#!/usr/bin/python3 -E
#
# Authors:
#   Rob Crittenden <rcritten@redhat.com>
#
# Copyright (C) 2012  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Configure the automount client for ldap.

from __future__ import print_function

import logging
import sys
import os
import time
import tempfile
import gssapi

try:
    from xml.etree import cElementTree as etree
except ImportError:
    from xml.etree import ElementTree as etree

import SSSDConfig
# pylint: disable=import-error
from six.moves.urllib.parse import urlsplit
# pylint: enable=import-error

from optparse import OptionParser  # pylint: disable=deprecated-module

from ipaclient.install import ipachangeconf, ipadiscovery
from ipalib import api, errors
from ipalib.install import sysrestore
from ipalib.install.kinit import kinit_keytab
from ipalib.util import check_client_configuration
from ipapython import ipautil
from ipapython.ipa_log_manager import standard_logging_setup
from ipapython.dn import DN
from ipaplatform.constants import constants
from ipaplatform.tasks import tasks
from ipaplatform import services
from ipaplatform.paths import paths
from ipapython.admintool import ScriptError


logger = logging.getLogger(os.path.basename(__file__))


def parse_options():
    usage = "%prog [options]\n"
    parser = OptionParser(usage=usage)
    parser.add_option("--server", dest="server", help="FQDN of IPA server")
    parser.add_option("--location", dest="location", help="Automount location",
        default="default")
    parser.add_option("-S", "--no-sssd", dest="sssd",
                      action="store_false", default=True,
                      help="Do not configure the client to use SSSD for automount")
    parser.add_option("--debug", dest="debug", action="store_true",
        default=False, help="enable debugging")
    parser.add_option("-U", "--unattended", dest="unattended",
        action="store_true", default=False,
        help="unattended installation never prompts the user")
    parser.add_option("--uninstall", dest="uninstall", action="store_true",
        default=False, help="Unconfigure automount")

    options, args = parser.parse_args()
    return options, args

def wait_for_sssd():
    """
    It takes a bit for sssd to get going, lets loop until it is
    serving data.

    This function returns nothing.
    """
    n = 0
    found = False
    time.sleep(1)
    while n < 10 and not found:
        try:
            ipautil.run([paths.GETENT, "passwd", "admin@%s" % api.env.realm])
            found = True
        except Exception:
            time.sleep(1)
            n = n + 1

    # This should never happen but if it does, may as well warn the user
    if not found:
        err_msg = ("Unable to find 'admin' user with "
                   "'getent passwd admin@%s'!" % api.env.realm)
        logger.debug('%s', err_msg)
        print(err_msg)
        print("This may mean that sssd didn't re-start properly after the configuration changes.")

def configure_xml(fstore):
    authconf = paths.AUTOFS_LDAP_AUTH_CONF
    fstore.backup_file(authconf)

    try:
        tree = etree.parse(authconf)
    except IOError as e:
        logger.debug('Unable to open file %s', e)
        logger.debug('Creating new from template')
        tree = etree.ElementTree(
            element=etree.Element('autofs_ldap_sasl_conf')
        )

    element = tree.getroot()
    if element.tag != 'autofs_ldap_sasl_conf':
        raise RuntimeError('Invalid XML root in file %s' % authconf)

    element.set('usetls', 'no')
    element.set('tlsrequired', 'no')
    element.set('authrequired', 'yes')
    element.set('authtype', 'GSSAPI')
    element.set('clientprinc', 'host/%s@%s' % (api.env.host, api.env.realm))

    try:
        tree.write(authconf, xml_declaration=True, encoding='UTF-8')
    except IOError as e:
        print("Unable to write %s: %s" % (authconf, e))
    else:
        print("Configured %s" % authconf)

def configure_nsswitch(fstore, options):
    """
    Point automount to ldap in nsswitch.conf. This function is for non-SSSD
    setups only
    """
    fstore.backup_file(paths.NSSWITCH_CONF)

    conf = ipachangeconf.IPAChangeConf("IPA Installer")
    conf.setOptionAssignment(':')

    nss_value = ' files ldap'

    opts = [{'name':'automount', 'type':'option', 'action':'set', 'value':nss_value},
            {'name':'empty', 'type':'empty'}]

    conf.changeConf(paths.NSSWITCH_CONF, opts)

    print("Configured %s" % paths.NSSWITCH_CONF)

def configure_autofs_sssd(fstore, statestore, autodiscover, options):
    try:
        sssdconfig = SSSDConfig.SSSDConfig()
        sssdconfig.import_config()
        domains = sssdconfig.list_active_domains()
    except Exception as e:
        sys.exit(e)

    try:
        sssdconfig.new_service('autofs')
    except SSSDConfig.ServiceAlreadyExists:
        pass
    except SSSDConfig.ServiceNotRecognizedError:
        logger.error("Unable to activate the Autofs service in SSSD config.")
        logger.info(
            "Please make sure you have SSSD built with autofs support "
            "installed.")
        logger.info(
            "Configure autofs support manually in /etc/sssd/sssd.conf.")
        sys.exit("Cannot create the autofs service in sssd.conf")

    sssdconfig.activate_service('autofs')

    domain = None
    for name in domains:
        domain = sssdconfig.get_domain(name)
        try:
            provider = domain.get_option('id_provider')
        except SSSDConfig.NoOptionError:
            continue
        if provider == "ipa":
            domain.add_provider('ipa', 'autofs')
            try:
                domain.get_option('ipa_automount_location')
                sys.exit('An automount location is already configured')
            except SSSDConfig.NoOptionError:
                domain.set_option('ipa_automount_location', options.location)
                break

    if domain is None:
        sys.exit('SSSD is not configured.')

    sssdconfig.save_domain(domain)
    sssdconfig.write(paths.SSSD_CONF)
    statestore.backup_state('autofs', 'sssd', True)

    sssd = services.service('sssd', api)
    sssd.restart()
    print("Restarting sssd, waiting for it to become available.")
    wait_for_sssd()

def configure_autofs(fstore, statestore, autodiscover, server, options):
    """
    fstore: the FileStore to back up files in
    options.server: the IPA server to use
    options.location: the Automount location to use
    """
    if not autodiscover:
        ldap_uri = "ldap://%s" % server
    else:
        ldap_uri = "ldap:///%s" % api.env.basedn

    search_base = str(DN(('cn', options.location), api.env.container_automount, api.env.basedn))
    replacevars = {
        'MAP_OBJECT_CLASS': 'automountMap',
        'ENTRY_OBJECT_CLASS': 'automount',
        'MAP_ATTRIBUTE': 'automountMapName',
        'ENTRY_ATTRIBUTE': 'automountKey',
        'VALUE_ATTRIBUTE': 'automountInformation',
        'SEARCH_BASE': search_base,
        'LDAP_URI': ldap_uri,
    }

    ipautil.backup_config_and_replace_variables(fstore,
        paths.SYSCONFIG_AUTOFS, replacevars=replacevars)
    tasks.restore_context(paths.SYSCONFIG_AUTOFS)
    statestore.backup_state('autofs', 'sssd', False)

    print("Configured %s" % paths.SYSCONFIG_AUTOFS)

def configure_autofs_common(fstore, statestore, options):
    autofs = services.knownservices.autofs
    statestore.backup_state('autofs', 'enabled', autofs.is_enabled())
    statestore.backup_state('autofs', 'running', autofs.is_running())
    try:
        autofs.restart()
        print("Started %s" % autofs.service_name)
    except Exception as e:
        logger.error("%s failed to restart: %s", autofs.service_name, e)
    try:
        autofs.enable()
    except Exception as e:
        print("Failed to configure automatic startup of the %s daemon" % (autofs.service_name))
        logger.error("Failed to enable automatic startup of the %s daemon: %s",
                     autofs.service_name, str(e))

def uninstall(fstore, statestore):
    print("Restoring configuration")
    if fstore.has_file(paths.SYSCONFIG_AUTOFS):
        fstore.restore_file(paths.SYSCONFIG_AUTOFS)
    if fstore.has_file(paths.NSSWITCH_CONF):
        fstore.restore_file(paths.NSSWITCH_CONF)
    if fstore.has_file(paths.AUTOFS_LDAP_AUTH_CONF):
        fstore.restore_file(paths.AUTOFS_LDAP_AUTH_CONF)
    if fstore.has_file(paths.SYSCONFIG_NFS):
        fstore.restore_file(paths.SYSCONFIG_NFS)
    if fstore.has_file(paths.IDMAPD_CONF):
        fstore.restore_file(paths.IDMAPD_CONF)
    if statestore.has_state('autofs'):
        enabled = statestore.restore_state('autofs', 'enabled')
        running = statestore.restore_state('autofs', 'running')
        sssd = statestore.restore_state('autofs', 'sssd')
        autofs = services.knownservices.autofs
        if not enabled:
            autofs.disable()
        if not running:
            autofs.stop()
        if sssd:
            try:
                sssdconfig = SSSDConfig.SSSDConfig()
                sssdconfig.import_config()
                sssdconfig.deactivate_service('autofs')
                domains = sssdconfig.list_active_domains()
                for name in domains:
                    domain = sssdconfig.get_domain(name)
                    try:
                        provider = domain.get_option('id_provider')
                    except SSSDConfig.NoOptionError:
                        continue
                    if provider == "ipa":
                        domain.remove_option('ipa_automount_location')
                        domain.remove_provider('autofs')
                        break
                sssdconfig.save_domain(domain)
                sssdconfig.write(paths.SSSD_CONF)
                sssd = services.service('sssd', api)
                sssd.restart()
                wait_for_sssd()
            except Exception as e:
                print('Unable to restore SSSD configuration: %s' % str(e))
                logger.debug('Unable to restore SSSD configuration: %s',
                             str(e))
    if statestore.has_state('rpcidmapd'):
        enabled = statestore.restore_state('rpcidmapd', 'enabled')
        running = statestore.restore_state('rpcidmapd', 'running')
        rpcidmapd = services.knownservices.rpcidmapd
        if not enabled:
            rpcidmapd.disable()
        if not running:
            rpcidmapd.stop()
    if statestore.has_state('rpcgssd'):
        enabled = statestore.restore_state('rpcgssd', 'enabled')
        running = statestore.restore_state('rpcgssd', 'running')
        rpcgssd = services.knownservices.rpcgssd
        if not enabled:
            rpcgssd.disable()
        if not running:
            rpcgssd.stop()

    return 0

def configure_nfs(fstore, statestore):
    """
    Configure secure NFS
    """
    replacevars = {
        constants.SECURE_NFS_VAR: 'yes',
    }
    ipautil.backup_config_and_replace_variables(fstore,
        paths.SYSCONFIG_NFS, replacevars=replacevars)
    tasks.restore_context(paths.SYSCONFIG_NFS)

    print("Configured %s" % paths.SYSCONFIG_NFS)

    # Prepare the changes
    # We need to use IPAChangeConf as simple regexp substitution
    # does not cut it here
    conf = ipachangeconf.IPAChangeConf("IPA automount installer")
    conf.case_insensitive_sections = False
    conf.setOptionAssignment(" = ")
    conf.setSectionNameDelimiters(("[", "]"))

    changes = [conf.setOption('Domain', api.env.domain)]
    section_with_changes = [conf.setSection('General', changes)]

    # Backup the file and apply the changes
    fstore.backup_file(paths.IDMAPD_CONF)
    conf.changeConf(paths.IDMAPD_CONF, section_with_changes)

    tasks.restore_context(paths.IDMAPD_CONF)

    print("Configured %s" % paths.IDMAPD_CONF)

    rpcidmapd = services.knownservices.rpcidmapd
    statestore.backup_state('rpcidmapd', 'enabled', rpcidmapd.is_enabled())
    statestore.backup_state('rpcidmapd', 'running', rpcidmapd.is_running())
    try:
        rpcidmapd.restart()
        print("Started %s" % rpcidmapd.service_name)
    except Exception as e:
        logger.error("%s failed to restart: %s", rpcidmapd.service_name, e)
    try:
        rpcidmapd.enable()
    except Exception as e:
        print("Failed to configure automatic startup of the %s daemon" % (rpcidmapd.service_name))
        logger.error("Failed to enable automatic startup of the %s daemon: %s",
                     rpcidmapd.service_name, str(e))

    rpcgssd = services.knownservices.rpcgssd
    statestore.backup_state('rpcgssd', 'enabled', rpcgssd.is_enabled())
    statestore.backup_state('rpcgssd', 'running', rpcgssd.is_running())
    try:
        rpcgssd.restart()
        print("Started %s" % rpcgssd.service_name)
    except Exception as e:
        logger.error("%s failed to restart: %s", rpcgssd.service_name, e)
    try:
        rpcgssd.enable()
    except Exception as e:
        print("Failed to configure automatic startup of the %s daemon" % (rpcgssd.service_name))
        logger.error("Failed to enable automatic startup of the %s daemon: %s",
                     rpcgssd.service_name, str(e))

def main():
    try:
        check_client_configuration()
    except ScriptError as e:
        sys.exit(e)

    fstore = sysrestore.FileStore(paths.IPA_CLIENT_SYSRESTORE)
    statestore = sysrestore.StateFile(paths.IPA_CLIENT_SYSRESTORE)

    options, _args = parse_options()

    standard_logging_setup(
        paths.IPACLIENT_INSTALL_LOG, verbose=False, debug=options.debug,
        filemode='a', console_format='%(message)s')

    cfg = dict(
        context='cli_installer',
        confdir=paths.ETC_IPA,
        in_server=False,
        debug=options.debug,
        verbose=0,
    )

    # Bootstrap API early so that env object is available
    api.bootstrap(**cfg)

    if options.uninstall:
        return uninstall(fstore, statestore)

    ca_cert_path = None
    if os.path.exists(paths.IPA_CA_CRT):
        ca_cert_path = paths.IPA_CA_CRT

    if statestore.has_state('autofs'):
        sys.exit('automount is already configured on this system.\n')

    autodiscover = False
    ds = ipadiscovery.IPADiscovery()
    if not options.server:
        print("Searching for IPA server...")
        ret = ds.search(ca_cert_path=ca_cert_path)
        logger.debug('Executing DNS discovery')
        if ret == ipadiscovery.NO_LDAP_SERVER:
            logger.debug('Autodiscovery did not find LDAP server')
            s = urlsplit(api.env.xmlrpc_uri)
            server = [s.netloc]
            logger.debug('Setting server to %s', s.netloc)
        else:
            autodiscover = True
            if not ds.servers:
                sys.exit('Autodiscovery was successful but didn\'t return a server')
            logger.debug('Autodiscovery success, possible servers %s',
                         ','.join(ds.servers))
            server = ds.servers[0]
    else:
        server = options.server
        logger.debug("Verifying that %s is an IPA server", server)
        ldapret = ds.ipacheckldap(server, api.env.realm, ca_cert_path)
        if ldapret[0] == ipadiscovery.NO_ACCESS_TO_LDAP:
            print("Anonymous access to the LDAP server is disabled.")
            print("Proceeding without strict verification.")
            print("Note: This is not an error if anonymous access has been explicitly restricted.")
        elif ldapret[0] == ipadiscovery.NO_TLS_LDAP:
            logger.warning("Unencrypted access to LDAP is not supported.")
        elif ldapret[0] != 0:
            sys.exit('Unable to confirm that %s is an IPA server' % server)

    if not autodiscover:
        print("IPA server: %s" % server)
        logger.debug('Using fixed server %s', server)
    else:
        print("IPA server: DNS discovery")
        logger.debug('Configuring to use DNS discovery')

    print("Location: %s" % options.location)
    logger.debug('Using automount location %s', options.location)

    ccache_dir = tempfile.mkdtemp()
    ccache_name = os.path.join(ccache_dir, 'ccache')
    try:
        try:
            host_princ = str('host/%s@%s' % (api.env.host, api.env.realm))
            kinit_keytab(host_princ, paths.KRB5_KEYTAB, ccache_name)
            os.environ['KRB5CCNAME'] = ccache_name
        except gssapi.exceptions.GSSError as e:
            sys.exit("Failed to obtain host TGT: %s" % e)

        # Finalize API when TGT obtained using host keytab exists
        api.finalize()

        # Now we have a TGT, connect to IPA
        try:
            api.Backend.rpcclient.connect()
        except errors.KerberosError as e:
            sys.exit('Cannot connect to the server due to ' + str(e))
        try:
            # Use the RPC directly so older servers are supported
            api.Backend.rpcclient.forward(
                'automountlocation_show',
                ipautil.fsdecode(options.location),
                version=u'2.0',
            )
        except errors.VersionError as e:
            sys.exit('This client is incompatible: ' + str(e))
        except errors.NotFound:
            sys.exit("Automount location '%s' does not exist" % options.location)
        except errors.PublicError as e:
            sys.exit("Cannot connect to the server due to generic error: %s" % str(e))
    finally:
        os.remove(ccache_name)
        os.rmdir(ccache_dir)

    if not options.unattended and not ipautil.user_input("Continue to configure the system with these values?", False):
        sys.exit("Installation aborted")

    try:
        if not options.sssd:
            configure_nsswitch(fstore, options)
        configure_nfs(fstore, statestore)
        if options.sssd:
            configure_autofs_sssd(fstore, statestore, autodiscover, options)
        else:
            configure_xml(fstore)
            configure_autofs(fstore, statestore, autodiscover, server, options)
        configure_autofs_common(fstore, statestore, options)
    except Exception as e:
        logger.debug('Raised exception %s', e)
        print("Installation failed. Rolling back changes.")
        uninstall(fstore, statestore)
        return 1

    return 0

try:
    if not os.geteuid()==0:
        sys.exit("\nMust be run as root\n")

    sys.exit(main())
except SystemExit as e:
    sys.exit(e)
except RuntimeError as e:
    sys.exit(e)
except (KeyboardInterrupt, EOFError):
    sys.exit(1)
