replmd: Refactor logic to check if replicated link is newer

This is precursor work for supporting single-link conflicts.

Split out the code to check if the link update is newer. It's now safe
to call this from the main codepath. This also means we can combine the 2
calls to get the seqnum into a single common call.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13055

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

diff --git a/source4/dsdb/samdb/ldb_modules/repl_meta_data.c b/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
index 60a9c8c419100cae37da3c5b9202fd22843c6a86..f0c5ab600a2086ad6a876ac5a80118c89e8331d2 100644 (file)
--- a/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
+++ b/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
@@ -7142,6 +7142,40 @@ static int replmd_verify_linked_attribute(struct replmd_replicated_request *ar,
        return ret;
 }
 
+/**
+ * @returns true if the replication linked attribute info is newer than we
+ * already have in our DB
+ * @param pdn the existing linked attribute info in our DB
+ * @param la the new linked attribute info received during replication
+ */
+static bool replmd_link_update_is_newer(struct parsed_dn *pdn,
+                                       struct drsuapi_DsReplicaLinkedAttribute *la)
+{
+       /* see if this update is newer than what we have already */
+       struct GUID invocation_id = GUID_zero();
+       uint32_t version = 0;
+       uint32_t originating_usn = 0;
+       NTTIME change_time = 0;
+
+       if (pdn == NULL) {
+
+               /* no existing info so update is newer */
+               return true;
+       }
+
+       dsdb_get_extended_dn_guid(pdn->dsdb_dn->dn, &invocation_id, "RMD_INVOCID");
+       dsdb_get_extended_dn_uint32(pdn->dsdb_dn->dn, &version, "RMD_VERSION");
+       dsdb_get_extended_dn_uint32(pdn->dsdb_dn->dn, &originating_usn, "RMD_ORIGINATING_USN");
+       dsdb_get_extended_dn_nttime(pdn->dsdb_dn->dn, &change_time, "RMD_CHANGETIME");
+
+       return replmd_update_is_newer(&invocation_id,
+                                     &la->meta_data.originating_invocation_id,
+                                     version,
+                                     la->meta_data.version,
+                                     change_time,
+                                     la->meta_data.originating_change_time);
+}
+
 /*
   process one linked attribute structure
  */
@@ -7244,40 +7278,24 @@ static int replmd_process_linked_attribute(struct ldb_module *module,
                return ret;
        }
 
+       if (!replmd_link_update_is_newer(pdn, la)) {
+               DEBUG(3,("Discarding older DRS linked attribute update to %s on %s from %s\n",
+                        old_el->name, ldb_dn_get_linearized(msg->dn),
+                        GUID_string(tmp_ctx, &la->meta_data.originating_invocation_id)));
+               talloc_free(tmp_ctx);
+               return LDB_SUCCESS;
+       }
+
+       /* get a seq_num for this change */
+       ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
 
        if (pdn != NULL) {
-               /* see if this update is newer than what we have already */
-               struct GUID invocation_id = GUID_zero();
-               uint32_t version = 0;
-               uint32_t originating_usn = 0;
-               NTTIME change_time = 0;
                uint32_t rmd_flags = dsdb_dn_rmd_flags(pdn->dsdb_dn->dn);
 
-               dsdb_get_extended_dn_guid(pdn->dsdb_dn->dn, &invocation_id, "RMD_INVOCID");
-               dsdb_get_extended_dn_uint32(pdn->dsdb_dn->dn, &version, "RMD_VERSION");
-               dsdb_get_extended_dn_uint32(pdn->dsdb_dn->dn, &originating_usn, "RMD_ORIGINATING_USN");
-               dsdb_get_extended_dn_nttime(pdn->dsdb_dn->dn, &change_time, "RMD_CHANGETIME");
-
-               if (!replmd_update_is_newer(&invocation_id,
-                                           &la->meta_data.originating_invocation_id,
-                                           version,
-                                           la->meta_data.version,
-                                           change_time,
-                                           la->meta_data.originating_change_time)) {
-                       DEBUG(3,("Discarding older DRS linked attribute update to %s on %s from %s\n",
-                                old_el->name, ldb_dn_get_linearized(msg->dn),
-                                GUID_string(tmp_ctx, &la->meta_data.originating_invocation_id)));
-                       talloc_free(tmp_ctx);
-                       return LDB_SUCCESS;
-               }
-
-               /* get a seq_num for this change */
-               ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
-               if (ret != LDB_SUCCESS) {
-                       talloc_free(tmp_ctx);
-                       return ret;
-               }
-
                if (!(rmd_flags & DSDB_RMD_FLAG_DELETED)) {
                        /* remove the existing backlink */
                        ret = replmd_add_backlink(module, replmd_private,
@@ -7303,12 +7321,7 @@ static int replmd_process_linked_attribute(struct ldb_module *module,
                }
        } else {
                unsigned offset;
-               /* get a seq_num for this change */
-               ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
-               if (ret != LDB_SUCCESS) {
-                       talloc_free(tmp_ctx);
-                       return ret;
-               }
+
                /*
                 * We know where the new one needs to be, from the *next
                 * pointer into pdn_list.