#!/usr/bin/python2
#
# Copyright (C) 2014  FreeIPA Contributors see COPYING for license
#
"""
This is FreeIPA's replacement for signerd from OpenDNSSEC suite version 1.4.x.

This program uses the same socket and protocol as original signerd and should
be activated via systemd socket activation using "ods-signer" command line
utility.

Alternativelly, it can be called directly and a command can be supplied as
first command line argument.

Purpose of this replacement is to upload keys generated by OpenDNSSEC to LDAP.
"""
from __future__ import print_function

from binascii import hexlify
from datetime import datetime
import dateutil.tz
import dns.dnssec
from gssapi.exceptions import GSSError
import logging
import os
import socket
import select
import sys
import systemd.daemon
import systemd.journal
import sqlite3
import traceback

import ipalib
from ipapython.dn import DN
from ipapython import ipaldap
from ipapython import ipautil
from ipaplatform.paths import paths

from ipapython.dnssec.abshsm import sync_pkcs11_metadata, wrappingmech_name2id
from ipapython.dnssec.ldapkeydb import LdapKeyDB
from ipapython.dnssec.localhsm import LocalHSM

DAEMONNAME = 'ipa-ods-exporter'
PRINCIPAL = None  # not initialized yet
WORKDIR = os.path.join(paths.VAR_OPENDNSSEC_DIR ,'tmp')
KEYTAB_FB = paths.IPA_ODS_EXPORTER_KEYTAB

ODS_SE_MAXLINE = 1024  # from ODS common/config.h
ODS_DB_LOCK_PATH = "%s%s" % (paths.OPENDNSSEC_KASP_DB, '.our_lock')

SECRETKEY_WRAPPING_MECH = 'rsaPkcsOaep'
PRIVKEY_WRAPPING_MECH = 'aesKeyWrapPad'

# Constants from OpenDNSSEC's enforcer/ksm/include/ksm/ksm.h
KSM_STATE_PUBLISH    = 2
KSM_STATE_READY      = 3
KSM_STATE_ACTIVE     = 4
KSM_STATE_RETIRE     = 5
KSM_STATE_DEAD       = 6
KSM_STATE_KEYPUBLISH = 10

# DNSKEY flag constants
dnskey_flag_by_value = {
    0x0001: 'SEP',
    0x0080: 'REVOKE',
    0x0100: 'ZONE'
}

def dnskey_flags_to_text_set(flags):
    """Convert a DNSKEY flags value to set texts
    @rtype: set([string])"""

    flags_set = set()
    mask = 0x1
    while mask <= 0x8000:
        if flags & mask:
            text = dnskey_flag_by_value.get(mask)
            if not text:
                text = hex(mask)
            flags_set.add(text)
        mask <<= 1
    return flags_set

def datetime2ldap(dt):
    return dt.strftime(ipalib.constants.LDAP_GENERALIZED_TIME_FORMAT)

def sql2datetime(sql_time):
    """Convert SQL date format from local time zone into UTC."""
    localtz = dateutil.tz.tzlocal()
    localtime = datetime.strptime(sql_time, "%Y-%m-%d %H:%M:%S").replace(
                                  tzinfo=localtz)
    utctz = dateutil.tz.gettz('UTC')
    return localtime.astimezone(utctz)

def sql2datetimes(row):
    row2key_map = {'generate': 'idnsSecKeyCreated',
                   'publish': 'idnsSecKeyPublish',
                   'active': 'idnsSecKeyActivate',
                   'retire': 'idnsSecKeyInactive',
                   'dead': 'idnsSecKeyDelete'}
    times = {}
    for column, key in row2key_map.items():
        if row[column] is not None:
            times[key] = sql2datetime(row[column])
    return times

def sql2ldap_algorithm(sql_algorithm):
    return {"idnsSecAlgorithm": dns.dnssec.algorithm_to_text(sql_algorithm)}

def sql2ldap_flags(sql_flags):
    dns_flags = dnskey_flags_to_text_set(sql_flags)
    ldap_flags = {}
    for flag in dns_flags:
        attr = 'idnsSecKey%s' % flag
        ldap_flags[attr] = 'TRUE'
    return ldap_flags

def sql2ldap_keyid(sql_keyid):
    assert len(sql_keyid) % 2 == 0
    assert len(sql_keyid) > 0
    # TODO: this is huge hack. BIND has some problems with % notation in URIs.
    # Workaround: OpenDNSSEC uses same value for ID also for label (but in hex).
    uri = "pkcs11:object=%s" % sql_keyid
    #uri += '%'.join(sql_keyid[i:i+2] for i in range(0, len(sql_keyid), 2))
    return {"idnsSecKeyRef": uri}

def ods2bind_timestamps(key_state, key_type, ods_times):
    """Transform (timestamps and key states) from ODS to set of BIND timestamps
    with equivalent meaning. At the same time, remove timestamps
    for future/planned state transitions to prevent ODS & BIND
    from desynchronizing.

    OpenDNSSEC database may contain timestamps for state transitions planned
    in the future, but timestamp itself is not sufficient information because
    there could be some additional condition which is guaded by OpenDNSSEC
    itself.

    BIND works directly with timestamps without any additional conditions.
    This difference causes problem when state transition planned in OpenDNSSEC
    does not happen as originally planned for some reason.

    At the same time, this difference causes problem when OpenDNSSEC on DNSSEC
    key master and BIND instances on replicas are not synchronized. This
    happens when DNSSEC key master is down, or a replication is down. Even
    a temporary desynchronization could cause DNSSEC validation failures
    which could have huge impact.

    To prevent this problem, this function removes all timestamps corresponding
    to future state transitions. As a result, BIND will not do state transition
    until it happens in OpenDNSSEC first and until the change is replicated.

    Also, timestamp mapping depends on key type and is not 1:1.
    For detailed description of the mapping please see
    https://fedorahosted.org/bind-dyndb-ldap/wiki/BIND9/Design/DNSSEC/OpenDNSSEC2BINDKeyStates
    """
    bind_times = {}
    # idnsSecKeyCreated is equivalent to SQL column 'created'
    bind_times['idnsSecKeyCreated'] = ods_times['idnsSecKeyCreated']

    # set of key states where publishing in DNS zone is desired is taken from
    # opendnssec/enforcer/ksm/ksm_request.c:KsmRequestIssueKeys()
    # TODO: support for RFC 5011, requires OpenDNSSEC v1.4.8+
    if ('idnsSecKeyPublish' in ods_times and
        key_state in {KSM_STATE_PUBLISH, KSM_STATE_READY, KSM_STATE_ACTIVE,
                      KSM_STATE_RETIRE, KSM_STATE_KEYPUBLISH}):
        bind_times['idnsSecKeyPublish'] = ods_times['idnsSecKeyPublish']

    # ZSK and KSK handling differs in enforcerd, see
    # opendnssec/enforcer/enforcerd/enforcer.c:commKeyConfig()
    if key_type == 'ZSK':
        # idnsSecKeyActivate cannot be set before the key reaches ACTIVE state
        if ('idnsSecKeyActivate' in ods_times and
            key_state in {KSM_STATE_ACTIVE, KSM_STATE_RETIRE, KSM_STATE_DEAD}):
                bind_times['idnsSecKeyActivate'] = ods_times['idnsSecKeyActivate']

        # idnsSecKeyInactive cannot be set before the key reaches RETIRE state
        if ('idnsSecKeyInactive' in ods_times and
            key_state in {KSM_STATE_RETIRE, KSM_STATE_DEAD}):
                bind_times['idnsSecKeyInactive'] = ods_times['idnsSecKeyInactive']

    elif key_type == 'KSK':
        # KSK is special: it is used for signing as long as it is in zone
        if ('idnsSecKeyPublish' in ods_times and
            key_state in {KSM_STATE_PUBLISH, KSM_STATE_READY, KSM_STATE_ACTIVE,
                          KSM_STATE_RETIRE, KSM_STATE_KEYPUBLISH}):
            bind_times['idnsSecKeyActivate'] = ods_times['idnsSecKeyPublish']
        # idnsSecKeyInactive is ignored for KSK on purpose

    else:
        assert False, "unsupported key type %s" % key_type

    # idnsSecKeyDelete is relevant only in DEAD state
    if 'idnsSecKeyDelete' in ods_times and key_state == KSM_STATE_DEAD:
        bind_times['idnsSecKeyDelete'] = ods_times['idnsSecKeyDelete']

    return bind_times

def get_ldap_zone(ldap, dns_base, name):
    zone_names = ["%s." % name, name]

    # find zone object: name can optionally end with period
    ldap_zone = None
    for zone_name in zone_names:
        zone_base = DN("idnsname=%s" % zone_name, dns_base)
        try:
            ldap_zone = ldap.get_entry(dn=zone_base,
                                       attrs_list=["idnsname"])
            break
        except ipalib.errors.NotFound:
            continue

    if ldap_zone is None:
        raise ipalib.errors.NotFound(
            reason='DNS zone "%s" not found in LDAP' % name)

    return ldap_zone

def get_ldap_keys_dn(zone_dn):
    """Container DN"""
    return DN("cn=keys", zone_dn)

def get_ldap_keys(ldap, zone_dn):
    """Keys objects"""
    keys_dn = get_ldap_keys_dn(zone_dn)
    ldap_filter = ldap.make_filter_from_attr('objectClass', 'idnsSecKey')
    ldap_keys = ldap.get_entries(base_dn=keys_dn, filter=ldap_filter)

    return ldap_keys

def get_ods_keys(zone_name):
    # get zone ID
    cur = db.execute("SELECT id FROM zones WHERE LOWER(name)=LOWER(?)",
                     (zone_name,))
    rows = cur.fetchall()
    assert len(rows) == 1, "exactly one DNS zone should exist in ODS DB"
    zone_id = rows[0][0]

    # get relevant keys for given zone ID:
    # ignore keys which were generated but not used yet
    # key state check is using constants from
    # OpenDNSSEC's enforcer/ksm/include/ksm/ksm.h
    # WARNING! OpenDNSSEC version 1 and 2 are using different constants!
    cur = db.execute("SELECT kp.HSMkey_id, kp.generate, kp.algorithm, "
                     "dnsk.publish, dnsk.active, dnsk.retire, dnsk.dead, "
                     "dnsk.keytype, dnsk.state "
                     "FROM keypairs AS kp "
                     "JOIN dnsseckeys AS dnsk ON kp.id = dnsk.keypair_id "
                     "WHERE dnsk.zone_id = ?", (zone_id,))
    keys = {}
    for row in cur:
        key_data = sql2ldap_flags(row['keytype'])
        assert key_data.get('idnsSecKeyZONE', None) == 'TRUE', \
                'unexpected key type 0x%x' % row['keytype']
        if key_data.get('idnsSecKeySEP', 'FALSE') == 'TRUE':
            key_type = 'KSK'
        else:
            key_type = 'ZSK'

        # transform key state to timestamps for BIND with equivalent semantics
        ods_times = sql2datetimes(row)
        key_data.update(ods2bind_timestamps(row['state'], key_type, ods_times))

        key_data.update(sql2ldap_algorithm(row['algorithm']))
        key_id = "%s-%s-%s" % (key_type,
                               datetime2ldap(key_data['idnsSecKeyCreated']),
                               row['HSMkey_id'])

        key_data.update(sql2ldap_keyid(row['HSMkey_id']))
        keys[key_id] = key_data
        log.debug("key %s metadata: %s", key_id, key_data)

    return keys

def sync_set_metadata_2ldap(log, source_set, target_set):
    """sync metadata from source key set to target key set in LDAP

    Keys not present in both sets are left intact."""
    log = log.getChild('sync_set_metadata_2ldap')
    matching_keys = set(source_set.keys()).intersection(set(target_set.keys()))
    log.info("keys in local HSM & LDAP: %s", hex_set(matching_keys))
    for key_id in matching_keys:
        sync_pkcs11_metadata(log, source_set[key_id], target_set[key_id])

def ldap2master_replica_keys_sync(log, ldapkeydb, localhsm):
    """LDAP=>master's local HSM replica key synchronization"""
    # import new replica keys from LDAP
    log = log.getChild('ldap2master_replica')
    log.debug("replica pub keys in LDAP: %s", hex_set(ldapkeydb.replica_pubkeys_wrap))
    log.debug("replica pub keys in SoftHSM: %s", hex_set(localhsm.replica_pubkeys_wrap))
    new_replica_keys = set(ldapkeydb.replica_pubkeys_wrap.keys()) \
            - set(localhsm.replica_pubkeys_wrap.keys())
    log.info("new replica keys in LDAP: %s", hex_set(new_replica_keys))
    for key_id in new_replica_keys:
        new_key_ldap = ldapkeydb.replica_pubkeys_wrap[key_id]
        log.debug('label=%s, id=%s, data=%s',
                new_key_ldap['ipk11label'],
                hexlify(new_key_ldap['ipk11id']),
                hexlify(new_key_ldap['ipapublickey']))
        localhsm.import_public_key(new_key_ldap, new_key_ldap['ipapublickey'])

    # set CKA_WRAP = FALSE for all replica keys removed from LDAP
    removed_replica_keys = set(localhsm.replica_pubkeys_wrap.keys()) \
            - set(ldapkeydb.replica_pubkeys_wrap.keys())
    log.info("obsolete replica keys in local HSM: %s",
            hex_set(removed_replica_keys))
    for key_id in removed_replica_keys:
        localhsm.replica_pubkeys_wrap[key_id]['ipk11wrap'] = False

    # synchronize replica key attributes from LDAP to local HSM
    sync_set_metadata_2ldap(log, localhsm.replica_pubkeys_wrap,
            ldapkeydb.replica_pubkeys_wrap)

def master2ldap_master_keys_sync(log, ldapkeydb, localhsm):
    ## master key -> LDAP synchronization
    # export new master keys to LDAP
    new_master_keys = set(localhsm.master_keys.keys()) \
            - set(ldapkeydb.master_keys.keys())
    log.debug("master keys in local HSM: %s", hex_set(localhsm.master_keys.keys()))
    log.debug("master keys in LDAP HSM: %s", hex_set(ldapkeydb.master_keys.keys()))
    log.debug("new master keys in local HSM: %s", hex_set(new_master_keys))
    for mkey_id in new_master_keys:
        mkey = localhsm.master_keys[mkey_id]
        ldapkeydb.import_master_key(mkey)

    # re-fill cache with keys we just added
    ldapkeydb.flush()
    log.debug('master keys in LDAP after flush: %s', hex_set(ldapkeydb.master_keys))

    # synchronize master key metadata to LDAP
    for mkey_id, mkey_local in localhsm.master_keys.items():
        log.debug('synchronizing master key metadata: 0x%s', hexlify(mkey_id))
        sync_pkcs11_metadata(log, mkey_local, ldapkeydb.master_keys[mkey_id])

    # re-wrap all master keys in LDAP with new replica keys (as necessary)
    enabled_replica_key_ids = set(localhsm.replica_pubkeys_wrap.keys())
    log.debug('enabled replica key ids: %s', hex_set(enabled_replica_key_ids))

    for mkey_id, mkey_ldap in ldapkeydb.master_keys.items():
        log.debug('processing master key data: 0x%s', hexlify(mkey_id))

        # check that all active replicas have own copy of master key
        used_replica_keys = set()
        for wrapped_entry in mkey_ldap.wrapped_entries:
            matching_keys = localhsm.find_keys(
                    uri=wrapped_entry.single_value['ipaWrappingKey'])
            for matching_key in matching_keys.values():
                assert matching_key['ipk11label'].startswith(u'dnssec-replica:'), \
                        'Wrapped key "%s" refers to PKCS#11 URI "%s" which is ' \
                        'not a know DNSSEC replica key: label "%s" does not start ' \
                        'with "dnssec-replica:" prefix' % (wrapped_entry.dn,
                                wrapped_entry['ipaWrappingKey'],
                                matching_key['ipk11label'])
                used_replica_keys.add(matching_key['ipk11id'])

        new_replica_keys = enabled_replica_key_ids - used_replica_keys
        log.debug('master key 0x%s is not wrapped with replica keys %s',
                hexlify(mkey_id), hex_set(new_replica_keys))

        # wrap master key with new replica keys
        mkey_local = localhsm.find_keys(id=mkey_id).popitem()[1]
        for replica_key_id in new_replica_keys:
            log.info('adding master key 0x%s wrapped with replica key 0x%s' % (
                hexlify(mkey_id), hexlify(replica_key_id)))
            replica_key = localhsm.replica_pubkeys_wrap[replica_key_id]
            keydata = localhsm.p11.export_wrapped_key(mkey_local.handle,
                    replica_key.handle,
                    wrappingmech_name2id[SECRETKEY_WRAPPING_MECH])
            mkey_ldap.add_wrapped_data(keydata, SECRETKEY_WRAPPING_MECH,
                    replica_key_id)

    ldapkeydb.flush()

def master2ldap_zone_keys_sync(log, ldapkeydb, localhsm):
    """add and update zone key material from local HSM to LDAP

    No key material will be removed, only new keys will be added or updated.
    Key removal is hanled by master2ldap_zone_keys_purge()."""
    log = log.getChild('master2ldap_zone_keys')
    keypairs_ldap = ldapkeydb.zone_keypairs
    log.debug("zone keys in LDAP: %s", hex_set(keypairs_ldap))

    pubkeys_local = localhsm.zone_pubkeys
    privkeys_local = localhsm.zone_privkeys
    log.debug("zone keys in local HSM: %s", hex_set(privkeys_local))

    assert set(pubkeys_local) == set(privkeys_local), (
            "IDs of private and public keys for DNS zones in local HSM does "
            "not match to key pairs: %s vs. %s" %
            (hex_set(pubkeys_local), hex_set(privkeys_local)))

    new_keys = set(pubkeys_local) - set(keypairs_ldap)
    log.debug("new zone keys in local HSM: %s", hex_set(new_keys))
    mkey = localhsm.active_master_key
    # wrap each new zone key pair with selected master key
    for zkey_id in new_keys:
        pubkey = pubkeys_local[zkey_id]
        pubkey_data = localhsm.p11.export_public_key(pubkey.handle)

        privkey = privkeys_local[zkey_id]
        privkey_data = localhsm.p11.export_wrapped_key(privkey.handle,
                wrapping_key=mkey.handle,
                wrapping_mech=wrappingmech_name2id[PRIVKEY_WRAPPING_MECH])
        ldapkeydb.import_zone_key(pubkey, pubkey_data, privkey, privkey_data,
                PRIVKEY_WRAPPING_MECH, mkey['ipk11id'])

    sync_set_metadata_2ldap(log, pubkeys_local, keypairs_ldap)
    sync_set_metadata_2ldap(log, privkeys_local, keypairs_ldap)
    ldapkeydb.flush()

def master2ldap_zone_keys_purge(log, ldapkeydb, localhsm):
    """purge removed key material from LDAP (but not metadata)

    Keys which are present in LDAP but not in local HSM will be removed.
    Key metadata must be removed first so references to removed key material
    are removed before actually removing the keys."""
    keypairs_ldap = ldapkeydb.zone_keypairs
    log.debug("zone keys in LDAP: %s", hex_set(keypairs_ldap))

    pubkeys_local = localhsm.zone_pubkeys
    privkeys_local = localhsm.zone_privkeys
    log.debug("zone keys in local HSM: %s", hex_set(privkeys_local))
    assert set(pubkeys_local) == set(privkeys_local), \
            "IDs of private and public keys for DNS zones in local HSM does " \
            "not match to key pairs: %s vs. %s" % \
            (hex_set(pubkeys_local), hex_set(privkeys_local))

    deleted_key_ids = set(keypairs_ldap) - set(pubkeys_local)
    log.debug("zone keys deleted from local HSM but present in LDAP: %s",
            hex_set(deleted_key_ids))
    for zkey_id in deleted_key_ids:
        keypairs_ldap[zkey_id].schedule_deletion()
    ldapkeydb.flush()

def hex_set(s):
    out = set()
    for i in s:
        out.add("0x%s" % hexlify(i))
    return out

def receive_systemd_command(log):
    fds = systemd.daemon.listen_fds()
    if len(fds) != 1:
        raise KeyError('Exactly one socket is expected.')

    sck = socket.fromfd(fds[0], socket.AF_UNIX, socket.SOCK_STREAM)
    rlist, wlist, xlist = select.select([sck], [], [], 0)
    if not rlist:
        log.critical('socket activation did not return socket with a command')
        sys.exit(0)

    log.debug('accepting new connection')
    conn, addr = sck.accept()
    log.debug('accepted new connection %s', repr(conn))

    # this implements cmdhandler_handle_cmd() logic
    cmd = conn.recv(ODS_SE_MAXLINE).strip()
    log.debug('received command "%s" from systemd socket', cmd)
    return (cmd, conn)

def parse_command(cmd):
    """Parse command to (exit code, message, zone_name) tuple.

    Exit code None means that execution should continue.
    """
    if cmd == 'ipa-hsm-update':
        return (0,
                'HSM synchronization finished, skipping zone synchronization.',
                None,
                cmd)

    elif cmd == 'ipa-full-update':
        return (None,
                'Synchronization of all zones was finished.',
                None,
                cmd)

    elif cmd.startswith('ldap-cleanup '):
        zone_name = cmd2ods_zone_name(cmd)
        return (None,
                'Zone "%s" metadata will be removed from LDAP.\n' % zone_name,
                zone_name,
                'ldap-cleanup')

    elif cmd.startswith('update '):
        zone_name = cmd2ods_zone_name(cmd)
        return (None,
                'Zone "%s" metadata will be updated in LDAP.\n' % zone_name,
                zone_name,
                'update')

    else:
        return (0,
                'Command "%s" is not supported by IPA; '
                'HSM synchronization was finished and the command '
                'will be ignored.' % cmd,
                None,
                None)


def send_systemd_reply(conn, reply):
        # Reply & close connection early.
        # This is necessary to let Enforcer to unlock the ODS DB.
        conn.send(reply + '\n')
        conn.shutdown(socket.SHUT_RDWR)
        conn.close()

def cmd2ods_zone_name(cmd):
    # ODS stores zone name without trailing period
    zone_name = cmd.split(' ', 1)[1].strip()
    if len(zone_name) > 1 and zone_name[-1] == '.':
        zone_name = zone_name[:-1]

    return zone_name

def sync_zone(log, ldap, dns_dn, zone_name):
    """synchronize metadata about zone keys for single DNS zone

    Key material has to be synchronized elsewhere.
    Keep in mind that keys could be shared among multiple zones!"""
    log.getChild("%s.%s" % (__name__, zone_name))
    log.debug('synchronizing zone "%s"', zone_name)
    ods_keys = get_ods_keys(zone_name)
    ods_keys_id = set(ods_keys.keys())

    ldap_zone = get_ldap_zone(ldap, dns_dn, zone_name)
    zone_dn = ldap_zone.dn

    keys_dn = get_ldap_keys_dn(zone_dn)
    try:
        ldap_keys = get_ldap_keys(ldap, zone_dn)
    except ipalib.errors.NotFound:
        # cn=keys container does not exist, create it
        ldap_keys = []
        ldap_keys_container = ldap.make_entry(keys_dn,
                                              objectClass=['nsContainer'])
        try:
            ldap.add_entry(ldap_keys_container)
        except ipalib.errors.DuplicateEntry:
            # ldap.get_entries() does not distinguish non-existent base DN
            # from empty result set so addition can fail because container
            # itself exists already
            pass

    ldap_keys_dict = {}
    for ldap_key in ldap_keys:
        cn = ldap_key['cn'][0]
        ldap_keys_dict[cn] = ldap_key

    ldap_keys = ldap_keys_dict  # shorthand
    ldap_keys_id = set(ldap_keys.keys())

    new_keys_id = ods_keys_id - ldap_keys_id
    log.info('new key metadata from ODS: %s', new_keys_id)
    for key_id in new_keys_id:
        cn = "cn=%s" % key_id
        key_dn = DN(cn, keys_dn)
        log.debug('adding key metadata "%s" to LDAP', key_dn)
        ldap_key = ldap.make_entry(key_dn,
                                   objectClass=['idnsSecKey'],
                                   **ods_keys[key_id])
        ldap.add_entry(ldap_key)

    deleted_keys_id = ldap_keys_id - ods_keys_id
    log.info('deleted key metadata in LDAP: %s', deleted_keys_id)
    for key_id in deleted_keys_id:
        cn = "cn=%s" % key_id
        key_dn = DN(cn, keys_dn)
        log.debug('deleting key metadata "%s" from LDAP', key_dn)
        ldap.delete_entry(key_dn)

    update_keys_id = ldap_keys_id.intersection(ods_keys_id)
    log.info('key metadata in LDAP & ODS: %s', update_keys_id)
    for key_id in update_keys_id:
        ldap_key = ldap_keys[key_id]
        ods_key = ods_keys[key_id]
        log.debug('updating key metadata "%s" in LDAP', ldap_key.dn)
        ldap_key.update(ods_key)
        try:
            ldap.update_entry(ldap_key)
        except ipalib.errors.EmptyModlist:
            continue

def cleanup_ldap_zone(log, ldap, dns_dn, zone_name):
    """delete all key metadata about zone keys for single DNS zone

    Key material has to be synchronized elsewhere.
    Keep in mind that keys could be shared among multiple zones!"""
    log = log.getChild("%s.%s" % (__name__, zone_name))
    log.debug('cleaning up key metadata from zone "%s"', zone_name)

    try:
        ldap_zone = get_ldap_zone(ldap, dns_dn, zone_name)
        ldap_keys = get_ldap_keys(ldap, ldap_zone.dn)
    except ipalib.errors.NotFound as ex:
        # zone or cn=keys container does not exist, we are done
        log.debug(str(ex))
        return

    for ldap_key in ldap_keys:
        log.debug('deleting key metadata "%s"', ldap_key.dn)
        ldap.delete_entry(ldap_key)

log = logging.getLogger('root')
# this service is usually socket-activated
log.addHandler(systemd.journal.JournalHandler())
log.setLevel(level=logging.DEBUG)

if len(sys.argv) > 2:
    print(__doc__)
    sys.exit(1)
# program was likely invoked from console, log to it
elif len(sys.argv) == 2:
    console = logging.StreamHandler()
    log.addHandler(console)

# IPA framework initialization
ipalib.api.bootstrap(in_server=True, log=None)  # no logging to file
ipalib.api.finalize()

# Kerberos initialization
PRINCIPAL = str('%s/%s' % (DAEMONNAME, ipalib.api.env.host))
log.debug('Kerberos principal: %s', PRINCIPAL)
ccache_name = paths.IPA_ODS_EXPORTER_CCACHE

try:
    ipautil.kinit_keytab(PRINCIPAL, paths.IPA_ODS_EXPORTER_KEYTAB, ccache_name,
                         attempts=5)
except GSSError as e:
    log.critical('Kerberos authentication failed: %s', e)
    sys.exit(1)

os.environ['KRB5CCNAME'] = ccache_name
log.debug('Got TGT')

# LDAP initialization
dns_dn = DN(ipalib.api.env.container_dns, ipalib.api.env.basedn)
ldap = ipaldap.LDAPClient(ipalib.api.env.ldap_uri)
log.debug('Connecting to LDAP')
ldap.gssapi_bind()
log.debug('Connected')


### DNSSEC master: key material upload & synchronization (but not deletion)
ldapkeydb = LdapKeyDB(log, ldap, DN(('cn', 'keys'), ('cn', 'sec'),
                                    ipalib.api.env.container_dns,
                                    ipalib.api.env.basedn))
localhsm = LocalHSM(paths.LIBSOFTHSM2_SO, 0,
        open(paths.DNSSEC_SOFTHSM_PIN).read())

ldap2master_replica_keys_sync(log, ldapkeydb, localhsm)
master2ldap_master_keys_sync(log, ldapkeydb, localhsm)
master2ldap_zone_keys_sync(log, ldapkeydb, localhsm)


### DNSSEC master: DNSSEC key metadata upload & synchronization & deletion
# command receive is delayed so the command will stay in socket queue until
# the problem with LDAP server or HSM is fixed
try:
    cmd, conn = receive_systemd_command(log)
    if len(sys.argv) != 1:
        log.critical('No additional parameters are accepted when '
                     'socket activation is used.')
        sys.exit(1)
# Handle cases where somebody ran the program without systemd.
except KeyError as e:
    if len(sys.argv) != 2:
        print(__doc__)
        print('ERROR: Exactly one parameter or socket activation is required.')
        sys.exit(1)
    conn = None
    cmd = sys.argv[1]

exitcode, msg, zone_name, cmd = parse_command(cmd)

if exitcode is not None:
    if conn:
        send_systemd_reply(conn, msg)
    log.info(msg)
    sys.exit(exitcode)
else:
    log.debug(msg)

# Open DB directly and read key timestamps etc.
db = None
try:
    # LOCK WARNING:
    # ods-enforcerd is holding kasp.db.our_lock when processing all zones and
    # the lock is unlocked only after all calls to ods-signer are finished,
    # i.e. when ods-enforcerd receives reply from each ods-signer call.
    #
    # Consequently, ipa-ods-exporter (ods-signerd implementation) must not
    # request kasp.db.our_lock to prevent deadlocks.
    # SQLite transaction isolation should suffice.
    # Beware: Reply can be sent back only after DB is unlocked and closed
    #         otherwise ods-enforcerd will fail.

    db = sqlite3.connect(paths.OPENDNSSEC_KASP_DB)
    db.row_factory = sqlite3.Row
    db.execute('BEGIN')

    if zone_name is not None:
        # only one zone should be processed
        if cmd == 'update':
            sync_zone(log, ldap, dns_dn, zone_name)
        elif cmd == 'ldap-cleanup':
            cleanup_ldap_zone(log, ldap, dns_dn, zone_name)
    else:
        # process all zones
        for zone_row in db.execute("SELECT name FROM zones"):
            sync_zone(log, ldap, dns_dn, zone_row['name'])

    ### DNSSEC master: DNSSEC key material purging
    # references to old key material were removed above in sync_zone()
    # so now we can purge old key material from LDAP
    master2ldap_zone_keys_purge(log, ldapkeydb, localhsm)

except Exception as ex:
    msg = "ipa-ods-exporter exception: %s" % traceback.format_exc(ex)
    log.exception(ex)
    raise ex

finally:
    try:
        if db:
            db.close()
    finally:
        if conn:
            send_systemd_reply(conn, msg)

log.debug('Done')