s4:drsuapi: make sure we report the meta data from the cycle start (bug #9508)

We should build the final highwatermark and uptodatevector of
a replication cycle at the start of the cycle. Before we
search for the currently missing objects.

Otherwise we risk that some objects get lost.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

diff --git a/source4/rpc_server/drsuapi/getncchanges.c b/source4/rpc_server/drsuapi/getncchanges.c
index 10965a3e812617b027b828cd658b3d99b7ddca6a..511925a4791b248eaee15146dd858e5a2ee2f71c 100644 (file)
--- a/source4/rpc_server/drsuapi/getncchanges.c
+++ b/source4/rpc_server/drsuapi/getncchanges.c
@@ -45,8 +45,11 @@ struct drsuapi_getncchanges_state {
        struct ldb_dn *ncRoot_dn;
        bool is_schema_nc;
        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;
        bool la_sorted;
@@ -1740,6 +1743,18 @@ allowed:
                extra_filter = lpcfg_parm_string(dce_call->conn->dce_ctx->lp_ctx, NULL, "drs", "object filter");
 
                getnc_state->min_usn = req10->highwatermark.highest_usn;
+               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_NOMEM;
+               }
+               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,
@@ -1767,6 +1782,10 @@ 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 (changes[i].usn > getnc_state->max_usn) {
+                               getnc_state->max_usn = changes[i].usn;
+                       }
                }
 
                if (req10->replica_flags & DRSUAPI_DRS_GET_ANC) {
@@ -1788,6 +1807,10 @@ 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);
        }
@@ -1920,6 +1943,18 @@ allowed:
                }
 
                uSN = ldb_msg_find_attr_as_int(msg, "uSNChanged", -1);
+               if (uSN > getnc_state->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.
+                        */
+                       uSN = 0;
+               }
                if (uSN > r->out.ctr->ctr6.new_highwatermark.tmp_highest_usn) {
                        r->out.ctr->ctr6.new_highwatermark.tmp_highest_usn = uSN;
                        r->out.ctr->ctr6.new_highwatermark.reserved_usn = 0;
@@ -2022,15 +2057,9 @@ allowed:
        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;
-               r->out.ctr->ctr6.new_highwatermark.reserved_usn = 0;
-
-               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;
-               }
+               r->out.ctr->ctr6.new_highwatermark = getnc_state->final_hwm;
+               r->out.ctr->ctr6.uptodateness_vector = talloc_move(mem_ctx,
+                                                       &getnc_state->final_udv);
 
                talloc_free(getnc_state);
                b_state->getncchanges_state = NULL;