freeipa/ipaserver/plugins/server.py

#
# Copyright (C) 2015  FreeIPA Contributors see COPYING for license
#

import dbus
import dbus.mainloop.glib
import ldap
import time

from ipalib import api, crud, errors, messages
from ipalib import Int, Flag, Str, DNSNameParam
from ipalib.plugable import Registry
from .baseldap import (
    LDAPSearch,
    LDAPRetrieve,
    LDAPDelete,
    LDAPObject,
    LDAPUpdate,
)
from ipalib.request import context
from ipalib import _, ngettext
from ipalib import output
from ipaplatform import services
from ipapython.dn import DN
from ipapython.dnsutil import DNSName
from ipaserver import topology
from ipaserver.servroles import ENABLED
from ipaserver.install import bindinstance, dnskeysyncinstance

__doc__ = _("""
IPA servers
""") + _("""
Get information about installed IPA servers.
""") + _("""
EXAMPLES:
""") + _("""
  Find all servers:
    ipa server-find
""") + _("""
  Show specific server:
    ipa server-show ipa.example.com
""")

register = Registry()


@register()
class server(LDAPObject):
    """
    IPA server
    """
    container_dn = api.env.container_masters
    object_name = _('server')
    object_name_plural = _('servers')
    object_class = ['top']
    possible_objectclasses = ['ipaLocationMember']
    search_attributes = ['cn']
    default_attributes = [
        'cn', 'iparepltopomanagedsuffix', 'ipamindomainlevel',
        'ipamaxdomainlevel', 'ipalocation', 'ipaserviceweight'
    ]
    label = _('IPA Servers')
    label_singular = _('IPA Server')
    attribute_members = {
        'iparepltopomanagedsuffix': ['topologysuffix'],
        'ipalocation': ['location'],
        'role': ['servrole'],
    }
    relationships = {
        'iparepltopomanagedsuffix': ('Managed', '', 'no_'),
        'ipalocation': ('IPA', 'in_', 'not_in_'),
        'role': ('Enabled', '', 'no_'),
    }
    permission_filter_objectclasses = ['ipaConfigObject']
    managed_permissions = {
        'System: Read Locations of IPA Servers': {
            'ipapermright': {'read', 'search', 'compare'},
            'ipapermdefaultattr': {
                'objectclass', 'cn', 'ipalocation', 'ipaserviceweight',
            },
            'default_privileges': {'DNS Administrators'},
        },
        'System: Read Status of Services on IPA Servers': {
            'ipapermright': {'read', 'search', 'compare'},
            'ipapermdefaultattr': {'objectclass', 'cn', 'ipaconfigstring'},
            'default_privileges': {'DNS Administrators'},
        }
    }

    takes_params = (
        Str(
            'cn',
            cli_name='name',
            primary_key=True,
            label=_('Server name'),
            doc=_('IPA server hostname'),
        ),
        Str(
            'iparepltopomanagedsuffix*',
            flags={'no_create', 'no_update', 'no_search'},
        ),
        Str(
            'iparepltopomanagedsuffix_topologysuffix*',
            label=_('Managed suffixes'),
            flags={'virtual_attribute', 'no_create', 'no_update', 'no_search'},
        ),
        Int(
            'ipamindomainlevel',
            cli_name='minlevel',
            label=_('Min domain level'),
            doc=_('Minimum domain level'),
            flags={'no_create', 'no_update'},
        ),
        Int(
            'ipamaxdomainlevel',
            cli_name='maxlevel',
            label=_('Max domain level'),
            doc=_('Maximum domain level'),
            flags={'no_create', 'no_update'},
        ),
        DNSNameParam(
            'ipalocation_location?',
            cli_name='location',
            label=_('Location'),
            doc=_('Server location'),
            only_relative=True,
            flags={'no_search'},
        ),
        Int(
            'ipaserviceweight?',
            cli_name='service_weight',
            label=_('Service weight'),
            doc=_('Weight for server services'),
            minvalue=0,
            maxvalue=65535,
            flags={'no_search'},
        ),
        Str(
            'service_relative_weight',
            label=_('Service relative weight'),
            doc=_('Relative weight for server services (counts per location)'),
            flags={'virtual_attribute','no_create', 'no_update', 'no_search'},
        ),
        Str(
            'enabled_role_servrole*',
            label=_('Enabled server roles'),
            doc=_('List of enabled roles'),
            flags={'virtual_attribute', 'no_create', 'no_update', 'no_search'}
        ),
    )

    def _get_suffixes(self):
        suffixes = self.api.Command.topologysuffix_find(
            all=True, raw=True,
        )['result']
        suffixes = [(s['iparepltopoconfroot'][0], s['dn']) for s in suffixes]
        return suffixes

    def _apply_suffixes(self, entry, suffixes):
        # change suffix DNs to topologysuffix entry DNs
        # this fixes LDAPObject.convert_attribute_members() for suffixes
        suffixes = dict(suffixes)
        if 'iparepltopomanagedsuffix' in entry:
            entry['iparepltopomanagedsuffix'] = [
                suffixes.get(m, m) for m in entry['iparepltopomanagedsuffix']
            ]

    def normalize_location(self, kw, **options):
        """
        Return the DN of location
        """
        if 'ipalocation_location' in kw:
            location = kw.pop('ipalocation_location')
            kw['ipalocation'] = (
                [self.api.Object.location.get_dn(location)]
                if location is not None else location
            )

    def convert_location(self, entry_attrs, **options):
        """
        Return a location name from DN
        """
        if options.get('raw'):
            return

        converted_locations = [
            DNSName(location_dn['idnsname']) for
            location_dn in entry_attrs.pop('ipalocation', [])
        ]

        if converted_locations:
            entry_attrs['ipalocation_location'] = converted_locations

    def get_enabled_roles(self, entry_attrs, **options):
        if options.get('raw', False) or options.get('no_members', False):
            return

        enabled_roles = self.api.Command.server_role_find(
            server_server=entry_attrs['cn'][0], status=ENABLED)['result']

        enabled_role_names = [r[u'role_servrole'] for r in enabled_roles]

        entry_attrs['enabled_role_servrole'] = enabled_role_names


@register()
class server_mod(LDAPUpdate):
    __doc__ = _('Modify information about an IPA server.')

    msg_summary = _('Modified IPA server "%(value)s"')

    def args_options_2_entry(self, *args, **options):
        kw = super(server_mod, self).args_options_2_entry(
            *args, **options)
        self.obj.normalize_location(kw, **options)
        return kw

    def pre_callback(self, ldap, dn, entry_attrs, attrs_list, *keys, **options):
        assert isinstance(dn, DN)

        if entry_attrs.get('ipalocation'):
            if not ldap.entry_exists(entry_attrs['ipalocation'][0]):
                self.api.Object.location.handle_not_found(
                    options['ipalocation_location'])

        if 'ipalocation' or 'ipaserviceweight' in entry_attrs:
            server_entry = ldap.get_entry(dn, ['objectclass'])

            # we need to extend object with ipaLocationMember objectclass
            entry_attrs['objectclass'] = (
                server_entry['objectclass'] + ['ipalocationmember']
            )

        return dn

    def post_callback(self, ldap, dn, entry_attrs, *keys, **options):
        assert isinstance(dn, DN)
        self.obj.get_enabled_roles(entry_attrs)

        if 'ipalocation_location' in options:
            ipalocation = entry_attrs.get('ipalocation')
            if ipalocation:
                ipalocation = ipalocation[0]['idnsname']
            else:
                ipalocation = u''
            try:
                self.api.Command.dnsserver_mod(
                    keys[0],
                    setattr=[
                        u'idnsSubstitutionVariable;ipalocation={loc}'.format(
                            loc=ipalocation)
                    ]
                )
            except errors.EmptyModlist:
                pass
            except errors.NotFound:
                # server is not DNS server
                pass

        if 'ipalocation_location' or 'ipaserviceweight' in options:
            self.add_message(messages.ServiceRestartRequired(
                service=services.service('named').systemd_name,
                server=keys[0], ))

            result = self.api.Command.dns_update_system_records()
            if not result.get('value'):
                self.add_message(messages.AutomaticDNSRecordsUpdateFailed())
        self.obj.convert_location(entry_attrs, **options)

        ipalocation = entry_attrs.get('ipalocation_location', [None])[0]
        if ipalocation:
            servers_in_loc = self.api.Command.server_find(
                in_location=ipalocation, no_members=False)['result']
            dns_server_in_loc = False
            for server in servers_in_loc:
                if 'DNS server' in server.get('enabled_role_servrole', ()):
                    dns_server_in_loc = True
                    break
            if not dns_server_in_loc:
                self.add_message(messages.LocationWithoutDNSServer(
                    location=ipalocation
                ))

        return dn


@register()
class server_find(LDAPSearch):
    __doc__ = _('Search for IPA servers.')

    msg_summary = ngettext(
        '%(count)d IPA server matched',
        '%(count)d IPA servers matched', 0
    )

    member_attributes = ['iparepltopomanagedsuffix', 'ipalocation', 'role']

    def args_options_2_entry(self, *args, **options):
        kw = super(server_find, self).args_options_2_entry(
            *args, **options)
        self.obj.normalize_location(kw, **options)
        return kw

    def get_options(self):
        for option in super(server_find, self).get_options():
            if option.name == 'topologysuffix':
                option = option.clone(cli_name='topologysuffixes')
            elif option.name == 'no_topologysuffix':
                option = option.clone(cli_name='no_topologysuffixes')
            # we do not want to test negative membership for roles
            elif option.name == 'no_servrole':
                continue
            yield option

    def get_member_filter(self, ldap, **options):
        options.pop('topologysuffix', None)
        options.pop('no_topologysuffix', None)

        options.pop('servrole', None)

        return super(server_find, self).get_member_filter(
            ldap, **options)

    def _get_enabled_servrole_filter(self, ldap, servroles):
        """
        return a filter matching any master which has all the specified roles
        enabled.
        """
        def _get_masters_with_enabled_servrole(role):
            role_status = self.api.Command.server_role_find(
                server_server=None,
                role_servrole=role,
                status=ENABLED)['result']

            return set(
                r[u'server_server'] for r in role_status)

        enabled_masters = _get_masters_with_enabled_servrole(
            servroles[0])

        for role in servroles[1:]:
            enabled_masters.intersection_update(
                _get_masters_with_enabled_servrole(role)
            )

        if not enabled_masters:
            return '(!(objectclass=*))'

        return ldap.make_filter_from_attr(
            'cn',
            list(enabled_masters),
            rules=ldap.MATCH_ANY
        )

    def pre_callback(self, ldap, filters, attrs_list, base_dn, scope,
                     *args, **options):
        included = options.get('topologysuffix')
        excluded = options.get('no_topologysuffix')

        if included or excluded:
            topologysuffix = self.api.Object.topologysuffix
            suffixes = self.obj._get_suffixes()
            suffixes = {s[1]: s[0] for s in suffixes}

            if included:
                included = [topologysuffix.get_dn(pk) for pk in included]
                try:
                    included = [suffixes[dn] for dn in included]
                except KeyError:
                    # force empty result
                    filter = '(!(objectclass=*))'
                else:
                    filter = ldap.make_filter_from_attr(
                        'iparepltopomanagedsuffix', included, ldap.MATCH_ALL
                    )
                filters = ldap.combine_filters(
                    (filters, filter), ldap.MATCH_ALL
                )

            if excluded:
                excluded = [topologysuffix.get_dn(pk) for pk in excluded]
                excluded = [suffixes[dn] for dn in excluded if dn in suffixes]
                filter = ldap.make_filter_from_attr(
                    'iparepltopomanagedsuffix', excluded, ldap.MATCH_NONE
                )
                filters = ldap.combine_filters(
                    (filters, filter), ldap.MATCH_ALL
                )

        if options.get('servrole', []):
            servrole_filter = self._get_enabled_servrole_filter(
                ldap, options['servrole'])
            filters = ldap.combine_filters(
                (filters, servrole_filter), ldap.MATCH_ALL)

        return (filters, base_dn, scope)

    def post_callback(self, ldap, entries, truncated, *args, **options):
        if not options.get('raw', False):
            suffixes = self.obj._get_suffixes()
            for entry in entries:
                self.obj._apply_suffixes(entry, suffixes)

        for entry in entries:
            self.obj.convert_location(entry, **options)
            self.obj.get_enabled_roles(entry, **options)
        return truncated


@register()
class server_show(LDAPRetrieve):
    __doc__ = _('Show IPA server.')

    def post_callback(self, ldap, dn, entry, *keys, **options):
        if not options.get('raw', False):
            suffixes = self.obj._get_suffixes()
            self.obj._apply_suffixes(entry, suffixes)

        self.obj.convert_location(entry, **options)
        self.obj.get_enabled_roles(entry, **options)

        return dn


@register()
class server_del(LDAPDelete):
    __doc__ = _('Delete IPA server.')
    msg_summary = _('Deleted IPA server "%(value)s"')

    takes_options = LDAPDelete.takes_options + (
        Flag(
            'ignore_topology_disconnect?',
            label=_('Ignore topology errors'),
            doc=_('Ignore topology connectivity problems after removal'),
            default=False,
        ),
        Flag(
            'ignore_last_of_role?',
            label=_('Ignore check for last remaining CA or DNS server'),
            doc=_('Skip a check whether the last CA master or DNS server is '
                  'removed'),
            default=False,
        ),
        Flag(
            'force?',
            label=_('Force server removal'),
            doc=_('Force server removal even if it does not exist'),
            default=False,
        ),
    )

    def _ensure_last_of_role(self, hostname, ignore_last_of_role=False):
        """
        1. When deleting server, check if there will be at least one remaining
           DNS and CA server.
        2. Pick CA renewal master
        """
        def handler(msg, ignore_last_of_role):
            if ignore_last_of_role:
                self.add_message(
                    messages.ServerRemovalWarning(
                        message=msg
                    )
                )
            else:
                raise errors.ServerRemovalError(reason=_(msg))

        ipa_config = self.api.Command.config_show()['result']
        dns_config = self.api.Command.dnsconfig_show()['result']

        ipa_masters = ipa_config['ipa_master_server']

        # skip these checks if the last master is being removed
        if ipa_masters == [hostname]:
            return

        ca_servers = ipa_config['ca_server_server']
        ca_renewal_master = ipa_config['ca_renewal_master_server']
        dns_servers = dns_config['dns_server_server']
        dnssec_keymaster = dns_config['dnssec_key_master_server']

        if ca_servers == [hostname]:
            raise errors.ServerRemovalError(
                reason=_("Deleting this server is not allowed as it would "
                         "leave your installation without a CA."))

        if dnssec_keymaster == hostname:
            handler(
                _("Replica is active DNSSEC key master. Uninstall "
                  "could break your DNS system. Please disable or "
                  "replace DNSSEC key master first."), ignore_last_of_role)

        if dns_servers == [hostname]:
            handler(
                _("Deleting this server will leave your installation "
                  "without a DNS."), ignore_last_of_role)

        if ignore_last_of_role:
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_("Ignoring these warnings and proceeding with "
                              "removal")))

        if ca_renewal_master == hostname:
            other_cas = [ca for ca in ca_servers if ca != hostname]

            # if this is the last CA there is no other server to become renewal
            # master
            if not other_cas:
                return

            self.api.Command.config_mod(ca_renewal_master_server=other_cas[0])

    def _check_topology_connectivity(self, topology_connectivity, master_cn):
        try:
            topology_connectivity.check_current_state()
        except ValueError as e:
            raise errors.ServerRemovalError(reason=e)

        try:
            topology_connectivity.check_state_after_removal(master_cn)
        except ValueError as e:
            raise errors.ServerRemovalError(reason=e)

    def _remove_server_principal_references(self, master):
        """
        This method removes information about the replica in parts
        of the shared tree that expose it, so clients stop trying to
        use this replica.
        """
        conn = self.Backend.ldap2
        env = self.api.env

        master_principal = "{}@{}".format(master, env)

        # remove replica memberPrincipal from s4u2proxy configuration
        s4u2proxy_subtree = DN(env.container_s4u2proxy,
                               env.basedn)
        dn1 = DN(('cn', 'ipa-http-delegation'), s4u2proxy_subtree)
        member_principal1 = "HTTP/{}".format(master_principal)

        dn2 = DN(('cn', 'ipa-ldap-delegation-targets'), s4u2proxy_subtree)
        member_principal2 = "ldap/{}".format(master_principal)

        dn3 = DN(('cn', 'ipa-cifs-delegation-targets'), s4u2proxy_subtree)
        member_principal3 = "cifs/{}".format(master_principal)

        for (dn, member_principal) in ((dn1, member_principal1),
                                       (dn2, member_principal2),
                                       (dn3, member_principal3)):
            try:
                mod = [(ldap.MOD_DELETE, 'memberPrincipal', member_principal)]
                conn.conn.modify_s(str(dn), mod)
            except (ldap.NO_SUCH_OBJECT, ldap.NO_SUCH_ATTRIBUTE):
                self.log.debug(
                    "Replica (%s) memberPrincipal (%s) not found in %s" %
                    (master, member_principal, dn))
            except Exception as e:
                self.add_message(
                    messages.ServerRemovalWarning(
                        message=_("Failed to clean memberPrincipal "
                                  "%(principal)s from s4u2proxy entry %(dn)s: "
                                  "%(err)s") % dict(
                                      principal=member_principal,
                                      dn=dn, err=e)))

        try:
            etc_basedn = DN(('cn', 'etc'), env.basedn)
            filter = '(dnaHostname=%s)' % master
            entries = conn.get_entries(
                etc_basedn, ldap.SCOPE_SUBTREE, filter=filter)
            if len(entries) != 0:
                for entry in entries:
                    conn.delete_entry(entry)
        except errors.NotFound:
            pass
        except Exception as e:
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_(
                        "Failed to clean up DNA hostname entries for "
                        "%(master)s: %(err)s") % dict(master=master, err=e)))

        try:
            dn = DN(('cn', 'default'), ('ou', 'profile'), env.basedn)
            ret = conn.get_entry(dn)
            srvlist = ret.single_value.get('defaultServerList', '')
            srvlist = srvlist[0].split()
            if master in srvlist:
                srvlist.remove(master)
                attr = ' '.join(srvlist)
                mod = [(ldap.MOD_REPLACE, 'defaultServerList', attr)]
                conn.conn.modify_s(str(dn), mod)
        except (errors.NotFound, ldap.NO_SUCH_ATTRIBUTE,
                ldap.TYPE_OR_VALUE_EXISTS):
            pass
        except Exception as e:
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_("Failed to remove server %(master)s from server "
                              "list: %(err)s") % dict(master=master, err=e)))

    def _remove_server_host_services(self, ldap, master):
        """
        delete server kerberos key and all its svc principals
        """
        try:
            entries = ldap.get_entries(
                self.api.env.basedn, ldap.SCOPE_SUBTREE,
                filter='(krbprincipalname=*/{}@{})'.format(
                    master, self.api.env.realm))

            if entries:
                entries.sort(key=lambda x: len(x.dn), reverse=True)
                for entry in entries:
                    ldap.delete_entry(entry)
        except errors.NotFound:
            pass
        except Exception as e:
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_("Failed to cleanup server principals/keys: "
                              "%(err)s") % dict(err=e)))

    def _cleanup_server_dns_records(self, hostname, **options):
        if not self.api.Command.dns_is_enabled(
                **options):
            return

        try:
            bindinstance.remove_master_dns_records(
                hostname, self.api.env.realm)
            dnskeysyncinstance.remove_replica_public_keys(hostname)
        except Exception as e:
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_(
                        "Failed to cleanup %(hostname)s DNS entries: "
                        "%(err)s") % dict(hostname=hostname, err=e)))

            self.add_message(
                messages.ServerRemovalWarning(
                    message=_("You may need to manually remove them from the "
                              "tree")))

    def pre_callback(self, ldap, dn, *keys, **options):
        pkey = self.obj.get_primary_key_from_dn(dn)

        if options.get('force', False):
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_("Forcing removal of %(hostname)s") % dict(
                        hostname=pkey)))

        # check the topology errors before and after removal
        self.context.topology_connectivity = topology.TopologyConnectivity(
            self.api)

        if options.get('ignore_topology_disconnect', False):
            self.add_message(
                messages.ServerRemovalWarning(
                    message=_("Ignoring topology connectivity errors.")))
        else:
            self._check_topology_connectivity(
                self.context.topology_connectivity, pkey)

        # ensure that we are not removing last CA/DNS server, DNSSec master and
        # CA renewal master
        self._ensure_last_of_role(
            pkey, ignore_last_of_role=options.get('ignore_last_of_role', False)
        )

        # remove the references to master's ldap/http principals
        self._remove_server_principal_references(pkey)

        # try to clean up the leftover DNS entries
        self._cleanup_server_dns_records(pkey)

        # finally destroy all Kerberos principals
        self._remove_server_host_services(ldap, pkey)

        return dn

    def exc_callback(self, keys, options, exc, call_func, *call_args,
                     **call_kwargs):
        if (options.get('force', False) and isinstance(exc, errors.NotFound)
                and call_func.__name__ == 'delete_entry'):
            self.add_message(
                message=messages.ServerRemovalWarning(
                    message=_("Server has already been deleted")))
            return

        raise exc

    def _check_deleted_segments(self, hostname, topology_connectivity,
                                starting_host):

        def wait_for_segment_removal(hostname, master_cns, suffix_name,
                                     orig_errors, new_errors):
            i = 0
            while True:
                left = self.api.Command.topologysegment_find(
                    suffix_name,
                    iparepltoposegmentleftnode=hostname,
                    sizelimit=0
                )['result']
                right = self.api.Command.topologysegment_find(
                    suffix_name,
                    iparepltoposegmentrightnode=hostname,
                    sizelimit=0
                )['result']

                # Relax check if topology was or is disconnected. Disconnected
                # topology can contain segments with already deleted servers
                # Check only if segments of servers, which can contact this
                # server, and the deleted server were removed.
                # This code should handle a case where there was a topology
                # with a central node(B):  A <-> B <-> C, where A is current
                # server. After removal of B, topology will be disconnected and
                # removal of segment B <-> C won't be replicated back to server
                # A, therefore presence of the segment has to be ignored.
                if orig_errors or new_errors:
                    # use errors after deletion because we don't care if some
                    # server can't contact the deleted one
                    cant_contact_me = [e[0] for e in new_errors
                                       if starting_host in e[2]]
                    can_contact_me = set(master_cns) - set(cant_contact_me)
                    left = [
                        s for s in left if s['iparepltoposegmentrightnode'][0]
                        in can_contact_me
                    ]
                    right = [
                        s for s in right if s['iparepltoposegmentleftnode'][0]
                        in can_contact_me
                    ]

                if not left and not right:
                    self.add_message(
                        messages.ServerRemovalInfo(
                            message=_("Agreements deleted")
                        ))
                    return
                time.sleep(2)
                if i == 2:  # taking too long, something is wrong, report
                    self.log.info(
                        "Waiting for removal of replication agreements")
                if i > 90:
                    self.log.info("Taking too long, skipping")
                    self.log.info("Following segments were not deleted:")
                    self.add_message(messages.ServerRemovalWarning(
                        message=_("Following segments were not deleted:")))
                    for s in left:
                        self.add_message(messages.ServerRemovalWarning(
                            message=u"  %s" % s['cn'][0]))
                    for s in right:
                        self.add_message(messages.ServerRemovalWarning(
                            message=u"  %s" % s['cn'][0]))
                    return
                i += 1

        topology_graphs = topology_connectivity.graphs

        orig_errors = topology_connectivity.errors
        new_errors = topology_connectivity.errors_after_master_removal(
            hostname
        )

        for suffix_name in topology_graphs:
            suffix_members = topology_graphs[suffix_name].vertices

            if hostname not in suffix_members:
                # If the server was already deleted, we can expect that all
                # removals had been done in previous run and dangling segments
                # were not deleted.
                self.log.info(
                    "Skipping replication agreement deletion check for "
                    "suffix '{0}'".format(suffix_name))
                continue

            self.log.info(
                "Checking for deleted segments in suffix '{0}'".format(
                    suffix_name))

            wait_for_segment_removal(
                hostname,
                list(suffix_members),
                suffix_name,
                orig_errors[suffix_name],
                new_errors[suffix_name])

    def post_callback(self, ldap, dn, *keys, **options):
        # there is no point in checking deleted segment on local host
        # we should do this only when removing other masters
        if self.api.env.host != keys[-1]:
            self._check_deleted_segments(
                keys[-1], self.context.topology_connectivity,
                self.api.env.host)

        return super(server_del, self).post_callback(
            ldap, dn, *keys, **options)


@register()
class server_conncheck(crud.PKQuery):
    __doc__ = _("Check connection to remote IPA server.")

    NO_CLI = True

    takes_args = (
        Str(
            'remote_cn',
            cli_name='remote_name',
            label=_('Remote server name'),
            doc=_('Remote IPA server hostname'),
        ),
    )

    has_output = output.standard_value

    def execute(self, *keys, **options):
        # the server must be the local host
        if keys[-2] != api.env.host:
            raise errors.ValidationError(
                name='cn', error=_("must be \"%s\"") % api.env.host)

        # the server entry must exist
        try:
            self.obj.get_dn_if_exists(*keys[:-1])
        except errors.NotFound:
            self.obj.handle_not_found(keys[-2])

        # the user must have the Replication Administrators privilege
        privilege = u'Replication Administrators'
        privilege_dn = self.api.Object.privilege.get_dn(privilege)
        ldap = self.obj.backend
        filter = ldap.make_filter({
            'krbprincipalname': context.principal,  # pylint: disable=no-member
            'memberof': privilege_dn},
            rules=ldap.MATCH_ALL)
        try:
            ldap.find_entries(base_dn=self.api.env.basedn, filter=filter)
        except errors.NotFound:
            raise errors.ACIError(
                info=_("not allowed to perform server connection check"))

        dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)

        bus = dbus.SystemBus()
        obj = bus.get_object('org.freeipa.server', '/',
                             follow_name_owner_changes=True)
        server = dbus.Interface(obj, 'org.freeipa.server')

        ret, stdout, stderr = server.conncheck(keys[-1])

        result = dict(
            result=(ret == 0),
            value=keys[-2],
        )

        for line in stdout.splitlines():
            messages.add_message(options['version'],
                                 result,
                                 messages.ExternalCommandOutput(line=line))

        return result