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repl_meta_data.c

/*
   ldb database library

   Copyright (C) Simo Sorce  2004-2008
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   Copyright (C) Andrew Tridgell 2005
   Copyright (C) Stefan Metzmacher <metze@samba.org> 2007
   Copyright (C) Matthieu Patou <mat@samba.org> 2010

   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/>.
*/

/*
 *  Name: ldb
 *
 *  Component: ldb repl_meta_data module
 *
 *  Description: - add a unique objectGUID onto every new record,
 *               - handle whenCreated, whenChanged timestamps
 *               - handle uSNCreated, uSNChanged numbers
 *               - handle replPropertyMetaData attribute
 *
 *  Author: Simo Sorce
 *  Author: Stefan Metzmacher
 */

#include "includes.h"
#include "ldb_module.h"
#include "dsdb/samdb/samdb.h"
#include "dsdb/common/proto.h"
#include "../libds/common/flags.h"
#include "librpc/gen_ndr/ndr_misc.h"
#include "librpc/gen_ndr/ndr_drsuapi.h"
#include "librpc/gen_ndr/ndr_drsblobs.h"
#include "param/param.h"
#include "libcli/security/dom_sid.h"
#include "lib/util/dlinklist.h"
#include "dsdb/samdb/ldb_modules/util.h"
#include "lib/util/binsearch.h"
#include "libcli/security/security.h"
#include "lib/util/tsort.h"

struct replmd_private {
      TALLOC_CTX *la_ctx;
      struct la_entry *la_list;
      TALLOC_CTX *bl_ctx;
      struct la_backlink *la_backlinks;
      struct nc_entry {
            struct nc_entry *prev, *next;
            struct ldb_dn *dn;
            uint64_t mod_usn;
            uint64_t mod_usn_urgent;
      } *ncs;
};

struct la_entry {
      struct la_entry *next, *prev;
      struct drsuapi_DsReplicaLinkedAttribute *la;
};

struct replmd_replicated_request {
      struct ldb_module *module;
      struct ldb_request *req;

      const struct dsdb_schema *schema;

      /* the controls we pass down */
      struct ldb_control **controls;

      /* details for the mode where we apply a bunch of inbound replication meessages */
      bool apply_mode;
      uint32_t index_current;
      struct dsdb_extended_replicated_objects *objs;

      struct ldb_message *search_msg;

      uint64_t seq_num;
      bool is_urgent;
};

enum urgent_situation {
      REPL_URGENT_ON_CREATE = 1,
      REPL_URGENT_ON_UPDATE = 2,
      REPL_URGENT_ON_DELETE = 4
};


static const struct {
      const char *update_name;
      enum urgent_situation repl_situation;
} urgent_objects[] = {
            {"nTDSDSA", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_DELETE)},
            {"crossRef", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_DELETE)},
            {"attributeSchema", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_UPDATE)},
            {"classSchema", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_UPDATE)},
            {"secret", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_UPDATE)},
            {"rIDManager", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_UPDATE)},
            {NULL, 0}
};

/* Attributes looked for when updating or deleting, to check for a urgent replication needed */
static const char *urgent_attrs[] = {
            "lockoutTime",
            "pwdLastSet",
            "userAccountControl",
            NULL
};


static bool replmd_check_urgent_objectclass(const struct ldb_message_element *objectclass_el,
                              enum urgent_situation situation)
{
      unsigned int i, j;
      for (i=0; urgent_objects[i].update_name; i++) {

            if ((situation & urgent_objects[i].repl_situation) == 0) {
                  continue;
            }

            for (j=0; j<objectclass_el->num_values; j++) {
                  const struct ldb_val *v = &objectclass_el->values[j];
                  if (ldb_attr_cmp((const char *)v->data, urgent_objects[i].update_name) == 0) {
                        return true;
                  }
            }
      }
      return false;
}

static bool replmd_check_urgent_attribute(const struct ldb_message_element *el)
{
      if (ldb_attr_in_list(urgent_attrs, el->name)) {
            return true;
      }
      return false;
}


static int replmd_replicated_apply_next(struct replmd_replicated_request *ar);

/*
  initialise the module
  allocate the private structure and build the list
  of partition DNs for use by replmd_notify()
 */
static int replmd_init(struct ldb_module *module)
{
      struct replmd_private *replmd_private;
      struct ldb_context *ldb = ldb_module_get_ctx(module);

      replmd_private = talloc_zero(module, struct replmd_private);
      if (replmd_private == NULL) {
            ldb_oom(ldb);
            return LDB_ERR_OPERATIONS_ERROR;
      }
      ldb_module_set_private(module, replmd_private);

      return ldb_next_init(module);
}

/*
  cleanup our per-transaction contexts
 */
static void replmd_txn_cleanup(struct replmd_private *replmd_private)
{
      talloc_free(replmd_private->la_ctx);
      replmd_private->la_list = NULL;
      replmd_private->la_ctx = NULL;

      talloc_free(replmd_private->bl_ctx);
      replmd_private->la_backlinks = NULL;
      replmd_private->bl_ctx = NULL;
}


struct la_backlink {
      struct la_backlink *next, *prev;
      const char *attr_name;
      struct GUID forward_guid, target_guid;
      bool active;
};

/*
  process a backlinks we accumulated during a transaction, adding and
  deleting the backlinks from the target objects
 */
static int replmd_process_backlink(struct ldb_module *module, struct la_backlink *bl)
{
      struct ldb_dn *target_dn, *source_dn;
      int ret;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      struct ldb_message *msg;
      TALLOC_CTX *tmp_ctx = talloc_new(bl);
      char *dn_string;

      /*
        - find DN of target
        - find DN of source
        - construct ldb_message
              - either an add or a delete
       */
      ret = dsdb_module_dn_by_guid(module, tmp_ctx, &bl->target_guid, &target_dn);
      if (ret != LDB_SUCCESS) {
            DEBUG(2,(__location__ ": WARNING: Failed to find target DN for linked attribute with GUID %s\n",
                   GUID_string(bl, &bl->target_guid)));
            return LDB_SUCCESS;
      }

      ret = dsdb_module_dn_by_guid(module, tmp_ctx, &bl->forward_guid, &source_dn);
      if (ret != LDB_SUCCESS) {
            ldb_asprintf_errstring(ldb, "Failed to find source DN for linked attribute with GUID %s\n",
                               GUID_string(bl, &bl->forward_guid));
            talloc_free(tmp_ctx);
            return ret;
      }

      msg = ldb_msg_new(tmp_ctx);
      if (msg == NULL) {
            ldb_module_oom(module);
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* construct a ldb_message for adding/deleting the backlink */
      msg->dn = target_dn;
      dn_string = ldb_dn_get_extended_linearized(tmp_ctx, source_dn, 1);
      if (!dn_string) {
            ldb_module_oom(module);
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }
      ret = ldb_msg_add_steal_string(msg, bl->attr_name, dn_string);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }
      msg->elements[0].flags = bl->active?LDB_FLAG_MOD_ADD:LDB_FLAG_MOD_DELETE;

      ret = dsdb_module_modify(module, msg, DSDB_FLAG_NEXT_MODULE);
      if (ret != LDB_SUCCESS) {
            ldb_asprintf_errstring(ldb, "Failed to %s backlink from %s to %s - %s",
                               bl->active?"add":"remove",
                               ldb_dn_get_linearized(source_dn),
                               ldb_dn_get_linearized(target_dn),
                               ldb_errstring(ldb));
            talloc_free(tmp_ctx);
            return ret;
      }
      talloc_free(tmp_ctx);
      return ret;
}

/*
  add a backlink to the list of backlinks to add/delete in the prepare
  commit
 */
static int replmd_add_backlink(struct ldb_module *module, const struct dsdb_schema *schema,
                         struct GUID *forward_guid, struct GUID *target_guid,
                         bool active, const struct dsdb_attribute *schema_attr, bool immediate)
{
      const struct dsdb_attribute *target_attr;
      struct la_backlink *bl;
      struct replmd_private *replmd_private =
            talloc_get_type_abort(ldb_module_get_private(module), struct replmd_private);

      target_attr = dsdb_attribute_by_linkID(schema, schema_attr->linkID ^ 1);
      if (!target_attr) {
            /*
             * windows 2003 has a broken schema where the
             * definition of msDS-IsDomainFor is missing (which is
             * supposed to be the backlink of the
             * msDS-HasDomainNCs attribute
             */
            return LDB_SUCCESS;
      }

      /* see if its already in the list */
      for (bl=replmd_private->la_backlinks; bl; bl=bl->next) {
            if (GUID_equal(forward_guid, &bl->forward_guid) &&
                GUID_equal(target_guid, &bl->target_guid) &&
                (target_attr->lDAPDisplayName == bl->attr_name ||
                 strcmp(target_attr->lDAPDisplayName, bl->attr_name) == 0)) {
                  break;
            }
      }

      if (bl) {
            /* we found an existing one */
            if (bl->active == active) {
                  return LDB_SUCCESS;
            }
            DLIST_REMOVE(replmd_private->la_backlinks, bl);
            talloc_free(bl);
            return LDB_SUCCESS;
      }

      if (replmd_private->bl_ctx == NULL) {
            replmd_private->bl_ctx = talloc_new(replmd_private);
            if (replmd_private->bl_ctx == NULL) {
                  ldb_module_oom(module);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
      }

      /* its a new one */
      bl = talloc(replmd_private->bl_ctx, struct la_backlink);
      if (bl == NULL) {
            ldb_module_oom(module);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* Ensure the schema does not go away before the bl->attr_name is used */
      if (!talloc_reference(bl, schema)) {
            talloc_free(bl);
            ldb_module_oom(module);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      bl->attr_name = target_attr->lDAPDisplayName;
      bl->forward_guid = *forward_guid;
      bl->target_guid = *target_guid;
      bl->active = active;

      /* the caller may ask for this backlink to be processed
         immediately */
      if (immediate) {
            int ret = replmd_process_backlink(module, bl);
            talloc_free(bl);
            return ret;
      }

      DLIST_ADD(replmd_private->la_backlinks, bl);

      return LDB_SUCCESS;
}


/*
 * Callback for most write operations in this module:
 *
 * notify the repl task that a object has changed. The notifies are
 * gathered up in the replmd_private structure then written to the
 * @REPLCHANGED object in each partition during the prepare_commit
 */
static int replmd_op_callback(struct ldb_request *req, struct ldb_reply *ares)
{
      int ret;
      struct replmd_replicated_request *ac =
            talloc_get_type_abort(req->context, struct replmd_replicated_request);
      struct replmd_private *replmd_private =
            talloc_get_type_abort(ldb_module_get_private(ac->module), struct replmd_private);
      struct nc_entry *modified_partition;
      struct ldb_control *partition_ctrl;
      const struct dsdb_control_current_partition *partition;

      struct ldb_control **controls;

      partition_ctrl = ldb_reply_get_control(ares, DSDB_CONTROL_CURRENT_PARTITION_OID);

      /* Remove the 'partition' control from what we pass up the chain */
      controls = controls_except_specified(ares->controls, ares, partition_ctrl);

      if (ares->error != LDB_SUCCESS) {
            return ldb_module_done(ac->req, controls,
                              ares->response, ares->error);
      }

      if (ares->type != LDB_REPLY_DONE) {
            ldb_set_errstring(ldb_module_get_ctx(ac->module), "Invalid reply type for notify\n!");
            return ldb_module_done(ac->req, NULL,
                               NULL, LDB_ERR_OPERATIONS_ERROR);
      }

      if (!partition_ctrl) {
            ldb_set_errstring(ldb_module_get_ctx(ac->module),"No partition control on reply");
            return ldb_module_done(ac->req, NULL,
                               NULL, LDB_ERR_OPERATIONS_ERROR);
      }

      partition = talloc_get_type_abort(partition_ctrl->data,
                            struct dsdb_control_current_partition);

      if (ac->seq_num > 0) {
            for (modified_partition = replmd_private->ncs; modified_partition;
                 modified_partition = modified_partition->next) {
                  if (ldb_dn_compare(modified_partition->dn, partition->dn) == 0) {
                        break;
                  }
            }

            if (modified_partition == NULL) {
                  modified_partition = talloc_zero(replmd_private, struct nc_entry);
                  if (!modified_partition) {
                        ldb_oom(ldb_module_get_ctx(ac->module));
                        return ldb_module_done(ac->req, NULL,
                                           NULL, LDB_ERR_OPERATIONS_ERROR);
                  }
                  modified_partition->dn = ldb_dn_copy(modified_partition, partition->dn);
                  if (!modified_partition->dn) {
                        ldb_oom(ldb_module_get_ctx(ac->module));
                        return ldb_module_done(ac->req, NULL,
                                           NULL, LDB_ERR_OPERATIONS_ERROR);
                  }
                  DLIST_ADD(replmd_private->ncs, modified_partition);
            }

            if (ac->seq_num > modified_partition->mod_usn) {
                  modified_partition->mod_usn = ac->seq_num;
                  if (ac->is_urgent) {
                        modified_partition->mod_usn_urgent = ac->seq_num;
                  }
            }
      }

      if (ac->apply_mode) {
            talloc_free(ares);
            ac->index_current++;

            ret = replmd_replicated_apply_next(ac);
            if (ret != LDB_SUCCESS) {
                  return ldb_module_done(ac->req, NULL, NULL, ret);
            }
            return ret;
      } else {
            /* free the partition control container here, for the
             * common path.  Other cases will have it cleaned up
             * eventually with the ares */
            talloc_free(partition_ctrl);
            return ldb_module_done(ac->req,
                               controls_except_specified(controls, ares, partition_ctrl),
                               ares->response, LDB_SUCCESS);
      }
}


/*
 * update a @REPLCHANGED record in each partition if there have been
 * any writes of replicated data in the partition
 */
static int replmd_notify_store(struct ldb_module *module)
{
      struct replmd_private *replmd_private =
            talloc_get_type(ldb_module_get_private(module), struct replmd_private);

      while (replmd_private->ncs) {
            int ret;
            struct nc_entry *modified_partition = replmd_private->ncs;

            ret = dsdb_module_save_partition_usn(module, modified_partition->dn,
                                         modified_partition->mod_usn,
                                         modified_partition->mod_usn_urgent);
            if (ret != LDB_SUCCESS) {
                  DEBUG(0,(__location__ ": Failed to save partition uSN for %s\n",
                         ldb_dn_get_linearized(modified_partition->dn)));
                  return ret;
            }
            DLIST_REMOVE(replmd_private->ncs, modified_partition);
            talloc_free(modified_partition);
      }

      return LDB_SUCCESS;
}


/*
  created a replmd_replicated_request context
 */
static struct replmd_replicated_request *replmd_ctx_init(struct ldb_module *module,
                                           struct ldb_request *req)
{
      struct ldb_context *ldb;
      struct replmd_replicated_request *ac;

      ldb = ldb_module_get_ctx(module);

      ac = talloc_zero(req, struct replmd_replicated_request);
      if (ac == NULL) {
            ldb_oom(ldb);
            return NULL;
      }

      ac->module = module;
      ac->req     = req;

      ac->schema = dsdb_get_schema(ldb, ac);
      if (!ac->schema) {
            ldb_debug_set(ldb, LDB_DEBUG_FATAL,
                        "replmd_modify: no dsdb_schema loaded");
            DEBUG(0,(__location__ ": %s\n", ldb_errstring(ldb)));
            return NULL;
      }

      return ac;
}

/*
  add a time element to a record
*/
static int add_time_element(struct ldb_message *msg, const char *attr, time_t t)
{
      struct ldb_message_element *el;
      char *s;

      if (ldb_msg_find_element(msg, attr) != NULL) {
            return LDB_SUCCESS;
      }

      s = ldb_timestring(msg, t);
      if (s == NULL) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      if (ldb_msg_add_string(msg, attr, s) != LDB_SUCCESS) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      el = ldb_msg_find_element(msg, attr);
      /* always set as replace. This works because on add ops, the flag
         is ignored */
      el->flags = LDB_FLAG_MOD_REPLACE;

      return LDB_SUCCESS;
}

/*
  add a uint64_t element to a record
*/
static int add_uint64_element(struct ldb_message *msg, const char *attr, uint64_t v)
{
      struct ldb_message_element *el;

      if (ldb_msg_find_element(msg, attr) != NULL) {
            return LDB_SUCCESS;
      }

      if (ldb_msg_add_fmt(msg, attr, "%llu", (unsigned long long)v) != LDB_SUCCESS) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      el = ldb_msg_find_element(msg, attr);
      /* always set as replace. This works because on add ops, the flag
         is ignored */
      el->flags = LDB_FLAG_MOD_REPLACE;

      return LDB_SUCCESS;
}

static int replmd_replPropertyMetaData1_attid_sort(const struct replPropertyMetaData1 *m1,
                                       const struct replPropertyMetaData1 *m2,
                                       const uint32_t *rdn_attid)
{
      if (m1->attid == m2->attid) {
            return 0;
      }

      /*
       * the rdn attribute should be at the end!
       * so we need to return a value greater than zero
       * which means m1 is greater than m2
       */
      if (m1->attid == *rdn_attid) {
            return 1;
      }

      /*
       * the rdn attribute should be at the end!
       * so we need to return a value less than zero
       * which means m2 is greater than m1
       */
      if (m2->attid == *rdn_attid) {
            return -1;
      }

      return m1->attid > m2->attid ? 1 : -1;
}

static int replmd_replPropertyMetaDataCtr1_sort(struct replPropertyMetaDataCtr1 *ctr1,
                                    const struct dsdb_schema *schema,
                                    struct ldb_dn *dn)
{
      const char *rdn_name;
      const struct dsdb_attribute *rdn_sa;

      rdn_name = ldb_dn_get_rdn_name(dn);
      if (!rdn_name) {
            DEBUG(0,(__location__ ": No rDN for %s?\n", ldb_dn_get_linearized(dn)));
            return LDB_ERR_OPERATIONS_ERROR;
      }

      rdn_sa = dsdb_attribute_by_lDAPDisplayName(schema, rdn_name);
      if (rdn_sa == NULL) {
            DEBUG(0,(__location__ ": No sa found for rDN %s for %s\n", rdn_name, ldb_dn_get_linearized(dn)));
            return LDB_ERR_OPERATIONS_ERROR;
      }

      DEBUG(6,("Sorting rpmd with attid exception %u rDN=%s DN=%s\n",
             rdn_sa->attributeID_id, rdn_name, ldb_dn_get_linearized(dn)));

      LDB_TYPESAFE_QSORT(ctr1->array, ctr1->count, &rdn_sa->attributeID_id, replmd_replPropertyMetaData1_attid_sort);

      return LDB_SUCCESS;
}

static int replmd_ldb_message_element_attid_sort(const struct ldb_message_element *e1,
                                     const struct ldb_message_element *e2,
                                     const struct dsdb_schema *schema)
{
      const struct dsdb_attribute *a1;
      const struct dsdb_attribute *a2;

      /*
       * TODO: make this faster by caching the dsdb_attribute pointer
       *       on the ldb_messag_element
       */

      a1 = dsdb_attribute_by_lDAPDisplayName(schema, e1->name);
      a2 = dsdb_attribute_by_lDAPDisplayName(schema, e2->name);

      /*
       * TODO: remove this check, we should rely on e1 and e2 having valid attribute names
       *       in the schema
       */
      if (!a1 || !a2) {
            return strcasecmp(e1->name, e2->name);
      }
      if (a1->attributeID_id == a2->attributeID_id) {
            return 0;
      }
      return a1->attributeID_id > a2->attributeID_id ? 1 : -1;
}

static void replmd_ldb_message_sort(struct ldb_message *msg,
                            const struct dsdb_schema *schema)
{
      LDB_TYPESAFE_QSORT(msg->elements, msg->num_elements, schema, replmd_ldb_message_element_attid_sort);
}

static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
                         const struct GUID *invocation_id, uint64_t seq_num,
                         uint64_t local_usn, NTTIME nttime, uint32_t version, bool deleted);


/*
  fix up linked attributes in replmd_add.
  This involves setting up the right meta-data in extended DN
  components, and creating backlinks to the object
 */
static int replmd_add_fix_la(struct ldb_module *module, struct ldb_message_element *el,
                       uint64_t seq_num, const struct GUID *invocationId, time_t t,
                       struct GUID *guid, const struct dsdb_attribute *sa)
{
      unsigned int i;
      TALLOC_CTX *tmp_ctx = talloc_new(el->values);
      struct ldb_context *ldb = ldb_module_get_ctx(module);

      /* We will take a reference to the schema in replmd_add_backlink */
      const struct dsdb_schema *schema = dsdb_get_schema(ldb, NULL);
      NTTIME now;

      unix_to_nt_time(&now, t);

      for (i=0; i<el->num_values; i++) {
            struct ldb_val *v = &el->values[i];
            struct dsdb_dn *dsdb_dn = dsdb_dn_parse(tmp_ctx, ldb, v, sa->syntax->ldap_oid);
            struct GUID target_guid;
            NTSTATUS status;
            int ret;

            /* note that the DN already has the extended
               components from the extended_dn_store module */
            status = dsdb_get_extended_dn_guid(dsdb_dn->dn, &target_guid, "GUID");
            if (!NT_STATUS_IS_OK(status) || GUID_all_zero(&target_guid)) {
                  ret = dsdb_module_guid_by_dn(module, dsdb_dn->dn, &target_guid);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
                  ret = dsdb_set_extended_dn_guid(dsdb_dn->dn, &target_guid, "GUID");
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
            }

            ret = replmd_build_la_val(el->values, v, dsdb_dn, invocationId,
                                seq_num, seq_num, now, 0, false);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            ret = replmd_add_backlink(module, schema, guid, &target_guid, true, sa, false);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }

      talloc_free(tmp_ctx);
      return LDB_SUCCESS;
}


/*
  intercept add requests
 */
static int replmd_add(struct ldb_module *module, struct ldb_request *req)
{
      struct ldb_context *ldb;
        struct ldb_control *control;
      struct replmd_replicated_request *ac;
      enum ndr_err_code ndr_err;
      struct ldb_request *down_req;
      struct ldb_message *msg;
        const DATA_BLOB *guid_blob;
      struct GUID guid;
      struct replPropertyMetaDataBlob nmd;
      struct ldb_val nmd_value;
      const struct GUID *our_invocation_id;
      time_t t = time(NULL);
      NTTIME now;
      char *time_str;
      int ret;
      unsigned int i;
      unsigned int functional_level;
      uint32_t ni=0;
      bool allow_add_guid = false;
      bool remove_current_guid = false;
      bool is_urgent = false;
      struct ldb_message_element *objectclass_el;

        /* check if there's a show relax control (used by provision to say 'I know what I'm doing') */
        control = ldb_request_get_control(req, LDB_CONTROL_RELAX_OID);
      if (control) {
            allow_add_guid = true;
      }

      /* do not manipulate our control entries */
      if (ldb_dn_is_special(req->op.add.message->dn)) {
            return ldb_next_request(module, req);
      }

      ldb = ldb_module_get_ctx(module);

      functional_level = dsdb_functional_level(ldb);

      ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_add\n");

      ac = replmd_ctx_init(module, req);
      if (!ac) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

        guid_blob = ldb_msg_find_ldb_val(req->op.add.message, "objectGUID");
      if ( guid_blob != NULL ) {
            if( !allow_add_guid ) {
                  ldb_debug_set(ldb, LDB_DEBUG_ERROR,
                        "replmd_add: it's not allowed to add an object with objectGUID\n");
                  talloc_free(ac);
                  return LDB_ERR_UNWILLING_TO_PERFORM;
            } else {
                  NTSTATUS status = GUID_from_data_blob(guid_blob,&guid);
                    if ( !NT_STATUS_IS_OK(status)) {
                              ldb_debug_set(ldb, LDB_DEBUG_ERROR,
                              "replmd_add: Unable to parse as a GUID the attribute objectGUID\n");
                        talloc_free(ac);
                        return LDB_ERR_UNWILLING_TO_PERFORM;
                  }
                  /* we remove this attribute as it can be a string and will not be treated
                  correctly and then we will readd it latter on in the good format*/
                  remove_current_guid = true;
            }
      } else {
            /* a new GUID */
            guid = GUID_random();
      }

      /* Get a sequence number from the backend */
      ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &ac->seq_num);
      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      /* get our invocationId */
      our_invocation_id = samdb_ntds_invocation_id(ldb);
      if (!our_invocation_id) {
            ldb_debug_set(ldb, LDB_DEBUG_ERROR,
                        "replmd_add: unable to find invocationId\n");
            talloc_free(ac);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* we have to copy the message as the caller might have it as a const */
      msg = ldb_msg_copy_shallow(ac, req->op.add.message);
      if (msg == NULL) {
            ldb_oom(ldb);
            talloc_free(ac);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* generated times */
      unix_to_nt_time(&now, t);
      time_str = ldb_timestring(msg, t);
      if (!time_str) {
            ldb_oom(ldb);
            talloc_free(ac);
            return LDB_ERR_OPERATIONS_ERROR;
      }
      if (remove_current_guid) {
            ldb_msg_remove_attr(msg,"objectGUID");
      }

      /*
       * remove autogenerated attributes
       */
      ldb_msg_remove_attr(msg, "whenCreated");
      ldb_msg_remove_attr(msg, "whenChanged");
      ldb_msg_remove_attr(msg, "uSNCreated");
      ldb_msg_remove_attr(msg, "uSNChanged");
      ldb_msg_remove_attr(msg, "replPropertyMetaData");

      /*
       * readd replicated attributes
       */
      ret = ldb_msg_add_string(msg, "whenCreated", time_str);
      if (ret != LDB_SUCCESS) {
            ldb_oom(ldb);
            talloc_free(ac);
            return ret;
      }

      /* build the replication meta_data */
      ZERO_STRUCT(nmd);
      nmd.version       = 1;
      nmd.ctr.ctr1.count      = msg->num_elements;
      nmd.ctr.ctr1.array      = talloc_array(msg,
                                     struct replPropertyMetaData1,
                                     nmd.ctr.ctr1.count);
      if (!nmd.ctr.ctr1.array) {
            ldb_oom(ldb);
            talloc_free(ac);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      for (i=0; i < msg->num_elements; i++) {
            struct ldb_message_element *e = &msg->elements[i];
            struct replPropertyMetaData1 *m = &nmd.ctr.ctr1.array[ni];
            const struct dsdb_attribute *sa;

            if (e->name[0] == '@') continue;

            sa = dsdb_attribute_by_lDAPDisplayName(ac->schema, e->name);
            if (!sa) {
                  ldb_debug_set(ldb, LDB_DEBUG_ERROR,
                              "replmd_add: attribute '%s' not defined in schema\n",
                              e->name);
                  talloc_free(ac);
                  return LDB_ERR_NO_SUCH_ATTRIBUTE;
            }

            if ((sa->systemFlags & DS_FLAG_ATTR_NOT_REPLICATED) || (sa->systemFlags & DS_FLAG_ATTR_IS_CONSTRUCTED)) {
                  /* if the attribute is not replicated (0x00000001)
                   * or constructed (0x00000004) it has no metadata
                   */
                  continue;
            }

            if (sa->linkID != 0 && functional_level > DS_DOMAIN_FUNCTION_2000) {
                  ret = replmd_add_fix_la(module, e, ac->seq_num, our_invocation_id, t, &guid, sa);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(ac);
                        return ret;
                  }
                  /* linked attributes are not stored in
                     replPropertyMetaData in FL above w2k */
                  continue;
            }

            m->attid                = sa->attributeID_id;
            m->version              = 1;
            m->originating_change_time    = now;
            m->originating_invocation_id  = *our_invocation_id;
            m->originating_usn            = ac->seq_num;
            m->local_usn                  = ac->seq_num;
            ni++;
      }

      /* fix meta data count */
      nmd.ctr.ctr1.count = ni;

      /*
       * sort meta data array, and move the rdn attribute entry to the end
       */
      ret = replmd_replPropertyMetaDataCtr1_sort(&nmd.ctr.ctr1, ac->schema, msg->dn);
      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      /* generated NDR encoded values */
      ndr_err = ndr_push_struct_blob(&nmd_value, msg,
                               &nmd,
                               (ndr_push_flags_fn_t)ndr_push_replPropertyMetaDataBlob);
      if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
            ldb_oom(ldb);
            talloc_free(ac);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /*
       * add the autogenerated values
       */
      ret = dsdb_msg_add_guid(msg, &guid, "objectGUID");
      if (ret != LDB_SUCCESS) {
            ldb_oom(ldb);
            talloc_free(ac);
            return ret;
      }
      ret = ldb_msg_add_string(msg, "whenChanged", time_str);
      if (ret != LDB_SUCCESS) {
            ldb_oom(ldb);
            talloc_free(ac);
            return ret;
      }
      ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNCreated", ac->seq_num);
      if (ret != LDB_SUCCESS) {
            ldb_oom(ldb);
            talloc_free(ac);
            return ret;
      }
      ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNChanged", ac->seq_num);
      if (ret != LDB_SUCCESS) {
            ldb_oom(ldb);
            talloc_free(ac);
            return ret;
      }
      ret = ldb_msg_add_value(msg, "replPropertyMetaData", &nmd_value, NULL);
      if (ret != LDB_SUCCESS) {
            ldb_oom(ldb);
            talloc_free(ac);
            return ret;
      }

      /*
       * sort the attributes by attid before storing the object
       */
      replmd_ldb_message_sort(msg, ac->schema);

      objectclass_el = ldb_msg_find_element(msg, "objectClass");
      is_urgent = replmd_check_urgent_objectclass(objectclass_el,
                                          REPL_URGENT_ON_CREATE);

      ac->is_urgent = is_urgent;
      ret = ldb_build_add_req(&down_req, ldb, ac,
                        msg,
                        req->controls,
                        ac, replmd_op_callback,
                        req);

      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      if (functional_level == DS_DOMAIN_FUNCTION_2000) {
            ret = ldb_request_add_control(down_req, DSDB_CONTROL_APPLY_LINKS, false, NULL);
            if (ret != LDB_SUCCESS) {
                  talloc_free(ac);
                  return ret;
            }
      }

      /* mark the control done */
      if (control) {
            control->critical = 0;
      }

      /* go on with the call chain */
      return ldb_next_request(module, down_req);
}


/*
 * update the replPropertyMetaData for one element
 */
static int replmd_update_rpmd_element(struct ldb_context *ldb,
                              struct ldb_message *msg,
                              struct ldb_message_element *el,
                              struct ldb_message_element *old_el,
                              struct replPropertyMetaDataBlob *omd,
                              const struct dsdb_schema *schema,
                              uint64_t *seq_num,
                              const struct GUID *our_invocation_id,
                              NTTIME now)
{
      uint32_t i;
      const struct dsdb_attribute *a;
      struct replPropertyMetaData1 *md1;

      a = dsdb_attribute_by_lDAPDisplayName(schema, el->name);
      if (a == NULL) {
            DEBUG(0,(__location__ ": Unable to find attribute %s in schema\n",
                   el->name));
            return LDB_ERR_OPERATIONS_ERROR;
      }

      if ((a->systemFlags & DS_FLAG_ATTR_NOT_REPLICATED) || (a->systemFlags & DS_FLAG_ATTR_IS_CONSTRUCTED)) {
            return LDB_SUCCESS;
      }

      /* if the attribute's value haven't changed then return LDB_SUCCESS     */
      if (old_el != NULL && ldb_msg_element_compare(el, old_el) == 0) {
            return LDB_SUCCESS;
      }

      for (i=0; i<omd->ctr.ctr1.count; i++) {
            if (a->attributeID_id == omd->ctr.ctr1.array[i].attid) break;
      }

      if (a->linkID != 0 && dsdb_functional_level(ldb) > DS_DOMAIN_FUNCTION_2000) {
            /* linked attributes are not stored in
               replPropertyMetaData in FL above w2k, but we do
               raise the seqnum for the object  */
            if (*seq_num == 0 &&
                ldb_sequence_number(ldb, LDB_SEQ_NEXT, seq_num) != LDB_SUCCESS) {
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            return LDB_SUCCESS;
      }

      if (i == omd->ctr.ctr1.count) {
            /* we need to add a new one */
            omd->ctr.ctr1.array = talloc_realloc(msg, omd->ctr.ctr1.array,
                                         struct replPropertyMetaData1, omd->ctr.ctr1.count+1);
            if (omd->ctr.ctr1.array == NULL) {
                  ldb_oom(ldb);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            omd->ctr.ctr1.count++;
            ZERO_STRUCT(omd->ctr.ctr1.array[i]);
      }

      /* Get a new sequence number from the backend. We only do this
       * if we have a change that requires a new
       * replPropertyMetaData element
       */
      if (*seq_num == 0) {
            int ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, seq_num);
            if (ret != LDB_SUCCESS) {
                  return LDB_ERR_OPERATIONS_ERROR;
            }
      }

      md1 = &omd->ctr.ctr1.array[i];
      md1->version++;
      md1->attid                     = a->attributeID_id;
      md1->originating_change_time   = now;
      md1->originating_invocation_id = *our_invocation_id;
      md1->originating_usn           = *seq_num;
      md1->local_usn                 = *seq_num;

      return LDB_SUCCESS;
}

static uint64_t find_max_local_usn(struct replPropertyMetaDataBlob omd)
{
      uint32_t count = omd.ctr.ctr1.count;
      uint64_t max = 0;
      uint32_t i;
      for (i=0; i < count; i++) {
            struct replPropertyMetaData1 m = omd.ctr.ctr1.array[i];
            if (max < m.local_usn) {
                  max = m.local_usn;
            }
      }
      return max;
}

/*
 * update the replPropertyMetaData object each time we modify an
 * object. This is needed for DRS replication, as the merge on the
 * client is based on this object
 */
static int replmd_update_rpmd(struct ldb_module *module,
                        const struct dsdb_schema *schema,
                        struct ldb_request *req,
                        struct ldb_message *msg, uint64_t *seq_num,
                        time_t t,
                        bool *is_urgent)
{
      const struct ldb_val *omd_value;
      enum ndr_err_code ndr_err;
      struct replPropertyMetaDataBlob omd;
      unsigned int i;
      NTTIME now;
      const struct GUID *our_invocation_id;
      int ret;
      const char *attrs[] = { "replPropertyMetaData", "*", NULL };
      const char *attrs2[] = { "uSNChanged", "objectClass", NULL };
      struct ldb_result *res;
      struct ldb_context *ldb;
      struct ldb_message_element *objectclass_el;
      enum urgent_situation situation;
      bool rodc, rmd_is_provided;

      ldb = ldb_module_get_ctx(module);

      our_invocation_id = samdb_ntds_invocation_id(ldb);
      if (!our_invocation_id) {
            /* this happens during an initial vampire while
               updating the schema */
            DEBUG(5,("No invocationID - skipping replPropertyMetaData update\n"));
            return LDB_SUCCESS;
      }

      unix_to_nt_time(&now, t);

      if (ldb_request_get_control(req, DSDB_CONTROL_CHANGEREPLMETADATA_OID)) {
            rmd_is_provided = true;
      } else {
            rmd_is_provided = false;
      }

      /* if isDeleted is present and is TRUE, then we consider we are deleting,
       * otherwise we consider we are updating */
      if (ldb_msg_check_string_attribute(msg, "isDeleted", "TRUE")) {
            situation = REPL_URGENT_ON_DELETE;
      } else {
            situation = REPL_URGENT_ON_UPDATE;
      }

      if (rmd_is_provided) {
            /* In this case the change_replmetadata control was supplied */
            /* We check that it's the only attribute that is provided
             * (it's a rare case so it's better to keep the code simplier)
             * We also check that the highest local_usn is bigger than
             * uSNChanged. */
            uint64_t db_seq;
            if( msg->num_elements != 1 ||
                  strncmp(msg->elements[0].name,
                        "replPropertyMetaData", 20) ) {
                  DEBUG(0,(__location__ ": changereplmetada control called without "\
                        "a specified replPropertyMetaData attribute or with others\n"));
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            if (situation == REPL_URGENT_ON_DELETE) {
                  DEBUG(0,(__location__ ": changereplmetada control can't be called when deleting an object\n"));
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            omd_value = ldb_msg_find_ldb_val(msg, "replPropertyMetaData");
            if (!omd_value) {
                  DEBUG(0,(__location__ ": replPropertyMetaData was not specified for Object %s\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            ndr_err = ndr_pull_struct_blob(omd_value, msg, &omd,
                                     (ndr_pull_flags_fn_t)ndr_pull_replPropertyMetaDataBlob);
            if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                  DEBUG(0,(__location__ ": Failed to parse replPropertyMetaData for %s\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            *seq_num = find_max_local_usn(omd);

            ret = dsdb_module_search_dn(module, msg, &res, msg->dn, attrs2,
                                  DSDB_FLAG_NEXT_MODULE |
                                  DSDB_SEARCH_SHOW_DELETED |
                                  DSDB_SEARCH_SHOW_EXTENDED_DN |
                                  DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
                                  DSDB_SEARCH_REVEAL_INTERNALS);

            if (ret != LDB_SUCCESS || res->count != 1) {
                  DEBUG(0,(__location__ ": Object %s failed to find uSNChanged\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            objectclass_el = ldb_msg_find_element(res->msgs[0], "objectClass");
            if (is_urgent && replmd_check_urgent_objectclass(objectclass_el,
                                                situation)) {
                  *is_urgent = true;
            }

            db_seq = ldb_msg_find_attr_as_uint64(res->msgs[0], "uSNChanged", 0);
            if (*seq_num <= db_seq) {
                  DEBUG(0,(__location__ ": changereplmetada control provided but max(local_usn)"\
                                    " is less or equal to uSNChanged (max = %lld uSNChanged = %lld)\n",
                                    *seq_num, db_seq));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

      } else {
            /* search for the existing replPropertyMetaDataBlob. We need
             * to use REVEAL and ask for DNs in storage format to support
             * the check for values being the same in
             * replmd_update_rpmd_element()
             */
            ret = dsdb_module_search_dn(module, msg, &res, msg->dn, attrs,
                                  DSDB_FLAG_NEXT_MODULE |
                                  DSDB_SEARCH_SHOW_DELETED |
                                  DSDB_SEARCH_SHOW_EXTENDED_DN |
                                  DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
                                  DSDB_SEARCH_REVEAL_INTERNALS);
            if (ret != LDB_SUCCESS || res->count != 1) {
                  DEBUG(0,(__location__ ": Object %s failed to find replPropertyMetaData\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            objectclass_el = ldb_msg_find_element(res->msgs[0], "objectClass");
            if (is_urgent && replmd_check_urgent_objectclass(objectclass_el,
                                                situation)) {
                  *is_urgent = true;
            }

            omd_value = ldb_msg_find_ldb_val(res->msgs[0], "replPropertyMetaData");
            if (!omd_value) {
                  DEBUG(0,(__location__ ": Object %s does not have a replPropertyMetaData attribute\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            ndr_err = ndr_pull_struct_blob(omd_value, msg, &omd,
                                     (ndr_pull_flags_fn_t)ndr_pull_replPropertyMetaDataBlob);
            if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                  DEBUG(0,(__location__ ": Failed to parse replPropertyMetaData for %s\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            if (omd.version != 1) {
                  DEBUG(0,(__location__ ": bad version %u in replPropertyMetaData for %s\n",
                         omd.version, ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            /*we have elements that will be modified*/
            if (msg->num_elements > 0) {
                  /*if we are RODC and this is a DRSR update then its ok*/
                  if (!ldb_request_get_control(req, DSDB_CONTROL_REPLICATED_UPDATE_OID)) {
                        ret = samdb_rodc(ldb, &rodc);
                        if (ret != LDB_SUCCESS) {
                              DEBUG(4, (__location__ ": unable to tell if we are an RODC\n"));
                        } else if (rodc) {
                              ldb_asprintf_errstring(ldb, "RODC modify is forbidden\n");
                              return LDB_ERR_REFERRAL;
                        }
                  }
            }

            for (i=0; i<msg->num_elements; i++) {
                  struct ldb_message_element *old_el;
                  old_el = ldb_msg_find_element(res->msgs[0], msg->elements[i].name);
                  ret = replmd_update_rpmd_element(ldb, msg, &msg->elements[i], old_el, &omd, schema, seq_num,
                                           our_invocation_id, now);
                  if (ret != LDB_SUCCESS) {
                        return ret;
                  }

                  if (is_urgent && !*is_urgent && (situation == REPL_URGENT_ON_UPDATE)) {
                        *is_urgent = replmd_check_urgent_attribute(&msg->elements[i]);
                  }

            }
      }
      /*
       * replmd_update_rpmd_element has done an update if the
       * seq_num is set
       */
      if (*seq_num != 0) {
            struct ldb_val *md_value;
            struct ldb_message_element *el;

            md_value = talloc(msg, struct ldb_val);
            if (md_value == NULL) {
                  ldb_oom(ldb);
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            ret = replmd_replPropertyMetaDataCtr1_sort(&omd.ctr.ctr1, schema, msg->dn);
            if (ret != LDB_SUCCESS) {
                  return ret;
            }

            ndr_err = ndr_push_struct_blob(md_value, msg, &omd,
                                     (ndr_push_flags_fn_t)ndr_push_replPropertyMetaDataBlob);
            if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                  DEBUG(0,(__location__ ": Failed to marshall replPropertyMetaData for %s\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            ret = ldb_msg_add_empty(msg, "replPropertyMetaData", LDB_FLAG_MOD_REPLACE, &el);
            if (ret != LDB_SUCCESS) {
                  DEBUG(0,(__location__ ": Failed to add updated replPropertyMetaData %s\n",
                         ldb_dn_get_linearized(msg->dn)));
                  return ret;
            }

            el->num_values = 1;
            el->values = md_value;
      }

      return LDB_SUCCESS;
}

struct parsed_dn {
      struct dsdb_dn *dsdb_dn;
      struct GUID *guid;
      struct ldb_val *v;
};

static int parsed_dn_compare(struct parsed_dn *pdn1, struct parsed_dn *pdn2)
{
      return GUID_compare(pdn1->guid, pdn2->guid);
}

static struct parsed_dn *parsed_dn_find(struct parsed_dn *pdn, int count, struct GUID *guid, struct ldb_dn *dn)
{
      struct parsed_dn *ret;
      if (dn && GUID_all_zero(guid)) {
            /* when updating a link using DRS, we sometimes get a
               NULL GUID. We then need to try and match by DN */
            int i;
            for (i=0; i<count; i++) {
                  if (ldb_dn_compare(pdn[i].dsdb_dn->dn, dn) == 0) {
                        dsdb_get_extended_dn_guid(pdn[i].dsdb_dn->dn, guid, "GUID");
                        return &pdn[i];
                  }
            }
            return NULL;
      }
      BINARY_ARRAY_SEARCH(pdn, count, guid, guid, GUID_compare, ret);
      return ret;
}

/*
  get a series of message element values as an array of DNs and GUIDs
  the result is sorted by GUID
 */
static int get_parsed_dns(struct ldb_module *module, TALLOC_CTX *mem_ctx,
                    struct ldb_message_element *el, struct parsed_dn **pdn,
                    const char *ldap_oid)
{
      unsigned int i;
      struct ldb_context *ldb = ldb_module_get_ctx(module);

      if (el == NULL) {
            *pdn = NULL;
            return LDB_SUCCESS;
      }

      (*pdn) = talloc_array(mem_ctx, struct parsed_dn, el->num_values);
      if (!*pdn) {
            ldb_module_oom(module);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      for (i=0; i<el->num_values; i++) {
            struct ldb_val *v = &el->values[i];
            NTSTATUS status;
            struct ldb_dn *dn;
            struct parsed_dn *p;

            p = &(*pdn)[i];

            p->dsdb_dn = dsdb_dn_parse(*pdn, ldb, v, ldap_oid);
            if (p->dsdb_dn == NULL) {
                  return LDB_ERR_INVALID_DN_SYNTAX;
            }

            dn = p->dsdb_dn->dn;

            p->guid = talloc(*pdn, struct GUID);
            if (p->guid == NULL) {
                  ldb_module_oom(module);
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            status = dsdb_get_extended_dn_guid(dn, p->guid, "GUID");
            if (NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                  /* we got a DN without a GUID - go find the GUID */
                  int ret = dsdb_module_guid_by_dn(module, dn, p->guid);
                  if (ret != LDB_SUCCESS) {
                        ldb_asprintf_errstring(ldb, "Unable to find GUID for DN %s\n",
                                           ldb_dn_get_linearized(dn));
                        return ret;
                  }
                  ret = dsdb_set_extended_dn_guid(dn, p->guid, "GUID");
                  if (ret != LDB_SUCCESS) {
                        return ret;
                  }
            } else if (!NT_STATUS_IS_OK(status)) {
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            /* keep a pointer to the original ldb_val */
            p->v = v;
      }

      TYPESAFE_QSORT(*pdn, el->num_values, parsed_dn_compare);

      return LDB_SUCCESS;
}

/*
  build a new extended DN, including all meta data fields

  RMD_FLAGS           = DSDB_RMD_FLAG_* bits
  RMD_ADDTIME         = originating_add_time
  RMD_INVOCID         = originating_invocation_id
  RMD_CHANGETIME      = originating_change_time
  RMD_ORIGINATING_USN = originating_usn
  RMD_LOCAL_USN       = local_usn
  RMD_VERSION         = version
 */
static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
                         const struct GUID *invocation_id, uint64_t seq_num,
                         uint64_t local_usn, NTTIME nttime, uint32_t version, bool deleted)
{
      struct ldb_dn *dn = dsdb_dn->dn;
      const char *tstring, *usn_string, *flags_string;
      struct ldb_val tval;
      struct ldb_val iid;
      struct ldb_val usnv, local_usnv;
      struct ldb_val vers, flagsv;
      NTSTATUS status;
      int ret;
      const char *dnstring;
      char *vstring;
      uint32_t rmd_flags = deleted?DSDB_RMD_FLAG_DELETED:0;

      tstring = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)nttime);
      if (!tstring) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      tval = data_blob_string_const(tstring);

      usn_string = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)seq_num);
      if (!usn_string) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      usnv = data_blob_string_const(usn_string);

      usn_string = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)local_usn);
      if (!usn_string) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      local_usnv = data_blob_string_const(usn_string);

      vstring = talloc_asprintf(mem_ctx, "%lu", (unsigned long)version);
      if (!vstring) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      vers = data_blob_string_const(vstring);

      status = GUID_to_ndr_blob(invocation_id, dn, &iid);
      if (!NT_STATUS_IS_OK(status)) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      flags_string = talloc_asprintf(mem_ctx, "%u", rmd_flags);
      if (!flags_string) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      flagsv = data_blob_string_const(flags_string);

      ret = ldb_dn_set_extended_component(dn, "RMD_FLAGS", &flagsv);
      if (ret != LDB_SUCCESS) return ret;
      ret = ldb_dn_set_extended_component(dn, "RMD_ADDTIME", &tval);
      if (ret != LDB_SUCCESS) return ret;
      ret = ldb_dn_set_extended_component(dn, "RMD_INVOCID", &iid);
      if (ret != LDB_SUCCESS) return ret;
      ret = ldb_dn_set_extended_component(dn, "RMD_CHANGETIME", &tval);
      if (ret != LDB_SUCCESS) return ret;
      ret = ldb_dn_set_extended_component(dn, "RMD_LOCAL_USN", &local_usnv);
      if (ret != LDB_SUCCESS) return ret;
      ret = ldb_dn_set_extended_component(dn, "RMD_ORIGINATING_USN", &usnv);
      if (ret != LDB_SUCCESS) return ret;
      ret = ldb_dn_set_extended_component(dn, "RMD_VERSION", &vers);
      if (ret != LDB_SUCCESS) return ret;

      dnstring = dsdb_dn_get_extended_linearized(mem_ctx, dsdb_dn, 1);
      if (dnstring == NULL) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      *v = data_blob_string_const(dnstring);

      return LDB_SUCCESS;
}

static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
                        struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
                        uint64_t seq_num, uint64_t local_usn, NTTIME nttime,
                        uint32_t version, bool deleted);

/*
  check if any links need upgrading from w2k format

  The parent_ctx is the ldb_message_element which contains the values array that dns[i].v points at, and which should be used for allocating any new value.
 */
static int replmd_check_upgrade_links(struct parsed_dn *dns, uint32_t count, struct ldb_message_element *parent_ctx, const struct GUID *invocation_id)
{
      uint32_t i;
      for (i=0; i<count; i++) {
            NTSTATUS status;
            uint32_t version;
            int ret;

            status = dsdb_get_extended_dn_uint32(dns[i].dsdb_dn->dn, &version, "RMD_VERSION");
            if (!NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                  continue;
            }

            /* it's an old one that needs upgrading */
            ret = replmd_update_la_val(parent_ctx->values, dns[i].v, dns[i].dsdb_dn, dns[i].dsdb_dn, invocation_id,
                                 1, 1, 0, 0, false);
            if (ret != LDB_SUCCESS) {
                  return ret;
            }
      }
      return LDB_SUCCESS;
}

/*
  update an extended DN, including all meta data fields

  see replmd_build_la_val for value names
 */
static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
                        struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
                        uint64_t seq_num, uint64_t local_usn, NTTIME nttime,
                        uint32_t version, bool deleted)
{
      struct ldb_dn *dn = dsdb_dn->dn;
      const char *tstring, *usn_string, *flags_string;
      struct ldb_val tval;
      struct ldb_val iid;
      struct ldb_val usnv, local_usnv;
      struct ldb_val vers, flagsv;
      const struct ldb_val *old_addtime;
      uint32_t old_version;
      NTSTATUS status;
      int ret;
      const char *dnstring;
      char *vstring;
      uint32_t rmd_flags = deleted?DSDB_RMD_FLAG_DELETED:0;

      tstring = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)nttime);
      if (!tstring) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      tval = data_blob_string_const(tstring);

      usn_string = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)seq_num);
      if (!usn_string) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      usnv = data_blob_string_const(usn_string);

      usn_string = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)local_usn);
      if (!usn_string) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      local_usnv = data_blob_string_const(usn_string);

      status = GUID_to_ndr_blob(invocation_id, dn, &iid);
      if (!NT_STATUS_IS_OK(status)) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      flags_string = talloc_asprintf(mem_ctx, "%u", rmd_flags);
      if (!flags_string) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      flagsv = data_blob_string_const(flags_string);

      ret = ldb_dn_set_extended_component(dn, "RMD_FLAGS", &flagsv);
      if (ret != LDB_SUCCESS) return ret;

      /* get the ADDTIME from the original */
      old_addtime = ldb_dn_get_extended_component(old_dsdb_dn->dn, "RMD_ADDTIME");
      if (old_addtime == NULL) {
            old_addtime = &tval;
      }
      if (dsdb_dn != old_dsdb_dn) {
            ret = ldb_dn_set_extended_component(dn, "RMD_ADDTIME", old_addtime);
            if (ret != LDB_SUCCESS) return ret;
      }

      /* use our invocation id */
      ret = ldb_dn_set_extended_component(dn, "RMD_INVOCID", &iid);
      if (ret != LDB_SUCCESS) return ret;

      /* changetime is the current time */
      ret = ldb_dn_set_extended_component(dn, "RMD_CHANGETIME", &tval);
      if (ret != LDB_SUCCESS) return ret;

      /* update the USN */
      ret = ldb_dn_set_extended_component(dn, "RMD_ORIGINATING_USN", &usnv);
      if (ret != LDB_SUCCESS) return ret;

      ret = ldb_dn_set_extended_component(dn, "RMD_LOCAL_USN", &local_usnv);
      if (ret != LDB_SUCCESS) return ret;

      /* increase the version by 1 */
      status = dsdb_get_extended_dn_uint32(old_dsdb_dn->dn, &old_version, "RMD_VERSION");
      if (NT_STATUS_IS_OK(status) && old_version >= version) {
            version = old_version+1;
      }
      vstring = talloc_asprintf(dn, "%lu", (unsigned long)version);
      vers = data_blob_string_const(vstring);
      ret = ldb_dn_set_extended_component(dn, "RMD_VERSION", &vers);
      if (ret != LDB_SUCCESS) return ret;

      dnstring = dsdb_dn_get_extended_linearized(mem_ctx, dsdb_dn, 1);
      if (dnstring == NULL) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      *v = data_blob_string_const(dnstring);

      return LDB_SUCCESS;
}

/*
  handle adding a linked attribute
 */
static int replmd_modify_la_add(struct ldb_module *module,
                        const struct dsdb_schema *schema,
                        struct ldb_message *msg,
                        struct ldb_message_element *el,
                        struct ldb_message_element *old_el,
                        const struct dsdb_attribute *schema_attr,
                        uint64_t seq_num,
                        time_t t,
                        struct GUID *msg_guid)
{
      unsigned int i;
      struct parsed_dn *dns, *old_dns;
      TALLOC_CTX *tmp_ctx = talloc_new(msg);
      int ret;
      struct ldb_val *new_values = NULL;
      unsigned int num_new_values = 0;
      unsigned old_num_values = old_el?old_el->num_values:0;
      const struct GUID *invocation_id;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      NTTIME now;

      unix_to_nt_time(&now, t);

      ret = get_parsed_dns(module, tmp_ctx, el, &dns, schema_attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      ret = get_parsed_dns(module, tmp_ctx, old_el, &old_dns, schema_attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      invocation_id = samdb_ntds_invocation_id(ldb);
      if (!invocation_id) {
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ret = replmd_check_upgrade_links(old_dns, old_num_values, old_el, invocation_id);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      /* for each new value, see if it exists already with the same GUID */
      for (i=0; i<el->num_values; i++) {
            struct parsed_dn *p = parsed_dn_find(old_dns, old_num_values, dns[i].guid, NULL);
            if (p == NULL) {
                  /* this is a new linked attribute value */
                  new_values = talloc_realloc(tmp_ctx, new_values, struct ldb_val, num_new_values+1);
                  if (new_values == NULL) {
                        ldb_module_oom(module);
                        talloc_free(tmp_ctx);
                        return LDB_ERR_OPERATIONS_ERROR;
                  }
                  ret = replmd_build_la_val(new_values, &new_values[num_new_values], dns[i].dsdb_dn,
                                      invocation_id, seq_num, seq_num, now, 0, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
                  num_new_values++;
            } else {
                  /* this is only allowed if the GUID was
                     previously deleted. */
                  uint32_t rmd_flags = dsdb_dn_rmd_flags(p->dsdb_dn->dn);

                  if (!(rmd_flags & DSDB_RMD_FLAG_DELETED)) {
                        ldb_asprintf_errstring(ldb, "Attribute %s already exists for target GUID %s",
                                           el->name, GUID_string(tmp_ctx, p->guid));
                        talloc_free(tmp_ctx);
                        return LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS;
                  }
                  ret = replmd_update_la_val(old_el->values, p->v, dns[i].dsdb_dn, p->dsdb_dn,
                                       invocation_id, seq_num, seq_num, now, 0, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
            }

            ret = replmd_add_backlink(module, schema, msg_guid, dns[i].guid, true, schema_attr, true);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }

      /* add the new ones on to the end of the old values, constructing a new el->values */
      el->values = talloc_realloc(msg->elements, old_el?old_el->values:NULL,
                            struct ldb_val,
                            old_num_values+num_new_values);
      if (el->values == NULL) {
            ldb_module_oom(module);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      memcpy(&el->values[old_num_values], new_values, num_new_values*sizeof(struct ldb_val));
      el->num_values = old_num_values + num_new_values;

      talloc_steal(msg->elements, el->values);
      talloc_steal(el->values, new_values);

      talloc_free(tmp_ctx);

      /* we now tell the backend to replace all existing values
         with the one we have constructed */
      el->flags = LDB_FLAG_MOD_REPLACE;

      return LDB_SUCCESS;
}


/*
  handle deleting all active linked attributes
 */
static int replmd_modify_la_delete(struct ldb_module *module,
                           const struct dsdb_schema *schema,
                           struct ldb_message *msg,
                           struct ldb_message_element *el,
                           struct ldb_message_element *old_el,
                           const struct dsdb_attribute *schema_attr,
                           uint64_t seq_num,
                           time_t t,
                           struct GUID *msg_guid)
{
      unsigned int i;
      struct parsed_dn *dns, *old_dns;
      TALLOC_CTX *tmp_ctx = talloc_new(msg);
      int ret;
      const struct GUID *invocation_id;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      NTTIME now;

      unix_to_nt_time(&now, t);

      /* check if there is nothing to delete */
      if ((!old_el || old_el->num_values == 0) &&
          el->num_values == 0) {
            return LDB_SUCCESS;
      }

      if (!old_el || old_el->num_values == 0) {
            return LDB_ERR_NO_SUCH_ATTRIBUTE;
      }

      ret = get_parsed_dns(module, tmp_ctx, el, &dns, schema_attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      ret = get_parsed_dns(module, tmp_ctx, old_el, &old_dns, schema_attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      invocation_id = samdb_ntds_invocation_id(ldb);
      if (!invocation_id) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ret = replmd_check_upgrade_links(old_dns, old_el->num_values, old_el, invocation_id);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      el->values = NULL;

      /* see if we are being asked to delete any links that
         don't exist or are already deleted */
      for (i=0; i<el->num_values; i++) {
            struct parsed_dn *p = &dns[i];
            struct parsed_dn *p2;
            uint32_t rmd_flags;

            p2 = parsed_dn_find(old_dns, old_el->num_values, p->guid, NULL);
            if (!p2) {
                  ldb_asprintf_errstring(ldb, "Attribute %s doesn't exist for target GUID %s",
                                     el->name, GUID_string(tmp_ctx, p->guid));
                  return LDB_ERR_NO_SUCH_ATTRIBUTE;
            }
            rmd_flags = dsdb_dn_rmd_flags(p2->dsdb_dn->dn);
            if (rmd_flags & DSDB_RMD_FLAG_DELETED) {
                  ldb_asprintf_errstring(ldb, "Attribute %s already deleted for target GUID %s",
                                     el->name, GUID_string(tmp_ctx, p->guid));
                  return LDB_ERR_NO_SUCH_ATTRIBUTE;
            }
      }

      /* for each new value, see if it exists already with the same GUID
         if it is not already deleted and matches the delete list then delete it
      */
      for (i=0; i<old_el->num_values; i++) {
            struct parsed_dn *p = &old_dns[i];
            uint32_t rmd_flags;

            if (el->num_values && parsed_dn_find(dns, el->num_values, p->guid, NULL) == NULL) {
                  continue;
            }

            rmd_flags = dsdb_dn_rmd_flags(p->dsdb_dn->dn);
            if (rmd_flags & DSDB_RMD_FLAG_DELETED) continue;

            ret = replmd_update_la_val(old_el->values, p->v, p->dsdb_dn, p->dsdb_dn,
                                 invocation_id, seq_num, seq_num, now, 0, true);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            ret = replmd_add_backlink(module, schema, msg_guid, old_dns[i].guid, false, schema_attr, true);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }

      el->values = talloc_steal(msg->elements, old_el->values);
      el->num_values = old_el->num_values;

      talloc_free(tmp_ctx);

      /* we now tell the backend to replace all existing values
         with the one we have constructed */
      el->flags = LDB_FLAG_MOD_REPLACE;

      return LDB_SUCCESS;
}

/*
  handle replacing a linked attribute
 */
static int replmd_modify_la_replace(struct ldb_module *module,
                            const struct dsdb_schema *schema,
                            struct ldb_message *msg,
                            struct ldb_message_element *el,
                            struct ldb_message_element *old_el,
                            const struct dsdb_attribute *schema_attr,
                            uint64_t seq_num,
                            time_t t,
                            struct GUID *msg_guid)
{
      unsigned int i;
      struct parsed_dn *dns, *old_dns;
      TALLOC_CTX *tmp_ctx = talloc_new(msg);
      int ret;
      const struct GUID *invocation_id;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      struct ldb_val *new_values = NULL;
      unsigned int num_new_values = 0;
      unsigned int old_num_values = old_el?old_el->num_values:0;
      NTTIME now;

      unix_to_nt_time(&now, t);

      /* check if there is nothing to replace */
      if ((!old_el || old_el->num_values == 0) &&
          el->num_values == 0) {
            return LDB_SUCCESS;
      }

      ret = get_parsed_dns(module, tmp_ctx, el, &dns, schema_attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      ret = get_parsed_dns(module, tmp_ctx, old_el, &old_dns, schema_attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      invocation_id = samdb_ntds_invocation_id(ldb);
      if (!invocation_id) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ret = replmd_check_upgrade_links(old_dns, old_num_values, old_el, invocation_id);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      /* mark all the old ones as deleted */
      for (i=0; i<old_num_values; i++) {
            struct parsed_dn *old_p = &old_dns[i];
            struct parsed_dn *p;
            uint32_t rmd_flags = dsdb_dn_rmd_flags(old_p->dsdb_dn->dn);

            if (rmd_flags & DSDB_RMD_FLAG_DELETED) continue;

            ret = replmd_add_backlink(module, schema, msg_guid, old_dns[i].guid, false, schema_attr, false);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            p = parsed_dn_find(dns, el->num_values, old_p->guid, NULL);
            if (p) {
                  /* we don't delete it if we are re-adding it */
                  continue;
            }

            ret = replmd_update_la_val(old_el->values, old_p->v, old_p->dsdb_dn, old_p->dsdb_dn,
                                 invocation_id, seq_num, seq_num, now, 0, true);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }

      /* for each new value, either update its meta-data, or add it
       * to old_el
      */
      for (i=0; i<el->num_values; i++) {
            struct parsed_dn *p = &dns[i], *old_p;

            if (old_dns &&
                (old_p = parsed_dn_find(old_dns,
                                  old_num_values, p->guid, NULL)) != NULL) {
                  /* update in place */
                  ret = replmd_update_la_val(old_el->values, old_p->v, old_p->dsdb_dn,
                                       old_p->dsdb_dn, invocation_id,
                                       seq_num, seq_num, now, 0, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
            } else {
                  /* add a new one */
                  new_values = talloc_realloc(tmp_ctx, new_values, struct ldb_val,
                                        num_new_values+1);
                  if (new_values == NULL) {
                        ldb_module_oom(module);
                        talloc_free(tmp_ctx);
                        return LDB_ERR_OPERATIONS_ERROR;
                  }
                  ret = replmd_build_la_val(new_values, &new_values[num_new_values], dns[i].dsdb_dn,
                                      invocation_id, seq_num, seq_num, now, 0, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
                  num_new_values++;
            }

            ret = replmd_add_backlink(module, schema, msg_guid, dns[i].guid, true, schema_attr, false);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }

      /* add the new values to the end of old_el */
      if (num_new_values != 0) {
            el->values = talloc_realloc(msg->elements, old_el?old_el->values:NULL,
                                  struct ldb_val, old_num_values+num_new_values);
            if (el->values == NULL) {
                  ldb_module_oom(module);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            memcpy(&el->values[old_num_values], &new_values[0],
                   sizeof(struct ldb_val)*num_new_values);
            el->num_values = old_num_values + num_new_values;
            talloc_steal(msg->elements, new_values);
      } else {
            el->values = old_el->values;
            el->num_values = old_el->num_values;
            talloc_steal(msg->elements, el->values);
      }

      talloc_free(tmp_ctx);

      /* we now tell the backend to replace all existing values
         with the one we have constructed */
      el->flags = LDB_FLAG_MOD_REPLACE;

      return LDB_SUCCESS;
}


/*
  handle linked attributes in modify requests
 */
static int replmd_modify_handle_linked_attribs(struct ldb_module *module,
                                     struct ldb_message *msg,
                                     uint64_t seq_num, time_t t)
{
      struct ldb_result *res;
      unsigned int i;
      int ret;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      struct ldb_message *old_msg;

      const struct dsdb_schema *schema;
      struct GUID old_guid;

      if (seq_num == 0) {
            /* there the replmd_update_rpmd code has already
             * checked and saw that there are no linked
             * attributes */
            return LDB_SUCCESS;
      }

      if (dsdb_functional_level(ldb) == DS_DOMAIN_FUNCTION_2000) {
            /* don't do anything special for linked attributes */
            return LDB_SUCCESS;
      }

      ret = dsdb_module_search_dn(module, msg, &res, msg->dn, NULL,
                                  DSDB_FLAG_NEXT_MODULE |
                                  DSDB_SEARCH_SHOW_DELETED |
                            DSDB_SEARCH_REVEAL_INTERNALS |
                            DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT);
      if (ret != LDB_SUCCESS) {
            return ret;
      }
      schema = dsdb_get_schema(ldb, res);
      if (!schema) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      old_msg = res->msgs[0];

      old_guid = samdb_result_guid(old_msg, "objectGUID");

      for (i=0; i<msg->num_elements; i++) {
            struct ldb_message_element *el = &msg->elements[i];
            struct ldb_message_element *old_el, *new_el;
            const struct dsdb_attribute *schema_attr
                  = dsdb_attribute_by_lDAPDisplayName(schema, el->name);
            if (!schema_attr) {
                  ldb_asprintf_errstring(ldb,
                                     "attribute %s is not a valid attribute in schema", el->name);
                  return LDB_ERR_OBJECT_CLASS_VIOLATION;
            }
            if (schema_attr->linkID == 0) {
                  continue;
            }
            if ((schema_attr->linkID & 1) == 1) {
                  /* Odd is for the target.  Illegal to modify */
                  ldb_asprintf_errstring(ldb,
                                     "attribute %s must not be modified directly, it is a linked attribute", el->name);
                  return LDB_ERR_UNWILLING_TO_PERFORM;
            }
            old_el = ldb_msg_find_element(old_msg, el->name);
            switch (el->flags & LDB_FLAG_MOD_MASK) {
            case LDB_FLAG_MOD_REPLACE:
                  ret = replmd_modify_la_replace(module, schema, msg, el, old_el, schema_attr, seq_num, t, &old_guid);
                  break;
            case LDB_FLAG_MOD_DELETE:
                  ret = replmd_modify_la_delete(module, schema, msg, el, old_el, schema_attr, seq_num, t, &old_guid);
                  break;
            case LDB_FLAG_MOD_ADD:
                  ret = replmd_modify_la_add(module, schema, msg, el, old_el, schema_attr, seq_num, t, &old_guid);
                  break;
            default:
                  ldb_asprintf_errstring(ldb,
                                     "invalid flags 0x%x for %s linked attribute",
                                     el->flags, el->name);
                  return LDB_ERR_UNWILLING_TO_PERFORM;
            }
            if (ret != LDB_SUCCESS) {
                  return ret;
            }
            if (old_el) {
                  ldb_msg_remove_attr(old_msg, el->name);
            }
            ldb_msg_add_empty(old_msg, el->name, 0, &new_el);
            new_el->num_values = el->num_values;
            new_el->values = talloc_steal(msg->elements, el->values);

            /* TODO: this relises a bit too heavily on the exact
               behaviour of ldb_msg_find_element and
               ldb_msg_remove_element */
            old_el = ldb_msg_find_element(msg, el->name);
            if (old_el != el) {
                  ldb_msg_remove_element(msg, old_el);
                  i--;
            }
      }

      talloc_free(res);
      return ret;
}



static int replmd_modify(struct ldb_module *module, struct ldb_request *req)
{
      struct ldb_context *ldb;
      struct replmd_replicated_request *ac;
      struct ldb_request *down_req;
      struct ldb_message *msg;
      time_t t = time(NULL);
      int ret;
      bool is_urgent = false;
      struct loadparm_context *lp_ctx;
      char *referral;
      unsigned int functional_level;

      /* do not manipulate our control entries */
      if (ldb_dn_is_special(req->op.mod.message->dn)) {
            return ldb_next_request(module, req);
      }

      ldb = ldb_module_get_ctx(module);
      functional_level = dsdb_functional_level(ldb);

      lp_ctx = talloc_get_type(ldb_get_opaque(ldb, "loadparm"),
                         struct loadparm_context);

      ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_modify\n");

      ac = replmd_ctx_init(module, req);
      if (!ac) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* we have to copy the message as the caller might have it as a const */
      msg = ldb_msg_copy_shallow(ac, req->op.mod.message);
      if (msg == NULL) {
            ldb_oom(ldb);
            talloc_free(ac);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ldb_msg_remove_attr(msg, "whenChanged");
      ldb_msg_remove_attr(msg, "uSNChanged");

      ret = replmd_update_rpmd(module, ac->schema, req, msg, &ac->seq_num, t, &is_urgent);
      if (ret == LDB_ERR_REFERRAL) {
            talloc_free(ac);

            referral = talloc_asprintf(req,
                                 "ldap://%s/%s",
                                 lpcfg_dnsdomain(lp_ctx),
                                 ldb_dn_get_linearized(msg->dn));
            ret = ldb_module_send_referral(req, referral);
            return ldb_module_done(req, NULL, NULL, ret);
      }

      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      ret = replmd_modify_handle_linked_attribs(module, msg, ac->seq_num, t);
      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      /* TODO:
       * - replace the old object with the newly constructed one
       */

      ac->is_urgent = is_urgent;

      ret = ldb_build_mod_req(&down_req, ldb, ac,
                        msg,
                        req->controls,
                        ac, replmd_op_callback,
                        req);
      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      /* If we are in functional level 2000, then
       * replmd_modify_handle_linked_attribs will have done
       * nothing */
      if (functional_level == DS_DOMAIN_FUNCTION_2000) {
            ret = ldb_request_add_control(down_req, DSDB_CONTROL_APPLY_LINKS, false, NULL);
            if (ret != LDB_SUCCESS) {
                  talloc_free(ac);
                  return ret;
            }
      }

      talloc_steal(down_req, msg);

      /* we only change whenChanged and uSNChanged if the seq_num
         has changed */
      if (ac->seq_num != 0) {
            if (add_time_element(msg, "whenChanged", t) != LDB_SUCCESS) {
                  talloc_free(ac);
                  return ret;
            }

            if (add_uint64_element(msg, "uSNChanged", ac->seq_num) != LDB_SUCCESS) {
                  talloc_free(ac);
                  return ret;
            }
      }

      /* go on with the call chain */
      return ldb_next_request(module, down_req);
}

static int replmd_rename_callback(struct ldb_request *req, struct ldb_reply *ares);

/*
  handle a rename request

  On a rename we need to do an extra ldb_modify which sets the
  whenChanged and uSNChanged attributes.  We do this in a callback after the success.
 */
static int replmd_rename(struct ldb_module *module, struct ldb_request *req)
{
      struct ldb_context *ldb;
      struct replmd_replicated_request *ac;
      int ret;
      struct ldb_request *down_req;

      /* do not manipulate our control entries */
      if (ldb_dn_is_special(req->op.mod.message->dn)) {
            return ldb_next_request(module, req);
      }

      ldb = ldb_module_get_ctx(module);

      ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_rename\n");

      ac = replmd_ctx_init(module, req);
      if (!ac) {
            return LDB_ERR_OPERATIONS_ERROR;
      }
      ret = ldb_build_rename_req(&down_req, ldb, ac,
                           ac->req->op.rename.olddn,
                           ac->req->op.rename.newdn,
                           ac->req->controls,
                           ac, replmd_rename_callback,
                           ac->req);

      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      /* go on with the call chain */
      return ldb_next_request(module, down_req);
}

/* After the rename is compleated, update the whenchanged etc */
static int replmd_rename_callback(struct ldb_request *req, struct ldb_reply *ares)
{
      struct ldb_context *ldb;
      struct replmd_replicated_request *ac;
      struct ldb_request *down_req;
      struct ldb_message *msg;
      time_t t = time(NULL);
      int ret;

      ac = talloc_get_type(req->context, struct replmd_replicated_request);
      ldb = ldb_module_get_ctx(ac->module);

      if (ares->error != LDB_SUCCESS) {
            return ldb_module_done(ac->req, ares->controls,
                              ares->response, ares->error);
      }

      if (ares->type != LDB_REPLY_DONE) {
            ldb_set_errstring(ldb,
                          "invalid ldb_reply_type in callback");
            talloc_free(ares);
            return ldb_module_done(ac->req, NULL, NULL,
                              LDB_ERR_OPERATIONS_ERROR);
      }

      /* Get a sequence number from the backend */
      ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &ac->seq_num);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      /* TODO:
       * - replace the old object with the newly constructed one
       */

      msg = ldb_msg_new(ac);
      if (msg == NULL) {
            ldb_oom(ldb);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      msg->dn = ac->req->op.rename.newdn;

      ret = ldb_build_mod_req(&down_req, ldb, ac,
                        msg,
                        req->controls,
                        ac, replmd_op_callback,
                        req);

      if (ret != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }
      talloc_steal(down_req, msg);

      if (add_time_element(msg, "whenChanged", t) != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      if (add_uint64_element(msg, "uSNChanged", ac->seq_num) != LDB_SUCCESS) {
            talloc_free(ac);
            return ret;
      }

      /* go on with the call chain - do the modify after the rename */
      return ldb_next_request(ac->module, down_req);
}

/*
   remove links from objects that point at this object when an object
   is deleted
 */
static int replmd_delete_remove_link(struct ldb_module *module,
                             const struct dsdb_schema *schema,
                             struct ldb_dn *dn,
                             struct ldb_message_element *el,
                             const struct dsdb_attribute *sa)
{
      unsigned int i;
      TALLOC_CTX *tmp_ctx = talloc_new(module);
      struct ldb_context *ldb = ldb_module_get_ctx(module);

      for (i=0; i<el->num_values; i++) {
            struct dsdb_dn *dsdb_dn;
            NTSTATUS status;
            int ret;
            struct GUID guid2;
            struct ldb_message *msg;
            const struct dsdb_attribute *target_attr;
            struct ldb_message_element *el2;
            struct ldb_val dn_val;

            if (dsdb_dn_is_deleted_val(&el->values[i])) {
                  continue;
            }

            dsdb_dn = dsdb_dn_parse(tmp_ctx, ldb, &el->values[i], sa->syntax->ldap_oid);
            if (!dsdb_dn) {
                  talloc_free(tmp_ctx);
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            status = dsdb_get_extended_dn_guid(dsdb_dn->dn, &guid2, "GUID");
            if (!NT_STATUS_IS_OK(status)) {
                  talloc_free(tmp_ctx);
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            /* remove the link */
            msg = ldb_msg_new(tmp_ctx);
            if (!msg) {
                  ldb_module_oom(module);
                  talloc_free(tmp_ctx);
                  return LDB_ERR_OPERATIONS_ERROR;
            }


            msg->dn = dsdb_dn->dn;

            target_attr = dsdb_attribute_by_linkID(schema, sa->linkID ^ 1);
            if (target_attr == NULL) {
                  continue;
            }

            ret = ldb_msg_add_empty(msg, target_attr->lDAPDisplayName, LDB_FLAG_MOD_DELETE, &el2);
            if (ret != LDB_SUCCESS) {
                  ldb_module_oom(module);
                  talloc_free(tmp_ctx);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            dn_val = data_blob_string_const(ldb_dn_get_linearized(dn));
            el2->values = &dn_val;
            el2->num_values = 1;

            ret = dsdb_module_modify(module, msg, DSDB_FLAG_OWN_MODULE);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }
      talloc_free(tmp_ctx);
      return LDB_SUCCESS;
}


/*
  handle update of replication meta data for deletion of objects

  This also handles the mapping of delete to a rename operation
  to allow deletes to be replicated.
 */
static int replmd_delete(struct ldb_module *module, struct ldb_request *req)
{
      int ret = LDB_ERR_OTHER;
      bool retb;
      struct ldb_dn *old_dn, *new_dn;
      const char *rdn_name;
      const struct ldb_val *rdn_value, *new_rdn_value;
      struct GUID guid;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      const struct dsdb_schema *schema;
      struct ldb_message *msg, *old_msg;
      struct ldb_message_element *el;
      TALLOC_CTX *tmp_ctx;
      struct ldb_result *res, *parent_res;
      const char *preserved_attrs[] = {
            /* yes, this really is a hard coded list. See MS-ADTS
               section 3.1.1.5.5.1.1 */
            "nTSecurityDescriptor", "attributeID", "attributeSyntax", "dNReferenceUpdate", "dNSHostName",
            "flatName", "governsID", "groupType", "instanceType", "lDAPDisplayName", "legacyExchangeDN",
            "isDeleted", "isRecycled", "lastKnownParent", "msDS-LastKnownRDN", "mS-DS-CreatorSID",
            "mSMQOwnerID", "nCName", "objectClass", "distinguishedName", "objectGUID", "objectSid",
            "oMSyntax", "proxiedObjectName", "name", "replPropertyMetaData", "sAMAccountName",
            "securityIdentifier", "sIDHistory", "subClassOf", "systemFlags", "trustPartner", "trustDirection",
            "trustType", "trustAttributes", "userAccountControl", "uSNChanged", "uSNCreated", "whenCreated",
            "whenChanged", NULL};
      unsigned int i, el_count = 0;
      enum deletion_state { OBJECT_NOT_DELETED=1, OBJECT_DELETED=2, OBJECT_RECYCLED=3,
                                    OBJECT_TOMBSTONE=4, OBJECT_REMOVED=5 };
      enum deletion_state deletion_state, next_deletion_state;
      bool enabled;

      if (ldb_dn_is_special(req->op.del.dn)) {
            return ldb_next_request(module, req);
      }

      tmp_ctx = talloc_new(ldb);
      if (!tmp_ctx) {
            ldb_oom(ldb);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      schema = dsdb_get_schema(ldb, tmp_ctx);
      if (!schema) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      old_dn = ldb_dn_copy(tmp_ctx, req->op.del.dn);

      /* we need the complete msg off disk, so we can work out which
         attributes need to be removed */
      ret = dsdb_module_search_dn(module, tmp_ctx, &res, old_dn, NULL,
                                  DSDB_FLAG_NEXT_MODULE |
                                  DSDB_SEARCH_SHOW_DELETED |
                            DSDB_SEARCH_REVEAL_INTERNALS |
                            DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }
      old_msg = res->msgs[0];


      ret = dsdb_recyclebin_enabled(module, &enabled);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      if (ldb_msg_check_string_attribute(old_msg, "isDeleted", "TRUE")) {
            if (!enabled) {
                  deletion_state = OBJECT_TOMBSTONE;
                  next_deletion_state = OBJECT_REMOVED;
            } else if (ldb_msg_check_string_attribute(old_msg, "isRecycled", "TRUE")) {
                  deletion_state = OBJECT_RECYCLED;
                  next_deletion_state = OBJECT_REMOVED;
            } else {
                  deletion_state = OBJECT_DELETED;
                  next_deletion_state = OBJECT_RECYCLED;
            }
      } else {
            deletion_state = OBJECT_NOT_DELETED;
            if (enabled) {
                  next_deletion_state = OBJECT_DELETED;
            } else {
                  next_deletion_state = OBJECT_TOMBSTONE;
            }
      }

      if (next_deletion_state == OBJECT_REMOVED) {
            struct auth_session_info *session_info =
                        (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
            if (security_session_user_level(session_info, NULL) != SECURITY_SYSTEM) {
                  ldb_asprintf_errstring(ldb, "Refusing to delete deleted object %s",
                              ldb_dn_get_linearized(old_msg->dn));
                  return LDB_ERR_UNWILLING_TO_PERFORM;
            }

            /* it is already deleted - really remove it this time */
            talloc_free(tmp_ctx);
            return ldb_next_request(module, req);
      }

      rdn_name = ldb_dn_get_rdn_name(old_dn);
      rdn_value = ldb_dn_get_rdn_val(old_dn);

      msg = ldb_msg_new(tmp_ctx);
      if (msg == NULL) {
            ldb_module_oom(module);
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      msg->dn = old_dn;

      if (deletion_state == OBJECT_NOT_DELETED){
            /* work out where we will be renaming this object to */
            ret = dsdb_get_deleted_objects_dn(ldb, tmp_ctx, old_dn, &new_dn);
            if (ret != LDB_SUCCESS) {
                  /* this is probably an attempted delete on a partition
                   * that doesn't allow delete operations, such as the
                   * schema partition */
                  ldb_asprintf_errstring(ldb, "No Deleted Objects container for DN %s",
                                       ldb_dn_get_linearized(old_dn));
                  talloc_free(tmp_ctx);
                  return LDB_ERR_UNWILLING_TO_PERFORM;
            }

            /* get the objects GUID from the search we just did */
            guid = samdb_result_guid(old_msg, "objectGUID");

            /* Add a formatted child */
            retb = ldb_dn_add_child_fmt(new_dn, "%s=%s\\0ADEL:%s",
                                    rdn_name,
                                    rdn_value->data,
                                    GUID_string(tmp_ctx, &guid));
            if (!retb) {
                  DEBUG(0,(__location__ ": Unable to add a formatted child to dn: %s",
                              ldb_dn_get_linearized(new_dn)));
                  talloc_free(tmp_ctx);
                  return LDB_ERR_OPERATIONS_ERROR;
            }

            ret = ldb_msg_add_string(msg, "isDeleted", "TRUE");
            if (ret != LDB_SUCCESS) {
                  DEBUG(0,(__location__ ": Failed to add isDeleted string to the msg\n"));
                  ldb_module_oom(module);
                  talloc_free(tmp_ctx);
                  return ret;
            }
            msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;
      }

      /*
        now we need to modify the object in the following ways:

        - add isDeleted=TRUE
        - update rDN and name, with new rDN
        - remove linked attributes
        - remove objectCategory and sAMAccountType
        - remove attribs not on the preserved list
           - preserved if in above list, or is rDN
        - remove all linked attribs from this object
        - remove all links from other objects to this object
        - add lastKnownParent
        - update replPropertyMetaData?

        see MS-ADTS "Tombstone Requirements" section 3.1.1.5.5.1.1
       */

      /* we need the storage form of the parent GUID */
      ret = dsdb_module_search_dn(module, tmp_ctx, &parent_res,
                            ldb_dn_get_parent(tmp_ctx, old_dn), NULL,
                            DSDB_FLAG_NEXT_MODULE |
                            DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
                            DSDB_SEARCH_REVEAL_INTERNALS|
                            DSDB_SEARCH_SHOW_DELETED);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      if (deletion_state == OBJECT_NOT_DELETED){
            ret = ldb_msg_add_steal_string(msg, "lastKnownParent",
                                       ldb_dn_get_extended_linearized(tmp_ctx, parent_res->msgs[0]->dn, 1));
            if (ret != LDB_SUCCESS) {
                  DEBUG(0,(__location__ ": Failed to add lastKnownParent string to the msg\n"));
                  ldb_module_oom(module);
                  talloc_free(tmp_ctx);
                  return ret;
            }
            msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;
      }

      switch (next_deletion_state){

      case OBJECT_DELETED:

            ret = ldb_msg_add_value(msg, "msDS-LastKnownRDN", rdn_value, NULL);
            if (ret != LDB_SUCCESS) {
                  DEBUG(0,(__location__ ": Failed to add msDS-LastKnownRDN string to the msg\n"));
                  ldb_module_oom(module);
                  talloc_free(tmp_ctx);
                  return ret;
            }
            msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;

            ret = ldb_msg_add_empty(msg, "objectCategory", LDB_FLAG_MOD_DELETE, NULL);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  ldb_module_oom(module);
                  return ret;
            }

            ret = ldb_msg_add_empty(msg, "sAMAccountType", LDB_FLAG_MOD_DELETE, NULL);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  ldb_module_oom(module);
                  return ret;
            }

            break;

      case OBJECT_RECYCLED:
      case OBJECT_TOMBSTONE:

            /* we also mark it as recycled, meaning this object can't be
               recovered (we are stripping its attributes) */
            if (dsdb_functional_level(ldb) >= DS_DOMAIN_FUNCTION_2008_R2) {
                  ret = ldb_msg_add_string(msg, "isRecycled", "TRUE");
                  if (ret != LDB_SUCCESS) {
                        DEBUG(0,(__location__ ": Failed to add isRecycled string to the msg\n"));
                        ldb_module_oom(module);
                        talloc_free(tmp_ctx);
                        return ret;
                  }
                  msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;
            }

            /* work out which of the old attributes we will be removing */
            for (i=0; i<old_msg->num_elements; i++) {
                  const struct dsdb_attribute *sa;
                  el = &old_msg->elements[i];
                  sa = dsdb_attribute_by_lDAPDisplayName(schema, el->name);
                  if (!sa) {
                        talloc_free(tmp_ctx);
                        return LDB_ERR_OPERATIONS_ERROR;
                  }
                  if (ldb_attr_cmp(el->name, rdn_name) == 0) {
                        /* don't remove the rDN */
                        continue;
                  }
                  if (sa->linkID && sa->linkID & 1) {
                        ret = replmd_delete_remove_link(module, schema, old_dn, el, sa);
                        if (ret != LDB_SUCCESS) {
                              talloc_free(tmp_ctx);
                              return LDB_ERR_OPERATIONS_ERROR;
                        }
                        continue;
                  }
                  if (!sa->linkID && ldb_attr_in_list(preserved_attrs, el->name)) {
                        continue;
                  }
                  ret = ldb_msg_add_empty(msg, el->name, LDB_FLAG_MOD_DELETE, &el);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        ldb_module_oom(module);
                        return ret;
                  }
            }
            break;

      default:
            break;
      }

      if (deletion_state == OBJECT_NOT_DELETED) {
            /* work out what the new rdn value is, for updating the
               rDN and name fields */
            new_rdn_value = ldb_dn_get_rdn_val(new_dn);

            ret = ldb_msg_add_value(msg, strlower_talloc(tmp_ctx, rdn_name), new_rdn_value, &el);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }
            el->flags = LDB_FLAG_MOD_REPLACE;

            el = ldb_msg_find_element(old_msg, "name");
            if (el) {
                  ret = ldb_msg_add_value(msg, "name", new_rdn_value, &el);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
                  el->flags = LDB_FLAG_MOD_REPLACE;
            }
      }

      ret = dsdb_module_modify(module, msg, DSDB_FLAG_OWN_MODULE);
      if (ret != LDB_SUCCESS) {
            ldb_asprintf_errstring(ldb, "replmd_delete: Failed to modify object %s in delete - %s",
                               ldb_dn_get_linearized(old_dn), ldb_errstring(ldb));
            talloc_free(tmp_ctx);
            return ret;
      }

      if (deletion_state == OBJECT_NOT_DELETED) {
            /* now rename onto the new DN */
            ret = dsdb_module_rename(module, old_dn, new_dn, DSDB_FLAG_NEXT_MODULE);
            if (ret != LDB_SUCCESS){
                  DEBUG(0,(__location__ ": Failed to rename object from '%s' to '%s' - %s\n",
                         ldb_dn_get_linearized(old_dn),
                         ldb_dn_get_linearized(new_dn),
                         ldb_errstring(ldb)));
                  talloc_free(tmp_ctx);
                  return ret;
            }
      }

      talloc_free(tmp_ctx);

      return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
}



static int replmd_replicated_request_error(struct replmd_replicated_request *ar, int ret)
{
      return ret;
}

static int replmd_replicated_request_werror(struct replmd_replicated_request *ar, WERROR status)
{
      int ret = LDB_ERR_OTHER;
      /* TODO: do some error mapping */
      return ret;
}

static int replmd_replicated_apply_add(struct replmd_replicated_request *ar)
{
      struct ldb_context *ldb;
      struct ldb_request *change_req;
      enum ndr_err_code ndr_err;
      struct ldb_message *msg;
      struct replPropertyMetaDataBlob *md;
      struct ldb_val md_value;
      unsigned int i;
      int ret;

      /*
       * TODO: check if the parent object exist
       */

      /*
       * TODO: handle the conflict case where an object with the
       *       same name exist
       */

      ldb = ldb_module_get_ctx(ar->module);
      msg = ar->objs->objects[ar->index_current].msg;
      md = ar->objs->objects[ar->index_current].meta_data;

      ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &ar->seq_num);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      ret = ldb_msg_add_value(msg, "objectGUID", &ar->objs->objects[ar->index_current].guid_value, NULL);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      ret = ldb_msg_add_string(msg, "whenChanged", ar->objs->objects[ar->index_current].when_changed);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNCreated", ar->seq_num);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNChanged", ar->seq_num);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      /* remove any message elements that have zero values */
      for (i=0; i<msg->num_elements; i++) {
            struct ldb_message_element *el = &msg->elements[i];

            if (el->num_values == 0) {
                  DEBUG(4,(__location__ ": Removing attribute %s with num_values==0\n",
                         el->name));
                  memmove(el, el+1, sizeof(*el)*(msg->num_elements - (i+1)));
                  msg->num_elements--;
                  i--;
                  continue;
            }
      }

      /*
       * the meta data array is already sorted by the caller
       */
      for (i=0; i < md->ctr.ctr1.count; i++) {
            md->ctr.ctr1.array[i].local_usn = ar->seq_num;
      }
      ndr_err = ndr_push_struct_blob(&md_value, msg, md,
                               (ndr_push_flags_fn_t)ndr_push_replPropertyMetaDataBlob);
      if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
            NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
            return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
      }
      ret = ldb_msg_add_value(msg, "replPropertyMetaData", &md_value, NULL);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      replmd_ldb_message_sort(msg, ar->schema);

      if (DEBUGLVL(4)) {
            char *s = ldb_ldif_message_string(ldb, ar, LDB_CHANGETYPE_ADD, msg);
            DEBUG(4, ("DRS replication add message:\n%s\n", s));
            talloc_free(s);
      }

      ret = ldb_build_add_req(&change_req,
                        ldb,
                        ar,
                        msg,
                        ar->controls,
                        ar,
                        replmd_op_callback,
                        ar->req);
      if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);

      return ldb_next_request(ar->module, change_req);
}

/*
   return true if an update is newer than an existing entry
   see section 5.11 of MS-ADTS
*/
static bool replmd_update_is_newer(const struct GUID *current_invocation_id,
                           const struct GUID *update_invocation_id,
                           uint32_t current_version,
                           uint32_t update_version,
                           NTTIME current_change_time,
                           NTTIME update_change_time)
{
      if (update_version != current_version) {
            return update_version > current_version;
      }
      if (update_change_time > current_change_time) {
            return true;
      }
      if (update_change_time == current_change_time) {
            return GUID_compare(update_invocation_id, current_invocation_id) > 0;
      }
      return false;
}

static bool replmd_replPropertyMetaData1_is_newer(struct replPropertyMetaData1 *cur_m,
                                      struct replPropertyMetaData1 *new_m)
{
      return replmd_update_is_newer(&cur_m->originating_invocation_id,
                              &new_m->originating_invocation_id,
                              cur_m->version,
                              new_m->version,
                              cur_m->originating_change_time,
                              new_m->originating_change_time);
}

static struct replPropertyMetaData1 *
replmd_replPropertyMetaData1_find_attid(struct replPropertyMetaDataBlob *md_blob,
                                        enum drsuapi_DsAttributeId attid)
{
      uint32_t i;
      struct replPropertyMetaDataCtr1 *rpmd_ctr = &md_blob->ctr.ctr1;

      for (i = 0; i < rpmd_ctr->count; i++) {
            if (rpmd_ctr->array[i].attid == attid) {
                  return &rpmd_ctr->array[i];
            }
      }
      return NULL;
}

static int replmd_replicated_apply_merge(struct replmd_replicated_request *ar)
{
      struct ldb_context *ldb;
      struct ldb_request *change_req;
      enum ndr_err_code ndr_err;
      struct ldb_message *msg;
      struct replPropertyMetaDataBlob *rmd;
      struct replPropertyMetaDataBlob omd;
      const struct ldb_val *omd_value;
      struct replPropertyMetaDataBlob nmd;
      struct ldb_val nmd_value;
      struct replPropertyMetaData1 *md_remote;
      struct replPropertyMetaData1 *md_local;
      unsigned int i;
      uint32_t j,ni=0;
      unsigned int removed_attrs = 0;
      int ret;

      ldb = ldb_module_get_ctx(ar->module);
      msg = ar->objs->objects[ar->index_current].msg;
      rmd = ar->objs->objects[ar->index_current].meta_data;
      ZERO_STRUCT(omd);
      omd.version = 1;

      /* find existing meta data */
      omd_value = ldb_msg_find_ldb_val(ar->search_msg, "replPropertyMetaData");
      if (omd_value) {
            ndr_err = ndr_pull_struct_blob(omd_value, ar, &omd,
                                     (ndr_pull_flags_fn_t)ndr_pull_replPropertyMetaDataBlob);
            if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                  NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
                  return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
            }

            if (omd.version != 1) {
                  return replmd_replicated_request_werror(ar, WERR_DS_DRA_INTERNAL_ERROR);
            }
      }

      /* check if remote 'name' has change,
       * which indicates a rename operation */
      md_remote = replmd_replPropertyMetaData1_find_attid(rmd, DRSUAPI_ATTRIBUTE_name);
      if (md_remote) {
            md_local = replmd_replPropertyMetaData1_find_attid(&omd, DRSUAPI_ATTRIBUTE_name);
            SMB_ASSERT(md_local);
            if (replmd_replPropertyMetaData1_is_newer(md_local, md_remote)) {
                  SMB_ASSERT(ldb_dn_compare(msg->dn, ar->search_msg->dn) != 0);
                  /* TODO: Find appropriate local name (dn) for the object
                   *       and modify msg->dn appropriately */

                  DEBUG(4,("replmd_replicated_request rename %s => %s\n",
                          ldb_dn_get_linearized(ar->search_msg->dn),
                          ldb_dn_get_linearized(msg->dn)));
                  /* pass rename to the next module
                   * so it doesn't appear as an originating update */
                  ret = dsdb_module_rename(ar->module,
                                           ar->search_msg->dn, msg->dn,
                                           DSDB_FLAG_NEXT_MODULE);
                  if (ret != LDB_SUCCESS) {
                        ldb_debug(ldb, LDB_DEBUG_FATAL,
                                  "replmd_replicated_request rename %s => %s failed - %s\n",
                                ldb_dn_get_linearized(ar->search_msg->dn),
                                ldb_dn_get_linearized(msg->dn),
                                ldb_errstring(ldb));
                        return replmd_replicated_request_werror(ar, WERR_DS_DRA_DB_ERROR);
                  }
            }
      }

      ZERO_STRUCT(nmd);
      nmd.version = 1;
      nmd.ctr.ctr1.count = omd.ctr.ctr1.count + rmd->ctr.ctr1.count;
      nmd.ctr.ctr1.array = talloc_array(ar,
                                struct replPropertyMetaData1,
                                nmd.ctr.ctr1.count);
      if (!nmd.ctr.ctr1.array) return replmd_replicated_request_werror(ar, WERR_NOMEM);

      /* first copy the old meta data */
      for (i=0; i < omd.ctr.ctr1.count; i++) {
            nmd.ctr.ctr1.array[ni]  = omd.ctr.ctr1.array[i];
            ni++;
      }

      /* now merge in the new meta data */
      for (i=0; i < rmd->ctr.ctr1.count; i++) {
            bool found = false;

            for (j=0; j < ni; j++) {
                  bool cmp;

                  if (rmd->ctr.ctr1.array[i].attid != nmd.ctr.ctr1.array[j].attid) {
                        continue;
                  }

                  cmp = replmd_replPropertyMetaData1_is_newer(&nmd.ctr.ctr1.array[j],
                                                    &rmd->ctr.ctr1.array[i]);
                  if (cmp) {
                        /* replace the entry */
                        nmd.ctr.ctr1.array[j] = rmd->ctr.ctr1.array[i];
                        found = true;
                        break;
                  }

                  if (rmd->ctr.ctr1.array[i].attid != DRSUAPI_ATTRIBUTE_instanceType) {
                        DEBUG(3,("Discarding older DRS attribute update to %s on %s from %s\n",
                               msg->elements[i-removed_attrs].name,
                               ldb_dn_get_linearized(msg->dn),
                               GUID_string(ar, &rmd->ctr.ctr1.array[i].originating_invocation_id)));
                  }

                  /* we don't want to apply this change so remove the attribute */
                  ldb_msg_remove_element(msg, &msg->elements[i-removed_attrs]);
                  removed_attrs++;

                  found = true;
                  break;
            }

            if (found) continue;

            nmd.ctr.ctr1.array[ni] = rmd->ctr.ctr1.array[i];
            ni++;
      }

      /*
       * finally correct the size of the meta_data array
       */
      nmd.ctr.ctr1.count = ni;

      /*
       * the rdn attribute (the alias for the name attribute),
       * 'cn' for most objects is the last entry in the meta data array
       * we have stored
       *
       * sort the new meta data array
       */
      ret = replmd_replPropertyMetaDataCtr1_sort(&nmd.ctr.ctr1, ar->schema, msg->dn);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      /*
       * check if some replicated attributes left, otherwise skip the ldb_modify() call
       */
      if (msg->num_elements == 0) {
            ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_replicated_apply_merge[%u]: skip replace\n",
                    ar->index_current);

            ar->index_current++;
            return replmd_replicated_apply_next(ar);
      }

      ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_replicated_apply_merge[%u]: replace %u attributes\n",
              ar->index_current, msg->num_elements);

      ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &ar->seq_num);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      for (i=0; i<ni; i++) {
            nmd.ctr.ctr1.array[i].local_usn = ar->seq_num;
      }

      /* create the meta data value */
      ndr_err = ndr_push_struct_blob(&nmd_value, msg, &nmd,
                               (ndr_push_flags_fn_t)ndr_push_replPropertyMetaDataBlob);
      if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
            NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
            return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
      }

      /*
       * when we know that we'll modify the record, add the whenChanged, uSNChanged
       * and replPopertyMetaData attributes
       */
      ret = ldb_msg_add_string(msg, "whenChanged", ar->objs->objects[ar->index_current].when_changed);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }
      ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNChanged", ar->seq_num);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }
      ret = ldb_msg_add_value(msg, "replPropertyMetaData", &nmd_value, NULL);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }

      replmd_ldb_message_sort(msg, ar->schema);

      /* we want to replace the old values */
      for (i=0; i < msg->num_elements; i++) {
            msg->elements[i].flags = LDB_FLAG_MOD_REPLACE;
      }

      if (DEBUGLVL(4)) {
            char *s = ldb_ldif_message_string(ldb, ar, LDB_CHANGETYPE_MODIFY, msg);
            DEBUG(4, ("DRS replication modify message:\n%s\n", s));
            talloc_free(s);
      }

      ret = ldb_build_mod_req(&change_req,
                        ldb,
                        ar,
                        msg,
                        ar->controls,
                        ar,
                        replmd_op_callback,
                        ar->req);
      if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);

      return ldb_next_request(ar->module, change_req);
}

static int replmd_replicated_apply_search_callback(struct ldb_request *req,
                                       struct ldb_reply *ares)
{
      struct replmd_replicated_request *ar = talloc_get_type(req->context,
                                     struct replmd_replicated_request);
      int ret;

      if (!ares) {
            return ldb_module_done(ar->req, NULL, NULL,
                              LDB_ERR_OPERATIONS_ERROR);
      }
      if (ares->error != LDB_SUCCESS &&
          ares->error != LDB_ERR_NO_SUCH_OBJECT) {
            return ldb_module_done(ar->req, ares->controls,
                              ares->response, ares->error);
      }

      switch (ares->type) {
      case LDB_REPLY_ENTRY:
            ar->search_msg = talloc_steal(ar, ares->message);
            break;

      case LDB_REPLY_REFERRAL:
            /* we ignore referrals */
            break;

      case LDB_REPLY_DONE:
            if (ar->search_msg != NULL) {
                  ret = replmd_replicated_apply_merge(ar);
            } else {
                  ret = replmd_replicated_apply_add(ar);
            }
            if (ret != LDB_SUCCESS) {
                  return ldb_module_done(ar->req, NULL, NULL, ret);
            }
      }

      talloc_free(ares);
      return LDB_SUCCESS;
}

static int replmd_replicated_uptodate_vector(struct replmd_replicated_request *ar);

static int replmd_replicated_apply_next(struct replmd_replicated_request *ar)
{
      struct ldb_context *ldb;
      int ret;
      char *tmp_str;
      char *filter;
      struct ldb_request *search_req;
      struct ldb_search_options_control *options;

      if (ar->index_current >= ar->objs->num_objects) {
            /* done with it, go to next stage */
            return replmd_replicated_uptodate_vector(ar);
      }

      ldb = ldb_module_get_ctx(ar->module);
      ar->search_msg = NULL;

      tmp_str = ldb_binary_encode(ar, ar->objs->objects[ar->index_current].guid_value);
      if (!tmp_str) return replmd_replicated_request_werror(ar, WERR_NOMEM);

      filter = talloc_asprintf(ar, "(objectGUID=%s)", tmp_str);
      if (!filter) return replmd_replicated_request_werror(ar, WERR_NOMEM);
      talloc_free(tmp_str);

      ret = ldb_build_search_req(&search_req,
                           ldb,
                           ar,
                           NULL,
                           LDB_SCOPE_SUBTREE,
                           filter,
                           NULL,
                           NULL,
                           ar,
                           replmd_replicated_apply_search_callback,
                           ar->req);

      ret = ldb_request_add_control(search_req, LDB_CONTROL_SHOW_DELETED_OID, true, NULL);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      /* we need to cope with cross-partition links, so search for
         the GUID over all partitions */
      options = talloc(search_req, struct ldb_search_options_control);
      if (options == NULL) {
            DEBUG(0, (__location__ ": out of memory\n"));
            return LDB_ERR_OPERATIONS_ERROR;
      }
      options->search_options = LDB_SEARCH_OPTION_PHANTOM_ROOT;

      ret = ldb_request_add_control(search_req,
                              LDB_CONTROL_SEARCH_OPTIONS_OID,
                              true, options);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);

      return ldb_next_request(ar->module, search_req);
}

static int replmd_replicated_uptodate_modify_callback(struct ldb_request *req,
                                          struct ldb_reply *ares)
{
      struct ldb_context *ldb;
      struct replmd_replicated_request *ar = talloc_get_type(req->context,
                                     struct replmd_replicated_request);
      ldb = ldb_module_get_ctx(ar->module);

      if (!ares) {
            return ldb_module_done(ar->req, NULL, NULL,
                              LDB_ERR_OPERATIONS_ERROR);
      }
      if (ares->error != LDB_SUCCESS) {
            return ldb_module_done(ar->req, ares->controls,
                              ares->response, ares->error);
      }

      if (ares->type != LDB_REPLY_DONE) {
            ldb_set_errstring(ldb, "Invalid reply type\n!");
            return ldb_module_done(ar->req, NULL, NULL,
                              LDB_ERR_OPERATIONS_ERROR);
      }

      talloc_free(ares);

      return ldb_module_done(ar->req, NULL, NULL, LDB_SUCCESS);
}

static int replmd_replicated_uptodate_modify(struct replmd_replicated_request *ar)
{
      struct ldb_context *ldb;
      struct ldb_request *change_req;
      enum ndr_err_code ndr_err;
      struct ldb_message *msg;
      struct replUpToDateVectorBlob ouv;
      const struct ldb_val *ouv_value;
      const struct drsuapi_DsReplicaCursor2CtrEx *ruv;
      struct replUpToDateVectorBlob nuv;
      struct ldb_val nuv_value;
      struct ldb_message_element *nuv_el = NULL;
      const struct GUID *our_invocation_id;
      struct ldb_message_element *orf_el = NULL;
      struct repsFromToBlob nrf;
      struct ldb_val *nrf_value = NULL;
      struct ldb_message_element *nrf_el = NULL;
      unsigned int i;
      uint32_t j,ni=0;
      bool found = false;
      time_t t = time(NULL);
      NTTIME now;
      int ret;

      ldb = ldb_module_get_ctx(ar->module);
      ruv = ar->objs->uptodateness_vector;
      ZERO_STRUCT(ouv);
      ouv.version = 2;
      ZERO_STRUCT(nuv);
      nuv.version = 2;

      unix_to_nt_time(&now, t);

      /*
       * first create the new replUpToDateVector
       */
      ouv_value = ldb_msg_find_ldb_val(ar->search_msg, "replUpToDateVector");
      if (ouv_value) {
            ndr_err = ndr_pull_struct_blob(ouv_value, ar, &ouv,
                                     (ndr_pull_flags_fn_t)ndr_pull_replUpToDateVectorBlob);
            if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                  NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
                  return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
            }

            if (ouv.version != 2) {
                  return replmd_replicated_request_werror(ar, WERR_DS_DRA_INTERNAL_ERROR);
            }
      }

      /*
       * the new uptodateness vector will at least
       * contain 1 entry, one for the source_dsa
       *
       * plus optional values from our old vector and the one from the source_dsa
       */
      nuv.ctr.ctr2.count = 1 + ouv.ctr.ctr2.count;
      if (ruv) nuv.ctr.ctr2.count += ruv->count;
      nuv.ctr.ctr2.cursors = talloc_array(ar,
                                  struct drsuapi_DsReplicaCursor2,
                                  nuv.ctr.ctr2.count);
      if (!nuv.ctr.ctr2.cursors) return replmd_replicated_request_werror(ar, WERR_NOMEM);

      /* first copy the old vector */
      for (i=0; i < ouv.ctr.ctr2.count; i++) {
            nuv.ctr.ctr2.cursors[ni] = ouv.ctr.ctr2.cursors[i];
            ni++;
      }

      /* get our invocation_id if we have one already attached to the ldb */
      our_invocation_id = samdb_ntds_invocation_id(ldb);

      /* merge in the source_dsa vector is available */
      for (i=0; (ruv && i < ruv->count); i++) {
            found = false;

            if (our_invocation_id &&
                GUID_equal(&ruv->cursors[i].source_dsa_invocation_id,
                         our_invocation_id)) {
                  continue;
            }

            for (j=0; j < ni; j++) {
                  if (!GUID_equal(&ruv->cursors[i].source_dsa_invocation_id,
                              &nuv.ctr.ctr2.cursors[j].source_dsa_invocation_id)) {
                        continue;
                  }

                  found = true;

                  /*
                   * we update only the highest_usn and not the latest_sync_success time,
                   * because the last success stands for direct replication
                   */
                  if (ruv->cursors[i].highest_usn > nuv.ctr.ctr2.cursors[j].highest_usn) {
                        nuv.ctr.ctr2.cursors[j].highest_usn = ruv->cursors[i].highest_usn;
                  }
                  break;
            }

            if (found) continue;

            /* if it's not there yet, add it */
            nuv.ctr.ctr2.cursors[ni] = ruv->cursors[i];
            ni++;
      }

      /*
       * merge in the current highwatermark for the source_dsa
       */
      found = false;
      for (j=0; j < ni; j++) {
            if (!GUID_equal(&ar->objs->source_dsa->source_dsa_invocation_id,
                        &nuv.ctr.ctr2.cursors[j].source_dsa_invocation_id)) {
                  continue;
            }

            found = true;

            /*
             * here we update the highest_usn and last_sync_success time
             * because we're directly replicating from the source_dsa
             *
             * and use the tmp_highest_usn because this is what we have just applied
             * to our ldb
             */
            nuv.ctr.ctr2.cursors[j].highest_usn       = ar->objs->source_dsa->highwatermark.tmp_highest_usn;
            nuv.ctr.ctr2.cursors[j].last_sync_success = now;
            break;
      }
      if (!found) {
            /*
             * here we update the highest_usn and last_sync_success time
             * because we're directly replicating from the source_dsa
             *
             * and use the tmp_highest_usn because this is what we have just applied
             * to our ldb
             */
            nuv.ctr.ctr2.cursors[ni].source_dsa_invocation_id= ar->objs->source_dsa->source_dsa_invocation_id;
            nuv.ctr.ctr2.cursors[ni].highest_usn            = ar->objs->source_dsa->highwatermark.tmp_highest_usn;
            nuv.ctr.ctr2.cursors[ni].last_sync_success      = now;
            ni++;
      }

      /*
       * finally correct the size of the cursors array
       */
      nuv.ctr.ctr2.count = ni;

      /*
       * sort the cursors
       */
      TYPESAFE_QSORT(nuv.ctr.ctr2.cursors, nuv.ctr.ctr2.count, drsuapi_DsReplicaCursor2_compare);

      /*
       * create the change ldb_message
       */
      msg = ldb_msg_new(ar);
      if (!msg) return replmd_replicated_request_werror(ar, WERR_NOMEM);
      msg->dn = ar->search_msg->dn;

      ndr_err = ndr_push_struct_blob(&nuv_value, msg, &nuv,
                               (ndr_push_flags_fn_t)ndr_push_replUpToDateVectorBlob);
      if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
            NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
            return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
      }
      ret = ldb_msg_add_value(msg, "replUpToDateVector", &nuv_value, &nuv_el);
      if (ret != LDB_SUCCESS) {
            return replmd_replicated_request_error(ar, ret);
      }
      nuv_el->flags = LDB_FLAG_MOD_REPLACE;

      /*
       * now create the new repsFrom value from the given repsFromTo1 structure
       */
      ZERO_STRUCT(nrf);
      nrf.version                         = 1;
      nrf.ctr.ctr1                              = *ar->objs->source_dsa;
      /* and fix some values... */
      nrf.ctr.ctr1.consecutive_sync_failures          = 0;
      nrf.ctr.ctr1.last_success                 = now;
      nrf.ctr.ctr1.last_attempt                 = now;
      nrf.ctr.ctr1.result_last_attempt          = WERR_OK;
      nrf.ctr.ctr1.highwatermark.highest_usn          = nrf.ctr.ctr1.highwatermark.tmp_highest_usn;

      /*
       * first see if we already have a repsFrom value for the current source dsa
       * if so we'll later replace this value
       */
      orf_el = ldb_msg_find_element(ar->search_msg, "repsFrom");
      if (orf_el) {
            for (i=0; i < orf_el->num_values; i++) {
                  struct repsFromToBlob *trf;

                  trf = talloc(ar, struct repsFromToBlob);
                  if (!trf) return replmd_replicated_request_werror(ar, WERR_NOMEM);

                  ndr_err = ndr_pull_struct_blob(&orf_el->values[i], trf, trf,
                                           (ndr_pull_flags_fn_t)ndr_pull_repsFromToBlob);
                  if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                        NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
                        return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
                  }

                  if (trf->version != 1) {
                        return replmd_replicated_request_werror(ar, WERR_DS_DRA_INTERNAL_ERROR);
                  }

                  /*
                   * we compare the source dsa objectGUID not the invocation_id
                   * because we want only one repsFrom value per source dsa
                   * and when the invocation_id of the source dsa has changed we don't need
                   * the old repsFrom with the old invocation_id
                   */
                  if (!GUID_equal(&trf->ctr.ctr1.source_dsa_obj_guid,
                              &ar->objs->source_dsa->source_dsa_obj_guid)) {
                        talloc_free(trf);
                        continue;
                  }

                  talloc_free(trf);
                  nrf_value = &orf_el->values[i];
                  break;
            }

            /*
             * copy over all old values to the new ldb_message
             */
            ret = ldb_msg_add_empty(msg, "repsFrom", 0, &nrf_el);
            if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);
            *nrf_el = *orf_el;
      }

      /*
       * if we haven't found an old repsFrom value for the current source dsa
       * we'll add a new value
       */
      if (!nrf_value) {
            struct ldb_val zero_value;
            ZERO_STRUCT(zero_value);
            ret = ldb_msg_add_value(msg, "repsFrom", &zero_value, &nrf_el);
            if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);

            nrf_value = &nrf_el->values[nrf_el->num_values - 1];
      }

      /* we now fill the value which is already attached to ldb_message */
      ndr_err = ndr_push_struct_blob(nrf_value, msg,
                               &nrf,
                               (ndr_push_flags_fn_t)ndr_push_repsFromToBlob);
      if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
            NTSTATUS nt_status = ndr_map_error2ntstatus(ndr_err);
            return replmd_replicated_request_werror(ar, ntstatus_to_werror(nt_status));
      }

      /*
       * the ldb_message_element for the attribute, has all the old values and the new one
       * so we'll replace the whole attribute with all values
       */
      nrf_el->flags = LDB_FLAG_MOD_REPLACE;

      if (DEBUGLVL(4)) {
            char *s = ldb_ldif_message_string(ldb, ar, LDB_CHANGETYPE_MODIFY, msg);
            DEBUG(4, ("DRS replication uptodate modify message:\n%s\n", s));
            talloc_free(s);
      }

      /* prepare the ldb_modify() request */
      ret = ldb_build_mod_req(&change_req,
                        ldb,
                        ar,
                        msg,
                        ar->controls,
                        ar,
                        replmd_replicated_uptodate_modify_callback,
                        ar->req);
      if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);

      return ldb_next_request(ar->module, change_req);
}

static int replmd_replicated_uptodate_search_callback(struct ldb_request *req,
                                          struct ldb_reply *ares)
{
      struct replmd_replicated_request *ar = talloc_get_type(req->context,
                                     struct replmd_replicated_request);
      int ret;

      if (!ares) {
            return ldb_module_done(ar->req, NULL, NULL,
                              LDB_ERR_OPERATIONS_ERROR);
      }
      if (ares->error != LDB_SUCCESS &&
          ares->error != LDB_ERR_NO_SUCH_OBJECT) {
            return ldb_module_done(ar->req, ares->controls,
                              ares->response, ares->error);
      }

      switch (ares->type) {
      case LDB_REPLY_ENTRY:
            ar->search_msg = talloc_steal(ar, ares->message);
            break;

      case LDB_REPLY_REFERRAL:
            /* we ignore referrals */
            break;

      case LDB_REPLY_DONE:
            if (ar->search_msg == NULL) {
                  ret = replmd_replicated_request_werror(ar, WERR_DS_DRA_INTERNAL_ERROR);
            } else {
                  ret = replmd_replicated_uptodate_modify(ar);
            }
            if (ret != LDB_SUCCESS) {
                  return ldb_module_done(ar->req, NULL, NULL, ret);
            }
      }

      talloc_free(ares);
      return LDB_SUCCESS;
}


static int replmd_replicated_uptodate_vector(struct replmd_replicated_request *ar)
{
      struct ldb_context *ldb;
      int ret;
      static const char *attrs[] = {
            "replUpToDateVector",
            "repsFrom",
            NULL
      };
      struct ldb_request *search_req;

      ldb = ldb_module_get_ctx(ar->module);
      ar->search_msg = NULL;

      ret = ldb_build_search_req(&search_req,
                           ldb,
                           ar,
                           ar->objs->partition_dn,
                           LDB_SCOPE_BASE,
                           "(objectClass=*)",
                           attrs,
                           NULL,
                           ar,
                           replmd_replicated_uptodate_search_callback,
                           ar->req);
      if (ret != LDB_SUCCESS) return replmd_replicated_request_error(ar, ret);

      return ldb_next_request(ar->module, search_req);
}



static int replmd_extended_replicated_objects(struct ldb_module *module, struct ldb_request *req)
{
      struct ldb_context *ldb;
      struct dsdb_extended_replicated_objects *objs;
      struct replmd_replicated_request *ar;
      struct ldb_control **ctrls;
      int ret;
      uint32_t i;
      struct replmd_private *replmd_private =
            talloc_get_type(ldb_module_get_private(module), struct replmd_private);

      ldb = ldb_module_get_ctx(module);

      ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_extended_replicated_objects\n");

      objs = talloc_get_type(req->op.extended.data, struct dsdb_extended_replicated_objects);
      if (!objs) {
            ldb_debug(ldb, LDB_DEBUG_FATAL, "replmd_extended_replicated_objects: invalid extended data\n");
            return LDB_ERR_PROTOCOL_ERROR;
      }

      if (objs->version != DSDB_EXTENDED_REPLICATED_OBJECTS_VERSION) {
            ldb_debug(ldb, LDB_DEBUG_FATAL, "replmd_extended_replicated_objects: extended data invalid version [%u != %u]\n",
                    objs->version, DSDB_EXTENDED_REPLICATED_OBJECTS_VERSION);
            return LDB_ERR_PROTOCOL_ERROR;
      }

      ar = replmd_ctx_init(module, req);
      if (!ar)
            return LDB_ERR_OPERATIONS_ERROR;

      /* Set the flags to have the replmd_op_callback run over the full set of objects */
      ar->apply_mode = true;
      ar->objs = objs;
      ar->schema = dsdb_get_schema(ldb, ar);
      if (!ar->schema) {
            ldb_debug_set(ldb, LDB_DEBUG_FATAL, "replmd_ctx_init: no loaded schema found\n");
            talloc_free(ar);
            DEBUG(0,(__location__ ": %s\n", ldb_errstring(ldb)));
            return LDB_ERR_CONSTRAINT_VIOLATION;
      }

      ctrls = req->controls;

      if (req->controls) {
            req->controls = talloc_memdup(ar, req->controls,
                                    talloc_get_size(req->controls));
            if (!req->controls) return replmd_replicated_request_werror(ar, WERR_NOMEM);
      }

      /* This allows layers further down to know if a change came in over replication */
      ret = ldb_request_add_control(req, DSDB_CONTROL_REPLICATED_UPDATE_OID, false, NULL);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      /* If this change contained linked attributes in the body
       * (rather than in the links section) we need to update
       * backlinks in linked_attributes */
      ret = ldb_request_add_control(req, DSDB_CONTROL_APPLY_LINKS, false, NULL);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      ar->controls = req->controls;
      req->controls = ctrls;

      DEBUG(4,("linked_attributes_count=%u\n", objs->linked_attributes_count));

      /* save away the linked attributes for the end of the
         transaction */
      for (i=0; i<ar->objs->linked_attributes_count; i++) {
            struct la_entry *la_entry;

            if (replmd_private->la_ctx == NULL) {
                  replmd_private->la_ctx = talloc_new(replmd_private);
            }
            la_entry = talloc(replmd_private->la_ctx, struct la_entry);
            if (la_entry == NULL) {
                  ldb_oom(ldb);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            la_entry->la = talloc(la_entry, struct drsuapi_DsReplicaLinkedAttribute);
            if (la_entry->la == NULL) {
                  talloc_free(la_entry);
                  ldb_oom(ldb);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            *la_entry->la = ar->objs->linked_attributes[i];

            /* we need to steal the non-scalars so they stay
               around until the end of the transaction */
            talloc_steal(la_entry->la, la_entry->la->identifier);
            talloc_steal(la_entry->la, la_entry->la->value.blob);

            DLIST_ADD(replmd_private->la_list, la_entry);
      }

      return replmd_replicated_apply_next(ar);
}

/*
  process one linked attribute structure
 */
static int replmd_process_linked_attribute(struct ldb_module *module,
                                 struct la_entry *la_entry)
{
      struct drsuapi_DsReplicaLinkedAttribute *la = la_entry->la;
      struct ldb_context *ldb = ldb_module_get_ctx(module);
      struct ldb_message *msg;
      TALLOC_CTX *tmp_ctx = talloc_new(la_entry);
      const struct dsdb_schema *schema = dsdb_get_schema(ldb, tmp_ctx);
      int ret;
      const struct dsdb_attribute *attr;
      struct dsdb_dn *dsdb_dn;
      uint64_t seq_num = 0;
      struct ldb_message_element *old_el;
      WERROR status;
      time_t t = time(NULL);
      struct ldb_result *res;
      const char *attrs[2];
      struct parsed_dn *pdn_list, *pdn;
      struct GUID guid = GUID_zero();
      NTSTATUS ntstatus;
      bool active = (la->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)?true:false;
      const struct GUID *our_invocation_id;

/*
linked_attributes[0]:
     &objs->linked_attributes[i]: struct drsuapi_DsReplicaLinkedAttribute
        identifier               : *
            identifier: struct drsuapi_DsReplicaObjectIdentifier
                __ndr_size               : 0x0000003a (58)
                __ndr_size_sid           : 0x00000000 (0)
                guid                     : 8e95b6a9-13dd-4158-89db-3220a5be5cc7
                sid                      : S-0-0
                __ndr_size_dn            : 0x00000000 (0)
                dn                       : ''
        attid                    : DRSUAPI_ATTRIBUTE_member (0x1F)
        value: struct drsuapi_DsAttributeValue
            __ndr_size               : 0x0000007e (126)
            blob                     : *
                blob                     : DATA_BLOB length=126
        flags                    : 0x00000001 (1)
               1: DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE
        originating_add_time     : Wed Sep  2 22:20:01 2009 EST
        meta_data: struct drsuapi_DsReplicaMetaData
            version                  : 0x00000015 (21)
            originating_change_time  : Wed Sep  2 23:39:07 2009 EST
            originating_invocation_id: 794640f3-18cf-40ee-a211-a93992b67a64
            originating_usn          : 0x000000000001e19c (123292)

(for cases where the link is to a normal DN)
     &target: struct drsuapi_DsReplicaObjectIdentifier3
        __ndr_size               : 0x0000007e (126)
        __ndr_size_sid           : 0x0000001c (28)
        guid                     : 7639e594-db75-4086-b0d4-67890ae46031
        sid                      : S-1-5-21-2848215498-2472035911-1947525656-19924
        __ndr_size_dn            : 0x00000022 (34)
        dn                       : 'CN=UOne,OU=TestOU,DC=vsofs8,DC=com'
 */

      /* find the attribute being modified */
      attr = dsdb_attribute_by_attributeID_id(schema, la->attid);
      if (attr == NULL) {
            DEBUG(0, (__location__ ": Unable to find attributeID 0x%x\n", la->attid));
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      attrs[0] = attr->lDAPDisplayName;
      attrs[1] = NULL;

      /* get the existing message from the db for the object with
         this GUID, returning attribute being modified. We will then
         use this msg as the basis for a modify call */
      ret = dsdb_module_search(module, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE, attrs,
                               DSDB_FLAG_NEXT_MODULE |
                         DSDB_SEARCH_SEARCH_ALL_PARTITIONS |
                         DSDB_SEARCH_SHOW_DELETED |
                         DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
                         DSDB_SEARCH_REVEAL_INTERNALS,
                         "objectGUID=%s", GUID_string(tmp_ctx, &la->identifier->guid));
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }
      if (res->count != 1) {
            ldb_asprintf_errstring(ldb, "DRS linked attribute for GUID %s - DN not found",
                               GUID_string(tmp_ctx, &la->identifier->guid));
            talloc_free(tmp_ctx);
            return LDB_ERR_NO_SUCH_OBJECT;
      }
      msg = res->msgs[0];

      if (msg->num_elements == 0) {
            ret = ldb_msg_add_empty(msg, attr->lDAPDisplayName, LDB_FLAG_MOD_REPLACE, &old_el);
            if (ret != LDB_SUCCESS) {
                  ldb_module_oom(module);
                  talloc_free(tmp_ctx);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
      } else {
            old_el = &msg->elements[0];
            old_el->flags = LDB_FLAG_MOD_REPLACE;
      }

      /* parse the existing links */
      ret = get_parsed_dns(module, tmp_ctx, old_el, &pdn_list, attr->syntax->ldap_oid);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      /* get our invocationId */
      our_invocation_id = samdb_ntds_invocation_id(ldb);
      if (!our_invocation_id) {
            ldb_debug_set(ldb, LDB_DEBUG_ERROR, __location__ ": unable to find invocationId\n");
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ret = replmd_check_upgrade_links(pdn_list, old_el->num_values, old_el, our_invocation_id);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      status = dsdb_dn_la_from_blob(ldb, attr, schema, tmp_ctx, la->value.blob, &dsdb_dn);
      if (!W_ERROR_IS_OK(status)) {
            ldb_asprintf_errstring(ldb, "Failed to parsed linked attribute blob for %s on %s - %s\n",
                               old_el->name, ldb_dn_get_linearized(msg->dn), win_errstr(status));
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ntstatus = dsdb_get_extended_dn_guid(dsdb_dn->dn, &guid, "GUID");
      if (!NT_STATUS_IS_OK(ntstatus) && active) {
            ldb_asprintf_errstring(ldb, "Failed to find GUID in linked attribute blob for %s on %s from %s",
                               old_el->name,
                               ldb_dn_get_linearized(dsdb_dn->dn),
                               ldb_dn_get_linearized(msg->dn));
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* re-resolve the DN by GUID, as the DRS server may give us an
         old DN value */
      ret = dsdb_module_dn_by_guid(module, dsdb_dn, &guid, &dsdb_dn->dn);
      if (ret != LDB_SUCCESS) {
            DEBUG(2,(__location__ ": WARNING: Failed to re-resolve GUID %s - using %s",
                   GUID_string(tmp_ctx, &guid),
                   ldb_dn_get_linearized(dsdb_dn->dn)));
      }

      /* see if this link already exists */
      pdn = parsed_dn_find(pdn_list, old_el->num_values, &guid, dsdb_dn->dn);
      if (pdn != NULL) {
            /* see if this update is newer than what we have already */
            struct GUID invocation_id = GUID_zero();
            uint32_t version = 0;
            NTTIME change_time = 0;
            uint32_t rmd_flags = dsdb_dn_rmd_flags(pdn->dsdb_dn->dn);

            dsdb_get_extended_dn_guid(pdn->dsdb_dn->dn, &invocation_id, "RMD_INVOCID");
            dsdb_get_extended_dn_uint32(pdn->dsdb_dn->dn, &version, "RMD_VERSION");
            dsdb_get_extended_dn_nttime(pdn->dsdb_dn->dn, &change_time, "RMD_CHANGETIME");

            if (!replmd_update_is_newer(&invocation_id,
                                  &la->meta_data.originating_invocation_id,
                                  version,
                                  la->meta_data.version,
                                  change_time,
                                  la->meta_data.originating_change_time)) {
                  DEBUG(3,("Discarding older DRS linked attribute update to %s on %s from %s\n",
                         old_el->name, ldb_dn_get_linearized(msg->dn),
                         GUID_string(tmp_ctx, &la->meta_data.originating_invocation_id)));
                  talloc_free(tmp_ctx);
                  return LDB_SUCCESS;
            }

            /* get a seq_num for this change */
            ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            if (!(rmd_flags & DSDB_RMD_FLAG_DELETED)) {
                  /* remove the existing backlink */
                  ret = replmd_add_backlink(module, schema, &la->identifier->guid, &guid, false, attr, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
            }

            ret = replmd_update_la_val(tmp_ctx, pdn->v, dsdb_dn, pdn->dsdb_dn,
                                 &la->meta_data.originating_invocation_id,
                                 la->meta_data.originating_usn, seq_num,
                                 la->meta_data.originating_change_time,
                                 la->meta_data.version,
                                 !active);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            if (active) {
                  /* add the new backlink */
                  ret = replmd_add_backlink(module, schema, &la->identifier->guid, &guid, true, attr, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
            }
      } else {
            /* get a seq_num for this change */
            ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            old_el->values = talloc_realloc(msg->elements, old_el->values,
                                    struct ldb_val, old_el->num_values+1);
            if (!old_el->values) {
                  ldb_module_oom(module);
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            old_el->num_values++;

            ret = replmd_build_la_val(tmp_ctx, &old_el->values[old_el->num_values-1], dsdb_dn,
                                &la->meta_data.originating_invocation_id,
                                la->meta_data.originating_usn, seq_num,
                                la->meta_data.originating_change_time,
                                la->meta_data.version,
                                (la->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)?false:true);
            if (ret != LDB_SUCCESS) {
                  talloc_free(tmp_ctx);
                  return ret;
            }

            if (active) {
                  ret = replmd_add_backlink(module, schema, &la->identifier->guid, &guid,
                                      true, attr, false);
                  if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                  }
            }
      }

      /* we only change whenChanged and uSNChanged if the seq_num
         has changed */
      if (add_time_element(msg, "whenChanged", t) != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      if (add_uint64_element(msg, "uSNChanged", seq_num) != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return LDB_ERR_OPERATIONS_ERROR;
      }

      ret = dsdb_check_single_valued_link(attr, old_el);
      if (ret != LDB_SUCCESS) {
            talloc_free(tmp_ctx);
            return ret;
      }

      ret = dsdb_module_modify(module, msg, DSDB_FLAG_NEXT_MODULE | DSDB_MODIFY_RELAX);
      if (ret != LDB_SUCCESS) {
            ldb_debug(ldb, LDB_DEBUG_WARNING, "Failed to apply linked attribute change '%s'\n%s\n",
                    ldb_errstring(ldb),
                    ldb_ldif_message_string(ldb, tmp_ctx, LDB_CHANGETYPE_MODIFY, msg));
            talloc_free(tmp_ctx);
            return ret;
      }

      talloc_free(tmp_ctx);

      return ret;
}

static int replmd_extended(struct ldb_module *module, struct ldb_request *req)
{
      if (strcmp(req->op.extended.oid, DSDB_EXTENDED_REPLICATED_OBJECTS_OID) == 0) {
            return replmd_extended_replicated_objects(module, req);
      }

      return ldb_next_request(module, req);
}


/*
  we hook into the transaction operations to allow us to
  perform the linked attribute updates at the end of the whole
  transaction. This allows a forward linked attribute to be created
  before the object is created. During a vampire, w2k8 sends us linked
  attributes before the objects they are part of.
 */
static int replmd_start_transaction(struct ldb_module *module)
{
      /* create our private structure for this transaction */
      struct replmd_private *replmd_private = talloc_get_type(ldb_module_get_private(module),
                                                struct replmd_private);
      replmd_txn_cleanup(replmd_private);

      /* free any leftover mod_usn records from cancelled
         transactions */
      while (replmd_private->ncs) {
            struct nc_entry *e = replmd_private->ncs;
            DLIST_REMOVE(replmd_private->ncs, e);
            talloc_free(e);
      }

      return ldb_next_start_trans(module);
}

/*
  on prepare commit we loop over our queued la_context structures and
  apply each of them
 */
static int replmd_prepare_commit(struct ldb_module *module)
{
      struct replmd_private *replmd_private =
            talloc_get_type(ldb_module_get_private(module), struct replmd_private);
      struct la_entry *la, *prev;
      struct la_backlink *bl;
      int ret;

      /* walk the list backwards, to do the first entry first, as we
       * added the entries with DLIST_ADD() which puts them at the
       * start of the list */
      for (la = DLIST_TAIL(replmd_private->la_list); la; la=prev) {
            prev = DLIST_PREV(la);
            DLIST_REMOVE(replmd_private->la_list, la);
            ret = replmd_process_linked_attribute(module, la);
            if (ret != LDB_SUCCESS) {
                  replmd_txn_cleanup(replmd_private);
                  return ret;
            }
      }

      /* process our backlink list, creating and deleting backlinks
         as necessary */
      for (bl=replmd_private->la_backlinks; bl; bl=bl->next) {
            ret = replmd_process_backlink(module, bl);
            if (ret != LDB_SUCCESS) {
                  replmd_txn_cleanup(replmd_private);
                  return ret;
            }
      }

      replmd_txn_cleanup(replmd_private);

      /* possibly change @REPLCHANGED */
      ret = replmd_notify_store(module);
      if (ret != LDB_SUCCESS) {
            return ret;
      }

      return ldb_next_prepare_commit(module);
}

static int replmd_del_transaction(struct ldb_module *module)
{
      struct replmd_private *replmd_private =
            talloc_get_type(ldb_module_get_private(module), struct replmd_private);
      replmd_txn_cleanup(replmd_private);

      return ldb_next_del_trans(module);
}


_PUBLIC_ const struct ldb_module_ops ldb_repl_meta_data_module_ops = {
      .name          = "repl_meta_data",
      .init_context        = replmd_init,
      .add               = replmd_add,
      .modify            = replmd_modify,
      .rename            = replmd_rename,
      .del             = replmd_delete,
      .extended          = replmd_extended,
      .start_transaction = replmd_start_transaction,
      .prepare_commit    = replmd_prepare_commit,
      .del_transaction   = replmd_del_transaction,
};

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