list)

    def _remove_enabled(self, object_id):
        modlist = [(ldap.MOD_DELETE,
                    'member',
                    [self._id_to_dn(object_id)])]
        with self.get_connection() as conn:
            try:
                conn.modify_s(self.enabled_emulation_dn, modlist)
            except (ldap.NO_SUCH_OBJECT, ldap.NO_SUCH_ATTRIBUTE):
                pass

    def create(self, values):
        if self.enabled_emulation:
            enabled_value = values.pop('enabled', True)
            ref = super(EnabledEmuMixIn, self).create(values)
            if 'enabled' not in self.attribute_ignore:
                if enabled_value:
                    self._add_enabled(ref['id'])
                ref['enabled'] = enabled_value
            return ref
        else:
            return super(EnabledEmuMixIn, self).create(values)

    def get(self, object_id, ldap_filter=None):
        with self.get_connection() as conn:
            ref = super(EnabledEmuMixIn, self).get(object_id, ldap_filter)
            if ('enabled' not in self.attribute_ignore and
                    self.enabled_emulation):
                ref['enabled'] = self._get_enabled(object_id, conn)
            return ref

    def get_all(self, ldap_filter=None):
        if 'enabled' not in self.attribute_ignore and self.enabled_emulation:
            # had to copy BaseLdap.get_all here to ldap_filter by DN
            tenant_list = [self._ldap_res_to_model(x)
                           for x in self._ldap_get_all(ldap_filter)
                           if x[0] != self.enabled_emulation_dn]
            with self.get_connection() as conn:
                for tenant_ref in tenant_list:
                    tenant_ref['enabled'] = self._get_enabled(
                        tenant_ref['id'], conn)
            return tenant_list
        else:
            return super(EnabledEmuMixIn, self).get_all(ldap_filter)

    def update(self, object_id, values, old_obj=None):
        if 'enabled' not in self.attribute_ignore and self.enabled_emulation:
            data = values.copy()
            enabled_value = data.pop('enabled', None)
            ref = super(EnabledEmuMixIn, self).update(object_id, data, old_obj)
            if enabled_value is not None:
                if enabled_value:
                    self._add_enabled(object_id)
                else:
                    self._remove_enabled(object_id)
                ref['enabled'] = enabled_value
            return ref
        else:
            return super(EnabledEmuMixIn, self).update(
                object_id, values, old_obj)

    def delete(self, object_id):
        if self.enabled_emulation:
            self._remove_enabled(object_id)
        super(EnabledEmuMixIn, self).delete(object_id)


class ProjectLdapStructureMixin(object):
    """Project LDAP Structure shared between LDAP backends.

    This is shared between the resource and assignment LDAP backends.

    """
    DEFAULT_OU = 'ou=Groups'
    DEFAULT_STRUCTURAL_CLASSES = []
    DEFAULT_OBJECTCLASS = 'groupOfNames'
    DEFAULT_ID_ATTR = 'cn'
    NotFound = exception.ProjectNotFound
    notfound_arg = 'project_id'  # NOTE(yorik-sar): while options_name = tenant
    options_name = 'project'
    attribute_options_names = {'name': 'name',
                               'description': 'desc',
                               'enabled': 'enabled',
                               'domain_id': 'domain_id'}
    immutable_attrs = ['name']