path: root/source4/scripting/bin/samba_kcc

#!/usr/bin/env python
#
# Compute our KCC topology
#
# Copyright (C) Dave Craft 2011
#
# 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/>.

import os
import sys
import random

# ensure we get messages out immediately, so they get in the samba logs,
# and don't get swallowed by a timeout
os.environ['PYTHONUNBUFFERED'] = '1'

# forcing GMT avoids a problem in some timezones with kerberos. Both MIT
# heimdal can get mutual authentication errors due to the 24 second difference
# between UTC and GMT when using some zone files (eg. the PDT zone from
# the US)
os.environ["TZ"] = "GMT"

# Find right directory when running from source tree
sys.path.insert(0, "bin/python")

import samba, ldb
import optparse
import logging

from samba           import getopt as options
from samba.auth      import system_session
from samba.samdb     import SamDB
from samba.kcc_utils import *

class KCC:
    """The Knowledge Consistency Checker class.  A container for
       objects and methods allowing a run of the KCC.  Produces
       a set of connections in the samdb for which the Distributed
       Replication Service can then utilize to replicate naming
       contexts
    """
    def __init__(self, samdb):
        """Initializes the partitions class which can hold
           our local DCs partitions or all the partitions in
           the forest
        """
        self.dsa_table     = {}    # dsa objects
        self.part_table    = {}    # partition objects
        self.site_table    = {}
        self.my_dsa_dnstr  = None  # My dsa DN
        self.my_site_dnstr = None
        self.samdb         = samdb
        return

    def load_my_site(self):
        """Loads the Site class for the local DSA
           Raises an Exception on error
        """
        self.my_site_dnstr = "CN=%s,CN=Sites,%s" % (samdb.server_site_name(),
                             samdb.get_config_basedn())
        site = Site(self.my_site_dnstr)

        site.load_site(samdb)
        self.site_table[self.my_site_dnstr] = site
        return

    def load_my_dsa(self):
        """Discover my nTDSDSA thru the rootDSE entry and
           instantiate and load the DSA.  The dsa is inserted
           into the dsa_table by dn string
           Raises an Exception on error.
        """
        dn = ldb.Dn(self.samdb, "")
        try:
            res = samdb.search(base=dn, scope=ldb.SCOPE_BASE,
                               attrs=["dsServiceName"])
        except ldb.LdbError, (enum, estr):
            raise Exception("Unable to find my nTDSDSA - (%s)" % estr)
            return

        dnstr = res[0]["dsServiceName"][0]

        # already loaded
        if dnstr in self.dsa_table.keys():
            return

        self.my_dsa_dnstr = dnstr
        dsa = DirectoryServiceAgent(dnstr)

        dsa.load_dsa(samdb)

        # Assign this dsa to my dsa table
        # and index by dsa dn
        self.dsa_table[dnstr] = dsa

        return

    def load_all_dsa(self):
        """Discover all nTDSDSA thru the sites entry and
           instantiate and load the DSAs.  Each dsa is inserted
           into the dsa_table by dn string.
           Raises an Exception on error.
        """
        try:
            res = self.samdb.search("CN=Sites,%s" %
                                    self.samdb.get_config_basedn(),
                                    scope=ldb.SCOPE_SUBTREE,
                                    expression="(objectClass=nTDSDSA)")
        except ldb.LdbError, (enum, estr):
            raise Exception("Unable to find nTDSDSAs - (%s)" % estr)
            return

        for msg in res:
            dnstr = str(msg.dn)

            # already loaded
            if dnstr in self.dsa_table.keys():
                continue

            dsa = DirectoryServiceAgent(dnstr)

            dsa.load_dsa(self.samdb)

            # Assign this dsa to my dsa table
            # and index by dsa dn
            self.dsa_table[dnstr] = dsa

        return

    def load_all_partitions(self):
        """Discover all NCs thru the Partitions dn and
           instantiate and load the NCs.  Each NC is inserted
           into the part_table by partition dn string (not
           the nCName dn string)
           Raises an Exception on error
        """
        try:
            res = self.samdb.search("CN=Partitions,%s" %
                                    self.samdb.get_config_basedn(),
                                    scope=ldb.SCOPE_SUBTREE,
                                    expression="(objectClass=crossRef)")
        except ldb.LdbError, (enum, estr):
            raise Exception("Unable to find partitions - (%s)" % estr)

        for msg in res:
            partstr = str(msg.dn)

            # already loaded
            if partstr in self.part_table.keys():
                continue

            part = Partition(partstr)

            part.load_partition(self.samdb)
            self.part_table[partstr] = part

        return

    def should_be_present_test(self):
        """Enumerate all loaded partitions and DSAs and test
           if NC should be present as replica
        """
        for partdn, part in self.part_table.items():

           for dsadn, dsa in self.dsa_table.items():
               needed, ro, partial = part.should_be_present(dsa)

               logger.info("dsadn:%s\nncdn:%s\nneeded=%s:ro=%s:partial=%s\n" % \
                           (dsa.dsa_dnstr, part.nc_dnstr, needed, ro, partial))
        return

    def refresh_failed_links_connections(self):
        # XXX - not implemented yet
        return

    def is_stale_link_connection(self, target_dsa):
        """Returns False if no tuple z exists in the kCCFailedLinks or
           kCCFailedConnections variables such that z.UUIDDsa is the
           objectGUID of the target dsa, z.FailureCount > 0, and
           the current time - z.TimeFirstFailure > 2 hours.
        """
        # XXX - not implemented yet
        return False

    def remove_unneeded_failed_links_connections(self):
        # XXX - not implemented yet
        return

    def remove_unneeded_ntds_connections(self):
        # XXX - not implemented yet
        return

    def translate_connections(self):
        # XXX - not implemented yet
        return

    def intersite(self):
        """The head method for generating the inter-site KCC replica
           connection graph and attendant nTDSConnection objects
           in the samdb
        """
        # XXX - not implemented yet
        return

    def update_rodc_connection(self):
        """Runs when the local DC is an RODC and updates the RODC NTFRS
           connection object.
        """
        # Given an nTDSConnection object cn1, such that cn1.options contains
        # NTDSCONN_OPT_RODC_TOPOLOGY, and another nTDSConnection object cn2,
        # does not contain NTDSCONN_OPT_RODC_TOPOLOGY, modify cn1 to ensure
        # that the following is true:
        #
        #     cn1.fromServer = cn2.fromServer
        #     cn1.schedule   = cn2.schedule
        #
        # If no such cn2 can be found, cn1 is not modified.
        # If no such cn1 can be found, nothing is modified by this task.

        # XXX - not implemented yet
        return

    def intrasite_max_node_edges(self, node_count):
        """Returns the maximum number of edges directed to a node in
           the intrasite replica graph.  The KCC does not create more
           than 50 edges directed to a single DC. To optimize replication,
           we compute that each node should have n+2 total edges directed
           to it such that (n) is the smallest non-negative integer
           satisfying (node_count <= 2*(n*n) + 6*n + 7)
           :param node_count: total number of nodes in the replica graph
        """
        n = 0
        while True:
            if node_count <= (2 * (n * n) + (6 * n) + 7):
                break
            n = n + 1
        n = n + 2
        if n < 50:
            return n
        return 50

    def construct_intrasite_graph(self, site_local, dc_local,
                                  nc_x, gc_only, detect_stale):

        # We're using the MS notation names here to allow
        # correlation back to the published algorithm.
        #
        # nc_x     - naming context (x) that we are testing if it
        #            "should be present" on the local DC
        # f_of_x   - replica (f) found on a DC (s) for NC (x)
        # dc_s     - DC where f_of_x replica was found
        # dc_local - local DC that potentially needs a replica
        #            (f_of_x)
        # r_list   - replica list R
        # p_of_x   - replica (p) is partial and found on a DC (s)
        #            for NC (x)
        # l_of_x   - replica (l) is the local replica for NC (x)
        #            that should appear on the local DC
        # r_len    = is length of replica list |R|
        #
        # If the DSA doesn't need a replica for this
        # partition (NC x) then continue
        needed, ro, partial = nc_x.should_be_present(dc_local)

        logger.debug("construct_intrasite_graph:\n" + \
                     "nc_x: %s\ndc_local: %s\n" % \
                     (nc_x, dc_local) + \
                     "gc_only: %s\nneeded: %s\nro: %s\npartial: %s" % \
                     (gc_only, needed, ro, partial))

        if needed == False:
            return

        # Create a NCReplica that matches what the local replica
        # should say.  We'll use this below in our r_list
        l_of_x = NCReplica(dc_local.dsa_dnstr, dc_local.dsa_guid, \
                           nc_x.nc_dnstr, nc_x.nc_guid, nc_x.nc_sid)

        l_of_x.identify_by_basedn(self.samdb)

        l_of_x.rep_partial  = partial
        l_of_x.rep_ro       = ro

        # Empty replica sequence list
        r_list = []

        # We'll loop thru all the DSAs looking for
        # writeable NC replicas that match the naming
        # context dn for (nc_x)
        #
        for dc_s_dn, dc_s in self.dsa_table.items():

            # If this partition (nc_x) doesn't appear as a
            # replica (f_of_x) on (dc_s) then continue
            if not nc_x.nc_dnstr in dc_s.rep_table.keys():
                continue

            # Pull out the NCReplica (f) of (x) with the dn
            # that matches NC (x) we are examining.
            f_of_x = dc_s.rep_table[nc_x.nc_dnstr]

            # Replica (f) of NC (x) must be writable
            if f_of_x.is_ro() == True:
                continue

            # Replica (f) of NC (x) must satisfy the
            # "is present" criteria for DC (s) that
            # it was found on
            if f_of_x.is_present() == False:
                continue

            # DC (s) must be a writable DSA other than
            # my local DC.  In other words we'd only replicate
            # from other writable DC
            if dc_s.is_ro() or dc_s is dc_local:
                continue

            # Certain replica graphs are produced only
            # for global catalogs, so test against
            # method input parameter
            if gc_only and dc_s.is_gc() == False:
                continue

            # DC (s) must be in the same site as the local DC
            # This is the intra-site algorithm.  We are not
            # replicating across multiple sites
            if site_local.is_same_site(dc_s) == False:
                continue

            # If NC (x) is intended to be read-only full replica
            # for a domain NC on the target DC then the source
            # DC should have functional level at minimum WIN2008
            #
            # Effectively we're saying that in order to replicate
            # to a targeted RODC (which was introduced in Windows 2008)
            # then we have to replicate from a DC that is also minimally
            # at that level.
            #
            # You can also see this requirement in the MS special
            # considerations for RODC which state that to deploy
            # an RODC, at least one writable domain controller in
            # the domain must be running Windows Server 2008
            if ro and partial == False and nc_x.nc_type == NCType.domain:
                if dc_s.is_minimum_behavior(DS_BEHAVIOR_WIN2008) == False:
                    continue

            # If we haven't been told to turn off stale connection
            # detection and this dsa has a stale connection then
            # continue
            if detect_stale and self.is_stale_link_connection(dc_s) == True:
               continue

            # Replica meets criteria.  Add it to table indexed
            # by the GUID of the DC that it appears on
            r_list.append(f_of_x)

        # If a partial (not full) replica of NC (x) "should be present"
        # on the local DC, append to R each partial replica (p of x)
        # such that p "is present" on a DC satisfying the same
        # criteria defined above for full replica DCs.
        if partial == True:

            # Now we loop thru all the DSAs looking for
            # partial NC replicas that match the naming
            # context dn for (NC x)
            for dc_s_dn, dc_s in self.dsa_table.items():

                # If this partition NC (x) doesn't appear as a
                # replica (p) of NC (x) on the dsa DC (s) then
                # continue
                if not nc_x.nc_dnstr in dc_s.rep_table.keys():
                    continue

                # Pull out the NCReplica with the dn that
                # matches NC (x) we are examining.
                p_of_x = dsa.rep_table[nc_x.nc_dnstr]

                # Replica (p) of NC (x) must be partial
                if p_of_x.is_partial() == False:
                    continue

                # Replica (p) of NC (x) must satisfy the
                # "is present" criteria for DC (s) that
                # it was found on
                if p_of_x.is_present() == False:
                    continue

                # DC (s) must be a writable DSA other than
                # my DSA.  In other words we'd only replicate
                # from other writable DSA
                if dc_s.is_ro() or dc_s is dc_local:
                    continue

                # Certain replica graphs are produced only
                # for global catalogs, so test against
                # method input parameter
                if gc_only and dc_s.is_gc() == False:
                    continue

                # DC (s) must be in the same site as the local DC
                # This is the intra-site algorithm.  We are not
                # replicating across multiple sites
                if site_local.is_same_site(dc_s) == False:
                    continue

                # This criteria is moot (a no-op) for this case
                # because we are scanning for (partial = True).  The
                # MS algorithm statement says partial replica scans
                # should adhere to the "same" criteria as full replica
                # scans so the criteria doesn't change here...its just
                # rendered pointless.
                #
                # The case that is occurring would be a partial domain
                # replica is needed on a local DC global catalog.  There
                # is no minimum windows behavior for those since GCs
                # have always been present.
                if ro and partial == False and nc_x.nc_type == NCType.domain:
                    if dc_s.is_minimum_behavior(DS_BEHAVIOR_WIN2008) == False:
                        continue

                # If we haven't been told to turn off stale connection
                # detection and this dsa has a stale connection then
                # continue
                if detect_stale and self.is_stale_link_connection(dc_s) == True:
                    continue

                # Replica meets criteria.  Add it to table indexed
                # by the GUID of the DSA that it appears on
                r_list.append(p_of_x)

        # Append to R the NC replica that "should be present"
        # on the local DC
        r_list.append(l_of_x)

        r_list.sort(sort_replica_by_dsa_guid)

        r_len = len(r_list)

        max_node_edges = self.intrasite_max_node_edges(r_len)

        # Add a node for each r_list element to the replica graph
        graph_list = []
        for rep in r_list:
            node = GraphNode(rep.rep_dsa_dnstr, max_node_edges)
            graph_list.append(node)

        # For each r(i) from (0 <= i < |R|-1)
        i = 0
        while i < (r_len-1):
            # Add an edge from r(i) to r(i+1) if r(i) is a full
            # replica or r(i+1) is a partial replica
            if r_list[i].is_partial() == False or \
               r_list[i+1].is_partial() == True:
                graph_list[i+1].add_edge_from(r_list[i].rep_dsa_dnstr)

            # Add an edge from r(i+1) to r(i) if r(i+1) is a full
            # replica or ri is a partial replica.
            if r_list[i+1].is_partial() == False or \
               r_list[i].is_partial() == True:
                graph_list[i].add_edge_from(r_list[i+1].rep_dsa_dnstr)
            i = i + 1

        # Add an edge from r|R|-1 to r0 if r|R|-1 is a full replica
        # or r0 is a partial replica.
        if r_list[r_len-1].is_partial() == False or \
           r_list[0].is_partial() == True:
            graph_list[0].add_edge_from(r_list[r_len-1].rep_dsa_dnstr)

        # Add an edge from r0 to r|R|-1 if r0 is a full replica or
        # r|R|-1 is a partial replica.
        if r_list[0].is_partial() == False or \
           r_list[r_len-1].is_partial() == True:
            graph_list[r_len-1].add_edge_from(r_list[0].rep_dsa_dnstr)

        # For each existing nTDSConnection object implying an edge
        # from rj of R to ri such that j != i, an edge from rj to ri
        # is not already in the graph, and the total edges directed
        # to ri is less than n+2, the KCC adds that edge to the graph.
        i = 0
        while i < r_len:
            dsa = self.dsa_table[graph_list[i].dsa_dnstr]
            graph_list[i].add_edges_from_connections(dsa)
            i = i + 1

        i = 0
        while i < r_len:
            tnode  = graph_list[i]

            # To optimize replication latency in sites with many NC replicas, the
            # KCC adds new edges directed to ri to bring the total edges to n+2,
            # where the NC replica rk of R from which the edge is directed
            # is chosen at random such that k != i and an edge from rk to ri
            # is not already in the graph.
            #
            # Note that the KCC tech ref does not give a number for the definition
            # of "sites with many NC replicas".   At a bare minimum to satisfy
            # n+2 edges directed at a node we have to have at least three replicas
            # in |R| (i.e. if n is zero then at least replicas from two other graph
            # nodes may direct edges to us).
            if r_len >= 3:
                # pick a random index
                findex = rindex = random.randint(0, r_len-1)

                # while this node doesn't have sufficient edges
                while tnode.has_sufficient_edges() == False:
                    # If this edge can be successfully added (i.e. not
                    # the same node and edge doesn't already exist) then
                    # select a new random index for the next round
                    if tnode.add_edge_from(graph_list[rindex].dsa_dnstr) == True:
                        findex = rindex = random.randint(0, r_len-1)
                    else:
                        # Otherwise continue looking against each node
                        # after the random selection
                        rindex = rindex + 1
                        if rindex >= r_len:
                            rindex = 0

                        if rindex == findex:
                            logger.error("Unable to satisfy max edge criteria!")
                            break

            # Print the graph node in debug mode
            logger.debug("%s" % tnode)

            # For each edge directed to the local DC, ensure a nTDSConnection
            # points to us that satisfies the KCC criteria
            if graph_list[i].dsa_dnstr == dc_local.dsa_dnstr:
                graph_list[i].add_connections_from_edges(dc_local)

            i = i + 1

        return

    def intrasite(self):
        """The head method for generating the intra-site KCC replica
           connection graph and attendant nTDSConnection objects
           in the samdb
        """
        # Retrieve my DSA
        mydsa = self.dsa_table[self.my_dsa_dnstr]

        logger.debug("intrasite enter:\nmydsa: %s" % mydsa)

        # Test whether local site has topology disabled
        mysite = self.site_table[self.my_site_dnstr]
        if mysite.is_intrasite_topology_disabled():
            return

        detect_stale = mysite.should_detect_stale()

        # Loop thru all the partitions.
        for partdn, part in self.part_table.items():
            self.construct_intrasite_graph(mysite, mydsa, part,  \
                                           False, \
                                           detect_stale)

        # If the DC is a GC server, the KCC constructs an additional NC
        # replica graph (and creates nTDSConnection objects) for the
        # config NC as above, except that only NC replicas that "are present"
        # on GC servers are added to R.
        for partdn, part in self.part_table.items():
            if part.is_config():
                self.construct_intrasite_graph(mysite, mydsa, part,  \
                                               True, \
                                               detect_stale)

        # The DC repeats the NC replica graph computation and nTDSConnection
        # creation for each of the NC replica graphs, this time assuming
        # that no DC has failed. It does so by re-executing the steps as
        # if the bit NTDSSETTINGS_OPT_IS_TOPL_DETECT_STALE_DISABLED were
        # set in the options attribute of the site settings object for
        # the local DC's site.  (ie. we set "detec_stale" flag to False)

        # Loop thru all the partitions.
        for partdn, part in self.part_table.items():
            self.construct_intrasite_graph(mysite, mydsa, part,  \
                                           False, \
                                           False) # don't detect stale

        # If the DC is a GC server, the KCC constructs an additional NC
        # replica graph (and creates nTDSConnection objects) for the
        # config NC as above, except that only NC replicas that "are present"
        # on GC servers are added to R.
        for partdn, part in self.part_table.items():
            if part.is_config():
                self.construct_intrasite_graph(mysite, mydsa, part,  \
                                               True, \
                                               False)  # don't detect stale

        # Commit any newly created connections to the samdb
        mydsa.commit_connection_table(self.samdb)

        logger.debug("intrasite exit:\nmydsa: %s" % mydsa)
        return

    def run(self):
        """Method to perform a complete run of the KCC and
           produce an updated topology for subsequent NC replica
           syncronization between domain controllers
        """
        # Setup
        try:
            self.load_my_dsa()
            self.load_all_dsa()
            self.load_all_partitions()
            self.load_my_site()

        except Exception, estr:
            logger.error("%s" % estr)
            return

        # self.should_be_present_test()

        # These are the published steps (in order) for the
        # MS description of the KCC algorithm

        # Step 1
        self.refresh_failed_links_connections()

        # Step 2
        self.intrasite()

        # Step 3
        self.intersite()

        # Step 4
        self.remove_unneeded_ntds_connections()

        # Step 5
        self.translate_connections()

        # Step 6
        self.remove_unneeded_failed_links_connections()

        # Step 7
        self.update_rodc_connection()

        return

##################################################
# Global Functions
##################################################
def sort_replica_by_dsa_guid(rep1, rep2):
    return cmp(rep1.rep_dsa_guid, rep2.rep_dsa_guid)

##################################################
# samba_kcc entry point
##################################################

parser    = optparse.OptionParser("samba_kcc [options]")
sambaopts = options.SambaOptions(parser)
credopts  = options.CredentialsOptions(parser)

parser.add_option_group(sambaopts)
parser.add_option_group(credopts)
parser.add_option_group(options.VersionOptions(parser))

parser.add_option("--debug", help="debug output", action="store_true")
parser.add_option("--seed",  help="random number seed")

logger = logging.getLogger("samba_kcc")
logger.addHandler(logging.StreamHandler(sys.stdout))

lp     = sambaopts.get_loadparm()
creds  = credopts.get_credentials(lp, fallback_machine=True)

opts, args = parser.parse_args()

if opts.debug:
    logger.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.WARNING)

# initialize seed from optional input parameter
if opts.seed:
    random.seed(int(opts.seed))
else:
    random.seed(0xACE5CA11)

private_dir = lp.get("private dir")
samdb_path  = os.path.join(private_dir, "samdb.ldb")

try:
    samdb = SamDB(url=lp.samdb_url(), session_info=system_session(),
                  credentials=creds, lp=lp)
except ldb.LdbError, (num, msg):
    logger.info("Unable to open sam database %s : %s" % (lp.samdb_url(), msg))
    sys.exit(1)

# Instantiate Knowledge Consistency Checker and perform run
kcc = KCC(samdb)
kcc.run()