#!/usr/bin/env python
# Copyright Luke Morrison <luc785@.hotmail.com> July 2013
# Co-Edited by Matthieu Pattou July 2013 from original August 2013
# Edited by Garming Sam Feb. 2014
# Edited by Luke Morrison April 2014
# Edited by David Mulder May 2017

# 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/>.

'''This script reads a log file of previous GPO, gets all GPO from sysvol
and sorts them by container. Then, it applies the ones that haven't been
applied, have changed, or is in the right container'''

import os
import sys

sys.path.insert(0, "/usr/lib/python2.7/site-packages")

import optparse
from samba import getopt as options
from samba.auth import system_session
try:
    from samba.samdb import SamDB
except:
    SamDB = None
from samba.gpclass import *
from samba.net import Net
from samba.dcerpc import nbt
from samba import smb
import samba.gpo as gpo
import logging
import chardet

''' Fetch the hostname of a writable DC '''
def get_dc_hostname(creds, lp):
    net = Net(creds=creds, lp=lp)
    cldap_ret = net.finddc(domain=lp.get('realm'), flags=(nbt.NBT_SERVER_LDAP |
        nbt.NBT_SERVER_DS))
    return cldap_ret.pdc_dns_name

''' Fetch a list of GUIDs for applicable GPOs '''
def get_gpo_list(dc_hostname, creds, lp):
    gpos = []
    ads = gpo.ADS_STRUCT(dc_hostname, lp, creds)
    if ads.connect():
        gpos = ads.get_gpo_list(creds.get_username())
    return gpos

def apply_gp(lp, creds, test_ldb, logger, store, gp_extensions):
    gp_db = store.get_gplog(creds.get_username())
    dc_hostname = get_dc_hostname(creds, lp)
    try:
        conn =  smb.SMB(dc_hostname, 'sysvol', lp=lp, creds=creds)
    except:
        logger.error('Error connecting to \'%s\' using SMB' % dc_hostname)
        raise
    gpos = get_gpo_list(dc_hostname, creds, lp)

    for gpo_obj in gpos:
        guid = gpo_obj.name
        if guid == 'Local Policy':
            continue
        path = os.path.join(lp.get('realm').lower(), 'Policies', guid)
        local_path = os.path.join(lp.get("path", "sysvol"), path)
        version = int(gpo.gpo_get_sysvol_gpt_version(local_path)[1])
        if version != store.get_int(guid):
            logger.info('GPO %s has changed' % guid)
            gp_db.state(GPOSTATE.APPLY)
        else:
            gp_db.state(GPOSTATE.ENFORCE)
        gp_db.set_guid(guid)
        store.start()
        for ext in gp_extensions:
            try:
                ext.parse(ext.list(path), test_ldb, conn, gp_db, lp)
            except Exception as e:
                logger.error('Failed to parse gpo %s for extension %s' % \
                    (guid, str(ext)))
                logger.error('Message was: ' + str(e))
                store.cancel()
                continue
        store.store(guid, '%i' % version)
        store.commit()

def unapply_log(gp_db):
    while True:
        item = gp_db.apply_log_pop()
        if item:
            yield item
        else:
            break

def unapply_gp(lp, creds, test_ldb, logger, store, gp_extensions):
    gp_db = store.get_gplog(creds.get_username())
    gp_db.state(GPOSTATE.UNAPPLY)
    for gpo_guid in unapply_log(gp_db):
        gp_db.set_guid(gpo_guid)
        unapply_attributes = gp_db.list(gp_extensions)
        for attr in unapply_attributes:
            attr_obj = attr[-1](logger, test_ldb, gp_db, lp, attr[0], attr[1])
            attr_obj.mapper()[attr[0]][0](attr[1]) # Set the old value
            gp_db.delete(str(attr_obj), attr[0])
        gp_db.commit()

if __name__ == "__main__":
    parser = optparse.OptionParser('samba_gpoupdate [options]')
    sambaopts = options.SambaOptions(parser)

    # Get the command line options
    parser.add_option_group(sambaopts)
    parser.add_option_group(options.VersionOptions(parser))
    credopts = options.CredentialsOptions(parser)
    parser.add_option('-H', '--url', dest='url', help='URL for the samdb')
    parser.add_option('-X', '--unapply', help='Unapply Group Policy',
                      action='store_true')
    parser.add_option('-M', '--machine', help='Apply machine policy',
                      action='store_true', default=False)
    parser.add_option_group(credopts)

    # Set the options and the arguments
    (opts, args) = parser.parse_args()

    # Set the loadparm context
    lp = sambaopts.get_loadparm()
    if not opts.url:
        url = lp.samdb_url()
    else:
        url = opts.url

    # Initialize the session
    creds = credopts.get_credentials(lp, fallback_machine=True)
    session = system_session()

    # Set up logging
    logger = logging.getLogger('samba_gpoupdate')
    logger.addHandler(logging.StreamHandler(sys.stdout))
    logger.setLevel(logging.CRITICAL)
    log_level = lp.log_level()
    if log_level == 1:
        logger.setLevel(logging.ERROR)
    elif log_level == 2:
        logger.setLevel(logging.WARNING)
    elif log_level == 3:
        logger.setLevel(logging.INFO)
    elif log_level >= 4:
        logger.setLevel(logging.DEBUG)

    cache_dir = lp.get('cache directory')
    store = GPOStorage(os.path.join(cache_dir, 'gpo.tdb'))

    gp_extensions = []
    if opts.machine:
        if lp.get('server role') == 'active directory domain controller':
            gp_extensions.append(gp_sec_ext(logger))
    else:
        pass # User extensions

    # Get a live instance of Samba
    if SamDB:
        test_ldb = SamDB(url, session_info=session, credentials=creds, lp=lp)
    else:
        test_ldb = None

    if not opts.unapply:
        apply_gp(lp, creds, test_ldb, logger, store, gp_extensions)
    else:
        unapply_gp(lp, creds, test_ldb, logger, store, gp_extensions)