Adding upstream version 2:4.17.12+dfsg.upstream/2%4.17.12+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3861 insertions, 0 deletions

diff --git a/source4/rpc_server/drsuapi/getncchanges.c b/source4/rpc_server/drsuapi/getncchanges.c
new file mode 100644
index 0000000..8864e79
--- /dev/null
+++ b/source4/rpc_server/drsuapi/getncchanges.c
@@ -0,0 +1,3861 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   implement the DSGetNCChanges call
+
+   Copyright (C) Anatoliy Atanasov 2009
+   Copyright (C) Andrew Tridgell 2009-2010
+   Copyright (C) Andrew Bartlett 2010-2016
+
+   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/>.
+*/
+
+#include "includes.h"
+#include "rpc_server/dcerpc_server.h"
+#include "dsdb/samdb/samdb.h"
+#include "param/param.h"
+#include "librpc/gen_ndr/ndr_drsblobs.h"
+#include "librpc/gen_ndr/ndr_drsuapi.h"
+#include "librpc/gen_ndr/ndr_security.h"
+#include "libcli/security/security.h"
+#include "libcli/security/session.h"
+#include "rpc_server/drsuapi/dcesrv_drsuapi.h"
+#include "../libcli/drsuapi/drsuapi.h"
+#include "lib/util/binsearch.h"
+#include "lib/util/tsort.h"
+#include "auth/session.h"
+#include "dsdb/common/util.h"
+#include "lib/dbwrap/dbwrap.h"
+#include "lib/dbwrap/dbwrap_rbt.h"
+#include "librpc/gen_ndr/ndr_misc.h"
+
+#undef DBGC_CLASS
+#define DBGC_CLASS            DBGC_DRS_REPL
+
+#define DRS_GUID_SIZE       16
+#define DEFAULT_MAX_OBJECTS 1000
+#define DEFAULT_MAX_LINKS   1500
+
+/*
+ * state of a partially-completed replication cycle. This state persists
+ * over multiple calls to dcesrv_drsuapi_DsGetNCChanges()
+ */
+struct drsuapi_getncchanges_state {
+	struct db_context *obj_cache;
+	struct GUID *guids;
+	uint32_t num_records;
+	uint32_t num_processed;
+	struct ldb_dn *ncRoot_dn;
+	struct GUID ncRoot_guid;
+	bool is_schema_nc;
+	bool is_get_anc;
+	bool broken_samba_4_5_get_anc_emulation;
+	bool is_get_tgt;
+	bool send_nc_root_first;
+	uint64_t min_usn;
+	uint64_t max_usn;
+	struct drsuapi_DsReplicaHighWaterMark last_hwm;
+	struct ldb_dn *last_dn;
+	struct drsuapi_DsReplicaHighWaterMark final_hwm;
+	struct drsuapi_DsReplicaCursor2CtrEx *final_udv;
+	struct drsuapi_DsReplicaLinkedAttribute *la_list;
+	uint32_t la_count;
+	uint32_t la_idx;
+
+	/* these are just used for debugging the replication's progress */
+	uint32_t links_given;
+	uint32_t total_links;
+};
+
+/* We must keep the GUIDs in NDR form for sorting */
+struct la_for_sorting {
+	const struct drsuapi_DsReplicaLinkedAttribute *link;
+	uint8_t target_guid[DRS_GUID_SIZE];
+	uint8_t source_guid[DRS_GUID_SIZE];
+};
+
+/*
+ * stores the state for a chunk of replication data. This state information
+ * only exists for a single call to dcesrv_drsuapi_DsGetNCChanges()
+ */
+struct getncchanges_repl_chunk {
+	uint32_t max_objects;
+	uint32_t max_links;
+	uint32_t tgt_la_count;
+	bool immediate_link_sync;
+	time_t max_wait;
+	time_t start;
+
+	/* stores the objects to be sent in this chunk */
+	uint32_t object_count;
+	struct drsuapi_DsReplicaObjectListItemEx *object_list;
+
+	/* the last object added to this replication chunk */
+	struct drsuapi_DsReplicaObjectListItemEx *last_object;
+};
+
+static int drsuapi_DsReplicaHighWaterMark_cmp(const struct drsuapi_DsReplicaHighWaterMark *h1,
+					      const struct drsuapi_DsReplicaHighWaterMark *h2)
+{
+	if (h1->highest_usn < h2->highest_usn) {
+		return -1;
+	} else if (h1->highest_usn > h2->highest_usn) {
+		return 1;
+	} else if (h1->tmp_highest_usn < h2->tmp_highest_usn) {
+		return -1;
+	} else if (h1->tmp_highest_usn > h2->tmp_highest_usn) {
+		return 1;
+	} else if (h1->reserved_usn < h2->reserved_usn) {
+		return -1;
+	} else if (h1->reserved_usn > h2->reserved_usn) {
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+  build a DsReplicaObjectIdentifier from a ldb msg
+ */
+static struct drsuapi_DsReplicaObjectIdentifier *get_object_identifier(TALLOC_CTX *mem_ctx,
+								       const struct ldb_message *msg)
+{
+	struct drsuapi_DsReplicaObjectIdentifier *identifier;
+	struct dom_sid *sid;
+
+	identifier = talloc(mem_ctx, struct drsuapi_DsReplicaObjectIdentifier);
+	if (identifier == NULL) {
+		return NULL;
+	}
+
+	identifier->dn = ldb_dn_alloc_linearized(identifier, msg->dn);
+	identifier->guid = samdb_result_guid(msg, "objectGUID");
+
+	sid = samdb_result_dom_sid(identifier, msg, "objectSid");
+	if (sid) {
+		identifier->sid = *sid;
+	} else {
+		ZERO_STRUCT(identifier->sid);
+	}
+	return identifier;
+}
+
+static int udv_compare(const struct GUID *guid1, struct GUID guid2)
+{
+	return GUID_compare(guid1, &guid2);
+}
+
+/*
+  see if we can filter an attribute using the uptodateness_vector
+ */
+static bool udv_filter(const struct drsuapi_DsReplicaCursorCtrEx *udv,
+		       const struct GUID *originating_invocation_id,
+		       uint64_t originating_usn)
+{
+	const struct drsuapi_DsReplicaCursor *c;
+	if (udv == NULL) return false;
+	BINARY_ARRAY_SEARCH(udv->cursors, udv->count, source_dsa_invocation_id,
+			    originating_invocation_id, udv_compare, c);
+	if (c && originating_usn <= c->highest_usn) {
+		return true;
+	}
+	return false;
+}
+
+static int uint32_t_cmp(uint32_t a1, uint32_t a2)
+{
+	if (a1 == a2) return 0;
+	return a1 > a2 ? 1 : -1;
+}
+
+static int uint32_t_ptr_cmp(uint32_t *a1, uint32_t *a2)
+{
+	if (*a1 == *a2) return 0;
+	return *a1 > *a2 ? 1 : -1;
+}
+
+static WERROR getncchanges_attid_remote_to_local(const struct dsdb_schema *schema,
+						 const struct dsdb_syntax_ctx *ctx,
+						 enum drsuapi_DsAttributeId remote_attid_as_enum,
+						 enum drsuapi_DsAttributeId *local_attid_as_enum,
+						 const struct dsdb_attribute **_sa)
+{
+	WERROR werr;
+	const struct dsdb_attribute *sa = NULL;
+
+	if (ctx->pfm_remote == NULL) {
+		DEBUG(7, ("No prefixMap supplied, falling back to local prefixMap.\n"));
+		goto fail;
+	}
+
+	werr = dsdb_attribute_drsuapi_remote_to_local(ctx,
+						      remote_attid_as_enum,
+						      local_attid_as_enum,
+						      _sa);
+	if (!W_ERROR_IS_OK(werr)) {
+		DEBUG(3, ("WARNING: Unable to resolve remote attid, falling back to local prefixMap.\n"));
+		goto fail;
+	}
+
+	return werr;
+fail:
+
+	sa = dsdb_attribute_by_attributeID_id(schema, remote_attid_as_enum);
+	if (sa == NULL) {
+		return WERR_DS_DRA_SCHEMA_MISMATCH;
+	} else {
+		if (local_attid_as_enum != NULL) {
+			*local_attid_as_enum = sa->attributeID_id;
+		}
+		if (_sa != NULL) {
+			*_sa = sa;
+		}
+		return WERR_OK;
+	}
+}
+
+static WERROR getncchanges_update_revealed_list(struct ldb_context *sam_ctx,
+						TALLOC_CTX *mem_ctx,
+						struct ldb_message **msg,
+						struct ldb_dn *object_dn,
+						const struct GUID *object_guid,
+						const struct dsdb_attribute *sa,
+						struct replPropertyMetaData1 *meta_data,
+						struct ldb_message *revealed_users)
+{
+	enum ndr_err_code ndr_err;
+	int ldb_err;
+	char *attr_str = NULL;
+	char *attr_hex = NULL;
+	DATA_BLOB attr_blob;
+	struct ldb_message_element *existing = NULL, *el_add = NULL, *el_del = NULL;
+	const char * const * secret_attributes = ldb_get_opaque(sam_ctx, "LDB_SECRET_ATTRIBUTE_LIST");
+
+	if (!ldb_attr_in_list(secret_attributes,
+			      sa->lDAPDisplayName)) {
+		return WERR_OK;
+	}
+
+
+	ndr_err = ndr_push_struct_blob(&attr_blob, mem_ctx, meta_data, (ndr_push_flags_fn_t)ndr_push_replPropertyMetaData1);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	attr_hex = hex_encode_talloc(mem_ctx, attr_blob.data, attr_blob.length);
+	if (attr_hex == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	attr_str = talloc_asprintf(mem_ctx, "B:%zd:%s:%s", attr_blob.length*2, attr_hex, ldb_dn_get_linearized(object_dn));
+	if (attr_str == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	existing = ldb_msg_find_element(revealed_users, "msDS-RevealedUsers");
+	if (existing != NULL) {
+		/* Replace the old value (if one exists) with the current one */
+		struct parsed_dn *link_dns;
+		struct parsed_dn *exact = NULL, *unused = NULL;
+		uint8_t attid[4];
+		DATA_BLOB partial_meta;
+
+		ldb_err = get_parsed_dns_trusted(mem_ctx, existing, &link_dns);
+		if (ldb_err != LDB_SUCCESS) {
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		/* Construct a partial metadata blob to match on in the DB */
+		SIVAL(attid, 0, sa->attributeID_id);
+		partial_meta.length = 4;
+		partial_meta.data = attid;
+
+		/* Binary search using GUID and attribute id for uniqueness */
+		ldb_err = parsed_dn_find(sam_ctx, link_dns, existing->num_values,
+					 object_guid, object_dn,
+					 partial_meta, 4,
+					 &exact, &unused,
+					 DSDB_SYNTAX_BINARY_DN, true);
+
+		if (ldb_err != LDB_SUCCESS) {
+			DEBUG(0,(__location__ ": Failed parsed DN find - %s\n",
+				 ldb_errstring(sam_ctx)));
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		if (exact != NULL) {
+			/* Perform some verification of the blob */
+			struct replPropertyMetaData1 existing_meta_data;
+			ndr_err = ndr_pull_struct_blob_all_noalloc(&exact->dsdb_dn->extra_part,
+								   &existing_meta_data,
+								   (ndr_pull_flags_fn_t)ndr_pull_replPropertyMetaData1);
+			if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+				return WERR_DS_DRA_INTERNAL_ERROR;
+			}
+
+			if (existing_meta_data.attid == sa->attributeID_id) {
+				ldb_err = ldb_msg_add_empty(*msg, "msDS-RevealedUsers", LDB_FLAG_MOD_DELETE, &el_del);
+				if (ldb_err != LDB_SUCCESS) {
+					return WERR_DS_DRA_INTERNAL_ERROR;
+				}
+
+				el_del->values = talloc_array((*msg)->elements, struct ldb_val, 1);
+				if (el_del->values == NULL) {
+					return WERR_NOT_ENOUGH_MEMORY;
+				}
+				el_del->values[0] = *exact->v;
+				el_del->num_values = 1;
+			} else {
+				return WERR_DS_DRA_INTERNAL_ERROR;
+			}
+		}
+	}
+
+	ldb_err = ldb_msg_add_empty(*msg, "msDS-RevealedUsers", LDB_FLAG_MOD_ADD, &el_add);
+	if (ldb_err != LDB_SUCCESS) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	el_add->values = talloc_array((*msg)->elements, struct ldb_val, 1);
+	if (el_add->values == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+
+	}
+
+	el_add->values[0] = data_blob_string_const(attr_str);
+	el_add->num_values = 1;
+
+	return WERR_OK;
+}
+
+/*
+ * This function filter attributes for build_object based on the
+ * uptodatenessvector and partial attribute set.
+ *
+ * Any secret attributes are forced here for REPL_SECRET, and audited at this
+ * point with msDS-RevealedUsers.
+ */
+static WERROR get_nc_changes_filter_attrs(struct drsuapi_DsReplicaObjectListItemEx *obj,
+					  struct replPropertyMetaDataBlob md,
+					  struct ldb_context *sam_ctx,
+					  const struct ldb_message *msg,
+					  const struct GUID *guid,
+					  uint32_t *count,
+					  uint64_t highest_usn,
+					  const struct dsdb_attribute *rdn_sa,
+					  struct dsdb_schema *schema,
+					  struct drsuapi_DsReplicaCursorCtrEx *uptodateness_vector,
+					  struct drsuapi_DsPartialAttributeSet *partial_attribute_set,
+					  uint32_t *local_pas,
+					  uint32_t *attids,
+					  bool exop_secret,
+					  struct ldb_message **revealed_list_msg,
+					  struct ldb_message *existing_revealed_list_msg)
+{
+	uint32_t i, n;
+	WERROR werr;
+	for (n=i=0; i<md.ctr.ctr1.count; i++) {
+		const struct dsdb_attribute *sa;
+		bool force_attribute = false;
+
+		/* if the attribute has not changed, and it is not the
+		   instanceType then don't include it */
+		if (md.ctr.ctr1.array[i].local_usn < highest_usn &&
+		    !exop_secret &&
+		    md.ctr.ctr1.array[i].attid != DRSUAPI_ATTID_instanceType) continue;
+
+		/* don't include the rDN */
+		if (md.ctr.ctr1.array[i].attid == rdn_sa->attributeID_id) continue;
+
+		sa = dsdb_attribute_by_attributeID_id(schema, md.ctr.ctr1.array[i].attid);
+		if (!sa) {
+			DEBUG(0,(__location__ ": Failed to find attribute in schema for attrid %u mentioned in replPropertyMetaData of %s\n",
+				 (unsigned int)md.ctr.ctr1.array[i].attid,
+				 ldb_dn_get_linearized(msg->dn)));
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		if (sa->linkID) {
+			struct ldb_message_element *el;
+			el = ldb_msg_find_element(msg, sa->lDAPDisplayName);
+			if (el && el->num_values && dsdb_dn_is_upgraded_link_val(&el->values[0])) {
+				/* don't send upgraded links inline */
+				continue;
+			}
+		}
+
+		if (exop_secret &&
+		    !dsdb_attr_in_rodc_fas(sa)) {
+			force_attribute = true;
+			DEBUG(4,("Forcing attribute %s in %s\n",
+				 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
+			werr = getncchanges_update_revealed_list(sam_ctx, obj,
+								 revealed_list_msg,
+								 msg->dn, guid, sa,
+								 &md.ctr.ctr1.array[i],
+								 existing_revealed_list_msg);
+			if (!W_ERROR_IS_OK(werr)) {
+				return werr;
+			}
+		}
+
+		/* filter by uptodateness_vector */
+		if (md.ctr.ctr1.array[i].attid != DRSUAPI_ATTID_instanceType &&
+		    !force_attribute &&
+		    udv_filter(uptodateness_vector,
+			       &md.ctr.ctr1.array[i].originating_invocation_id,
+			       md.ctr.ctr1.array[i].originating_usn)) {
+			continue;
+		}
+
+		/* filter by partial_attribute_set */
+		if (partial_attribute_set && !force_attribute) {
+			uint32_t *result = NULL;
+			BINARY_ARRAY_SEARCH_V(local_pas, partial_attribute_set->num_attids, sa->attributeID_id,
+					      uint32_t_cmp, result);
+			if (result == NULL) {
+				continue;
+			}
+		}
+
+		obj->meta_data_ctr->meta_data[n].originating_change_time = md.ctr.ctr1.array[i].originating_change_time;
+		obj->meta_data_ctr->meta_data[n].version = md.ctr.ctr1.array[i].version;
+		obj->meta_data_ctr->meta_data[n].originating_invocation_id = md.ctr.ctr1.array[i].originating_invocation_id;
+		obj->meta_data_ctr->meta_data[n].originating_usn = md.ctr.ctr1.array[i].originating_usn;
+		attids[n] = md.ctr.ctr1.array[i].attid;
+
+		n++;
+	}
+
+	*count = n;
+
+	return WERR_OK;
+}
+
+/* 
+  drsuapi_DsGetNCChanges for one object
+*/
+static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItemEx *obj,
+					  const struct ldb_message *msg,
+					  struct ldb_context *sam_ctx,
+					  struct drsuapi_getncchanges_state *getnc_state,
+					  struct dsdb_schema *schema,
+					  DATA_BLOB *session_key,
+					  struct drsuapi_DsGetNCChangesRequest10 *req10,
+					  bool force_object_return,
+					  uint32_t *local_pas,
+					  struct ldb_dn *machine_dn,
+					  const struct GUID *guid)
+{
+	const struct ldb_val *md_value;
+	uint32_t i, n;
+	struct replPropertyMetaDataBlob md;
+	uint32_t rid = 0;
+	int ldb_err;
+	enum ndr_err_code ndr_err;
+	uint32_t *attids;
+	const char *rdn;
+	const struct dsdb_attribute *rdn_sa;
+	uint64_t uSNChanged;
+	unsigned int instanceType;
+	struct dsdb_syntax_ctx syntax_ctx;
+	struct ldb_result *res = NULL;
+	WERROR werr;
+	int ret;
+	uint32_t replica_flags = req10->replica_flags;
+	struct drsuapi_DsPartialAttributeSet *partial_attribute_set =
+			req10->partial_attribute_set;
+	struct drsuapi_DsReplicaCursorCtrEx *uptodateness_vector =
+			req10->uptodateness_vector;
+	enum drsuapi_DsExtendedOperation extended_op = req10->extended_op;
+	bool is_schema_nc = getnc_state->is_schema_nc;
+	uint64_t highest_usn = getnc_state->min_usn;
+
+	/* make dsdb sytanx context for conversions */
+	dsdb_syntax_ctx_init(&syntax_ctx, sam_ctx, schema);
+	syntax_ctx.is_schema_nc = is_schema_nc;
+
+	uSNChanged = ldb_msg_find_attr_as_uint64(msg, "uSNChanged", 0);
+	instanceType = ldb_msg_find_attr_as_uint(msg, "instanceType", 0);
+	if (instanceType & INSTANCE_TYPE_IS_NC_HEAD) {
+		obj->is_nc_prefix = true;
+		obj->parent_object_guid = NULL;
+	} else {
+		obj->is_nc_prefix = false;
+		obj->parent_object_guid = talloc(obj, struct GUID);
+		if (obj->parent_object_guid == NULL) {
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+		*obj->parent_object_guid = samdb_result_guid(msg, "parentGUID");
+		if (GUID_all_zero(obj->parent_object_guid)) {
+			DEBUG(0,(__location__ ": missing parentGUID for %s\n",
+				 ldb_dn_get_linearized(msg->dn)));
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+	}
+	obj->next_object = NULL;
+
+	md_value = ldb_msg_find_ldb_val(msg, "replPropertyMetaData");
+	if (!md_value) {
+		/* nothing to send */
+		return WERR_OK;
+	}
+
+	if (instanceType & INSTANCE_TYPE_UNINSTANT) {
+		/* don't send uninstantiated objects */
+		return WERR_OK;
+	}
+
+	if (uSNChanged <= highest_usn) {
+		/* nothing to send */
+		return WERR_OK;
+	}
+
+	ndr_err = ndr_pull_struct_blob(md_value, obj, &md,
+				       (ndr_pull_flags_fn_t)ndr_pull_replPropertyMetaDataBlob);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	if (md.version != 1) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	rdn = ldb_dn_get_rdn_name(msg->dn);
+	if (rdn == NULL) {
+		DEBUG(0,(__location__ ": No rDN for %s\n", ldb_dn_get_linearized(msg->dn)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	rdn_sa = dsdb_attribute_by_lDAPDisplayName(schema, rdn);
+	if (rdn_sa == NULL) {
+		DEBUG(0,(__location__ ": Can't find dsds_attribute for rDN %s in %s\n",
+			 rdn, ldb_dn_get_linearized(msg->dn)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	obj->meta_data_ctr = talloc(obj, struct drsuapi_DsReplicaMetaDataCtr);
+	attids = talloc_array(obj, uint32_t, md.ctr.ctr1.count);
+
+	obj->object.identifier = get_object_identifier(obj, msg);
+	if (obj->object.identifier == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+	dom_sid_split_rid(NULL, &obj->object.identifier->sid, NULL, &rid);
+
+	obj->meta_data_ctr->meta_data = talloc_array(obj, struct drsuapi_DsReplicaMetaData, md.ctr.ctr1.count);
+
+	if (extended_op == DRSUAPI_EXOP_REPL_SECRET) {
+		/* Get the existing revealed users for the destination */
+		struct ldb_message *revealed_list_msg = NULL;
+		struct ldb_message *existing_revealed_list_msg = NULL;
+		const char *machine_attrs[] = {
+			"msDS-RevealedUsers",
+			NULL
+		};
+
+		revealed_list_msg = ldb_msg_new(sam_ctx);
+		if (revealed_list_msg == NULL) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+		revealed_list_msg->dn = machine_dn;
+
+		ret = ldb_transaction_start(sam_ctx);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(0,(__location__ ": Failed transaction start - %s\n",
+				 ldb_errstring(sam_ctx)));
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		ldb_err = dsdb_search_dn(sam_ctx, obj, &res, machine_dn, machine_attrs, DSDB_SEARCH_SHOW_EXTENDED_DN);
+		if (ldb_err != LDB_SUCCESS || res->count != 1) {
+			ldb_transaction_cancel(sam_ctx);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		existing_revealed_list_msg = res->msgs[0];
+
+		werr = get_nc_changes_filter_attrs(obj, md, sam_ctx, msg,
+						   guid, &n, highest_usn,
+						   rdn_sa, schema,
+						   uptodateness_vector,
+						   partial_attribute_set, local_pas,
+						   attids,
+						   true,
+						   &revealed_list_msg,
+						   existing_revealed_list_msg);
+		if (!W_ERROR_IS_OK(werr)) {
+			ldb_transaction_cancel(sam_ctx);
+			return werr;
+		}
+
+		if (revealed_list_msg != NULL) {
+			ret = ldb_modify(sam_ctx, revealed_list_msg);
+			if (ret != LDB_SUCCESS) {
+				DEBUG(0,(__location__ ": Failed to alter revealed links - %s\n",
+					 ldb_errstring(sam_ctx)));
+				ldb_transaction_cancel(sam_ctx);
+				return WERR_DS_DRA_INTERNAL_ERROR;
+			}
+		}
+
+		ret = ldb_transaction_commit(sam_ctx);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(0,(__location__ ": Failed transaction commit - %s\n",
+				 ldb_errstring(sam_ctx)));
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+	} else {
+		werr = get_nc_changes_filter_attrs(obj, md, sam_ctx, msg, guid,
+						   &n, highest_usn, rdn_sa,
+						   schema, uptodateness_vector,
+						   partial_attribute_set, local_pas,
+						   attids,
+						   false,
+						   NULL,
+						   NULL);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+	}
+
+	/* ignore it if its an empty change. Note that renames always
+	 * change the 'name' attribute, so they won't be ignored by
+	 * this
+
+	 * the force_object_return check is used to force an empty
+	 * object return when we timeout in the getncchanges loop.
+	 * This allows us to return an empty object, which keeps the
+	 * client happy while preventing timeouts
+	 */
+	if (n == 0 ||
+	    (n == 1 &&
+	     attids[0] == DRSUAPI_ATTID_instanceType &&
+	     !force_object_return)) {
+		talloc_free(obj->meta_data_ctr);
+		obj->meta_data_ctr = NULL;
+		return WERR_OK;
+	}
+
+	obj->meta_data_ctr->count = n;
+
+	obj->object.flags = DRSUAPI_DS_REPLICA_OBJECT_FROM_MASTER;
+	obj->object.attribute_ctr.num_attributes = obj->meta_data_ctr->count;
+	obj->object.attribute_ctr.attributes = talloc_array(obj, struct drsuapi_DsReplicaAttribute,
+							    obj->object.attribute_ctr.num_attributes);
+	if (obj->object.attribute_ctr.attributes == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	/*
+	 * Note that the meta_data array and the attributes array must
+	 * be the same size and in the same order
+	 */
+	for (i=0; i<obj->object.attribute_ctr.num_attributes; i++) {
+		struct ldb_message_element *el;
+		const struct dsdb_attribute *sa;
+
+		sa = dsdb_attribute_by_attributeID_id(schema, attids[i]);
+		if (!sa) {
+			DEBUG(0,("Unable to find attributeID %u in schema\n", attids[i]));
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		el = ldb_msg_find_element(msg, sa->lDAPDisplayName);
+		if (el == NULL) {
+			/* this happens for attributes that have been removed */
+			DEBUG(5,("No element '%s' for attributeID %u in message\n",
+				 sa->lDAPDisplayName, attids[i]));
+			ZERO_STRUCT(obj->object.attribute_ctr.attributes[i]);
+			obj->object.attribute_ctr.attributes[i].attid =
+					dsdb_attribute_get_attid(sa, syntax_ctx.is_schema_nc);
+		} else {
+			werr = sa->syntax->ldb_to_drsuapi(&syntax_ctx, sa, el, obj,
+			                                  &obj->object.attribute_ctr.attributes[i]);
+			if (!W_ERROR_IS_OK(werr)) {
+				DEBUG(0,("Unable to convert %s on %s to DRS object - %s\n",
+					 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn),
+					 win_errstr(werr)));
+				return werr;
+			}
+			/* if DRSUAPI_DRS_SPECIAL_SECRET_PROCESSING is set
+			 * check if attribute is secret and send a null value
+			 */
+			if (replica_flags & DRSUAPI_DRS_SPECIAL_SECRET_PROCESSING) {
+				drsuapi_process_secret_attribute(&obj->object.attribute_ctr.attributes[i],
+								 &obj->meta_data_ctr->meta_data[i]);
+			}
+			/* some attributes needs to be encrypted
+			   before being sent */
+			werr = drsuapi_encrypt_attribute(obj, session_key, rid, 
+							 &obj->object.attribute_ctr.attributes[i]);
+			if (!W_ERROR_IS_OK(werr)) {
+				DEBUG(0,("Unable to encrypt %s on %s in DRS object - %s\n",
+					 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn),
+					 win_errstr(werr)));
+				return werr;
+			}
+		}
+		if (attids[i] != obj->object.attribute_ctr.attributes[i].attid) {
+			DEBUG(0, ("Unable to replicate attribute %s on %s via DRS, incorrect attributeID:  "
+				  "0x%08x vs 0x%08x "
+				  "Run dbcheck!\n",
+				  sa->lDAPDisplayName,
+				  ldb_dn_get_linearized(msg->dn),
+				  attids[i],
+				  obj->object.attribute_ctr.attributes[i].attid));
+			return WERR_DS_DATABASE_ERROR;
+		}
+	}
+
+	return WERR_OK;
+}
+
+/*
+  add one linked attribute from an object to the list of linked
+  attributes in a getncchanges request
+ */
+static WERROR get_nc_changes_add_la(TALLOC_CTX *mem_ctx,
+				    struct ldb_context *sam_ctx,
+				    const struct dsdb_schema *schema,
+				    const struct dsdb_attribute *sa,
+				    const struct ldb_message *msg,
+				    struct dsdb_dn *dsdb_dn,
+				    struct drsuapi_DsReplicaLinkedAttribute **la_list,
+				    uint32_t *la_count,
+				    bool is_schema_nc)
+{
+	struct drsuapi_DsReplicaLinkedAttribute *la;
+	bool active;
+	NTSTATUS status;
+	WERROR werr;
+
+	(*la_list) = talloc_realloc(mem_ctx, *la_list, struct drsuapi_DsReplicaLinkedAttribute, (*la_count)+1);
+	W_ERROR_HAVE_NO_MEMORY(*la_list);
+
+	la = &(*la_list)[*la_count];
+
+	la->identifier = get_object_identifier(*la_list, msg);
+	W_ERROR_HAVE_NO_MEMORY(la->identifier);
+
+	active = (dsdb_dn_rmd_flags(dsdb_dn->dn) & DSDB_RMD_FLAG_DELETED) == 0;
+
+	if (!active) {
+		/* We have to check that the inactive link still point to an existing object */
+		struct GUID guid;
+		struct ldb_dn *tdn;
+		int ret;
+		const char *v;
+
+		v = ldb_msg_find_attr_as_string(msg, "isDeleted", "FALSE");
+		if (strncmp(v, "TRUE", 4) == 0) {
+			/*
+			  * Note: we skip the transmition of the deleted link even if the other part used to
+			  * know about it because when we transmit the deletion of the object, the link will
+			  * be deleted too due to deletion of object where link points and Windows do so.
+			  */
+			if (dsdb_functional_level(sam_ctx) >= DS_DOMAIN_FUNCTION_2008_R2) {
+				v = ldb_msg_find_attr_as_string(msg, "isRecycled", "FALSE");
+				/*
+				 * On Windows 2008R2 isRecycled is always present even if FL or DL are < FL 2K8R2
+				 * if it join an existing domain with deleted objets, it firsts impose to have a
+				 * schema with the is-Recycled object and for all deleted objects it adds the isRecycled
+				 * either during initial replication or after the getNCChanges.
+				 * Behavior of samba has been changed to always have this attribute if it's present in the schema.
+				 *
+				 * So if FL <2K8R2 isRecycled might be here or not but we don't care, it's meaning less.
+				 * If FL >=2K8R2 we are sure that this attribute will be here.
+				 * For this kind of forest level we do not return the link if the object is recycled
+				 * (isRecycled = true).
+				 */
+				if (strncmp(v, "TRUE", 4) == 0) {
+					DEBUG(2, (" object %s is recycled, not returning linked attribute !\n",
+								ldb_dn_get_linearized(msg->dn)));
+					return WERR_OK;
+				}
+			} else {
+				return WERR_OK;
+			}
+		}
+		status = dsdb_get_extended_dn_guid(dsdb_dn->dn, &guid, "GUID");
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(0,(__location__ " Unable to extract GUID in linked attribute '%s' in '%s'\n",
+				sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
+			return ntstatus_to_werror(status);
+		}
+		ret = dsdb_find_dn_by_guid(sam_ctx, mem_ctx, &guid, 0, &tdn);
+		if (ret == LDB_ERR_NO_SUCH_OBJECT) {
+			DEBUG(2, (" Search of guid %s returned 0 objects, skipping it !\n",
+						GUID_string(mem_ctx, &guid)));
+			return WERR_OK;
+		} else if (ret != LDB_SUCCESS) {
+			DEBUG(0, (__location__ " Search of guid %s failed with error code %d\n",
+						GUID_string(mem_ctx, &guid),
+						ret));
+			return WERR_OK;
+		}
+	}
+	la->attid = dsdb_attribute_get_attid(sa, is_schema_nc);
+	la->flags = active?DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE:0;
+
+	status = dsdb_get_extended_dn_uint32(dsdb_dn->dn, &la->meta_data.version, "RMD_VERSION");
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0,(__location__ " No RMD_VERSION in linked attribute '%s' in '%s'\n",
+			 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
+		return ntstatus_to_werror(status);
+	}
+	status = dsdb_get_extended_dn_nttime(dsdb_dn->dn, &la->meta_data.originating_change_time, "RMD_CHANGETIME");
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0,(__location__ " No RMD_CHANGETIME in linked attribute '%s' in '%s'\n",
+			 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
+		return ntstatus_to_werror(status);
+	}
+	status = dsdb_get_extended_dn_guid(dsdb_dn->dn, &la->meta_data.originating_invocation_id, "RMD_INVOCID");
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0,(__location__ " No RMD_INVOCID in linked attribute '%s' in '%s'\n",
+			 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
+		return ntstatus_to_werror(status);
+	}
+	status = dsdb_get_extended_dn_uint64(dsdb_dn->dn, &la->meta_data.originating_usn, "RMD_ORIGINATING_USN");
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0,(__location__ " No RMD_ORIGINATING_USN in linked attribute '%s' in '%s'\n",
+			 sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
+		return ntstatus_to_werror(status);
+	}
+
+	status = dsdb_get_extended_dn_nttime(dsdb_dn->dn, &la->originating_add_time, "RMD_ADDTIME");
+	if (!NT_STATUS_IS_OK(status)) {
+		/* this is possible for upgraded links */
+		la->originating_add_time = la->meta_data.originating_change_time;
+	}
+
+	werr = dsdb_dn_la_to_blob(sam_ctx, sa, schema, *la_list, dsdb_dn, &la->value.blob);
+	W_ERROR_NOT_OK_RETURN(werr);
+
+	(*la_count)++;
+	return WERR_OK;
+}
+
+
+/*
+  add linked attributes from an object to the list of linked
+  attributes in a getncchanges request
+ */
+static WERROR get_nc_changes_add_links(struct ldb_context *sam_ctx,
+				       TALLOC_CTX *mem_ctx,
+				       bool is_schema_nc,
+				       struct dsdb_schema *schema,
+				       uint64_t highest_usn,
+				       uint32_t replica_flags,
+				       const struct ldb_message *msg,
+				       struct drsuapi_DsReplicaLinkedAttribute **la_list,
+				       uint32_t *la_count,
+				       struct drsuapi_DsReplicaCursorCtrEx *uptodateness_vector)
+{
+	unsigned int i;
+	TALLOC_CTX *tmp_ctx = NULL;
+	uint64_t uSNChanged = ldb_msg_find_attr_as_uint64(msg, "uSNChanged", 0);
+	bool is_critical = ldb_msg_find_attr_as_bool(msg, "isCriticalSystemObject", false);
+
+	if (replica_flags & DRSUAPI_DRS_CRITICAL_ONLY) {
+		if (!is_critical) {
+			return WERR_OK;
+		}
+	}
+
+	if (uSNChanged <= highest_usn) {
+		return WERR_OK;
+	}
+
+	tmp_ctx = talloc_new(mem_ctx);
+	if (tmp_ctx == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	for (i=0; i<msg->num_elements; i++) {
+		struct ldb_message_element *el = &msg->elements[i];
+		const struct dsdb_attribute *sa;
+		unsigned int j;
+
+		sa = dsdb_attribute_by_lDAPDisplayName(schema, el->name);
+
+		if (!sa || sa->linkID == 0 || (sa->linkID & 1)) {
+			/* we only want forward links */
+			continue;
+		}
+
+		if (el->num_values && !dsdb_dn_is_upgraded_link_val(&el->values[0])) {
+			/* its an old style link, it will have been
+			 * sent in the main replication data */
+			continue;
+		}
+
+		for (j=0; j<el->num_values; j++) {
+			struct dsdb_dn *dsdb_dn;
+			uint64_t local_usn;
+			uint64_t originating_usn;
+			NTSTATUS status, status2;
+			WERROR werr;
+			struct GUID originating_invocation_id;
+
+			dsdb_dn = dsdb_dn_parse(tmp_ctx, sam_ctx, &el->values[j], sa->syntax->ldap_oid);
+			if (dsdb_dn == NULL) {
+				DEBUG(1,(__location__ ": Failed to parse DN for %s in %s\n",
+					 el->name, ldb_dn_get_linearized(msg->dn)));
+				talloc_free(tmp_ctx);
+				return WERR_DS_DRA_INTERNAL_ERROR;
+			}
+
+			status = dsdb_get_extended_dn_uint64(dsdb_dn->dn, &local_usn, "RMD_LOCAL_USN");
+			if (!NT_STATUS_IS_OK(status)) {
+				/* this can happen for attributes
+				   given to us with old style meta
+				   data */
+				continue;
+			}
+
+			if (local_usn > uSNChanged) {
+				DEBUG(1,(__location__ ": uSNChanged less than RMD_LOCAL_USN for %s on %s\n",
+					 el->name, ldb_dn_get_linearized(msg->dn)));
+				talloc_free(tmp_ctx);
+				return WERR_DS_DRA_INTERNAL_ERROR;
+			}
+
+			if (local_usn <= highest_usn) {
+				continue;
+			}
+
+			status = dsdb_get_extended_dn_guid(dsdb_dn->dn,
+							   &originating_invocation_id,
+							   "RMD_INVOCID");
+			status2 = dsdb_get_extended_dn_uint64(dsdb_dn->dn,
+							      &originating_usn,
+							      "RMD_ORIGINATING_USN");
+
+			if (NT_STATUS_IS_OK(status) && NT_STATUS_IS_OK(status2)) {
+				if (udv_filter(uptodateness_vector,
+					       &originating_invocation_id,
+					       originating_usn)) {
+					continue;
+				}
+			}
+
+			werr = get_nc_changes_add_la(mem_ctx, sam_ctx, schema,
+						     sa, msg, dsdb_dn, la_list,
+						     la_count, is_schema_nc);
+			if (!W_ERROR_IS_OK(werr)) {
+				talloc_free(tmp_ctx);
+				return werr;
+			}
+		}
+	}
+
+	talloc_free(tmp_ctx);
+	return WERR_OK;
+}
+
+/*
+  fill in the cursors return based on the replUpToDateVector for the ncRoot_dn
+ */
+static WERROR get_nc_changes_udv(struct ldb_context *sam_ctx,
+				 struct ldb_dn *ncRoot_dn,
+				 struct drsuapi_DsReplicaCursor2CtrEx *udv)
+{
+	int ret;
+
+	udv->version = 2;
+	udv->reserved1 = 0;
+	udv->reserved2 = 0;
+
+	ret = dsdb_load_udv_v2(sam_ctx, ncRoot_dn, udv, &udv->cursors, &udv->count);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed to load UDV for %s - %s\n",
+			 ldb_dn_get_linearized(ncRoot_dn), ldb_errstring(sam_ctx)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	return WERR_OK;
+}
+
+
+/* comparison function for linked attributes - see CompareLinks() in
+ * MS-DRSR section 4.1.10.5.17 */
+static int linked_attribute_compare(const struct la_for_sorting *la1,
+				    const struct la_for_sorting *la2)
+{
+	int c;
+	c = memcmp(la1->source_guid,
+		   la2->source_guid, sizeof(la2->source_guid));
+	if (c != 0) {
+		return c;
+	}
+
+	if (la1->link->attid != la2->link->attid) {
+		return la1->link->attid < la2->link->attid? -1:1;
+	}
+
+	if ((la1->link->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE) !=
+	    (la2->link->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)) {
+		return (la1->link->flags &
+			DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)? 1:-1;
+	}
+
+	return memcmp(la1->target_guid,
+		      la2->target_guid, sizeof(la2->target_guid));
+}
+
+struct drsuapi_changed_objects {
+	struct ldb_dn *dn;
+	struct GUID guid;
+	uint64_t usn;
+};
+
+
+/*
+  sort the objects we send by tree order (Samba 4.5 emulation)
+ */
+static int site_res_cmp_anc_order(struct drsuapi_changed_objects *m1,
+				  struct drsuapi_changed_objects *m2,
+				  struct drsuapi_getncchanges_state *getnc_state)
+{
+	return ldb_dn_compare(m2->dn, m1->dn);
+}
+
+/*
+  sort the objects we send first by uSNChanged
+ */
+static int site_res_cmp_usn_order(struct drsuapi_changed_objects *m1,
+				  struct drsuapi_changed_objects *m2,
+				  struct drsuapi_getncchanges_state *getnc_state)
+{
+	if (m1->usn == m2->usn) {
+		return ldb_dn_compare(m2->dn, m1->dn);
+	}
+
+	if (m1->usn < m2->usn) {
+		return -1;
+	}
+
+	return 1;
+}
+
+
+/*
+  handle a DRSUAPI_EXOP_FSMO_RID_ALLOC call
+ */
+static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
+				     TALLOC_CTX *mem_ctx,
+				     struct drsuapi_DsGetNCChangesRequest10 *req10,
+				     struct drsuapi_DsGetNCChangesCtr6 *ctr6,
+				     struct ldb_dn **rid_manager_dn)
+{
+	struct ldb_dn *req_dn, *ntds_dn = NULL;
+	int ret;
+	struct ldb_context *ldb = b_state->sam_ctx;
+	struct ldb_result *ext_res;
+	struct dsdb_fsmo_extended_op *exop;
+	bool is_us;
+
+	/*
+	  steps:
+	    - verify that the DN being asked for is the RID Manager DN
+	    - verify that we are the RID Manager
+	 */
+
+	/* work out who is the RID Manager, also return to caller */
+	ret = samdb_rid_manager_dn(ldb, mem_ctx, rid_manager_dn);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0, (__location__ ": Failed to find RID Manager object - %s\n", ldb_errstring(ldb)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	ret = drs_ObjectIdentifier_to_dn_and_nc_root(mem_ctx,
+						     ldb,
+						     req10->naming_context,
+						     &req_dn,
+						     NULL);
+	if (ret != LDB_SUCCESS) {
+		DBG_ERR("RID Alloc request for invalid DN %s: %s\n",
+			drs_ObjectIdentifier_to_debug_string(mem_ctx, req10->naming_context),
+			ldb_strerror(ret));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_MISMATCH;
+		return WERR_OK;
+	}
+
+	if (ldb_dn_compare(req_dn, *rid_manager_dn) != 0) {
+		/* that isn't the RID Manager DN */
+		DBG_ERR("RID Alloc request for wrong DN %s\n",
+			drs_ObjectIdentifier_to_debug_string(mem_ctx,
+							     req10->naming_context));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_MISMATCH;
+		return WERR_OK;
+	}
+
+	/* TODO: make sure ntds_dn is a valid nTDSDSA object */
+	ret = dsdb_find_dn_by_guid(ldb, mem_ctx, &req10->destination_dsa_guid, 0, &ntds_dn);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0, (__location__ ": Unable to find NTDS object for guid %s - %s\n",
+			  GUID_string(mem_ctx, &req10->destination_dsa_guid), ldb_errstring(ldb)));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_UNKNOWN_CALLER;
+		return WERR_OK;
+	}
+
+	/* find the DN of the RID Manager */
+	ret = samdb_reference_dn_is_our_ntdsa(ldb, *rid_manager_dn, "fSMORoleOwner", &is_us);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,("Failed to find fSMORoleOwner in RID Manager object\n"));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_FSMO_NOT_OWNER;
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	if (!is_us) {
+		/* we're not the RID Manager - go away */
+		DEBUG(0,(__location__ ": RID Alloc request when not RID Manager\n"));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_FSMO_NOT_OWNER;
+		return WERR_OK;
+	}
+
+	exop = talloc(mem_ctx, struct dsdb_fsmo_extended_op);
+	W_ERROR_HAVE_NO_MEMORY(exop);
+
+	exop->fsmo_info = req10->fsmo_info;
+	exop->destination_dsa_guid = req10->destination_dsa_guid;
+
+	ret = ldb_transaction_start(ldb);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed transaction start - %s\n",
+			 ldb_errstring(ldb)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	ret = ldb_extended(ldb, DSDB_EXTENDED_ALLOCATE_RID_POOL, exop, &ext_res);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed extended allocation RID pool operation - %s\n",
+			 ldb_errstring(ldb)));
+		ldb_transaction_cancel(ldb);
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	ret = ldb_transaction_commit(ldb);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed transaction commit - %s\n",
+			 ldb_errstring(ldb)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	talloc_free(ext_res);
+
+	DEBUG(2,("Allocated RID pool for server %s\n",
+		 GUID_string(mem_ctx, &req10->destination_dsa_guid)));
+
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_SUCCESS;
+
+	return WERR_OK;
+}
+
+/*
+  handle a DRSUAPI_EXOP_REPL_SECRET call
+ */
+static WERROR getncchanges_repl_secret(struct drsuapi_bind_state *b_state,
+				       TALLOC_CTX *mem_ctx,
+				       struct drsuapi_DsGetNCChangesRequest10 *req10,
+				       struct dom_sid *user_sid,
+				       struct drsuapi_DsGetNCChangesCtr6 *ctr6,
+				       bool has_get_all_changes,
+				       struct ldb_dn **machine_dn)
+{
+	struct drsuapi_DsReplicaObjectIdentifier *ncRoot = req10->naming_context;
+	struct ldb_dn *obj_dn = NULL;
+	struct ldb_message *ntds_msg = NULL;
+	struct ldb_dn *ntds_dn = NULL, *server_dn = NULL;
+	struct ldb_dn *rodc_dn, *krbtgt_link_dn;
+	int ret;
+	const char *ntds_attrs[] = { NULL };
+	const char *rodc_attrs[] = { "msDS-KrbTgtLink",
+				     "msDS-NeverRevealGroup",
+				     "msDS-RevealOnDemandGroup",
+				     "userAccountControl",
+				     NULL };
+	const char *obj_attrs[] = { "tokenGroups", "objectSid", "UserAccountControl", "msDS-KrbTgtLinkBL", NULL };
+	struct ldb_result *rodc_res = NULL, *obj_res = NULL;
+	WERROR werr;
+	struct GUID_txt_buf guid_buf;
+
+	DEBUG(3,(__location__ ": DRSUAPI_EXOP_REPL_SECRET extended op on %s\n",
+		 drs_ObjectIdentifier_to_debug_string(mem_ctx, ncRoot)));
+
+	/*
+	 * we need to work out if we will allow this DC to
+	 * replicate the secrets for this object
+	 *
+	 * see 4.1.10.5.14 GetRevealSecretsPolicyForUser for details
+	 * of this function
+	 */
+
+	if (b_state->sam_ctx_system == NULL) {
+		/* this operation needs system level access */
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_ACCESS_DENIED;
+		return WERR_DS_DRA_ACCESS_DENIED;
+	}
+
+	/*
+	 * Before we accept or deny, fetch the machine DN for the destination
+	 * DSA GUID.
+	 *
+	 * If we are the RODC, we will check that this matches the SID.
+	 */
+	ret = samdb_get_ntds_obj_by_guid(mem_ctx,
+					 b_state->sam_ctx_system,
+					 &req10->destination_dsa_guid,
+					 ntds_attrs,
+					 &ntds_msg);
+	if (ret != LDB_SUCCESS) {
+		goto dest_dsa_error;
+	}
+
+	ntds_dn = ntds_msg->dn;
+
+	server_dn = ldb_dn_get_parent(mem_ctx, ntds_dn);
+	if (server_dn == NULL) {
+		goto failed;
+	}
+
+	ret = samdb_reference_dn(b_state->sam_ctx_system, mem_ctx, server_dn,
+				 "serverReference", machine_dn);
+
+	if (ret != LDB_SUCCESS) {
+		goto dest_dsa_error;
+	}
+
+	/*
+	 * In MS-DRSR.pdf 5.99 IsGetNCChangesPermissionGranted
+	 *
+	 * The pseudo code indicate
+	 * revealsecrets = true
+	 * if IsRevealSecretRequest(msgIn) then
+	 *   if AccessCheckCAR(ncRoot, Ds-Replication-Get-Changes-All) = false
+	 *   then
+	 *     if (msgIn.ulExtendedOp = EXOP_REPL_SECRETS) then
+	 *     <... check if this account is ok to be replicated on this DC ...>
+	 *     <... and if not reveal secrets = no ...>
+	 *     else
+	 *       reveal secrets = false
+	 *     endif
+	 *   endif
+	 * endif
+	 *
+	 * Which basically means that if you have GET_ALL_CHANGES rights (~== RWDC)
+	 * then you can do EXOP_REPL_SECRETS
+	 */
+	ret = drs_ObjectIdentifier_to_dn_and_nc_root(mem_ctx,
+							b_state->sam_ctx_system,
+							ncRoot,
+							&obj_dn,
+							NULL);
+	if (ret != LDB_SUCCESS) {
+		DBG_ERR("RevealSecretRequest for for invalid DN %s\n",
+			 drs_ObjectIdentifier_to_debug_string(mem_ctx, ncRoot));
+		goto failed;
+	}
+
+	if (!ldb_dn_validate(obj_dn)) goto failed;
+
+	if (has_get_all_changes) {
+		goto allowed;
+	}
+
+	rodc_dn = ldb_dn_new_fmt(mem_ctx, b_state->sam_ctx_system, "<SID=%s>",
+				 dom_sid_string(mem_ctx, user_sid));
+	if (!ldb_dn_validate(rodc_dn)) goto failed;
+
+	/*
+	 * do the two searches we need
+	 * We need DSDB_SEARCH_SHOW_EXTENDED_DN as we get a SID lists
+	 * out of the extended DNs
+	 */
+	ret = dsdb_search_dn(b_state->sam_ctx_system, mem_ctx, &rodc_res, rodc_dn, rodc_attrs,
+			     DSDB_SEARCH_SHOW_EXTENDED_DN);
+	if (ret != LDB_SUCCESS || rodc_res->count != 1) goto failed;
+
+	ret = dsdb_search_dn(b_state->sam_ctx_system, mem_ctx, &obj_res, obj_dn, obj_attrs, 0);
+	if (ret != LDB_SUCCESS || obj_res->count != 1) goto failed;
+
+	/*
+	 * Must be an RODC account at this point, verify machine DN matches the
+	 * SID account
+	 */
+	if (ldb_dn_compare(rodc_res->msgs[0]->dn, *machine_dn) != 0) {
+		goto denied;
+	}
+
+	/* an RODC is allowed to get its own krbtgt account secrets */
+	krbtgt_link_dn = samdb_result_dn(b_state->sam_ctx_system, mem_ctx,
+					 rodc_res->msgs[0], "msDS-KrbTgtLink", NULL);
+	if (krbtgt_link_dn != NULL &&
+	    ldb_dn_compare(obj_dn, krbtgt_link_dn) == 0) {
+		goto allowed;
+	}
+
+	werr = samdb_confirm_rodc_allowed_to_repl_to(b_state->sam_ctx_system,
+						     user_sid,
+						     rodc_res->msgs[0],
+						     obj_res->msgs[0]);
+
+	if (W_ERROR_IS_OK(werr)) {
+		goto allowed;
+	}
+
+	/* default deny */
+denied:
+	DEBUG(2,(__location__ ": Denied single object with secret replication for %s by RODC %s\n",
+		 ldb_dn_get_linearized(obj_dn), ldb_dn_get_linearized(rodc_res->msgs[0]->dn)));
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_NONE;
+	return WERR_DS_DRA_SECRETS_DENIED;
+
+allowed:
+	DEBUG(2,(__location__ ": Allowed single object with secret replication for %s by %s %s\n",
+		 ldb_dn_get_linearized(obj_dn), has_get_all_changes?"RWDC":"RODC",
+		 ldb_dn_get_linearized(*machine_dn)));
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_SUCCESS;
+	req10->highwatermark.highest_usn = 0;
+	return WERR_OK;
+
+failed:
+	DEBUG(2,(__location__ ": Failed single secret replication for %s by RODC %s\n",
+		 ldb_dn_get_linearized(obj_dn), dom_sid_string(mem_ctx, user_sid)));
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_NONE;
+	return WERR_DS_DRA_BAD_DN;
+
+dest_dsa_error:
+	DBG_WARNING("Failed secret replication for %s by RODC %s as dest_dsa_guid %s is invalid\n",
+		    ldb_dn_get_linearized(obj_dn),
+		    dom_sid_string(mem_ctx, user_sid),
+		    GUID_buf_string(&req10->destination_dsa_guid,
+				    &guid_buf));
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_NONE;
+	return WERR_DS_DRA_DB_ERROR;
+}
+
+/*
+  handle a DRSUAPI_EXOP_REPL_OBJ call
+ */
+static WERROR getncchanges_repl_obj(struct drsuapi_bind_state *b_state,
+				    TALLOC_CTX *mem_ctx,
+				    struct drsuapi_DsGetNCChangesRequest10 *req10,
+				    struct dom_sid *user_sid,
+				    struct drsuapi_DsGetNCChangesCtr6 *ctr6)
+{
+	struct drsuapi_DsReplicaObjectIdentifier *ncRoot = req10->naming_context;
+
+	DEBUG(3,(__location__ ": DRSUAPI_EXOP_REPL_OBJ extended op on %s\n",
+		 drs_ObjectIdentifier_to_debug_string(mem_ctx, ncRoot)));
+
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_SUCCESS;
+	return WERR_OK;
+}
+
+
+/*
+  handle DRSUAPI_EXOP_FSMO_REQ_ROLE,
+  DRSUAPI_EXOP_FSMO_RID_REQ_ROLE,
+  and DRSUAPI_EXOP_FSMO_REQ_PDC calls
+ */
+static WERROR getncchanges_change_master(struct drsuapi_bind_state *b_state,
+					 TALLOC_CTX *mem_ctx,
+					 struct drsuapi_DsGetNCChangesRequest10 *req10,
+					 struct drsuapi_DsGetNCChangesCtr6 *ctr6)
+{
+	struct ldb_dn *req_dn, *ntds_dn;
+	int ret;
+	unsigned int i;
+	struct ldb_context *ldb = b_state->sam_ctx;
+	struct ldb_message *msg;
+	bool is_us;
+
+	/*
+	  steps:
+	    - verify that the client dn exists
+	    - verify that we are the current master
+	 */
+
+	ret = drs_ObjectIdentifier_to_dn_and_nc_root(mem_ctx, ldb, req10->naming_context,
+						     &req_dn, NULL);
+	if (ret != LDB_SUCCESS) {
+		/* that is not a valid dn */
+		DBG_ERR("FSMO role transfer request for invalid DN %s: %s\n",
+			drs_ObjectIdentifier_to_debug_string(mem_ctx, req10->naming_context),
+			ldb_strerror(ret));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_MISMATCH;
+		return WERR_OK;
+	}
+
+	/* find the DN of the current role owner */
+	ret = samdb_reference_dn_is_our_ntdsa(ldb, req_dn, "fSMORoleOwner", &is_us);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,("Failed to find fSMORoleOwner in RID Manager object\n"));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_FSMO_NOT_OWNER;
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	if (!is_us) {
+		/* we're not the RID Manager or role owner - go away */
+		DEBUG(0,(__location__ ": FSMO role or RID manager transfer owner request when not role owner\n"));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_FSMO_NOT_OWNER;
+		return WERR_OK;
+	}
+
+	/* change the current master */
+	msg = ldb_msg_new(ldb);
+	W_ERROR_HAVE_NO_MEMORY(msg);
+	ret = drs_ObjectIdentifier_to_dn_and_nc_root(msg, ldb, req10->naming_context,
+						     &msg->dn, NULL);
+	if (ret != LDB_SUCCESS) {
+		/* that is not a valid dn */
+		DBG_ERR("FSMO role transfer request for invalid DN %s: %s\n",
+			drs_ObjectIdentifier_to_debug_string(mem_ctx, req10->naming_context),
+			ldb_strerror(ret));
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_MISMATCH;
+		return WERR_OK;
+	}
+
+	/* TODO: make sure ntds_dn is a valid nTDSDSA object */
+	ret = dsdb_find_dn_by_guid(ldb, msg, &req10->destination_dsa_guid, 0, &ntds_dn);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0, (__location__ ": Unable to find NTDS object for guid %s - %s\n",
+			  GUID_string(mem_ctx, &req10->destination_dsa_guid), ldb_errstring(ldb)));
+		talloc_free(msg);
+		ctr6->extended_ret = DRSUAPI_EXOP_ERR_UNKNOWN_CALLER;
+		return WERR_OK;
+	}
+
+	ret = ldb_msg_add_string(msg, "fSMORoleOwner", ldb_dn_get_linearized(ntds_dn));
+	if (ret != 0) {
+		talloc_free(msg);
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	for (i=0;i<msg->num_elements;i++) {
+		msg->elements[i].flags = LDB_FLAG_MOD_REPLACE;
+	}
+
+	ret = ldb_transaction_start(ldb);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed transaction start - %s\n",
+			 ldb_errstring(ldb)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	ret = ldb_modify(ldb, msg);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed to change current owner - %s\n",
+			 ldb_errstring(ldb)));
+		ldb_transaction_cancel(ldb);
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	ret = ldb_transaction_commit(ldb);
+	if (ret != LDB_SUCCESS) {
+		DEBUG(0,(__location__ ": Failed transaction commit - %s\n",
+			 ldb_errstring(ldb)));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	ctr6->extended_ret = DRSUAPI_EXOP_ERR_SUCCESS;
+
+	return WERR_OK;
+}
+
+/*
+  see if this getncchanges request includes a request to reveal secret information
+ */
+static WERROR dcesrv_drsuapi_is_reveal_secrets_request(struct drsuapi_bind_state *b_state,
+						       struct drsuapi_DsGetNCChangesRequest10 *req10,
+						       struct dsdb_schema_prefixmap *pfm_remote,
+						       bool *is_secret_request)
+{
+	enum drsuapi_DsExtendedOperation exop;
+	uint32_t i;
+	struct dsdb_schema *schema;
+	struct dsdb_syntax_ctx syntax_ctx;
+
+	*is_secret_request = true;
+
+	exop = req10->extended_op;
+
+	switch (exop) {
+	case DRSUAPI_EXOP_FSMO_REQ_ROLE:
+	case DRSUAPI_EXOP_FSMO_RID_ALLOC:
+	case DRSUAPI_EXOP_FSMO_RID_REQ_ROLE:
+	case DRSUAPI_EXOP_FSMO_REQ_PDC:
+	case DRSUAPI_EXOP_FSMO_ABANDON_ROLE:
+		/* FSMO exops can reveal secrets */
+		*is_secret_request = true;
+		return WERR_OK;
+	case DRSUAPI_EXOP_REPL_SECRET:
+	case DRSUAPI_EXOP_REPL_OBJ:
+	case DRSUAPI_EXOP_NONE:
+		break;
+	}
+
+	if (req10->replica_flags & DRSUAPI_DRS_SPECIAL_SECRET_PROCESSING) {
+		*is_secret_request = false;
+		return WERR_OK;
+	}
+
+	if (exop == DRSUAPI_EXOP_REPL_SECRET ||
+	    req10->partial_attribute_set == NULL) {
+		/* they want secrets */
+		*is_secret_request = true;
+		return WERR_OK;
+	}
+
+	schema = dsdb_get_schema(b_state->sam_ctx, NULL);
+	dsdb_syntax_ctx_init(&syntax_ctx, b_state->sam_ctx, schema);
+	syntax_ctx.pfm_remote = pfm_remote;
+
+	/* check the attributes they asked for */
+	for (i=0; i<req10->partial_attribute_set->num_attids; i++) {
+		const struct dsdb_attribute *sa;
+		WERROR werr = getncchanges_attid_remote_to_local(schema,
+								 &syntax_ctx,
+								 req10->partial_attribute_set->attids[i],
+								 NULL,
+								 &sa);
+
+		if (!W_ERROR_IS_OK(werr)) {
+			DEBUG(0,(__location__": attid 0x%08X not found: %s\n",
+				 req10->partial_attribute_set->attids[i], win_errstr(werr)));
+			return werr;
+		}
+
+		if (!dsdb_attr_in_rodc_fas(sa)) {
+			*is_secret_request = true;
+			return WERR_OK;
+		}
+	}
+
+	if (req10->partial_attribute_set_ex) {
+		/* check the extended attributes they asked for */
+		for (i=0; i<req10->partial_attribute_set_ex->num_attids; i++) {
+			const struct dsdb_attribute *sa;
+			WERROR werr = getncchanges_attid_remote_to_local(schema,
+									 &syntax_ctx,
+									 req10->partial_attribute_set_ex->attids[i],
+									 NULL,
+									 &sa);
+
+			if (!W_ERROR_IS_OK(werr)) {
+				DEBUG(0,(__location__": attid 0x%08X not found: %s\n",
+					 req10->partial_attribute_set_ex->attids[i], win_errstr(werr)));
+				return werr;
+			}
+
+			if (!dsdb_attr_in_rodc_fas(sa)) {
+				*is_secret_request = true;
+				return WERR_OK;
+			}
+		}
+	}
+
+	*is_secret_request = false;
+	return WERR_OK;
+}
+
+/*
+  see if this getncchanges request is only for attributes in the GC
+  partial attribute set
+ */
+static WERROR dcesrv_drsuapi_is_gc_pas_request(struct drsuapi_bind_state *b_state,
+					       struct drsuapi_DsGetNCChangesRequest10 *req10,
+					       struct dsdb_schema_prefixmap *pfm_remote,
+					       bool *is_gc_pas_request)
+{
+	enum drsuapi_DsExtendedOperation exop;
+	uint32_t i;
+	struct dsdb_schema *schema;
+	struct dsdb_syntax_ctx syntax_ctx;
+
+	exop = req10->extended_op;
+
+	switch (exop) {
+	case DRSUAPI_EXOP_FSMO_REQ_ROLE:
+	case DRSUAPI_EXOP_FSMO_RID_ALLOC:
+	case DRSUAPI_EXOP_FSMO_RID_REQ_ROLE:
+	case DRSUAPI_EXOP_FSMO_REQ_PDC:
+	case DRSUAPI_EXOP_FSMO_ABANDON_ROLE:
+	case DRSUAPI_EXOP_REPL_SECRET:
+		*is_gc_pas_request = false;
+		return WERR_OK;
+	case DRSUAPI_EXOP_REPL_OBJ:
+	case DRSUAPI_EXOP_NONE:
+		break;
+	}
+
+	if (req10->partial_attribute_set == NULL) {
+		/* they want it all */
+		*is_gc_pas_request = false;
+		return WERR_OK;
+	}
+
+	schema = dsdb_get_schema(b_state->sam_ctx, NULL);
+	dsdb_syntax_ctx_init(&syntax_ctx, b_state->sam_ctx, schema);
+	syntax_ctx.pfm_remote = pfm_remote;
+
+	/* check the attributes they asked for */
+	for (i=0; i<req10->partial_attribute_set->num_attids; i++) {
+		const struct dsdb_attribute *sa;
+		WERROR werr = getncchanges_attid_remote_to_local(schema,
+								 &syntax_ctx,
+								 req10->partial_attribute_set->attids[i],
+								 NULL,
+								 &sa);
+
+		if (!W_ERROR_IS_OK(werr)) {
+			DEBUG(0,(__location__": attid 0x%08X not found: %s\n",
+				 req10->partial_attribute_set->attids[i], win_errstr(werr)));
+			return werr;
+		}
+
+		if (!sa->isMemberOfPartialAttributeSet) {
+			*is_gc_pas_request = false;
+			return WERR_OK;
+		}
+	}
+
+	if (req10->partial_attribute_set_ex) {
+		/* check the extended attributes they asked for */
+		for (i=0; i<req10->partial_attribute_set_ex->num_attids; i++) {
+			const struct dsdb_attribute *sa;
+			WERROR werr = getncchanges_attid_remote_to_local(schema,
+									 &syntax_ctx,
+									 req10->partial_attribute_set_ex->attids[i],
+									 NULL,
+									 &sa);
+
+			if (!W_ERROR_IS_OK(werr)) {
+				DEBUG(0,(__location__": attid 0x%08X not found: %s\n",
+					 req10->partial_attribute_set_ex->attids[i], win_errstr(werr)));
+				return werr;
+			}
+
+			if (!sa->isMemberOfPartialAttributeSet) {
+				*is_gc_pas_request = false;
+				return WERR_OK;
+			}
+		}
+	}
+
+	*is_gc_pas_request = true;
+	return WERR_OK;
+}
+
+
+/*
+  map from req8 to req10
+ */
+static struct drsuapi_DsGetNCChangesRequest10 *
+getncchanges_map_req8(TALLOC_CTX *mem_ctx,
+		      struct drsuapi_DsGetNCChangesRequest8 *req8)
+{
+	struct drsuapi_DsGetNCChangesRequest10 *req10 = talloc_zero(mem_ctx,
+								    struct drsuapi_DsGetNCChangesRequest10);
+	if (req10 == NULL) {
+		return NULL;
+	}
+
+	req10->destination_dsa_guid = req8->destination_dsa_guid;
+	req10->source_dsa_invocation_id = req8->source_dsa_invocation_id;
+	req10->naming_context = req8->naming_context;
+	req10->highwatermark = req8->highwatermark;
+	req10->uptodateness_vector = req8->uptodateness_vector;
+	req10->replica_flags = req8->replica_flags;
+	req10->max_object_count = req8->max_object_count;
+	req10->max_ndr_size = req8->max_ndr_size;
+	req10->extended_op = req8->extended_op;
+	req10->fsmo_info = req8->fsmo_info;
+	req10->partial_attribute_set = req8->partial_attribute_set;
+	req10->partial_attribute_set_ex = req8->partial_attribute_set_ex;
+	req10->mapping_ctr = req8->mapping_ctr;
+
+	return req10;
+}
+
+static const char *collect_objects_attrs[] = { "uSNChanged",
+					       "objectGUID" ,
+					       NULL };
+
+/**
+ * Collects object for normal replication cycle.
+ */
+static WERROR getncchanges_collect_objects(struct drsuapi_bind_state *b_state,
+					   TALLOC_CTX *mem_ctx,
+					   struct drsuapi_getncchanges_state *getnc_state,
+					   struct drsuapi_DsGetNCChangesRequest10 *req10,
+					   struct ldb_dn *search_dn,
+					   const char *extra_filter,
+					   struct ldb_result **search_res)
+{
+	int ret;
+	char* search_filter;
+	enum ldb_scope scope = LDB_SCOPE_SUBTREE;
+	bool critical_only = false;
+
+	if (req10->replica_flags & DRSUAPI_DRS_CRITICAL_ONLY) {
+		critical_only = true;
+	}
+
+	if (req10->extended_op == DRSUAPI_EXOP_REPL_OBJ ||
+	    req10->extended_op == DRSUAPI_EXOP_REPL_SECRET) {
+		scope = LDB_SCOPE_BASE;
+		critical_only = false;
+	}
+
+	/* Construct response. */
+	search_filter = talloc_asprintf(mem_ctx,
+					"(uSNChanged>=%llu)",
+					(unsigned long long)(getnc_state->min_usn+1));
+
+	if (extra_filter) {
+		search_filter = talloc_asprintf(mem_ctx, "(&%s(%s))", search_filter, extra_filter);
+	}
+
+	if (critical_only) {
+		search_filter = talloc_asprintf(mem_ctx,
+						"(&%s(isCriticalSystemObject=TRUE))",
+						search_filter);
+	}
+
+	if (req10->replica_flags & DRSUAPI_DRS_ASYNC_REP) {
+		scope = LDB_SCOPE_BASE;
+	}
+
+	if (!search_dn) {
+		search_dn = getnc_state->ncRoot_dn;
+	}
+
+	DEBUG(2,(__location__ ": getncchanges on %s using filter %s\n",
+		 ldb_dn_get_linearized(getnc_state->ncRoot_dn), search_filter));
+	ret = drsuapi_search_with_extended_dn(b_state->sam_ctx, getnc_state, search_res,
+					      search_dn, scope,
+					      collect_objects_attrs,
+					      search_filter);
+	if (ret != LDB_SUCCESS) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	return WERR_OK;
+}
+
+/**
+ * Collects object for normal replication cycle.
+ */
+static WERROR getncchanges_collect_objects_exop(struct drsuapi_bind_state *b_state,
+						TALLOC_CTX *mem_ctx,
+						struct drsuapi_getncchanges_state *getnc_state,
+						struct drsuapi_DsGetNCChangesRequest10 *req10,
+						struct drsuapi_DsGetNCChangesCtr6 *ctr6,
+						struct ldb_dn *search_dn,
+						const char *extra_filter,
+						struct ldb_result **search_res)
+{
+	/* we have nothing to do in case of ex-op failure */
+	if (ctr6->extended_ret != DRSUAPI_EXOP_ERR_SUCCESS) {
+		return WERR_OK;
+	}
+
+	switch (req10->extended_op) {
+	case DRSUAPI_EXOP_FSMO_RID_ALLOC:
+	{
+		int ret;
+		struct ldb_dn *ntds_dn = NULL;
+		struct ldb_dn *server_dn = NULL;
+		struct ldb_dn *machine_dn = NULL;
+		struct ldb_dn *rid_set_dn = NULL;
+		struct ldb_result *search_res2 = NULL;
+		struct ldb_result *search_res3 = NULL;
+		TALLOC_CTX *frame = talloc_stackframe();
+		/* get RID manager, RID set and server DN (in that order) */
+
+		/* This first search will get the RID Manager */
+		ret = drsuapi_search_with_extended_dn(b_state->sam_ctx, frame,
+						      search_res,
+						      search_dn, LDB_SCOPE_BASE,
+						      collect_objects_attrs,
+						      NULL);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to get RID Manager object %s - %s",
+				  ldb_dn_get_linearized(search_dn),
+				  ldb_errstring(b_state->sam_ctx)));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		if ((*search_res)->count != 1) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to get RID Manager object %s - %u objects returned",
+				  ldb_dn_get_linearized(search_dn),
+				  (*search_res)->count));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		/* Now extend it to the RID set */
+
+		/* Find the computer account DN for the destination
+		 * dsa GUID specified */
+
+		ret = dsdb_find_dn_by_guid(b_state->sam_ctx, frame,
+					   &req10->destination_dsa_guid, 0,
+					   &ntds_dn);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Unable to find NTDS object for guid %s - %s\n",
+				  GUID_string(frame,
+					      &req10->destination_dsa_guid),
+				  ldb_errstring(b_state->sam_ctx)));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		server_dn = ldb_dn_get_parent(frame, ntds_dn);
+		if (!server_dn) {
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		ret = samdb_reference_dn(b_state->sam_ctx, frame, server_dn,
+					 "serverReference", &machine_dn);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to find serverReference in %s - %s",
+				  ldb_dn_get_linearized(server_dn),
+				  ldb_errstring(b_state->sam_ctx)));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		ret = samdb_reference_dn(b_state->sam_ctx, frame, machine_dn,
+					 "rIDSetReferences", &rid_set_dn);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to find rIDSetReferences in %s - %s",
+				  ldb_dn_get_linearized(server_dn),
+				  ldb_errstring(b_state->sam_ctx)));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+
+		/* This first search will get the RID Manager, now get the RID set */
+		ret = drsuapi_search_with_extended_dn(b_state->sam_ctx, frame,
+						      &search_res2,
+						      rid_set_dn, LDB_SCOPE_BASE,
+						      collect_objects_attrs,
+						      NULL);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to get RID Set object %s - %s",
+				  ldb_dn_get_linearized(rid_set_dn),
+				  ldb_errstring(b_state->sam_ctx)));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		if (search_res2->count != 1) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to get RID Set object %s - %u objects returned",
+				  ldb_dn_get_linearized(rid_set_dn),
+				  search_res2->count));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		/* Finally get the server DN */
+		ret = drsuapi_search_with_extended_dn(b_state->sam_ctx, frame,
+						      &search_res3,
+						      machine_dn, LDB_SCOPE_BASE,
+						      collect_objects_attrs,
+						      NULL);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to get server object %s - %s",
+				  ldb_dn_get_linearized(server_dn),
+				  ldb_errstring(b_state->sam_ctx)));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		if (search_res3->count != 1) {
+			DEBUG(1, ("DRSUAPI_EXOP_FSMO_RID_ALLOC: Failed to get server object %s - %u objects returned",
+				  ldb_dn_get_linearized(server_dn),
+				  search_res3->count));
+			TALLOC_FREE(frame);
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		/* Now extend the original search_res with these answers */
+		(*search_res)->count = 3;
+
+		(*search_res)->msgs = talloc_realloc(frame, (*search_res)->msgs,
+						     struct ldb_message *,
+						     (*search_res)->count);
+		if ((*search_res)->msgs == NULL) {
+			TALLOC_FREE(frame);
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+
+
+		talloc_steal(mem_ctx, *search_res);
+		(*search_res)->msgs[1] =
+			talloc_steal((*search_res)->msgs, search_res2->msgs[0]);
+		(*search_res)->msgs[2] =
+			talloc_steal((*search_res)->msgs, search_res3->msgs[0]);
+
+		TALLOC_FREE(frame);
+		return WERR_OK;
+	}
+	default:
+		/* TODO: implement extended op specific collection
+		 * of objects. Right now we just normal procedure
+		 * for collecting objects */
+		return getncchanges_collect_objects(b_state,
+						    mem_ctx,
+						    getnc_state,
+						    req10,
+						    search_dn,
+						    extra_filter,
+						    search_res);
+	}
+}
+
+static void dcesrv_drsuapi_update_highwatermark(const struct ldb_message *msg,
+						uint64_t max_usn,
+						struct drsuapi_DsReplicaHighWaterMark *hwm)
+{
+	uint64_t uSN = ldb_msg_find_attr_as_uint64(msg, "uSNChanged", 0);
+
+	if (uSN > max_usn) {
+		/*
+		 * Only report the max_usn we had at the start
+		 * of the replication cycle.
+		 *
+		 * If this object has changed lately we better
+		 * let the destination dsa refetch the change.
+		 * This is better than the risk of loosing some
+		 * objects or linked attributes.
+		 */
+		return;
+	}
+
+	if (uSN <= hwm->tmp_highest_usn) {
+		return;
+	}
+
+	hwm->tmp_highest_usn = uSN;
+	hwm->reserved_usn = 0;
+}
+
+/**
+ * Adds an object's GUID to the cache of objects already sent.
+ * This avoids us sending the same object multiple times when
+ * the GetNCChanges request uses a flag like GET_ANC.
+ */
+static WERROR dcesrv_drsuapi_obj_cache_add(struct db_context *obj_cache,
+					   const struct GUID *guid)
+{
+	enum ndr_err_code ndr_err;
+	uint8_t guid_buf[DRS_GUID_SIZE] = { 0, };
+	DATA_BLOB b = {
+		.data = guid_buf,
+		.length = sizeof(guid_buf),
+	};
+	TDB_DATA key = {
+		.dptr = b.data,
+		.dsize = b.length,
+	};
+	TDB_DATA val = {
+		.dptr = NULL,
+		.dsize = 0,
+	};
+	NTSTATUS status;
+
+	ndr_err = ndr_push_struct_into_fixed_blob(&b, guid,
+			(ndr_push_flags_fn_t)ndr_push_GUID);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	status = dbwrap_store(obj_cache, key, val, TDB_REPLACE);
+	if (!NT_STATUS_IS_OK(status)) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	return WERR_OK;
+}
+
+/**
+ * Checks if the object with the GUID specified already exists in the
+ * object cache, i.e. it's already been sent in a GetNCChanges response.
+ */
+static WERROR dcesrv_drsuapi_obj_cache_exists(struct db_context *obj_cache,
+					      const struct GUID *guid)
+{
+	enum ndr_err_code ndr_err;
+	uint8_t guid_buf[DRS_GUID_SIZE] = { 0, };
+	DATA_BLOB b = {
+		.data = guid_buf,
+		.length = sizeof(guid_buf),
+	};
+	TDB_DATA key = {
+		.dptr = b.data,
+		.dsize = b.length,
+	};
+	bool exists;
+
+	ndr_err = ndr_push_struct_into_fixed_blob(&b, guid,
+			(ndr_push_flags_fn_t)ndr_push_GUID);
+	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	exists = dbwrap_exists(obj_cache, key);
+	if (!exists) {
+		return WERR_OBJECT_NOT_FOUND;
+	}
+
+	return WERR_OBJECT_NAME_EXISTS;
+}
+
+/**
+ * Copies the la_list specified into a sorted array, ready to be sent in a
+ * GetNCChanges response.
+ */
+static WERROR getncchanges_get_sorted_array(const struct drsuapi_DsReplicaLinkedAttribute *la_list,
+					    const uint32_t link_count,
+					    struct ldb_context *sam_ctx,
+					    TALLOC_CTX *mem_ctx,
+					    const struct dsdb_schema *schema,
+					    struct la_for_sorting **ret_array)
+{
+	int j;
+	struct la_for_sorting *guid_array;
+	WERROR werr = WERR_OK;
+
+	*ret_array = NULL;
+	guid_array = talloc_array(mem_ctx, struct la_for_sorting, link_count);
+	if (guid_array == NULL) {
+		DEBUG(0, ("Out of memory allocating %u linked attributes for sorting", link_count));
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	for (j = 0; j < link_count; j++) {
+
+		/* we need to get the target GUIDs to compare */
+		struct dsdb_dn *dn;
+		const struct drsuapi_DsReplicaLinkedAttribute *la = &la_list[j];
+		const struct dsdb_attribute *schema_attrib;
+		const struct ldb_val *target_guid;
+		DATA_BLOB source_guid;
+		TALLOC_CTX *frame = talloc_stackframe();
+		NTSTATUS status;
+
+		schema_attrib = dsdb_attribute_by_attributeID_id(schema, la->attid);
+
+		werr = dsdb_dn_la_from_blob(sam_ctx, schema_attrib, schema, frame, la->value.blob, &dn);
+		if (!W_ERROR_IS_OK(werr)) {
+			DEBUG(0,(__location__ ": Bad la blob in sort\n"));
+			TALLOC_FREE(frame);
+			return werr;
+		}
+
+		/* Extract the target GUID in NDR form */
+		target_guid = ldb_dn_get_extended_component(dn->dn, "GUID");
+		if (target_guid == NULL
+				|| target_guid->length != sizeof(guid_array[0].target_guid)) {
+			status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
+		} else {
+			/* Repack the source GUID as NDR for sorting */
+			status = GUID_to_ndr_blob(&la->identifier->guid,
+						  frame,
+						  &source_guid);
+		}
+
+		if (!NT_STATUS_IS_OK(status)
+				|| source_guid.length != sizeof(guid_array[0].source_guid)) {
+			DEBUG(0,(__location__ ": Bad la guid in sort\n"));
+			TALLOC_FREE(frame);
+			return ntstatus_to_werror(status);
+		}
+
+		guid_array[j].link = &la_list[j];
+		memcpy(guid_array[j].target_guid, target_guid->data,
+		       sizeof(guid_array[j].target_guid));
+		memcpy(guid_array[j].source_guid, source_guid.data,
+		       sizeof(guid_array[j].source_guid));
+		TALLOC_FREE(frame);
+	}
+
+	TYPESAFE_QSORT(guid_array, link_count, linked_attribute_compare);
+
+	*ret_array = guid_array;
+
+	return werr;
+}
+
+
+/**
+ * Adds any ancestor/parent objects of the child_obj specified.
+ * This is needed when the GET_ANC flag is specified in the request.
+ * @param new_objs if parents are added, this gets updated to point to a chain
+ * of parent objects (with the parents first and the child last)
+ */
+static WERROR getncchanges_add_ancestors(const struct GUID *parent_object_guid,
+					 struct ldb_dn *child_dn,
+					 TALLOC_CTX *mem_ctx,
+					 struct ldb_context *sam_ctx,
+					 struct drsuapi_getncchanges_state *getnc_state,
+					 struct dsdb_schema *schema,
+					 DATA_BLOB *session_key,
+					 struct drsuapi_DsGetNCChangesRequest10 *req10,
+					 uint32_t *local_pas,
+					 struct ldb_dn *machine_dn,
+					 struct drsuapi_DsReplicaObjectListItemEx **new_objs)
+{
+	int ret;
+	const struct GUID *next_anc_guid = NULL;
+	WERROR werr = WERR_OK;
+	static const char * const msg_attrs[] = {
+					    "*",
+					    "nTSecurityDescriptor",
+					    "parentGUID",
+					    "replPropertyMetaData",
+					    DSDB_SECRET_ATTRIBUTES,
+					    NULL };
+
+	next_anc_guid = parent_object_guid;
+
+	while (next_anc_guid != NULL) {
+		struct drsuapi_DsReplicaObjectListItemEx *anc_obj = NULL;
+		struct ldb_message *anc_msg = NULL;
+		struct ldb_result *anc_res = NULL;
+		struct ldb_dn *anc_dn = NULL;
+
+		/*
+		 * For the GET_ANC case (but not the 'send NC root
+		 * first' case), don't send an object twice.
+		 *
+		 * (If we've sent the object, then we've also sent all
+		 * its parents as well)
+		 */
+		if (getnc_state->obj_cache) {
+			werr = dcesrv_drsuapi_obj_cache_exists(getnc_state->obj_cache,
+							       next_anc_guid);
+			if (W_ERROR_EQUAL(werr, WERR_OBJECT_NAME_EXISTS)) {
+				return WERR_OK;
+			}
+			if (W_ERROR_IS_OK(werr)) {
+				return WERR_INTERNAL_ERROR;
+			}
+			if (!W_ERROR_EQUAL(werr, WERR_OBJECT_NOT_FOUND)) {
+				return werr;
+			}
+		}
+
+		anc_obj = talloc_zero(mem_ctx,
+				      struct drsuapi_DsReplicaObjectListItemEx);
+		if (anc_obj == NULL) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+
+		anc_dn = ldb_dn_new_fmt(anc_obj, sam_ctx, "<GUID=%s>",
+					GUID_string(anc_obj, next_anc_guid));
+		if (anc_dn == NULL) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+
+		ret = drsuapi_search_with_extended_dn(sam_ctx, anc_obj,
+						      &anc_res, anc_dn,
+						      LDB_SCOPE_BASE,
+						      msg_attrs, NULL);
+		if (ret != LDB_SUCCESS) {
+			const char *anc_str = NULL;
+			const char *obj_str = NULL;
+
+			anc_str = ldb_dn_get_extended_linearized(anc_obj,
+								 anc_dn,
+								 1);
+			obj_str = ldb_dn_get_extended_linearized(anc_obj,
+								 child_dn,
+								 1);
+
+			DBG_ERR("getncchanges: failed to fetch ANC "
+				"DN %s for DN %s - %s\n",
+				anc_str, obj_str, ldb_errstring(sam_ctx));
+			return WERR_DS_DRA_INCONSISTENT_DIT;
+		}
+
+		anc_msg = anc_res->msgs[0];
+
+		werr = get_nc_changes_build_object(anc_obj, anc_msg,
+						   sam_ctx,
+						   getnc_state,
+						   schema, session_key,
+						   req10,
+						   false, /* force_object_return */
+						   local_pas,
+						   machine_dn,
+						   next_anc_guid);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+
+		/*
+		 * Regardless of whether we actually use it or not,
+		 * we add it to the cache so we don't look at it again
+		 *
+		 * The only time we are here without
+		 * getnc_state->obj_cache is for the forced addition
+		 * of the NC root to the start of the reply, this we
+		 * want to add each and every call..
+		 */
+		if (getnc_state->obj_cache) {
+			werr = dcesrv_drsuapi_obj_cache_add(getnc_state->obj_cache,
+							    next_anc_guid);
+			if (!W_ERROR_IS_OK(werr)) {
+				return werr;
+			}
+		}
+
+		/*
+		 * Any ancestors which are below the highwatermark
+		 * or uptodateness_vector shouldn't be added,
+		 * but we still look further up the
+		 * tree for ones which have been changed recently.
+		 */
+		if (anc_obj->meta_data_ctr != NULL) {
+
+			/*
+			 * prepend the parent to the list so that the client-side
+			 * adds the parent object before it adds the children
+			 */
+			anc_obj->next_object = *new_objs;
+			*new_objs = anc_obj;
+		}
+
+		anc_msg = NULL;
+		TALLOC_FREE(anc_res);
+		TALLOC_FREE(anc_dn);
+
+		/*
+		 * We may need to resolve more parents...
+		 */
+		next_anc_guid = anc_obj->parent_object_guid;
+	}
+	return werr;
+}
+
+/**
+ * Adds a list of new objects into the current chunk of replication data to send
+ */
+static void getncchanges_chunk_add_objects(struct getncchanges_repl_chunk *repl_chunk,
+					   struct drsuapi_DsReplicaObjectListItemEx *obj_list)
+{
+	struct drsuapi_DsReplicaObjectListItemEx *obj;
+
+	/*
+	 * We track the last object added to the replication chunk, so just add
+	 * the new object-list onto the end
+	 */
+	if (repl_chunk->object_list == NULL) {
+		repl_chunk->object_list = obj_list;
+	} else {
+		repl_chunk->last_object->next_object = obj_list;
+	}
+
+	for (obj = obj_list; obj != NULL; obj = obj->next_object) {
+		repl_chunk->object_count += 1;
+
+		/*
+		 * Remember the last object in the response - we'll use this to
+		 * link the next object(s) processed onto the existing list
+		 */
+		if (obj->next_object == NULL) {
+			repl_chunk->last_object = obj;
+		}
+	}
+}
+
+/**
+ * Gets the object to send, packed into an RPC struct ready to send. This also
+ * adds the object to the object cache, and adds any ancestors (if needed).
+ * @param msg - DB search result for the object to add
+ * @param guid - GUID of the object to add
+ * @param ret_obj_list - returns the object ready to be sent (in a list, along
+ * with any ancestors that might be needed). NULL if nothing to send.
+ */
+static WERROR getncchanges_get_obj_to_send(const struct ldb_message *msg,
+					   TALLOC_CTX *mem_ctx,
+					   struct ldb_context *sam_ctx,
+					   struct drsuapi_getncchanges_state *getnc_state,
+					   struct dsdb_schema *schema,
+					   DATA_BLOB *session_key,
+					   struct drsuapi_DsGetNCChangesRequest10 *req10,
+					   bool force_object_return,
+					   uint32_t *local_pas,
+					   struct ldb_dn *machine_dn,
+					   const struct GUID *guid,
+					   struct drsuapi_DsReplicaObjectListItemEx **ret_obj_list)
+{
+	struct drsuapi_DsReplicaObjectListItemEx *obj;
+	WERROR werr;
+
+	*ret_obj_list = NULL;
+
+	obj = talloc_zero(mem_ctx, struct drsuapi_DsReplicaObjectListItemEx);
+	W_ERROR_HAVE_NO_MEMORY(obj);
+
+	werr = get_nc_changes_build_object(obj, msg, sam_ctx, getnc_state,
+					   schema, session_key, req10,
+					   force_object_return,
+					   local_pas, machine_dn, guid);
+	if (!W_ERROR_IS_OK(werr)) {
+		return werr;
+	}
+
+	/*
+	 * The object may get filtered out by the UTDV's USN and not actually
+	 * sent, in which case there's nothing more to do here
+	 */
+	if (obj->meta_data_ctr == NULL) {
+		TALLOC_FREE(obj);
+		return WERR_OK;
+	}
+
+	if (getnc_state->obj_cache != NULL) {
+		werr = dcesrv_drsuapi_obj_cache_add(getnc_state->obj_cache,
+						    guid);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+	}
+
+	*ret_obj_list = obj;
+
+	/*
+	 * If required, also add any ancestors that the client may need to know
+	 * about before it can resolve this object. These get prepended to the
+	 * ret_obj_list so the client adds them first.
+	 *
+	 * We allow this to be disabled to permit testing of a
+	 * client-side fallback for the broken behaviour in Samba 4.5
+	 * and earlier.
+	 */
+	if (getnc_state->is_get_anc
+	    && !getnc_state->broken_samba_4_5_get_anc_emulation) {
+		werr = getncchanges_add_ancestors(obj->parent_object_guid,
+						  msg->dn, mem_ctx,
+						  sam_ctx, getnc_state,
+						  schema, session_key,
+						  req10, local_pas,
+						  machine_dn, ret_obj_list);
+	}
+
+	return werr;
+}
+
+/**
+ * Returns the number of links that are waiting to be sent
+ */
+static uint32_t getncchanges_chunk_links_pending(struct getncchanges_repl_chunk *repl_chunk,
+						 struct drsuapi_getncchanges_state *getnc_state)
+{
+	uint32_t links_to_send = 0;
+
+	if (getnc_state->is_get_tgt) {
+
+		/*
+		 * when the GET_TGT flag is set, only include the linked
+		 * attributes whose target object has already been checked
+		 * (i.e. they're ready to send).
+		 */
+		if (repl_chunk->tgt_la_count > getnc_state->la_idx) {
+			links_to_send = (repl_chunk->tgt_la_count -
+					 getnc_state->la_idx);
+		}
+	} else {
+		links_to_send = getnc_state->la_count - getnc_state->la_idx;
+	}
+
+	return links_to_send;
+}
+
+/**
+ * Returns the max number of links that will fit in the current replication chunk
+ */
+static uint32_t getncchanges_chunk_max_links(struct getncchanges_repl_chunk *repl_chunk)
+{
+	uint32_t max_links = 0;
+
+	if (repl_chunk->max_links != DEFAULT_MAX_LINKS ||
+	    repl_chunk->max_objects != DEFAULT_MAX_OBJECTS) {
+
+		/*
+		 * We're using non-default settings, so don't try to adjust
+		 * them, just trust the user has configured decent values
+		 */
+		max_links = repl_chunk->max_links;
+
+	} else if (repl_chunk->max_links > repl_chunk->object_count) {
+
+		/*
+		 * This is just an approximate guess to avoid overfilling the
+		 * replication chunk. It's the logic we've used historically.
+		 * E.g. if we've already sent 1000 objects, then send 1000 fewer
+		 * links. For comparison, the max that Windows seems to send is
+		 * ~2700 links and ~250 objects (although this may vary based
+		 * on timeouts)
+		 */
+		max_links = repl_chunk->max_links - repl_chunk->object_count;
+	}
+
+	return max_links;
+}
+
+/**
+ * Returns true if the current GetNCChanges() call has taken longer than its
+ * allotted time. This prevents the client from timing out.
+ */
+static bool getncchanges_chunk_timed_out(struct getncchanges_repl_chunk *repl_chunk)
+{
+	return (time(NULL) - repl_chunk->start > repl_chunk->max_wait);
+}
+
+/**
+ * Returns true if the current chunk of replication data has reached the
+ * max_objects and/or max_links thresholds.
+ */
+static bool getncchanges_chunk_is_full(struct getncchanges_repl_chunk *repl_chunk,
+				       struct drsuapi_getncchanges_state *getnc_state)
+{
+	bool chunk_full = false;
+	uint32_t links_to_send;
+	uint32_t chunk_limit;
+
+	/* check if the current chunk is already full with objects */
+	if (repl_chunk->object_count >= repl_chunk->max_objects) {
+		chunk_full = true;
+
+	} else if (repl_chunk->object_count > 0 &&
+		   getncchanges_chunk_timed_out(repl_chunk)) {
+
+		/*
+		 * We've exceeded our allotted time building this chunk,
+		 * and we have at least one object to send back to the client
+		 */
+		chunk_full = true;
+
+	} else if (repl_chunk->immediate_link_sync) {
+
+		/* check if the chunk is already full with links */
+		links_to_send = getncchanges_chunk_links_pending(repl_chunk,
+								 getnc_state);
+
+		chunk_limit = getncchanges_chunk_max_links(repl_chunk);
+
+		/*
+		 * The chunk is full if we've got more links to send than will
+		 * fit in one chunk
+		 */
+		if (links_to_send > 0 && chunk_limit <= links_to_send) {
+			chunk_full = true;
+		}
+	}
+
+	return chunk_full;
+}
+
+/**
+ * Goes through any new linked attributes and checks that the target object
+ * will be known to the client, i.e. we've already sent it in an replication
+ * chunk. If not, then it adds the target object to the current replication
+ * chunk. This is only done when the client specifies DRS_GET_TGT.
+ */
+static WERROR getncchanges_chunk_add_la_targets(struct getncchanges_repl_chunk *repl_chunk,
+						struct drsuapi_getncchanges_state *getnc_state,
+						uint32_t start_la_index,
+						TALLOC_CTX *mem_ctx,
+						struct ldb_context *sam_ctx,
+						struct dsdb_schema *schema,
+						DATA_BLOB *session_key,
+						struct drsuapi_DsGetNCChangesRequest10 *req10,
+						uint32_t *local_pas,
+						struct ldb_dn *machine_dn)
+{
+	int ret;
+	uint32_t i;
+	uint32_t max_la_index;
+	uint32_t max_links;
+	uint32_t target_count = 0;
+	WERROR werr = WERR_OK;
+	static const char * const msg_attrs[] = {
+					    "*",
+					    "nTSecurityDescriptor",
+					    "parentGUID",
+					    "replPropertyMetaData",
+					    DSDB_SECRET_ATTRIBUTES,
+					    NULL };
+
+	/*
+	 * A object can potentially link to thousands of targets. Only bother
+	 * checking as many targets as will fit into the current response
+	 */
+	max_links = getncchanges_chunk_max_links(repl_chunk);
+	max_la_index = MIN(getnc_state->la_count,
+			   start_la_index + max_links);
+
+	/* loop through any linked attributes to check */
+	for (i = start_la_index;
+	     (i < max_la_index &&
+	      !getncchanges_chunk_is_full(repl_chunk, getnc_state));
+	     i++) {
+
+		struct GUID target_guid;
+		struct drsuapi_DsReplicaObjectListItemEx *new_objs = NULL;
+		const struct drsuapi_DsReplicaLinkedAttribute *la;
+		struct ldb_result *msg_res;
+		struct ldb_dn *search_dn;
+		TALLOC_CTX *tmp_ctx;
+		struct dsdb_dn *dn;
+		const struct dsdb_attribute *schema_attrib;
+		NTSTATUS status;
+		bool same_nc;
+
+		la = &getnc_state->la_list[i];
+		tmp_ctx = talloc_new(mem_ctx);
+
+		/*
+		 * Track what linked attribute targets we've checked. We might
+		 * not have time to check them all, so we should only send back
+		 * the ones we've actually checked.
+		 */
+		repl_chunk->tgt_la_count = i + 1;
+
+		/* get the GUID of the linked attribute's target object */
+		schema_attrib = dsdb_attribute_by_attributeID_id(schema,
+								 la->attid);
+
+		werr = dsdb_dn_la_from_blob(sam_ctx, schema_attrib, schema,
+					    tmp_ctx, la->value.blob, &dn);
+
+		if (!W_ERROR_IS_OK(werr)) {
+			DEBUG(0,(__location__ ": Bad la blob\n"));
+			return werr;
+		}
+
+		status = dsdb_get_extended_dn_guid(dn->dn, &target_guid, "GUID");
+
+		if (!NT_STATUS_IS_OK(status)) {
+			return ntstatus_to_werror(status);
+		}
+
+		/*
+		 * if the target isn't in the cache, then the client
+		 * might not know about it, so send the target now
+		 */
+		werr = dcesrv_drsuapi_obj_cache_exists(getnc_state->obj_cache,
+						       &target_guid);
+
+		if (W_ERROR_EQUAL(werr, WERR_OBJECT_NAME_EXISTS)) {
+
+			/* target already sent, nothing to do */
+			TALLOC_FREE(tmp_ctx);
+			continue;
+		}
+
+		same_nc = dsdb_objects_have_same_nc(sam_ctx, tmp_ctx, dn->dn,
+						    getnc_state->ncRoot_dn);
+
+		/* don't try to fetch target objects from another partition */
+		if (!same_nc) {
+			TALLOC_FREE(tmp_ctx);
+			continue;
+		}
+
+		search_dn = ldb_dn_new_fmt(tmp_ctx, sam_ctx, "<GUID=%s>",
+					   GUID_string(tmp_ctx, &target_guid));
+		W_ERROR_HAVE_NO_MEMORY(search_dn);
+
+		ret = drsuapi_search_with_extended_dn(sam_ctx, tmp_ctx,
+						      &msg_res, search_dn,
+						      LDB_SCOPE_BASE,
+						      msg_attrs, NULL);
+
+		/*
+		 * Don't fail the replication if we can't find the target.
+		 * This could happen for a one-way linked attribute, if the
+		 * target is deleted and then later expunged (thus, the source
+		 * object can be left with a hanging link). Continue to send
+		 * the the link (the client-side has already tried once with
+		 * GET_TGT, so it should just end up ignoring it).
+		 */
+		if (ret == LDB_ERR_NO_SUCH_OBJECT) {
+			DBG_WARNING("Encountered unknown link target DN %s\n",
+				    ldb_dn_get_extended_linearized(tmp_ctx, dn->dn, 1));
+			TALLOC_FREE(tmp_ctx);
+			continue;
+
+		} else if (ret != LDB_SUCCESS) {
+			DBG_ERR("Failed to fetch link target DN %s - %s\n",
+				ldb_dn_get_extended_linearized(tmp_ctx, dn->dn, 1),
+				ldb_errstring(sam_ctx));
+			return WERR_DS_DRA_INCONSISTENT_DIT;
+		}
+
+		/*
+		 * Construct an object, ready to send (this will include
+		 * the object's ancestors as well, if GET_ANC is set)
+		 */
+		werr = getncchanges_get_obj_to_send(msg_res->msgs[0], mem_ctx,
+						    sam_ctx, getnc_state,
+						    schema, session_key, req10,
+						    false, local_pas,
+						    machine_dn, &target_guid,
+						    &new_objs);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+
+		if (new_objs != NULL) {
+			target_count++;
+			getncchanges_chunk_add_objects(repl_chunk, new_objs);
+		}
+		TALLOC_FREE(tmp_ctx);
+	}
+
+	if (target_count > 0) {
+		DEBUG(3, ("GET_TGT: checked %u link-attrs, added %u target objs\n",
+			  i - start_la_index, target_count));
+	}
+
+	return WERR_OK;
+}
+
+/**
+ * Creates a helper struct used for building a chunk of replication data,
+ * i.e. used over a single call to dcesrv_drsuapi_DsGetNCChanges().
+ */
+static struct getncchanges_repl_chunk * getncchanges_chunk_new(TALLOC_CTX *mem_ctx,
+							       struct dcesrv_call_state *dce_call,
+							       struct drsuapi_DsGetNCChangesRequest10 *req10)
+{
+	struct getncchanges_repl_chunk *repl_chunk;
+
+	repl_chunk = talloc_zero(mem_ctx, struct getncchanges_repl_chunk);
+
+	repl_chunk->start = time(NULL);
+
+	repl_chunk->max_objects = lpcfg_parm_int(dce_call->conn->dce_ctx->lp_ctx, NULL,
+						 "drs", "max object sync",
+						 DEFAULT_MAX_OBJECTS);
+
+	/*
+	 * The client control here only applies in normal replication, not extended
+	 * operations, which return a fixed set, even if the caller
+	 * sets max_object_count == 0
+	 */
+	if (req10->extended_op == DRSUAPI_EXOP_NONE) {
+
+		/*
+		 * use this to force single objects at a time, which is useful
+		 * for working out what object is giving problems
+		 */
+		if (req10->max_object_count < repl_chunk->max_objects) {
+			repl_chunk->max_objects = req10->max_object_count;
+		}
+	}
+
+	repl_chunk->max_links =
+			lpcfg_parm_int(dce_call->conn->dce_ctx->lp_ctx, NULL,
+				       "drs", "max link sync",
+					DEFAULT_MAX_LINKS);
+
+	repl_chunk->immediate_link_sync =
+			lpcfg_parm_bool(dce_call->conn->dce_ctx->lp_ctx, NULL,
+					"drs", "immediate link sync", false);
+
+	/*
+	 * Maximum time that we can spend in a getncchanges
+	 * in order to avoid timeout of the other part.
+	 * 10 seconds by default.
+	 */
+	repl_chunk->max_wait = lpcfg_parm_int(dce_call->conn->dce_ctx->lp_ctx,
+					      NULL, "drs", "max work time", 10);
+
+	return repl_chunk;
+}
+
+/*
+  drsuapi_DsGetNCChanges
+
+  see MS-DRSR 4.1.10.5.2 for basic logic of this function
+*/
+WERROR dcesrv_drsuapi_DsGetNCChanges(struct dcesrv_call_state *dce_call, TALLOC_CTX *mem_ctx,
+				     struct drsuapi_DsGetNCChanges *r)
+{
+	struct auth_session_info *session_info =
+		dcesrv_call_session_info(dce_call);
+	struct imessaging_context *imsg_ctx =
+		dcesrv_imessaging_context(dce_call->conn);
+	struct drsuapi_DsReplicaObjectIdentifier *untrusted_ncRoot;
+	int ret;
+	uint32_t i, k;
+	struct dsdb_schema *schema;
+	struct drsuapi_DsReplicaOIDMapping_Ctr *ctr;
+	struct getncchanges_repl_chunk *repl_chunk;
+	NTSTATUS status;
+	DATA_BLOB session_key;
+	WERROR werr;
+	struct dcesrv_handle *h;
+	struct drsuapi_bind_state *b_state;
+	struct drsuapi_getncchanges_state *getnc_state = NULL;
+	struct drsuapi_DsGetNCChangesRequest10 *req10;
+	uint32_t options;
+	uint32_t link_count = 0;
+	struct ldb_dn *search_dn = NULL;
+	bool am_rodc;
+	enum security_user_level security_level;
+	struct ldb_context *sam_ctx;
+	struct dom_sid *user_sid;
+	bool is_secret_request;
+	bool is_gc_pas_request;
+	struct drsuapi_changed_objects *changes;
+	bool has_get_all_changes = false;
+	struct GUID invocation_id;
+	static const struct drsuapi_DsReplicaLinkedAttribute no_linked_attr;
+	struct dsdb_schema_prefixmap *pfm_remote = NULL;
+	bool full = true;
+	uint32_t *local_pas = NULL;
+	struct ldb_dn *machine_dn = NULL; /* Only used for REPL SECRET EXOP */
+
+	DCESRV_PULL_HANDLE_WERR(h, r->in.bind_handle, DRSUAPI_BIND_HANDLE);
+	b_state = h->data;
+
+	/* sam_ctx_system is not present for non-administrator users */
+	sam_ctx = b_state->sam_ctx_system?b_state->sam_ctx_system:b_state->sam_ctx;
+
+	invocation_id = *(samdb_ntds_invocation_id(sam_ctx));
+
+	*r->out.level_out = 6;
+
+	r->out.ctr->ctr6.linked_attributes_count = 0;
+	r->out.ctr->ctr6.linked_attributes = discard_const_p(struct drsuapi_DsReplicaLinkedAttribute, &no_linked_attr);
+
+	r->out.ctr->ctr6.object_count = 0;
+	r->out.ctr->ctr6.nc_object_count = 0;
+	r->out.ctr->ctr6.more_data = false;
+	r->out.ctr->ctr6.uptodateness_vector = NULL;
+	r->out.ctr->ctr6.source_dsa_guid = *(samdb_ntds_objectGUID(sam_ctx));
+	r->out.ctr->ctr6.source_dsa_invocation_id = *(samdb_ntds_invocation_id(sam_ctx));
+	r->out.ctr->ctr6.first_object = NULL;
+
+	/* Check request revision. 
+	 */
+	switch (r->in.level) {
+	case 8:
+		req10 = getncchanges_map_req8(mem_ctx, &r->in.req->req8);
+		if (req10 == NULL) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+		break;
+	case 10:
+		req10 = &r->in.req->req10;
+		break;
+	default:
+		DEBUG(0,(__location__ ": Request for DsGetNCChanges with unsupported level %u\n",
+			 r->in.level));
+		return WERR_REVISION_MISMATCH;
+	}
+
+	repl_chunk = getncchanges_chunk_new(mem_ctx, dce_call, req10);
+
+	if (repl_chunk == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	/* a RODC doesn't allow for any replication */
+	ret = samdb_rodc(sam_ctx, &am_rodc);
+	if (ret == LDB_SUCCESS && am_rodc) {
+		DEBUG(0,(__location__ ": DsGetNCChanges attempt on RODC\n"));
+		return WERR_DS_DRA_SOURCE_DISABLED;
+	}
+
+	/*
+	 * Help our tests pass by pre-checking the
+	 * destination_dsa_guid before the NC permissions.  Info on
+	 * valid DSA GUIDs is not sensitive so this isn't a leak
+	 */
+	switch (req10->extended_op) {
+	case DRSUAPI_EXOP_FSMO_REQ_ROLE:
+	case DRSUAPI_EXOP_FSMO_RID_ALLOC:
+	case DRSUAPI_EXOP_FSMO_RID_REQ_ROLE:
+	case DRSUAPI_EXOP_FSMO_REQ_PDC:
+	case DRSUAPI_EXOP_FSMO_ABANDON_ROLE:
+	{
+		const char *attrs[] = { NULL };
+
+		ret = samdb_get_ntds_obj_by_guid(mem_ctx,
+						 sam_ctx,
+						 &req10->destination_dsa_guid,
+						 attrs,
+						 NULL);
+		if (ret == LDB_ERR_NO_SUCH_OBJECT) {
+			/*
+			 * Error out with an EXOP error but success at
+			 * the top level return value
+			 */
+			r->out.ctr->ctr6.extended_ret = DRSUAPI_EXOP_ERR_UNKNOWN_CALLER;
+			return WERR_OK;
+		} else if (ret != LDB_SUCCESS) {
+			return WERR_DS_DRA_INTERNAL_ERROR;
+		}
+
+		break;
+	}
+	case DRSUAPI_EXOP_REPL_SECRET:
+	case DRSUAPI_EXOP_REPL_OBJ:
+	case DRSUAPI_EXOP_NONE:
+		break;
+	}
+
+	/* Perform access checks. */
+	untrusted_ncRoot = req10->naming_context;
+	if (untrusted_ncRoot == NULL) {
+		DEBUG(0,(__location__ ": Request for DsGetNCChanges with no NC\n"));
+		return WERR_DS_DRA_INVALID_PARAMETER;
+	}
+
+	if (samdb_ntds_options(sam_ctx, &options) != LDB_SUCCESS) {
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	if ((options & DS_NTDSDSA_OPT_DISABLE_OUTBOUND_REPL) &&
+	    !(req10->replica_flags & DRSUAPI_DRS_SYNC_FORCED)) {
+		return WERR_DS_DRA_SOURCE_DISABLED;
+	}
+
+	user_sid = &session_info->security_token->sids[PRIMARY_USER_SID_INDEX];
+
+	/*
+	 * all clients must have GUID_DRS_GET_CHANGES.  This finds the
+	 * actual NC root of the given value and checks that, allowing
+	 * REPL_OBJ to work safely
+	 */
+	werr = drs_security_access_check_nc_root(sam_ctx,
+						 mem_ctx,
+						 session_info->security_token,
+						 req10->naming_context,
+						 GUID_DRS_GET_CHANGES);
+
+	if (W_ERROR_EQUAL(werr, WERR_DS_DRA_BAD_NC)) {
+		/*
+		 * These extended operations need a different error if
+		 * the supplied DN can't be found
+		 */
+		switch (req10->extended_op) {
+		case DRSUAPI_EXOP_REPL_OBJ:
+		case DRSUAPI_EXOP_REPL_SECRET:
+			return WERR_DS_DRA_BAD_DN;
+		default:
+			return werr;
+		}
+	}
+	if (!W_ERROR_IS_OK(werr)) {
+		return werr;
+	}
+
+	if (dsdb_functional_level(sam_ctx) >= DS_DOMAIN_FUNCTION_2008) {
+		full = req10->partial_attribute_set == NULL &&
+		       req10->partial_attribute_set_ex == NULL;
+	} else {
+		full = (options & DRSUAPI_DRS_WRIT_REP) != 0;
+	}
+
+	werr = dsdb_schema_pfm_from_drsuapi_pfm(&req10->mapping_ctr, true,
+						mem_ctx, &pfm_remote, NULL);
+
+	/* We were supplied a partial attribute set, without the prefix map! */
+	if (!full && !W_ERROR_IS_OK(werr)) {
+		if (req10->mapping_ctr.num_mappings == 0) {
+			/*
+			 * Despite the fact MS-DRSR specifies that this shouldn't
+			 * happen, Windows RODCs will in fact not provide a prefixMap.
+			 */
+			DEBUG(5,(__location__ ": Failed to provide a remote prefixMap,"
+				 " falling back to local prefixMap\n"));
+		} else {
+			DEBUG(0,(__location__ ": Failed to decode remote prefixMap: %s\n",
+				 win_errstr(werr)));
+			return werr;
+		}
+	}
+
+	/* allowed if the GC PAS and client has
+	   GUID_DRS_GET_FILTERED_ATTRIBUTES */
+	werr = dcesrv_drsuapi_is_gc_pas_request(b_state, req10, pfm_remote, &is_gc_pas_request);
+	if (!W_ERROR_IS_OK(werr)) {
+		return werr;
+	}
+	if (is_gc_pas_request) {
+		werr = drs_security_access_check_nc_root(sam_ctx,
+							 mem_ctx,
+							 session_info->security_token,
+							 req10->naming_context,
+							 GUID_DRS_GET_FILTERED_ATTRIBUTES);
+		if (W_ERROR_IS_OK(werr)) {
+			goto allowed;
+		}
+	}
+
+	werr = dcesrv_drsuapi_is_reveal_secrets_request(b_state, req10,
+							pfm_remote,
+							&is_secret_request);
+	if (!W_ERROR_IS_OK(werr)) {
+		return werr;
+	}
+	if (is_secret_request) {
+		werr = drs_security_access_check_nc_root(sam_ctx,
+							 mem_ctx,
+							 session_info->security_token,
+							 req10->naming_context,
+							 GUID_DRS_GET_ALL_CHANGES);
+		if (!W_ERROR_IS_OK(werr)) {
+			/* Only bail if this is not a EXOP_REPL_SECRET */
+			if (req10->extended_op != DRSUAPI_EXOP_REPL_SECRET) {
+				return werr;
+			}
+		} else {
+			has_get_all_changes = true;
+		}
+	}
+
+allowed:
+	/* for non-administrator replications, check that they have
+	   given the correct source_dsa_invocation_id */
+	security_level = security_session_user_level(session_info,
+						     samdb_domain_sid(sam_ctx));
+	if (security_level == SECURITY_RO_DOMAIN_CONTROLLER) {
+		if (req10->replica_flags & DRSUAPI_DRS_WRIT_REP) {
+			/* we rely on this flag being unset for RODC requests */
+			req10->replica_flags &= ~DRSUAPI_DRS_WRIT_REP;
+		}
+	}
+
+	if (req10->replica_flags & DRSUAPI_DRS_FULL_SYNC_PACKET) {
+		/* Ignore the _in_ uptpdateness vector*/
+		req10->uptodateness_vector = NULL;
+	}
+
+	if (GUID_all_zero(&req10->source_dsa_invocation_id)) {
+		req10->source_dsa_invocation_id = invocation_id;
+	}
+
+	if (!GUID_equal(&req10->source_dsa_invocation_id, &invocation_id)) {
+		/*
+		 * The given highwatermark is only valid relative to the
+		 * specified source_dsa_invocation_id.
+		 */
+		ZERO_STRUCT(req10->highwatermark);
+	}
+
+	/*
+	 * An extended operation is "special single-response cycle"
+	 * per MS-DRSR 4.1.10.1.1 "Start and Finish" so we don't need
+	 * to guess if this is a continuation of any long-term
+	 * state.
+	 *
+	 * Otherwise, maintain (including marking as stale, which is
+	 * what the below is for) the replication state.
+	 *
+	 * Note that point 5 "The server implementation MAY declare
+	 * the supplied values ... as too stale to use."  would allow
+	 * resetting the state at almost any point, Microsoft Azure AD
+	 * Connect will switch back and forth between a REPL_OBJ and a
+	 * full replication, so we must not reset the statue during
+	 * extended operations.
+	 */
+	if (req10->extended_op == DRSUAPI_EXOP_NONE &&
+	    b_state->getncchanges_full_repl_state != NULL) {
+		/*
+		 * Knowing that this is not an extended operation, we
+		 * can access (and validate) the full replication
+		 * state
+		 */
+		getnc_state = b_state->getncchanges_full_repl_state;
+	}
+
+	/* see if a previous replication has been abandoned */
+	if (getnc_state != NULL) {
+		struct ldb_dn *new_dn;
+		ret = drs_ObjectIdentifier_to_dn_and_nc_root(getnc_state,
+							     sam_ctx,
+							     untrusted_ncRoot,
+							     &new_dn,
+							     NULL);
+		if (ret != LDB_SUCCESS) {
+			/*
+			 * This can't fail as we have done this above
+			 * implicitly but not got the DN out, but
+			 * print a good error message regardless just
+			 * in case.
+			 */
+			DBG_ERR("Bad DN '%s' as Naming Context for GetNCChanges: %s\n",
+				drs_ObjectIdentifier_to_debug_string(mem_ctx, untrusted_ncRoot),
+				ldb_strerror(ret));
+			return WERR_DS_DRA_INVALID_PARAMETER;
+		}
+		if (ldb_dn_compare(new_dn, getnc_state->ncRoot_dn) != 0) {
+			DEBUG(0,(__location__ ": DsGetNCChanges 2nd replication on different DN %s %s (last_dn %s)\n",
+				 ldb_dn_get_linearized(new_dn),
+				 ldb_dn_get_linearized(getnc_state->ncRoot_dn),
+				 ldb_dn_get_linearized(getnc_state->last_dn)));
+			TALLOC_FREE(getnc_state);
+			b_state->getncchanges_full_repl_state = NULL;
+		}
+	}
+
+	if (getnc_state != NULL) {
+		ret = drsuapi_DsReplicaHighWaterMark_cmp(&getnc_state->last_hwm,
+							 &req10->highwatermark);
+		if (ret != 0) {
+			DEBUG(0,(__location__ ": DsGetNCChanges 2nd replication "
+				 "on DN %s %s highwatermark (last_dn %s)\n",
+				 ldb_dn_get_linearized(getnc_state->ncRoot_dn),
+				 (ret > 0) ? "older" : "newer",
+				 ldb_dn_get_linearized(getnc_state->last_dn)));
+			TALLOC_FREE(getnc_state);
+			b_state->getncchanges_full_repl_state = NULL;
+		}
+	}
+
+	 /*
+	  * This is either a new replication cycle, or an extended
+	  * operation.  A new cycle is triggered above by the
+	  * TALLOC_FREE() which sets getnc_state to NULL.
+	  */
+	if (getnc_state == NULL) {
+		struct ldb_result *res = NULL;
+		const char *attrs[] = {
+			"instanceType",
+			"objectGuID",
+			NULL
+		};
+		uint32_t nc_instanceType;
+		struct ldb_dn *ncRoot_dn;
+
+		ret = drs_ObjectIdentifier_to_dn_and_nc_root(mem_ctx,
+							     sam_ctx,
+							     untrusted_ncRoot,
+							     &ncRoot_dn,
+							     NULL);
+		if (ret != LDB_SUCCESS) {
+			DBG_ERR("Bad DN '%s' as Naming Context or EXOP DN for GetNCChanges: %s\n",
+				drs_ObjectIdentifier_to_debug_string(mem_ctx, untrusted_ncRoot),
+				ldb_strerror(ret));
+			return WERR_DS_DRA_BAD_DN;
+		}
+
+		ret = dsdb_search_dn(sam_ctx, mem_ctx, &res,
+				     ncRoot_dn, attrs,
+				     DSDB_SEARCH_SHOW_DELETED |
+				     DSDB_SEARCH_SHOW_RECYCLED);
+		if (ret != LDB_SUCCESS) {
+			DBG_WARNING("Failed to find ncRoot_dn %s\n",
+				    ldb_dn_get_linearized(ncRoot_dn));
+			return WERR_DS_DRA_BAD_DN;
+		}
+		nc_instanceType = ldb_msg_find_attr_as_int(res->msgs[0],
+							   "instanceType",
+							   0);
+
+		if (req10->extended_op != DRSUAPI_EXOP_NONE) {
+			r->out.ctr->ctr6.extended_ret = DRSUAPI_EXOP_ERR_SUCCESS;
+		}
+
+		/*
+		 * This is the first replication cycle and it is
+		 * a good place to handle extended operations
+		 *
+		 * FIXME: we don't fully support extended operations yet
+		 */
+		switch (req10->extended_op) {
+		case DRSUAPI_EXOP_NONE:
+			if ((nc_instanceType & INSTANCE_TYPE_IS_NC_HEAD) == 0) {
+				const char *dn_str
+					= ldb_dn_get_linearized(ncRoot_dn);
+
+				DBG_NOTICE("Rejecting full replication on "
+					   "not NC %s", dn_str);
+
+				return WERR_DS_CANT_FIND_EXPECTED_NC;
+			}
+
+			break;
+		case DRSUAPI_EXOP_FSMO_RID_ALLOC:
+			werr = getncchanges_rid_alloc(b_state, mem_ctx, req10, &r->out.ctr->ctr6, &search_dn);
+			W_ERROR_NOT_OK_RETURN(werr);
+			if (r->out.ctr->ctr6.extended_ret != DRSUAPI_EXOP_ERR_SUCCESS) {
+				return WERR_OK;
+			}
+			break;
+		case DRSUAPI_EXOP_REPL_SECRET:
+			werr = getncchanges_repl_secret(b_state, mem_ctx, req10,
+						        user_sid,
+						        &r->out.ctr->ctr6,
+						        has_get_all_changes,
+							&machine_dn);
+			r->out.result = werr;
+			W_ERROR_NOT_OK_RETURN(werr);
+			break;
+		case DRSUAPI_EXOP_FSMO_REQ_ROLE:
+			werr = getncchanges_change_master(b_state, mem_ctx, req10, &r->out.ctr->ctr6);
+			W_ERROR_NOT_OK_RETURN(werr);
+			if (r->out.ctr->ctr6.extended_ret != DRSUAPI_EXOP_ERR_SUCCESS) {
+				return WERR_OK;
+			}
+			break;
+		case DRSUAPI_EXOP_FSMO_RID_REQ_ROLE:
+			werr = getncchanges_change_master(b_state, mem_ctx, req10, &r->out.ctr->ctr6);
+			W_ERROR_NOT_OK_RETURN(werr);
+			if (r->out.ctr->ctr6.extended_ret != DRSUAPI_EXOP_ERR_SUCCESS) {
+				return WERR_OK;
+			}
+			break;
+		case DRSUAPI_EXOP_FSMO_REQ_PDC:
+			werr = getncchanges_change_master(b_state, mem_ctx, req10, &r->out.ctr->ctr6);
+			W_ERROR_NOT_OK_RETURN(werr);
+			if (r->out.ctr->ctr6.extended_ret != DRSUAPI_EXOP_ERR_SUCCESS) {
+				return WERR_OK;
+			}
+			break;
+		case DRSUAPI_EXOP_REPL_OBJ:
+			werr = getncchanges_repl_obj(b_state, mem_ctx, req10, user_sid, &r->out.ctr->ctr6);
+			r->out.result = werr;
+			W_ERROR_NOT_OK_RETURN(werr);
+			break;
+
+		case DRSUAPI_EXOP_FSMO_ABANDON_ROLE:
+
+			DEBUG(0,(__location__ ": Request for DsGetNCChanges unsupported extended op 0x%x\n",
+				 (unsigned)req10->extended_op));
+			return WERR_DS_DRA_NOT_SUPPORTED;
+		}
+
+		/*
+		 * Initialize the state, initially for the remainder
+		 * of this call (EXOPs)
+		 *
+		 * An extended operation is a "special single-response
+		 * cycle" per MS-DRSR 4.1.10.1.1 "Start and Finish"
+		 *
+		 */
+		getnc_state = talloc_zero(mem_ctx, struct drsuapi_getncchanges_state);
+		if (getnc_state == NULL) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+
+		if (req10->extended_op == DRSUAPI_EXOP_NONE) {
+			/*
+			 * Promote the memory to being a store of
+			 * long-term state that we will use over the
+			 * replication cycle for full replication
+			 * requests
+			 *
+			 * Store the state in a clearly named location
+			 * for pulling back only during full
+			 * replications
+			 */
+			b_state->getncchanges_full_repl_state
+				= talloc_steal(b_state, getnc_state);
+		}
+
+		getnc_state->ncRoot_dn = ncRoot_dn;
+		talloc_steal(getnc_state, ncRoot_dn);
+
+		getnc_state->ncRoot_guid = samdb_result_guid(res->msgs[0],
+							     "objectGUID");
+
+		/* find out if we are to replicate Schema NC */
+		ret = ldb_dn_compare_base(ldb_get_schema_basedn(sam_ctx),
+					  ncRoot_dn);
+		getnc_state->is_schema_nc = (0 == ret);
+
+		TALLOC_FREE(res);
+	}
+
+	/* we need the session key for encrypting password attributes */
+	status = dcesrv_auth_session_key(dce_call, &session_key);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(0,(__location__ ": Failed to get session key\n"));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	/* 
+	   TODO: MS-DRSR section 4.1.10.1.1
+	   Work out if this is the start of a new cycle */
+
+	if (getnc_state->guids == NULL) {
+		const char *extra_filter;
+		struct ldb_result *search_res = NULL;
+		static const struct drsuapi_DsReplicaCursorCtrEx empty_udv;
+		const struct drsuapi_DsReplicaCursorCtrEx *udv = NULL;
+
+		extra_filter = lpcfg_parm_string(dce_call->conn->dce_ctx->lp_ctx, NULL, "drs", "object filter");
+
+		if (req10->extended_op == DRSUAPI_EXOP_NONE) {
+			if (req10->uptodateness_vector != NULL) {
+				udv = req10->uptodateness_vector;
+			} else {
+				udv = &empty_udv;
+			}
+
+			getnc_state->min_usn = req10->highwatermark.highest_usn;
+			for (i = 0; i < udv->count; i++) {
+				bool match;
+				const struct drsuapi_DsReplicaCursor *cur =
+					&udv->cursors[i];
+
+				match = GUID_equal(&invocation_id,
+						   &cur->source_dsa_invocation_id);
+				if (!match) {
+					continue;
+				}
+				if (cur->highest_usn > getnc_state->min_usn) {
+					getnc_state->min_usn = cur->highest_usn;
+				}
+				break;
+			}
+		} else {
+			/* We do not want REPL_SECRETS or REPL_SINGLE to return empty-handed */
+			udv = &empty_udv;
+			getnc_state->min_usn = 0;
+		}
+
+		getnc_state->max_usn = getnc_state->min_usn;
+
+		getnc_state->final_udv = talloc_zero(getnc_state,
+					struct drsuapi_DsReplicaCursor2CtrEx);
+		if (getnc_state->final_udv == NULL) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+		werr = get_nc_changes_udv(sam_ctx, getnc_state->ncRoot_dn,
+					  getnc_state->final_udv);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+
+		if (req10->extended_op == DRSUAPI_EXOP_NONE) {
+			werr = getncchanges_collect_objects(b_state, mem_ctx,
+							    getnc_state, req10,
+							    search_dn, extra_filter,
+							    &search_res);
+		} else {
+			werr = getncchanges_collect_objects_exop(b_state, mem_ctx,
+								 getnc_state, req10,
+								 &r->out.ctr->ctr6,
+								 search_dn, extra_filter,
+								 &search_res);
+		}
+		W_ERROR_NOT_OK_RETURN(werr);
+
+		/* extract out the GUIDs list */
+		getnc_state->num_records = search_res ? search_res->count : 0;
+		getnc_state->guids = talloc_array(getnc_state, struct GUID, getnc_state->num_records);
+		W_ERROR_HAVE_NO_MEMORY(getnc_state->guids);
+
+		changes = talloc_array(getnc_state,
+				       struct drsuapi_changed_objects,
+				       getnc_state->num_records);
+		W_ERROR_HAVE_NO_MEMORY(changes);
+
+		for (i=0; i<getnc_state->num_records; i++) {
+			changes[i].dn = search_res->msgs[i]->dn;
+			changes[i].guid = samdb_result_guid(search_res->msgs[i], "objectGUID");
+			changes[i].usn = ldb_msg_find_attr_as_uint64(search_res->msgs[i], "uSNChanged", 0);
+
+			if (changes[i].usn > getnc_state->max_usn) {
+				getnc_state->max_usn = changes[i].usn;
+			}
+
+			if (req10->extended_op == DRSUAPI_EXOP_NONE &&
+			    GUID_equal(&changes[i].guid, &getnc_state->ncRoot_guid))
+			{
+				getnc_state->send_nc_root_first = true;
+			}
+		}
+
+		if (req10->extended_op == DRSUAPI_EXOP_NONE) {
+			getnc_state->is_get_anc =
+				((req10->replica_flags & DRSUAPI_DRS_GET_ANC) != 0);
+			if (getnc_state->is_get_anc
+				&& lpcfg_parm_bool(dce_call->conn->dce_ctx->lp_ctx,
+						    NULL,
+						    "drs",
+						    "broken_samba_4.5_get_anc_emulation",
+						   false)) {
+				getnc_state->broken_samba_4_5_get_anc_emulation = true;
+			}
+			if (lpcfg_parm_bool(dce_call->conn->dce_ctx->lp_ctx,
+					     NULL,
+					     "drs",
+					     "get_tgt_support",
+					     true)) {
+				getnc_state->is_get_tgt =
+					((req10->more_flags & DRSUAPI_DRS_GET_TGT) != 0);
+			}
+		}
+
+		/* RID_ALLOC returns 3 objects in a fixed order */
+		if (req10->extended_op == DRSUAPI_EXOP_FSMO_RID_ALLOC) {
+			/* Do nothing */
+		} else if (getnc_state->broken_samba_4_5_get_anc_emulation) {
+			LDB_TYPESAFE_QSORT(changes,
+					   getnc_state->num_records,
+					   getnc_state,
+					   site_res_cmp_anc_order);
+		} else {
+			LDB_TYPESAFE_QSORT(changes,
+					   getnc_state->num_records,
+					   getnc_state,
+					   site_res_cmp_usn_order);
+		}
+
+		for (i=0; i < getnc_state->num_records; i++) {
+			getnc_state->guids[i] = changes[i].guid;
+			if (GUID_all_zero(&getnc_state->guids[i])) {
+				DEBUG(2,("getncchanges: bad objectGUID from %s\n",
+					 ldb_dn_get_linearized(search_res->msgs[i]->dn)));
+				return WERR_DS_DRA_INTERNAL_ERROR;
+			}
+		}
+
+		getnc_state->final_hwm.tmp_highest_usn = getnc_state->max_usn;
+		getnc_state->final_hwm.reserved_usn = 0;
+		getnc_state->final_hwm.highest_usn = getnc_state->max_usn;
+
+		talloc_free(search_res);
+		talloc_free(changes);
+
+		/*
+		 * when using GET_ANC or GET_TGT, cache the objects that have
+		 * been already sent, to avoid sending them multiple times
+		 */
+		if (getnc_state->is_get_anc || getnc_state->is_get_tgt) {
+			DEBUG(3,("Using object cache, GET_ANC %u, GET_TGT %u\n",
+				 getnc_state->is_get_anc,
+				 getnc_state->is_get_tgt));
+
+			getnc_state->obj_cache = db_open_rbt(getnc_state);
+			if (getnc_state->obj_cache == NULL) {
+				return WERR_NOT_ENOUGH_MEMORY;
+			}
+		}
+	}
+
+	if (req10->uptodateness_vector) {
+		/* make sure its sorted */
+		TYPESAFE_QSORT(req10->uptodateness_vector->cursors,
+			       req10->uptodateness_vector->count,
+			       drsuapi_DsReplicaCursor_compare);
+	}
+
+	/* Prefix mapping */
+	schema = dsdb_get_schema(sam_ctx, mem_ctx);
+	if (!schema) {
+		DEBUG(0,("No schema in sam_ctx\n"));
+		return WERR_DS_DRA_INTERNAL_ERROR;
+	}
+
+	r->out.ctr->ctr6.naming_context = talloc(mem_ctx, struct drsuapi_DsReplicaObjectIdentifier);
+	if (r->out.ctr->ctr6.naming_context == NULL) {
+		return WERR_NOT_ENOUGH_MEMORY;
+	}
+
+	/*
+	 * Match Windows and echo back the original values from the request, even if
+	 * they say DummyDN for the string NC
+	 */
+	*r->out.ctr->ctr6.naming_context = *untrusted_ncRoot;
+
+	/* find the SID if there is one */
+	dsdb_find_sid_by_dn(sam_ctx, getnc_state->ncRoot_dn, &r->out.ctr->ctr6.naming_context->sid);
+
+	/* Set GUID */
+	r->out.ctr->ctr6.naming_context->guid = getnc_state->ncRoot_guid;
+
+	dsdb_get_oid_mappings_drsuapi(schema, true, mem_ctx, &ctr);
+	r->out.ctr->ctr6.mapping_ctr = *ctr;
+
+	r->out.ctr->ctr6.source_dsa_guid = *(samdb_ntds_objectGUID(sam_ctx));
+	r->out.ctr->ctr6.source_dsa_invocation_id = *(samdb_ntds_invocation_id(sam_ctx));
+
+	r->out.ctr->ctr6.old_highwatermark = req10->highwatermark;
+	r->out.ctr->ctr6.new_highwatermark = req10->highwatermark;
+
+	/*
+	 * If the client has already set GET_TGT then we know they can handle
+	 * receiving the linked attributes interleaved with the source objects
+	 */
+	if (getnc_state->is_get_tgt) {
+		repl_chunk->immediate_link_sync = true;
+	}
+
+	if (req10->partial_attribute_set != NULL) {
+		struct dsdb_syntax_ctx syntax_ctx;
+		uint32_t j = 0;
+
+		dsdb_syntax_ctx_init(&syntax_ctx, sam_ctx, schema);
+		syntax_ctx.pfm_remote = pfm_remote;
+
+		local_pas = talloc_array(b_state, uint32_t, req10->partial_attribute_set->num_attids);
+
+		for (j = 0; j < req10->partial_attribute_set->num_attids; j++) {
+			getncchanges_attid_remote_to_local(schema,
+							   &syntax_ctx,
+							   req10->partial_attribute_set->attids[j],
+							   (enum drsuapi_DsAttributeId *)&local_pas[j],
+							   NULL);
+		}
+
+		TYPESAFE_QSORT(local_pas,
+			       req10->partial_attribute_set->num_attids,
+			       uint32_t_ptr_cmp);
+	}
+
+	/*
+	 * If we have the NC root in this replication, send it
+	 * first regardless.  However, don't bump the USN now,
+	 * treat it as if it was sent early due to GET_ANC
+	 *
+	 * This is triggered for each call, so every page of responses
+	 * gets the NC root as the first object, up to the point where
+	 * it naturally occurs in the replication.
+	 */
+
+	if (getnc_state->send_nc_root_first) {
+		struct drsuapi_DsReplicaObjectListItemEx *new_objs = NULL;
+
+		werr = getncchanges_add_ancestors(&getnc_state->ncRoot_guid,
+						  NULL, mem_ctx,
+						  sam_ctx, getnc_state,
+						  schema, &session_key,
+						  req10, local_pas,
+						  machine_dn, &new_objs);
+
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+
+		getncchanges_chunk_add_objects(repl_chunk, new_objs);
+
+		DEBUG(8,(__location__ ": replicating NC root %s\n",
+			 ldb_dn_get_linearized(getnc_state->ncRoot_dn)));
+	}
+
+	/*
+	 * Check in case we're still processing the links from an object in the
+	 * previous chunk. We want to send the links (and any targets needed)
+	 * before moving on to the next object.
+	 */
+	if (getnc_state->is_get_tgt) {
+		werr = getncchanges_chunk_add_la_targets(repl_chunk,
+							 getnc_state,
+							 getnc_state->la_idx,
+							 mem_ctx, sam_ctx,
+							 schema, &session_key,
+							 req10, local_pas,
+							 machine_dn);
+
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+	}
+
+	for (i=getnc_state->num_processed;
+	     i<getnc_state->num_records &&
+		     !getncchanges_chunk_is_full(repl_chunk, getnc_state);
+	    i++) {
+		struct drsuapi_DsReplicaObjectListItemEx *new_objs = NULL;
+		struct ldb_message *msg;
+		static const char * const msg_attrs[] = {
+					    "*",
+					    "nTSecurityDescriptor",
+					    "parentGUID",
+					    "replPropertyMetaData",
+					    DSDB_SECRET_ATTRIBUTES,
+					    NULL };
+		struct ldb_result *msg_res;
+		struct ldb_dn *msg_dn;
+		bool obj_already_sent = false;
+		TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
+		uint32_t old_la_index;
+
+		/*
+		 * Once we get to the 'natural' place to send the NC
+		 * root, stop sending it at the front of each reply
+		 * and make sure to suppress sending it now
+		 *
+		 * We don't just 'continue' here as we must send links
+		 * and unlike Windows we want to update the
+		 * tmp_highest_usn
+		 */
+
+		if (getnc_state->send_nc_root_first &&
+		    GUID_equal(&getnc_state->guids[i], &getnc_state->ncRoot_guid))
+		{
+			getnc_state->send_nc_root_first = false;
+			obj_already_sent = true;
+		}
+
+		msg_dn = ldb_dn_new_fmt(tmp_ctx, sam_ctx, "<GUID=%s>",
+					GUID_string(tmp_ctx, &getnc_state->guids[i]));
+		W_ERROR_HAVE_NO_MEMORY(msg_dn);
+
+		/*
+		 * by re-searching here we avoid having a lot of full
+		 * records in memory between calls to getncchanges.
+		 *
+		 * We expect that we may get some objects that vanish
+		 * (tombstone expunge) between the first and second
+		 * check.
+		 */
+		ret = drsuapi_search_with_extended_dn(sam_ctx, tmp_ctx, &msg_res,
+						      msg_dn,
+						      LDB_SCOPE_BASE, msg_attrs, NULL);
+		if (ret != LDB_SUCCESS) {
+			if (ret != LDB_ERR_NO_SUCH_OBJECT) {
+				DEBUG(1,("getncchanges: failed to fetch DN %s - %s\n",
+					 ldb_dn_get_extended_linearized(tmp_ctx, msg_dn, 1),
+					 ldb_errstring(sam_ctx)));
+			}
+			TALLOC_FREE(tmp_ctx);
+			continue;
+		}
+
+		if (msg_res->count == 0) {
+			DEBUG(1,("getncchanges: got LDB_SUCCESS but failed"
+				 "to get any results in fetch of DN "
+				 "%s (race with tombstone expunge?)\n",
+				 ldb_dn_get_extended_linearized(tmp_ctx,
+								msg_dn, 1)));
+			TALLOC_FREE(tmp_ctx);
+			continue;
+		}
+
+		msg = msg_res->msgs[0];
+
+		/*
+		 * Check if we've already sent the object as an ancestor of
+		 * another object. If so, we don't need to send it again
+		 */
+		if (getnc_state->obj_cache != NULL) {
+			werr = dcesrv_drsuapi_obj_cache_exists(getnc_state->obj_cache,
+							       &getnc_state->guids[i]);
+			if (W_ERROR_EQUAL(werr, WERR_OBJECT_NAME_EXISTS)) {
+				obj_already_sent = true;
+			}
+		}
+
+		if (!obj_already_sent) {
+			bool max_wait_reached;
+
+			max_wait_reached = getncchanges_chunk_timed_out(repl_chunk);
+
+			/*
+			 * Construct an object, ready to send (this will include
+			 * the object's ancestors as well, if needed)
+			 */
+			werr = getncchanges_get_obj_to_send(msg, mem_ctx, sam_ctx,
+							    getnc_state, schema,
+							    &session_key, req10,
+							    max_wait_reached,
+							    local_pas, machine_dn,
+							    &getnc_state->guids[i],
+							    &new_objs);
+			if (!W_ERROR_IS_OK(werr)) {
+				return werr;
+			}
+		}
+
+		old_la_index = getnc_state->la_count;
+
+		/*
+		 * We've reached the USN where this object naturally occurs.
+		 * Regardless of whether we've already sent the object (as an
+		 * ancestor), we add its links and update the HWM at this point
+		 */
+		werr = get_nc_changes_add_links(sam_ctx, getnc_state,
+						getnc_state->is_schema_nc,
+						schema, getnc_state->min_usn,
+						req10->replica_flags,
+						msg,
+						&getnc_state->la_list,
+						&getnc_state->la_count,
+						req10->uptodateness_vector);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+
+		dcesrv_drsuapi_update_highwatermark(msg,
+					getnc_state->max_usn,
+					&r->out.ctr->ctr6.new_highwatermark);
+
+		if (new_objs != NULL) {
+
+			/*
+			 * Add the object (and, if GET_ANC, any parents it may
+			 * have) into the current chunk of replication data
+			 */
+			getncchanges_chunk_add_objects(repl_chunk, new_objs);
+
+			talloc_free(getnc_state->last_dn);
+			/*
+			 * talloc_steal() as we still need msg->dn to
+			 * be a valid pointer for the log on the next
+			 * line.
+			 *
+			 * msg only remains in scope for the next 25
+			 * lines or so anyway.
+			 */
+			getnc_state->last_dn = talloc_steal(getnc_state, msg->dn);
+		}
+
+		DEBUG(8,(__location__ ": %s object %s new tmp_highest_usn=%" PRIu64 "\n",
+			 new_objs ? "replicating" : "skipping send of",
+			 ldb_dn_get_linearized(msg->dn),
+			 r->out.ctr->ctr6.new_highwatermark.tmp_highest_usn));
+
+		getnc_state->total_links += (getnc_state->la_count - old_la_index);
+
+		/*
+		 * If the GET_TGT flag was set, check any new links added to
+		 * make sure the client knows about the link target object
+		 */
+		if (getnc_state->is_get_tgt) {
+			werr = getncchanges_chunk_add_la_targets(repl_chunk,
+								 getnc_state,
+								 old_la_index,
+								 mem_ctx, sam_ctx,
+								 schema, &session_key,
+								 req10, local_pas,
+								 machine_dn);
+
+			if (!W_ERROR_IS_OK(werr)) {
+				return werr;
+			}
+		}
+
+		TALLOC_FREE(tmp_ctx);
+	}
+
+	/* copy the constructed object list into the response message */
+	r->out.ctr->ctr6.object_count = repl_chunk->object_count;
+	r->out.ctr->ctr6.first_object = repl_chunk->object_list;
+
+	getnc_state->num_processed = i;
+
+	if (i < getnc_state->num_records) {
+		r->out.ctr->ctr6.more_data = true;
+	}
+
+	/* the client can us to call UpdateRefs on its behalf to
+	   re-establish monitoring of the NC */
+	if ((req10->replica_flags & (DRSUAPI_DRS_ADD_REF | DRSUAPI_DRS_REF_GCSPN)) &&
+	    !GUID_all_zero(&req10->destination_dsa_guid)) {
+		struct drsuapi_DsReplicaUpdateRefsRequest1 ureq;
+		DEBUG(3,("UpdateRefs on getncchanges for %s\n",
+			 GUID_string(mem_ctx, &req10->destination_dsa_guid)));
+
+		/*
+		 * We pass the pre-validation NC root here as
+		 * drsuapi_UpdateRefs() has to check its own input
+		 * values due to being called from
+		 * dcesrv_drsuapi_DsReplicaUpdateRefs()
+		 */
+
+		ureq.naming_context = untrusted_ncRoot;
+		ureq.dest_dsa_dns_name = samdb_ntds_msdcs_dns_name(sam_ctx, mem_ctx,
+								   &req10->destination_dsa_guid);
+		if (!ureq.dest_dsa_dns_name) {
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+		ureq.dest_dsa_guid = req10->destination_dsa_guid;
+		ureq.options = DRSUAPI_DRS_ADD_REF |
+			DRSUAPI_DRS_ASYNC_OP |
+			DRSUAPI_DRS_GETCHG_CHECK;
+
+		/* we also need to pass through the
+		   DRSUAPI_DRS_REF_GCSPN bit so that repsTo gets flagged
+		   to send notifies using the GC SPN */
+		ureq.options |= (req10->replica_flags & DRSUAPI_DRS_REF_GCSPN);
+
+		werr = drsuapi_UpdateRefs(imsg_ctx,
+					  dce_call->event_ctx,
+					  b_state,
+					  mem_ctx,
+					  &ureq);
+		if (!W_ERROR_IS_OK(werr)) {
+			DEBUG(0,(__location__ ": Failed UpdateRefs on %s for %s in DsGetNCChanges - %s\n",
+				 drs_ObjectIdentifier_to_debug_string(mem_ctx, untrusted_ncRoot),
+				 ureq.dest_dsa_dns_name,
+				 win_errstr(werr)));
+		}
+	}
+
+	/*
+	 * Work out how many links we can send in this chunk. The default is to
+	 * send all the links last, but there is a config option to send them
+	 * immediately, in the same chunk as their source object
+	 */
+	if (!r->out.ctr->ctr6.more_data || repl_chunk->immediate_link_sync) {
+		link_count = getncchanges_chunk_links_pending(repl_chunk,
+							      getnc_state);
+		link_count = MIN(link_count,
+				 getncchanges_chunk_max_links(repl_chunk));
+	}
+
+	/* If we've got linked attributes to send, add them now */
+	if (link_count > 0) {
+		struct la_for_sorting *la_sorted;
+
+		/*
+		 * Grab a chunk of linked attributes off the list and put them
+		 * in sorted array, ready to send
+		 */
+		werr = getncchanges_get_sorted_array(&getnc_state->la_list[getnc_state->la_idx],
+						     link_count,
+						     sam_ctx, getnc_state,
+						     schema,
+						     &la_sorted);
+		if (!W_ERROR_IS_OK(werr)) {
+			return werr;
+		}
+
+		r->out.ctr->ctr6.linked_attributes_count = link_count;
+		r->out.ctr->ctr6.linked_attributes = talloc_array(r->out.ctr, struct drsuapi_DsReplicaLinkedAttribute, link_count);
+		if (r->out.ctr->ctr6.linked_attributes == NULL) {
+			DEBUG(0, ("Out of memory allocating %u linked attributes for output", link_count));
+			return WERR_NOT_ENOUGH_MEMORY;
+		}
+
+		for (k = 0; k < link_count; k++) {
+			r->out.ctr->ctr6.linked_attributes[k] = *la_sorted[k].link;
+		}
+
+		getnc_state->la_idx += link_count;
+		getnc_state->links_given += link_count;
+
+		if (getnc_state->la_idx < getnc_state->la_count) {
+			r->out.ctr->ctr6.more_data = true;
+		} else {
+
+			/*
+			 * We've now sent all the links seen so far, so we can
+			 * reset la_list back to an empty list again. Note that
+			 * the steal means the linked attribute memory gets
+			 * freed after this RPC message is sent on the wire.
+			 */
+			talloc_steal(mem_ctx, getnc_state->la_list);
+			getnc_state->la_list = NULL;
+			getnc_state->la_idx = 0;
+			getnc_state->la_count = 0;
+		}
+
+		TALLOC_FREE(la_sorted);
+	}
+
+	if (req10->replica_flags & DRSUAPI_DRS_GET_NC_SIZE) {
+		/*
+		 * TODO: This implementation is wrong
+		 * we should find out the total number of
+		 * objects and links in the whole naming context
+		 * at the start of the cycle and return these
+		 * values in each message.
+		 *
+		 * For now we keep our current strategy and return
+		 * the number of objects for this cycle and the number
+		 * of links we found so far during the cycle.
+		 */
+		r->out.ctr->ctr6.nc_object_count = getnc_state->num_records;
+		r->out.ctr->ctr6.nc_linked_attributes_count = getnc_state->total_links;
+	}
+
+	if (req10->extended_op != DRSUAPI_EXOP_NONE) {
+		r->out.ctr->ctr6.uptodateness_vector = NULL;
+		r->out.ctr->ctr6.nc_object_count = 0;
+		ZERO_STRUCT(r->out.ctr->ctr6.new_highwatermark);
+	} else if (!r->out.ctr->ctr6.more_data) {
+
+		/* this is the last response in the replication cycle */
+		r->out.ctr->ctr6.new_highwatermark = getnc_state->final_hwm;
+		r->out.ctr->ctr6.uptodateness_vector = talloc_move(mem_ctx,
+								   &getnc_state->final_udv);
+
+		/*
+		 * Free the state info stored for the replication cycle. Note
+		 * that the RPC message we're sending contains links stored in
+		 * getnc_state. mem_ctx is local to this RPC call, so the memory
+		 * will get freed after the RPC message is sent on the wire.
+		 *
+		 * We must not do this for an EXOP, as that should not
+		 * end the replication state, which is why that is
+		 * checked first above.
+		 */
+		talloc_steal(mem_ctx, getnc_state);
+		b_state->getncchanges_full_repl_state = NULL;
+	} else {
+		ret = drsuapi_DsReplicaHighWaterMark_cmp(&r->out.ctr->ctr6.old_highwatermark,
+							 &r->out.ctr->ctr6.new_highwatermark);
+		if (ret == 0) {
+			/*
+			 * We need to make sure that we never return the
+			 * same highwatermark within the same replication
+			 * cycle more than once. Otherwise we cannot detect
+			 * when the client uses an unexptected highwatermark.
+			 *
+			 * This is a HACK which is needed because our
+			 * object ordering is wrong and set tmp_highest_usn
+			 * to a value that is higher than what we already
+			 * sent to the client (destination dsa).
+			 */
+			r->out.ctr->ctr6.new_highwatermark.reserved_usn += 1;
+		}
+
+		getnc_state->last_hwm = r->out.ctr->ctr6.new_highwatermark;
+	}
+
+	TALLOC_FREE(repl_chunk);
+
+	DEBUG(r->out.ctr->ctr6.more_data?4:2,
+	      ("DsGetNCChanges with uSNChanged >= %llu flags 0x%08x on %s gave %u objects (done %u/%u) %u links (done %u/%u (as %s))\n",
+	       (unsigned long long)(req10->highwatermark.highest_usn+1),
+	       req10->replica_flags,
+	       drs_ObjectIdentifier_to_debug_string(mem_ctx, untrusted_ncRoot),
+	       r->out.ctr->ctr6.object_count,
+	       i, r->out.ctr->ctr6.more_data?getnc_state->num_records:i,
+	       r->out.ctr->ctr6.linked_attributes_count,
+	       getnc_state->links_given, getnc_state->total_links,
+	       dom_sid_string(mem_ctx, user_sid)));
+
+#if 0
+	if (!r->out.ctr->ctr6.more_data && req10->extended_op != DRSUAPI_EXOP_NONE) {
+		NDR_PRINT_FUNCTION_DEBUG(drsuapi_DsGetNCChanges, NDR_BOTH, r);
+	}
+#endif
+
+	return WERR_OK;
+}
+