s4:rpc_server/drsuapi: make use dcesrv_call_session_info()
[samba.git] / source4 / rpc_server / drsuapi / getncchanges.c
index f65fa2c0949e1d28d705924b1674d5f1bd3272cb..f3f819a410e786e7ebedc7153dd82d92e8f14ddf 100644 (file)
@@ -4,8 +4,9 @@
    implement the DSGetNCChanges call
 
    Copyright (C) Anatoliy Atanasov 2009
-   Copyright (C) Andrew Tridgell 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
 #include "libcli/security/session.h"
 #include "rpc_server/drsuapi/dcesrv_drsuapi.h"
 #include "rpc_server/dcerpc_server_proto.h"
+#include "rpc_server/common/sid_helper.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 is_get_tgt;
+       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,
-                                                                      struct ldb_message *msg)
+                                                                      const struct ldb_message *msg)
 {
        struct drsuapi_DsReplicaObjectIdentifier *identifier;
        struct dom_sid *sid;
@@ -77,66 +165,351 @@ static bool udv_filter(const struct drsuapi_DsReplicaCursorCtrEx *udv,
 {
        const struct drsuapi_DsReplicaCursor *c;
        if (udv == NULL) return false;
-       BINARY_ARRAY_SEARCH(udv->cursors, udv->count, source_dsa_invocation_id, 
+       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 attid_cmp(enum drsuapi_DsAttributeId a1, enum drsuapi_DsAttributeId a2)
+static int uint32_t_cmp(uint32_t a1, uint32_t a2)
 {
        if (a1 == a2) return 0;
-       return ((uint32_t)a1) > ((uint32_t)a2) ? 1 : -1;
+       return a1 > a2 ? 1 : -1;
+}
+
+static int uint32_t_ptr_cmp(uint32_t *a1, uint32_t *a2, void *unused)
+{
+       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;
+       }
 }
 
 /*
-  check if an attribute is in a partial_attribute_set
+ * Similar to function in repl_meta_data without the extra
+ * dependencies.
  */
-static bool check_partial_attribute_set(const struct dsdb_attribute *sa,
-                                       struct drsuapi_DsPartialAttributeSet *pas)
+static WERROR get_parsed_dns_trusted(TALLOC_CTX *mem_ctx, struct ldb_message_element *el,
+                                 struct parsed_dn **pdn)
+{
+       /* Here we get a list of 'struct parsed_dns' without the parsing */
+       int i;
+       *pdn = talloc_zero_array(mem_ctx, struct parsed_dn,
+                                el->num_values);
+       if (!*pdn) {
+               return WERR_DS_DRA_INTERNAL_ERROR;
+       }
+
+       for (i = 0; i < el->num_values; i++) {
+               (*pdn)[i].v = &el->values[i];
+       }
+
+       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 drsuapi_DsAttributeId *result;
-       BINARY_ARRAY_SEARCH_V(pas->attids, pas->num_attids, (enum drsuapi_DsAttributeId)sa->attributeID_id,
-                             attid_cmp, result);
-       return result != NULL;
+       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;
+               WERROR werr;
+               uint8_t attid[4];
+               DATA_BLOB partial_meta;
+
+               werr = get_parsed_dns_trusted(mem_ctx, existing, &link_dns);
+               if (!W_ERROR_IS_OK(werr)) {
+                       return werr;
+               }
+
+               /* 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,
-                                         struct ldb_message *msg,
+                                         const struct ldb_message *msg,
                                          struct ldb_context *sam_ctx,
-                                         struct ldb_dn *ncRoot_dn,
-                                         bool   is_schema_nc,
+                                         struct drsuapi_getncchanges_state *getnc_state,
                                          struct dsdb_schema *schema,
                                          DATA_BLOB *session_key,
-                                         uint64_t highest_usn,
-                                         uint32_t replica_flags,
-                                         struct drsuapi_DsPartialAttributeSet *partial_attribute_set,
-                                         struct drsuapi_DsReplicaCursorCtrEx *uptodateness_vector,
-                                         enum drsuapi_DsExtendedOperation extended_op,
-                                         bool force_object_return)
+                                         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;
@@ -155,7 +528,7 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
                }
        }
        obj->next_object = NULL;
-       
+
        md_value = ldb_msg_find_ldb_val(msg, "replPropertyMetaData");
        if (!md_value) {
                /* nothing to send */
@@ -167,12 +540,17 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
                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;
        }
@@ -185,7 +563,7 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
 
        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", 
+               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;
        }
@@ -195,68 +573,84 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
 
        obj->object.identifier = get_object_identifier(obj, msg);
        if (obj->object.identifier == NULL) {
-               return WERR_NOMEM;
+               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);
-       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 &&
-                   extended_op != DRSUAPI_EXOP_REPL_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;
+       obj->meta_data_ctr->meta_data = talloc_array(obj, struct drsuapi_DsReplicaMetaData, md.ctr.ctr1.count);
 
-               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 (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;
 
-               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;
-                       }
+               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;
                }
 
-               if (extended_op == DRSUAPI_EXOP_REPL_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)));
+               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;
                }
 
-               /* 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;
+               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;
                }
 
-               /* filter by partial_attribute_set */
-               if (partial_attribute_set && !check_partial_attribute_set(sa, partial_attribute_set)) {
-                       continue;
+               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;
+                       }
                }
 
-               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++;
+               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
@@ -284,7 +678,7 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
        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_NOMEM;
+               return WERR_NOT_ENOUGH_MEMORY;
        }
 
        /*
@@ -293,9 +687,8 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
         */
        for (i=0; i<obj->object.attribute_ctr.num_attributes; i++) {
                struct ldb_message_element *el;
-               WERROR werr;
                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]));
@@ -314,8 +707,9 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
                        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 to DRS object - %s\n", 
-                                        sa->lDAPDisplayName, win_errstr(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
@@ -330,11 +724,22 @@ static WERROR get_nc_changes_build_object(struct drsuapi_DsReplicaObjectListItem
                        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 in DRS object - %s\n", 
-                                        sa->lDAPDisplayName, win_errstr(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;
@@ -348,10 +753,11 @@ 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,
-                                   struct ldb_message *msg,
+                                   const struct ldb_message *msg,
                                    struct dsdb_dn *dsdb_dn,
                                    struct drsuapi_DsReplicaLinkedAttribute **la_list,
-                                   uint32_t *la_count)
+                                   uint32_t *la_count,
+                                   bool is_schema_nc)
 {
        struct drsuapi_DsReplicaLinkedAttribute *la;
        bool active;
@@ -411,7 +817,7 @@ static WERROR get_nc_changes_add_la(TALLOC_CTX *mem_ctx,
                                sa->lDAPDisplayName, ldb_dn_get_linearized(msg->dn)));
                        return ntstatus_to_werror(status);
                }
-               ret = dsdb_find_dn_by_guid(sam_ctx, mem_ctx, &guid, &tdn);
+               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)));
@@ -423,7 +829,7 @@ static WERROR get_nc_changes_add_la(TALLOC_CTX *mem_ctx,
                        return WERR_OK;
                }
        }
-       la->attid = sa->attributeID_id;
+       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");
@@ -471,18 +877,34 @@ static WERROR get_nc_changes_add_la(TALLOC_CTX *mem_ctx,
  */
 static WERROR get_nc_changes_add_links(struct ldb_context *sam_ctx,
                                       TALLOC_CTX *mem_ctx,
-                                      struct ldb_dn *ncRoot_dn,
+                                      bool is_schema_nc,
                                       struct dsdb_schema *schema,
                                       uint64_t highest_usn,
                                       uint32_t replica_flags,
-                                      struct ldb_message *msg,
+                                      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 = talloc_new(mem_ctx);
-       uint64_t uSNChanged = ldb_msg_find_attr_as_int(msg, "uSNChanged", -1);
+       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];
@@ -505,8 +927,10 @@ static WERROR get_nc_changes_add_links(struct ldb_context *sam_ctx,
                for (j=0; j<el->num_values; j++) {
                        struct dsdb_dn *dsdb_dn;
                        uint64_t local_usn;
-                       NTSTATUS status;
+                       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) {
@@ -531,12 +955,28 @@ static WERROR get_nc_changes_add_links(struct ldb_context *sam_ctx,
                                return WERR_DS_DRA_INTERNAL_ERROR;
                        }
 
-                       if (local_usn < highest_usn) {
+                       if (local_usn <= highest_usn) {
                                continue;
                        }
 
-                       werr = get_nc_changes_add_la(mem_ctx, sam_ctx, schema, sa, msg,
-                                                    dsdb_dn, la_list, la_count);
+                       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;
@@ -567,75 +1007,36 @@ static WERROR get_nc_changes_udv(struct ldb_context *sam_ctx,
                         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 drsuapi_DsReplicaLinkedAttribute *la1,
-                                   const struct drsuapi_DsReplicaLinkedAttribute *la2,
-                                   struct ldb_context *sam_ctx)
+static int linked_attribute_compare(const struct la_for_sorting *la1,
+                                   const struct la_for_sorting *la2,
+                                   void *opaque)
 {
        int c;
-       WERROR werr;
-       TALLOC_CTX *tmp_ctx;
-       const struct dsdb_schema *schema;
-       const struct dsdb_attribute *schema_attrib;
-       struct dsdb_dn *dn1, *dn2;
-       struct GUID guid1, guid2;
-       NTSTATUS status;
-
-       c = GUID_compare(&la1->identifier->guid,
-                        &la2->identifier->guid);
-       if (c != 0) return c;
-
-       if (la1->attid != la2->attid) {
-               return la1->attid < la2->attid? -1:1;
-       }
-
-       if ((la1->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE) !=
-           (la2->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)) {
-               return (la1->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)? 1:-1;
-       }
-
-       /* we need to get the target GUIDs to compare */
-       tmp_ctx = talloc_new(sam_ctx);
-
-       schema = dsdb_get_schema(sam_ctx, tmp_ctx);
-       schema_attrib = dsdb_attribute_by_attributeID_id(schema, la1->attid);
-
-       werr = dsdb_dn_la_from_blob(sam_ctx, schema_attrib, schema, tmp_ctx, la1->value.blob, &dn1);
-       if (!W_ERROR_IS_OK(werr)) {
-               DEBUG(0,(__location__ ": Bad la1 blob in sort\n"));
-               talloc_free(tmp_ctx);
-               return 0;
+       c = memcmp(la1->source_guid,
+                  la2->source_guid, sizeof(la2->source_guid));
+       if (c != 0) {
+               return c;
        }
 
-       werr = dsdb_dn_la_from_blob(sam_ctx, schema_attrib, schema, tmp_ctx, la2->value.blob, &dn2);
-       if (!W_ERROR_IS_OK(werr)) {
-               DEBUG(0,(__location__ ": Bad la2 blob in sort\n"));
-               talloc_free(tmp_ctx);
-               return 0;
+       if (la1->link->attid != la2->link->attid) {
+               return la1->link->attid < la2->link->attid? -1:1;
        }
 
-       status = dsdb_get_extended_dn_guid(dn1->dn, &guid1, "GUID");
-       if (!NT_STATUS_IS_OK(status)) {
-               DEBUG(0,(__location__ ": Bad la1 guid in sort\n"));
-               talloc_free(tmp_ctx);
-               return 0;
-       }
-       status = dsdb_get_extended_dn_guid(dn2->dn, &guid2, "GUID");
-       if (!NT_STATUS_IS_OK(status)) {
-               DEBUG(0,(__location__ ": Bad la2 guid in sort\n"));
-               talloc_free(tmp_ctx);
-               return 0;
+       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;
        }
 
-       talloc_free(tmp_ctx);
-
-       return GUID_compare(&guid1, &guid2);
+       return memcmp(la1->target_guid,
+                     la2->target_guid, sizeof(la2->target_guid));
 }
 
 struct drsuapi_changed_objects {
@@ -644,35 +1045,34 @@ struct drsuapi_changed_objects {
        uint64_t usn;
 };
 
-/*
-  sort the objects we send by tree order
- */
-static int site_res_cmp_parent_order(struct drsuapi_changed_objects *m1,
-                                       struct drsuapi_changed_objects *m2)
-{
-       return ldb_dn_compare(m2->dn, m1->dn);
-}
-
 /*
   sort the objects we send first by uSNChanged
  */
-static int site_res_cmp_dn_usn_order(struct drsuapi_changed_objects *m1,
-                                       struct drsuapi_changed_objects *m2)
+static int site_res_cmp_usn_order(struct drsuapi_changed_objects *m1,
+                                 struct drsuapi_changed_objects *m2,
+                                 struct drsuapi_getncchanges_state *getnc_state)
 {
-       unsigned usnchanged1, usnchanged2;
-       unsigned cn1, cn2;
+       int ret;
 
-       cn1 = ldb_dn_get_comp_num(m1->dn);
-       cn2 = ldb_dn_get_comp_num(m2->dn);
-       if (cn1 != cn2) {
-               return cn1 > cn2 ? 1 : -1;
+       ret = ldb_dn_compare(getnc_state->ncRoot_dn, m1->dn);
+       if (ret == 0) {
+               return -1;
        }
-       usnchanged1 = m1->usn;
-       usnchanged2 = m2->usn;
-       if (usnchanged1 == usnchanged2) {
-               return 0;
+
+       ret = ldb_dn_compare(getnc_state->ncRoot_dn, m2->dn);
+       if (ret == 0) {
+               return 1;
+       }
+
+       if (m1->usn == m2->usn) {
+               return ldb_dn_compare(m2->dn, m1->dn);
+       }
+
+       if (m1->usn < m2->usn) {
+               return -1;
        }
-       return usnchanged1 > usnchanged2 ? 1 : -1;
+
+       return 1;
 }
 
 
@@ -682,9 +1082,10 @@ static int site_res_cmp_dn_usn_order(struct drsuapi_changed_objects *m1,
 static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
                                     TALLOC_CTX *mem_ctx,
                                     struct drsuapi_DsGetNCChangesRequest10 *req10,
-                                    struct drsuapi_DsGetNCChangesCtr6 *ctr6)
+                                    struct drsuapi_DsGetNCChangesCtr6 *ctr6,
+                                    struct ldb_dn **rid_manager_dn)
 {
-       struct ldb_dn *rid_manager_dn, *req_dn;
+       struct ldb_dn *req_dn, *ntds_dn = NULL;
        int ret;
        struct ldb_context *ldb = b_state->sam_ctx;
        struct ldb_result *ext_res;
@@ -697,8 +1098,8 @@ static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
            - verify that we are the RID Manager
         */
 
-       /* work out who is the RID Manager */
-       ret = samdb_rid_manager_dn(ldb, mem_ctx, &rid_manager_dn);
+       /* 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;
@@ -706,7 +1107,7 @@ static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
 
        req_dn = drs_ObjectIdentifier_to_dn(mem_ctx, ldb, req10->naming_context);
        if (!ldb_dn_validate(req_dn) ||
-           ldb_dn_compare(req_dn, rid_manager_dn) != 0) {
+           ldb_dn_compare(req_dn, *rid_manager_dn) != 0) {
                /* that isn't the RID Manager DN */
                DEBUG(0,(__location__ ": RID Alloc request for wrong DN %s\n",
                         drs_ObjectIdentifier_to_string(mem_ctx, req10->naming_context)));
@@ -714,8 +1115,17 @@ static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
                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);
+       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;
@@ -742,15 +1152,6 @@ static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
                return WERR_DS_DRA_INTERNAL_ERROR;
        }
 
-       /*
-        * FIXME (kim): this is a temp hack to return just few object,
-        * but not the whole domain NC.
-        * We should remove this hack and implement a 'scope'
-        * building function to return just the set of object
-        * documented for DRSUAPI_EXOP_FSMO_RID_ALLOC extended_op
-        */
-       ldb_sequence_number(ldb, LDB_SEQ_HIGHEST_SEQ, &req10->highwatermark.highest_usn);
-
        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",
@@ -776,105 +1177,6 @@ static WERROR getncchanges_rid_alloc(struct drsuapi_bind_state *b_state,
        return WERR_OK;
 }
 
-/*
-  return an array of SIDs from a ldb_message given an attribute name
-  assumes the SIDs are in extended DN format
- */
-static WERROR samdb_result_sid_array_dn(struct ldb_context *sam_ctx,
-                                       struct ldb_message *msg,
-                                       TALLOC_CTX *mem_ctx,
-                                       const char *attr,
-                                       const struct dom_sid ***sids)
-{
-       struct ldb_message_element *el;
-       unsigned int i;
-
-       el = ldb_msg_find_element(msg, attr);
-       if (!el) {
-               *sids = NULL;
-               return WERR_OK;
-       }
-
-       (*sids) = talloc_array(mem_ctx, const struct dom_sid *, el->num_values + 1);
-       W_ERROR_HAVE_NO_MEMORY(*sids);
-
-       for (i=0; i<el->num_values; i++) {
-               struct ldb_dn *dn = ldb_dn_from_ldb_val(mem_ctx, sam_ctx, &el->values[i]);
-               NTSTATUS status;
-               struct dom_sid *sid;
-
-               sid = talloc(*sids, struct dom_sid);
-               W_ERROR_HAVE_NO_MEMORY(sid);
-               status = dsdb_get_extended_dn_sid(dn, sid, "SID");
-               if (!NT_STATUS_IS_OK(status)) {
-                       return WERR_INTERNAL_DB_CORRUPTION;
-               }
-               (*sids)[i] = sid;
-       }
-       (*sids)[i] = NULL;
-
-       return WERR_OK;
-}
-
-
-/*
-  return an array of SIDs from a ldb_message given an attribute name
-  assumes the SIDs are in NDR form
- */
-static WERROR samdb_result_sid_array_ndr(struct ldb_context *sam_ctx,
-                                        struct ldb_message *msg,
-                                        TALLOC_CTX *mem_ctx,
-                                        const char *attr,
-                                        const struct dom_sid ***sids)
-{
-       struct ldb_message_element *el;
-       unsigned int i;
-
-       el = ldb_msg_find_element(msg, attr);
-       if (!el) {
-               *sids = NULL;
-               return WERR_OK;
-       }
-
-       (*sids) = talloc_array(mem_ctx, const struct dom_sid *, el->num_values + 1);
-       W_ERROR_HAVE_NO_MEMORY(*sids);
-
-       for (i=0; i<el->num_values; i++) {
-               enum ndr_err_code ndr_err;
-               struct dom_sid *sid;
-
-               sid = talloc(*sids, struct dom_sid);
-               W_ERROR_HAVE_NO_MEMORY(sid);
-
-               ndr_err = ndr_pull_struct_blob(&el->values[i], sid, sid,
-                                              (ndr_pull_flags_fn_t)ndr_pull_dom_sid);
-               if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
-                       return WERR_INTERNAL_DB_CORRUPTION;
-               }
-               (*sids)[i] = sid;
-       }
-       (*sids)[i] = NULL;
-
-       return WERR_OK;
-}
-
-/*
-  see if any SIDs in list1 are in list2
- */
-static bool sid_list_match(const struct dom_sid **list1, const struct dom_sid **list2)
-{
-       unsigned int i, j;
-       /* do we ever have enough SIDs here to worry about O(n^2) ? */
-       for (i=0; list1[i]; i++) {
-               for (j=0; list2[j]; j++) {
-                       if (dom_sid_equal(list1[i], list2[j])) {
-                               return true;
-                       }
-               }
-       }
-       return false;
-}
-
 /*
   handle a DRSUAPI_EXOP_REPL_SECRET call
  */
@@ -882,22 +1184,28 @@ 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)
+                                      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, *rodc_dn, *krbtgt_link_dn;
+       struct ldb_dn *obj_dn = NULL;
+       struct ldb_dn *ntds_dn = NULL, *server_dn = NULL;
+       struct ldb_dn *rodc_dn, *krbtgt_link_dn;
        int ret;
-       const char *rodc_attrs[] = { "msDS-KrbTgtLink", "msDS-NeverRevealGroup", "msDS-RevealOnDemandGroup", NULL };
+       const char *rodc_attrs[] = { "msDS-KrbTgtLink", "msDS-NeverRevealGroup", "msDS-RevealOnDemandGroup", "objectGUID", NULL };
        const char *obj_attrs[] = { "tokenGroups", "objectSid", "UserAccountControl", "msDS-KrbTgtLinkBL", NULL };
-       struct ldb_result *rodc_res, *obj_res;
+       struct ldb_result *rodc_res = NULL, *obj_res = NULL;
        const struct dom_sid **never_reveal_sids, **reveal_sids, **token_sids;
+       const struct dom_sid *object_sid = NULL;
        WERROR werr;
+       const struct dom_sid *additional_sids[] = { NULL, NULL };
 
        DEBUG(3,(__location__ ": DRSUAPI_EXOP_REPL_SECRET extended op on %s\n",
                 drs_ObjectIdentifier_to_string(mem_ctx, ncRoot)));
 
        /*
-        * we need to work out if we will allow this RODC to
+        * 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
@@ -907,12 +1215,61 @@ static WERROR getncchanges_repl_secret(struct drsuapi_bind_state *b_state,
        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_SOURCE_DISABLED;
+               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 = dsdb_find_dn_by_guid(b_state->sam_ctx_system, mem_ctx,
+                                  &req10->destination_dsa_guid, 0,
+                                  &ntds_dn);
+       if (ret != LDB_SUCCESS) {
+               goto failed;
+       }
+
+       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 failed;
+       }
+
+       /*
+        * 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
+        */
        obj_dn = drs_ObjectIdentifier_to_dn(mem_ctx, b_state->sam_ctx_system, ncRoot);
        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;
@@ -926,11 +1283,21 @@ static WERROR getncchanges_repl_secret(struct drsuapi_bind_state *b_state,
        if (ret != LDB_SUCCESS || obj_res->count != 1) goto failed;
 
        /* if the object SID is equal to the user_sid, allow */
-       if (dom_sid_equal(user_sid,
-                         samdb_result_dom_sid(mem_ctx, obj_res->msgs[0], "objectSid"))) {
+       object_sid = samdb_result_dom_sid(mem_ctx, obj_res->msgs[0], "objectSid");
+       if (dom_sid_equal(user_sid, object_sid)) {
                goto allowed;
        }
 
+       additional_sids[0] = object_sid;
+
+       /*
+        * 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);
@@ -963,8 +1330,14 @@ static WERROR getncchanges_repl_secret(struct drsuapi_bind_state *b_state,
                goto denied;
        }
 
+       /*
+        * The SID list needs to include itself as well as the tokenGroups.
+        *
+        * TODO determine if sIDHistory is required for this check
+        */
        werr = samdb_result_sid_array_ndr(b_state->sam_ctx_system, obj_res->msgs[0],
-                                        mem_ctx, "tokenGroups", &token_sids);
+                                         mem_ctx, "tokenGroups", &token_sids,
+                                         additional_sids, 1);
        if (!W_ERROR_IS_OK(werr) || token_sids==NULL) {
                goto denied;
        }
@@ -981,26 +1354,26 @@ static WERROR getncchanges_repl_secret(struct drsuapi_bind_state *b_state,
 
        /* default deny */
 denied:
-       DEBUG(2,(__location__ ": Denied RODC secret replication for %s by RODC %s\n",
+       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_ACCESS_DENIED;
+       return WERR_DS_DRA_SECRETS_DENIED;
 
 allowed:
-       DEBUG(2,(__location__ ": Allowed RODC secret replication for %s by RODC %s\n",
-                ldb_dn_get_linearized(obj_dn), ldb_dn_get_linearized(rodc_res->msgs[0]->dn)));
+       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 RODC secret replication for %s by RODC %s\n",
+       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;
 }
 
-
 /*
   handle a DRSUAPI_EXOP_REPL_OBJ call
  */
@@ -1052,8 +1425,7 @@ static WERROR getncchanges_change_master(struct drsuapi_bind_state *b_state,
                return WERR_OK;
        }
 
-       /* retrieve the current role owner */
-       /* find the DN of the RID Manager */
+       /* 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"));
@@ -1062,8 +1434,8 @@ static WERROR getncchanges_change_master(struct drsuapi_bind_state *b_state,
        }
 
        if (!is_us) {
-               /* we're not the RID Manager - go away */
-               DEBUG(0,(__location__ ": RID Alloc request when not RID Manager\n"));
+               /* 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;
        }
@@ -1075,7 +1447,7 @@ static WERROR getncchanges_change_master(struct drsuapi_bind_state *b_state,
        W_ERROR_HAVE_NO_MEMORY(msg->dn);
 
        /* TODO: make sure ntds_dn is a valid nTDSDSA object */
-       ret = dsdb_find_dn_by_guid(ldb, msg, &req10->destination_dsa_guid, &ntds_dn);
+       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)));
@@ -1121,33 +1493,18 @@ static WERROR getncchanges_change_master(struct drsuapi_bind_state *b_state,
        return WERR_OK;
 }
 
-/* state of a partially completed getncchanges call */
-struct drsuapi_getncchanges_state {
-       struct GUID *guids;
-       uint32_t num_records;
-       uint32_t num_processed;
-       struct ldb_dn *ncRoot_dn;
-       bool is_schema_nc;
-       uint64_t min_usn;
-       uint64_t highest_usn;
-       struct ldb_dn *last_dn;
-       struct drsuapi_DsReplicaLinkedAttribute *la_list;
-       uint32_t la_count;
-       bool la_sorted;
-       uint32_t la_idx;
-       struct drsuapi_DsReplicaCursorCtrEx *uptodateness_vector;
-};
-
 /*
   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;
 
@@ -1181,14 +1538,24 @@ static WERROR dcesrv_drsuapi_is_reveal_secrets_request(struct drsuapi_bind_state
        }
 
        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;
-               sa = dsdb_attribute_by_attributeID_id(schema, req10->partial_attribute_set->attids[i]);
-               if (sa == NULL) {
-                       return WERR_DS_DRA_SCHEMA_MISMATCH;
+               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;
@@ -1199,10 +1566,18 @@ static WERROR dcesrv_drsuapi_is_reveal_secrets_request(struct drsuapi_bind_state
                /* check the extended attributes they asked for */
                for (i=0; i<req10->partial_attribute_set_ex->num_attids; i++) {
                        const struct dsdb_attribute *sa;
-                       sa = dsdb_attribute_by_attributeID_id(schema, req10->partial_attribute_set_ex->attids[i]);
-                       if (sa == NULL) {
-                               return WERR_DS_DRA_SCHEMA_MISMATCH;
+                       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;
@@ -1220,11 +1595,13 @@ static WERROR dcesrv_drsuapi_is_reveal_secrets_request(struct drsuapi_bind_state
  */
 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;
 
@@ -1249,14 +1626,24 @@ static WERROR dcesrv_drsuapi_is_gc_pas_request(struct drsuapi_bind_state *b_stat
        }
 
        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;
-               sa = dsdb_attribute_by_attributeID_id(schema, req10->partial_attribute_set->attids[i]);
-               if (sa == NULL) {
-                       return WERR_DS_DRA_SCHEMA_MISMATCH;
+               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;
@@ -1267,10 +1654,18 @@ static WERROR dcesrv_drsuapi_is_gc_pas_request(struct drsuapi_bind_state *b_stat
                /* check the extended attributes they asked for */
                for (i=0; i<req10->partial_attribute_set_ex->num_attids; i++) {
                        const struct dsdb_attribute *sa;
-                       sa = dsdb_attribute_by_attributeID_id(schema, req10->partial_attribute_set_ex->attids[i]);
-                       if (sa == NULL) {
-                               return WERR_DS_DRA_SCHEMA_MISMATCH;
+                       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;
@@ -1313,6 +1708,9 @@ getncchanges_map_req8(TALLOC_CTX *mem_ctx,
        return req10;
 }
 
+static const char *collect_objects_attrs[] = { "uSNChanged",
+                                              "objectGUID" ,
+                                              NULL };
 
 /**
  * Collects object for normal replication cycle.
@@ -1327,21 +1725,19 @@ static WERROR getncchanges_collect_objects(struct drsuapi_bind_state *b_state,
        int ret;
        char* search_filter;
        enum ldb_scope scope = LDB_SCOPE_SUBTREE;
-       //const char *extra_filter;
        struct drsuapi_getncchanges_state *getnc_state = b_state->getncchanges_state;
-       const char *attrs[] = { "uSNChanged",
-                               "objectGUID" ,
-                               NULL };
+       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;
        }
 
-       //extra_filter = lpcfg_parm_string(dce_call->conn->dce_ctx->lp_ctx, NULL, "drs", "object filter");
-
-       //getnc_state->min_usn = req10->highwatermark.highest_usn;
-
        /* Construct response. */
        search_filter = talloc_asprintf(mem_ctx,
                                        "(uSNChanged>=%llu)",
@@ -1351,7 +1747,7 @@ static WERROR getncchanges_collect_objects(struct drsuapi_bind_state *b_state,
                search_filter = talloc_asprintf(mem_ctx, "(&%s(%s))", search_filter, extra_filter);
        }
 
-       if (req10->replica_flags & DRSUAPI_DRS_CRITICAL_ONLY) {
+       if (critical_only) {
                search_filter = talloc_asprintf(mem_ctx,
                                                "(&%s(isCriticalSystemObject=TRUE))",
                                                search_filter);
@@ -1368,7 +1764,8 @@ static WERROR getncchanges_collect_objects(struct drsuapi_bind_state *b_state,
        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, attrs,
+                                             search_dn, scope,
+                                             collect_objects_attrs,
                                              search_filter);
        if (ret != LDB_SUCCESS) {
                return WERR_DS_DRA_INTERNAL_ERROR;
@@ -1393,132 +1790,1065 @@ static WERROR getncchanges_collect_objects_exop(struct drsuapi_bind_state *b_sta
                return WERR_OK;
        }
 
-       /* 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, req10, search_dn, extra_filter, search_res);
-}
+       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;
+               }
 
-/* 
-  drsuapi_DsGetNCChanges
+               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;
+               }
 
-  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 drsuapi_DsReplicaObjectIdentifier *ncRoot;
-       int ret;
-       uint32_t i;
-       struct dsdb_schema *schema;
-       struct drsuapi_DsReplicaOIDMapping_Ctr *ctr;
-       struct drsuapi_DsReplicaObjectListItemEx **currentObject;
-       NTSTATUS status;
-       DATA_BLOB session_key;
-       WERROR werr;
-       struct dcesrv_handle *h;
-       struct drsuapi_bind_state *b_state;     
-       struct drsuapi_getncchanges_state *getnc_state;
-       struct drsuapi_DsGetNCChangesRequest10 *req10;
-       uint32_t options;
-       uint32_t max_objects;
-       uint32_t max_links;
-       uint32_t link_count = 0;
-       uint32_t link_total = 0;
-       uint32_t link_given = 0;
-       struct ldb_dn *search_dn = NULL;
-       bool am_rodc, null_scope=false;
-       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;
-       time_t max_wait;
-       time_t start = time(NULL);
-       bool max_wait_reached = false;
+               /* Now extend it to the RID set */
 
-       DCESRV_PULL_HANDLE_WERR(h, r->in.bind_handle, DRSUAPI_BIND_HANDLE);
-       b_state = h->data;
+               /* Find the computer account DN for the destination
+                * dsa GUID specified */
 
-       sam_ctx = b_state->sam_ctx_system?b_state->sam_ctx_system:b_state->sam_ctx;
+               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;
+               }
 
-       *r->out.level_out = 6;
-       /* TODO: linked attributes*/
-       r->out.ctr->ctr6.linked_attributes_count = 0;
-       r->out.ctr->ctr6.linked_attributes = NULL;
+               server_dn = ldb_dn_get_parent(frame, ntds_dn);
+               if (!server_dn) {
+                       TALLOC_FREE(frame);
+                       return WERR_DS_DRA_INTERNAL_ERROR;
+               }
 
-       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;
+               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;
+               }
 
-       /* 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;
-       }
+               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;
+               }
 
-       /* Check request revision. 
-        */
-       switch (r->in.level) {
-       case 8:
-               req10 = getncchanges_map_req8(mem_ctx, &r->in.req->req8);
-               if (req10 == NULL) {
-                       return WERR_NOMEM;
+
+               /* 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;
                }
-               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;
-       }
 
+               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;
+               }
 
-        /* Perform access checks. */
-       /* TODO: we need to support a sync on a specific non-root
-        * DN. We'll need to find the real partition root here */
-       ncRoot = req10->naming_context;
-       if (ncRoot == NULL) {
-               DEBUG(0,(__location__ ": Request for DsGetNCChanges with no NC\n"));
-               return WERR_DS_DRA_INVALID_PARAMETER;
-       }
+               /* 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, 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);
+       }
+
+       LDB_TYPESAFE_QSORT(guid_array, link_count, NULL, 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(struct drsuapi_DsReplicaObjectListItemEx *child_obj,
+                                        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 = child_obj->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;
+
+               /*
+                * Don't send an object twice. (If we've sent the object, then
+                * we've also sent all its parents as well)
+                */
+               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
+                */
+               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.
+        */
+       if (getnc_state->is_get_anc) {
+               werr = getncchanges_add_ancestors(obj, 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 drsuapi_DsReplicaObjectIdentifier *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;
+       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;
+       }
+
+        /* Perform access checks. */
+       /* TODO: we need to support a sync on a specific non-root
+        * DN. We'll need to find the real partition root here */
+       ncRoot = req10->naming_context;
+       if (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 (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 = &dce_call->conn->auth_state.session_info->security_token->sids[PRIMARY_USER_SID_INDEX];
+       user_sid = &session_info->security_token->sids[PRIMARY_USER_SID_INDEX];
 
        /* all clients must have GUID_DRS_GET_CHANGES */
-       werr = drs_security_access_check_nc_root(b_state->sam_ctx,
+       werr = drs_security_access_check_nc_root(sam_ctx,
                                                 mem_ctx,
-                                                dce_call->conn->auth_state.session_info->security_token,
+                                                session_info->security_token,
                                                 req10->naming_context,
                                                 GUID_DRS_GET_CHANGES);
        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, &is_gc_pas_request);
+       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(b_state->sam_ctx,
+               werr = drs_security_access_check_nc_root(sam_ctx,
                                                         mem_ctx,
-                                                        dce_call->conn->auth_state.session_info->security_token,
+                                                        session_info->security_token,
                                                         req10->naming_context,
                                                         GUID_DRS_GET_FILTERED_ATTRIBUTES);
                if (W_ERROR_IS_OK(werr)) {
@@ -1526,25 +2856,32 @@ WERROR dcesrv_drsuapi_DsGetNCChanges(struct dcesrv_call_state *dce_call, TALLOC_
                }
        }
 
-       werr = dcesrv_drsuapi_is_reveal_secrets_request(b_state, req10, &is_secret_request);
+       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 && req10->extended_op != DRSUAPI_EXOP_REPL_SECRET) {
-               werr = drs_security_access_check_nc_root(b_state->sam_ctx,
+       if (is_secret_request) {
+               werr = drs_security_access_check_nc_root(sam_ctx,
                                                         mem_ctx,
-                                                        dce_call->conn->auth_state.session_info->security_token,
+                                                        session_info->security_token,
                                                         req10->naming_context,
                                                         GUID_DRS_GET_ALL_CHANGES);
                if (!W_ERROR_IS_OK(werr)) {
-                       return 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(dce_call->conn->auth_state.session_info,
+       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) {
@@ -1556,7 +2893,19 @@ allowed:
        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);
+       }
 
        getnc_state = b_state->getncchanges_state;
 
@@ -1568,23 +2917,52 @@ allowed:
                                 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);
-                       getnc_state = NULL;
+                       TALLOC_FREE(getnc_state);
+                       b_state->getncchanges_state = NULL;
+               }
+       }
+
+       if (getnc_state) {
+               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_state = NULL;
                }
        }
 
        if (getnc_state == NULL) {
-               getnc_state = talloc_zero(b_state, struct drsuapi_getncchanges_state);
-               if (getnc_state == NULL) {
-                       return WERR_NOMEM;
+               struct ldb_result *res = NULL;
+               const char *attrs[] = {
+                       "instanceType",
+                       "objectGuID",
+                       NULL
+               };
+               uint32_t nc_instanceType;
+               struct ldb_dn *ncRoot_dn;
+
+               ncRoot_dn = drs_ObjectIdentifier_to_dn(mem_ctx, sam_ctx, ncRoot);
+               if (ncRoot_dn == NULL) {
+                       return WERR_NOT_ENOUGH_MEMORY;
                }
-               b_state->getncchanges_state = getnc_state;
-               getnc_state->ncRoot_dn = drs_ObjectIdentifier_to_dn(getnc_state, sam_ctx, ncRoot);
 
-               /* find out if we are to replicate Schema NC */
-               ret = ldb_dn_compare(getnc_state->ncRoot_dn,
-                                    ldb_get_schema_basedn(b_state->sam_ctx));
-               getnc_state->is_schema_nc = (0 == ret);
+               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;
@@ -1598,28 +2976,53 @@ allowed:
                 */
                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);
+                       werr = getncchanges_rid_alloc(b_state, mem_ctx, req10, &r->out.ctr->ctr6, &search_dn);
                        W_ERROR_NOT_OK_RETURN(werr);
-                       search_dn = ldb_get_default_basedn(sam_ctx);
+                       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);
+                       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);
@@ -1633,6 +3036,27 @@ allowed:
                                 (unsigned)req10->extended_op));
                        return WERR_DS_DRA_NOT_SUPPORTED;
                }
+
+               /* Initialize the state we'll store over the replication cycle */
+               getnc_state = talloc_zero(b_state, struct drsuapi_getncchanges_state);
+               if (getnc_state == NULL) {
+                       return WERR_NOT_ENOUGH_MEMORY;
+               }
+               b_state->getncchanges_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");
+               ncRoot->guid = getnc_state->ncRoot_guid;
+
+               /* 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);
        }
 
        if (!ldb_dn_validate(getnc_state->ncRoot_dn) ||
@@ -1642,11 +3066,13 @@ allowed:
                return WERR_DS_DRA_INVALID_PARAMETER;
        }
 
+       ncRoot->guid = getnc_state->ncRoot_guid;
+
        /* we need the session key for encrypting password attributes */
        status = dcesrv_inherited_session_key(dce_call->conn, &session_key);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(0,(__location__ ": Failed to get session key\n"));
-               return WERR_DS_DRA_INTERNAL_ERROR;              
+               return WERR_DS_DRA_INTERNAL_ERROR;
        }
 
        /* 
@@ -1656,10 +3082,52 @@ allowed:
        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");
 
-               getnc_state->min_usn = req10->highwatermark.highest_usn;
+               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, req10,
@@ -1687,24 +3155,20 @@ allowed:
                        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 (req10->replica_flags & DRSUAPI_DRS_GET_ANC) {
-                       TYPESAFE_QSORT(changes,
-                                      getnc_state->num_records,
-                                      site_res_cmp_parent_order);
-               } else {
-                       TYPESAFE_QSORT(changes,
-                                      getnc_state->num_records,
-                                      site_res_cmp_dn_usn_order);
+                       if (changes[i].usn > getnc_state->max_usn) {
+                               getnc_state->max_usn = changes[i].usn;
+                       }
                }
 
-               getnc_state->uptodateness_vector = talloc_steal(getnc_state, req10->uptodateness_vector);
-               if (getnc_state->uptodateness_vector) {
-                       /* make sure its sorted */
-                       TYPESAFE_QSORT(getnc_state->uptodateness_vector->cursors,
-                                      getnc_state->uptodateness_vector->count,
-                                      drsuapi_DsReplicaCursor_compare);
+               /* RID_ALLOC returns 3 objects in a fixed order */
+               if (req10->extended_op == DRSUAPI_EXOP_FSMO_RID_ALLOC) {
+                       /* Do nothing */
+               } 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++) {
@@ -1716,8 +3180,41 @@ allowed:
                        }
                }
 
+               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);
+
+               if (req10->extended_op == DRSUAPI_EXOP_NONE) {
+                       getnc_state->is_get_anc =
+                               ((req10->replica_flags & DRSUAPI_DRS_GET_ANC) != 0);
+                       getnc_state->is_get_tgt =
+                               ((req10->more_flags & DRSUAPI_DRS_GET_TGT) != 0);
+               }
+
+               /*
+                * 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 */
@@ -1728,14 +3225,10 @@ allowed:
        }
 
        r->out.ctr->ctr6.naming_context = talloc(mem_ctx, struct drsuapi_DsReplicaObjectIdentifier);
-       *r->out.ctr->ctr6.naming_context = *ncRoot;
-
-       if (dsdb_find_guid_by_dn(sam_ctx, getnc_state->ncRoot_dn,
-                                &r->out.ctr->ctr6.naming_context->guid) != LDB_SUCCESS) {
-               DEBUG(0,(__location__ ": Failed to find GUID of ncRoot_dn %s\n",
-                        ldb_dn_get_linearized(getnc_state->ncRoot_dn)));
-               return WERR_DS_DRA_INTERNAL_ERROR;
+       if (r->out.ctr->ctr6.naming_context == NULL) {
+               return WERR_NOT_ENOUGH_MEMORY;
        }
+       *r->out.ctr->ctr6.naming_context = *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);
@@ -1749,35 +3242,61 @@ allowed:
        r->out.ctr->ctr6.old_highwatermark = req10->highwatermark;
        r->out.ctr->ctr6.new_highwatermark = req10->highwatermark;
 
-       r->out.ctr->ctr6.first_object = NULL;
-       currentObject = &r->out.ctr->ctr6.first_object;
-
-       /* use this to force single objects at a time, which is useful
-        * for working out what object is giving problems
-        */
-       max_objects = lpcfg_parm_int(dce_call->conn->dce_ctx->lp_ctx, NULL, "drs", "max object sync", 1000);
-       if (req10->max_object_count < max_objects) {
-               max_objects = req10->max_object_count;
-       }
        /*
-        * TODO: work out how the maximum should be calculated
+        * If the client has already set GET_TGT then we know they can handle
+        * receiving the linked attributes interleaved with the source objects
         */
-       max_links = lpcfg_parm_int(dce_call->conn->dce_ctx->lp_ctx, NULL, "drs", "max link sync", 1500);
+       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);
+               }
+
+               LDB_TYPESAFE_QSORT(local_pas,
+                                  req10->partial_attribute_set->num_attids,
+                                  NULL,
+                                  uint32_t_ptr_cmp);
+       }
 
        /*
-        * Maximum time that we can spend in a getncchanges
-        * in order to avoid timeout of the other part.
-        * 10 seconds by default.
+        * 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.
         */
-       max_wait = lpcfg_parm_int(dce_call->conn->dce_ctx->lp_ctx, NULL, "drs", "max work time", 10);
+       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 &&
-                    !null_scope &&
-                    (r->out.ctr->ctr6.object_count < max_objects)
-                    && !max_wait_reached;
+                    !getncchanges_chunk_is_full(repl_chunk, getnc_state);
            i++) {
-               int uSN;
-               struct drsuapi_DsReplicaObjectListItemEx *obj;
+               struct drsuapi_DsReplicaObjectListItemEx *new_objs = NULL;
                struct ldb_message *msg;
                static const char * const msg_attrs[] = {
                                            "*",
@@ -1788,91 +3307,151 @@ allowed:
                                            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;
 
-               obj = talloc_zero(mem_ctx, struct drsuapi_DsReplicaObjectListItemEx);
-               W_ERROR_HAVE_NO_MEMORY(obj);
-
-               msg_dn = ldb_dn_new_fmt(obj, sam_ctx, "<GUID=%s>", GUID_string(obj, &getnc_state->guids[i]));
+               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
+               /*
+                * 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, obj, &msg_res,
+               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(obj, msg_dn, 1), ldb_errstring(sam_ctx)));
+                                        ldb_dn_get_extended_linearized(tmp_ctx, msg_dn, 1),
+                                        ldb_errstring(sam_ctx)));
                        }
-                       talloc_free(obj);
+                       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];
 
-               max_wait_reached = (time(NULL) - start > max_wait);
-
-               werr = get_nc_changes_build_object(obj, msg,
-                                                  sam_ctx, getnc_state->ncRoot_dn,
-                                                  getnc_state->is_schema_nc,
-                                                  schema, &session_key, getnc_state->min_usn,
-                                                  req10->replica_flags,
-                                                  req10->partial_attribute_set,
-                                                  getnc_state->uptodateness_vector,
-                                                  req10->extended_op,
-                                                  max_wait_reached);
-               if (!W_ERROR_IS_OK(werr)) {
-                       return werr;
+               /*
+                * 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->ncRoot_dn,
+                                               getnc_state->is_schema_nc,
                                                schema, getnc_state->min_usn,
                                                req10->replica_flags,
                                                msg,
                                                &getnc_state->la_list,
                                                &getnc_state->la_count,
-                                               getnc_state->uptodateness_vector);
+                                               req10->uptodateness_vector);
                if (!W_ERROR_IS_OK(werr)) {
                        return werr;
                }
 
-               uSN = ldb_msg_find_attr_as_int(msg, "uSNChanged", -1);
-               if (uSN > r->out.ctr->ctr6.new_highwatermark.tmp_highest_usn) {
-                       r->out.ctr->ctr6.new_highwatermark.tmp_highest_usn = uSN;
-               }
-               if (uSN > getnc_state->highest_usn) {
-                       getnc_state->highest_usn = uSN;
-               }
+               dcesrv_drsuapi_update_highwatermark(msg,
+                                       getnc_state->max_usn,
+                                       &r->out.ctr->ctr6.new_highwatermark);
 
-               if (obj->meta_data_ctr == NULL) {
-                       DEBUG(8,(__location__ ": getncchanges skipping send of object %s\n",
-                                ldb_dn_get_linearized(msg->dn)));
-                       /* no attributes to send */
-                       talloc_free(obj);
-                       continue;
+               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);
+                       getnc_state->last_dn = talloc_move(getnc_state, &msg->dn);
                }
 
-               r->out.ctr->ctr6.object_count++;
-               
-               *currentObject = obj;
-               currentObject = &obj->next_object;
+               DEBUG(8,(__location__ ": %s object %s\n",
+                        new_objs ? "replicating" : "skipping send of",
+                        ldb_dn_get_linearized(msg->dn)));
+
+               getnc_state->total_links += (getnc_state->la_count - old_la_index);
 
-               talloc_free(getnc_state->last_dn);
-               getnc_state->last_dn = ldb_dn_copy(getnc_state, msg->dn);
+               /*
+                * 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);
 
-               DEBUG(8,(__location__ ": replicating object %s\n", ldb_dn_get_linearized(msg->dn)));
+                       if (!W_ERROR_IS_OK(werr)) {
+                               return werr;
+                       }
+               }
 
-               talloc_free(msg_res);
-               talloc_free(msg_dn);
+               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;
 
-       r->out.ctr->ctr6.nc_object_count = getnc_state->num_records;
+       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 */
@@ -1882,10 +3461,10 @@ allowed:
                DEBUG(3,("UpdateRefs on getncchanges for %s\n",
                         GUID_string(mem_ctx, &req10->destination_dsa_guid)));
                ureq.naming_context = ncRoot;
-               ureq.dest_dsa_dns_name = samdb_ntds_msdcs_dns_name(b_state->sam_ctx, mem_ctx,
+               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_NOMEM;
+                       return WERR_NOT_ENOUGH_MEMORY;
                }
                ureq.dest_dsa_guid = req10->destination_dsa_guid;
                ureq.options = DRSUAPI_DRS_ADD_REF |
@@ -1897,65 +3476,128 @@ allowed:
                   to send notifies using the GC SPN */
                ureq.options |= (req10->replica_flags & DRSUAPI_DRS_REF_GCSPN);
 
-               werr = drsuapi_UpdateRefs(b_state, mem_ctx, &ureq);
+               werr = drsuapi_UpdateRefs(dce_call->msg_ctx,
+                                         dce_call->event_ctx, b_state,
+                                         mem_ctx, &ureq);
                if (!W_ERROR_IS_OK(werr)) {
-                       DEBUG(0,(__location__ ": Failed UpdateRefs in DsGetNCChanges - %s\n",
+                       DEBUG(0,(__location__ ": Failed UpdateRefs on %s for %s in DsGetNCChanges - %s\n",
+                                drs_ObjectIdentifier_to_string(mem_ctx, ncRoot), ureq.dest_dsa_dns_name,
                                 win_errstr(werr)));
                }
        }
 
        /*
-        * TODO:
-        * This is just a guess, how to calculate the
-        * number of linked attributes to send, we need to
-        * find out how to do this right.
+        * 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.object_count >= max_links) {
-               max_links = 0;
-       } else {
-               max_links -= r->out.ctr->ctr6.object_count;
+       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));
        }
 
-       link_total = getnc_state->la_count;
+       /* If we've got linked attributes to send, add them now */
+       if (link_count > 0) {
+               struct la_for_sorting *la_sorted;
 
-       if (i < getnc_state->num_records) {
-               r->out.ctr->ctr6.more_data = true;
-       } else {
-               /* sort the whole array the first time */
-               if (!getnc_state->la_sorted) {
-                       LDB_TYPESAFE_QSORT(getnc_state->la_list, getnc_state->la_count,
-                                          sam_ctx, linked_attribute_compare);
-                       getnc_state->la_sorted = true;
+               /*
+                * 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;
                }
 
-               link_count = getnc_state->la_count - getnc_state->la_idx;
-               link_count = MIN(max_links, link_count);
-
                r->out.ctr->ctr6.linked_attributes_count = link_count;
-               r->out.ctr->ctr6.linked_attributes = getnc_state->la_list + getnc_state->la_idx;
+               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;
-               link_given = getnc_state->la_idx;
+               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 (!r->out.ctr->ctr6.more_data) {
-               talloc_steal(mem_ctx, getnc_state->la_list);
 
-               r->out.ctr->ctr6.uptodateness_vector = talloc(mem_ctx, struct drsuapi_DsReplicaCursor2CtrEx);
-               r->out.ctr->ctr6.new_highwatermark.highest_usn = r->out.ctr->ctr6.new_highwatermark.tmp_highest_usn;
+               /* 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);
 
-               werr = get_nc_changes_udv(sam_ctx, getnc_state->ncRoot_dn,
-                                         r->out.ctr->ctr6.uptodateness_vector);
-               if (!W_ERROR_IS_OK(werr)) {
-                       return werr;
+               /*
+                * 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.
+                */
+               talloc_steal(mem_ctx, getnc_state);
+               b_state->getncchanges_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;
                }
 
-               talloc_free(getnc_state);
-               b_state->getncchanges_state = NULL;
+               getnc_state->last_hwm = r->out.ctr->ctr6.new_highwatermark;
        }
 
        if (req10->extended_op != DRSUAPI_EXOP_NONE) {
@@ -1964,6 +3606,8 @@ allowed:
                ZERO_STRUCT(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),
@@ -1971,7 +3615,7 @@ allowed:
               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,
-              link_given, link_total,
+              getnc_state->links_given, getnc_state->total_links,
               dom_sid_string(mem_ctx, user_sid)));
 
 #if 0
@@ -1982,3 +3626,4 @@ allowed:
 
        return WERR_OK;
 }
+