lib: introduce new 'pre_validate' northbound callback

This callback can be used to validate subsections of the
configuration being committed before validating the configuration
changes themselves. It's useful to perform more complex validations
that depend on the relationship between multiple nodes.

Only YANG-level validation (performed by libyang) and the
NB_EV_VALIDATE validation (that can be used to validate individual
configuration changes) proved to be insufficient in some cases.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

diff --git a/lib/northbound.c b/lib/northbound.c
index a814f23e14421d0b65a832d7fc4e5b33758c234a..fe7c8bfbc6de56295e0d59358fa5acd318f60195 100644 (file)
--- a/lib/northbound.c
+++ b/lib/northbound.c
@@ -64,6 +64,9 @@ static bool transaction_in_progress;
 
 static int nb_callback_configuration(const enum nb_event event,
                                     struct nb_config_change *change);
+static void nb_log_callback(const enum nb_event event,
+                           enum nb_operation operation, const char *xpath,
+                           const char *value);
 static struct nb_transaction *nb_transaction_new(struct nb_config *config,
                                                 struct nb_config_cbs *changes,
                                                 enum nb_client client,
@@ -211,6 +214,8 @@ static unsigned int nb_node_validate_cbs(const struct nb_node *nb_node)
                                     !!nb_node->cbs.destroy, false);
        error += nb_node_validate_cb(nb_node, NB_OP_MOVE, !!nb_node->cbs.move,
                                     false);
+       error += nb_node_validate_cb(nb_node, NB_OP_PRE_VALIDATE,
+                                    !!nb_node->cbs.pre_validate, true);
        error += nb_node_validate_cb(nb_node, NB_OP_APPLY_FINISH,
                                     !!nb_node->cbs.apply_finish, true);
        error += nb_node_validate_cb(nb_node, NB_OP_GET_ELEM,
@@ -583,14 +588,45 @@ static int nb_candidate_validate_yang(struct nb_config *candidate)
 }
 
 /* Perform code-level validation using the northbound callbacks. */
-static int nb_candidate_validate_changes(struct nb_config *candidate,
-                                        struct nb_config_cbs *changes)
+static int nb_candidate_validate_code(struct nb_config *candidate,
+                                     struct nb_config_cbs *changes)
 {
        struct nb_config_cb *cb;
+       struct lyd_node *root, *next, *child;
+       int ret;
+
+       /* First validate the candidate as a whole. */
+       LY_TREE_FOR (candidate->dnode, root) {
+               LY_TREE_DFS_BEGIN (root, next, child) {
+                       struct nb_node *nb_node;
+
+                       nb_node = child->schema->priv;
+                       if (!nb_node->cbs.pre_validate)
+                               goto next;
+
+                       if (DEBUG_MODE_CHECK(&nb_dbg_cbs_config,
+                                            DEBUG_MODE_ALL)) {
+                               char xpath[XPATH_MAXLEN];
 
+                               yang_dnode_get_path(child, xpath,
+                                                   sizeof(xpath));
+                               nb_log_callback(NB_EV_VALIDATE,
+                                               NB_OP_PRE_VALIDATE, xpath,
+                                               NULL);
+                       }
+
+                       ret = (*nb_node->cbs.pre_validate)(child);
+                       if (ret != NB_OK)
+                               return NB_ERR_VALIDATION;
+
+               next:
+                       LY_TREE_DFS_END(root, next, child);
+               }
+       }
+
+       /* Now validate the configuration changes. */
        RB_FOREACH (cb, nb_config_cbs, changes) {
                struct nb_config_change *change = (struct nb_config_change *)cb;
-               int ret;
 
                ret = nb_callback_configuration(NB_EV_VALIDATE, change);
                if (ret != NB_OK)
@@ -612,7 +648,7 @@ int nb_candidate_validate(struct nb_config *candidate)
        pthread_rwlock_rdlock(&running_config->lock);
        {
                nb_config_diff(running_config, candidate, &changes);
-               ret = nb_candidate_validate_changes(candidate, &changes);
+               ret = nb_candidate_validate_code(candidate, &changes);
                nb_config_diff_del_changes(&changes);
        }
        pthread_rwlock_unlock(&running_config->lock);
@@ -643,8 +679,7 @@ int nb_candidate_commit_prepare(struct nb_config *candidate,
                        return NB_ERR_NO_CHANGES;
                }
 
-               if (nb_candidate_validate_changes(candidate, &changes)
-                   != NB_OK) {
+               if (nb_candidate_validate_code(candidate, &changes) != NB_OK) {
                        flog_warn(
                                EC_LIB_NB_CANDIDATE_INVALID,
                                "%s: failed to validate candidate configuration",
@@ -1550,6 +1585,7 @@ bool nb_operation_is_valid(enum nb_operation operation,
                        return false;
                }
                return true;
+       case NB_OP_PRE_VALIDATE:
        case NB_OP_APPLY_FINISH:
                if (!CHECK_FLAG(snode->flags, LYS_CONFIG_W))
                        return false;
@@ -1768,6 +1804,8 @@ const char *nb_operation_name(enum nb_operation operation)
                return "destroy";
        case NB_OP_MOVE:
                return "move";
+       case NB_OP_PRE_VALIDATE:
+               return "pre_validate";
        case NB_OP_APPLY_FINISH:
                return "apply_finish";
        case NB_OP_GET_ELEM:

diff --git a/lib/northbound.h b/lib/northbound.h
index ce79d907f9fd9aca81e6eb2bb97b823688f7be12..502fbb9d680d865e08b811cbb4395232b98adf02 100644 (file)
--- a/lib/northbound.h
+++ b/lib/northbound.h
@@ -72,6 +72,7 @@ enum nb_operation {
        NB_OP_MODIFY,
        NB_OP_DESTROY,
        NB_OP_MOVE,
+       NB_OP_PRE_VALIDATE,
        NB_OP_APPLY_FINISH,
        NB_OP_GET_ELEM,
        NB_OP_GET_NEXT,
@@ -196,6 +197,19 @@ struct nb_callbacks {
         */
        int (*move)(enum nb_event event, const struct lyd_node *dnode);
 
+       /*
+        * Optional configuration callback.
+        *
+        * This callback can be used to validate subsections of the
+        * configuration being committed before validating the configuration
+        * changes themselves. It's useful to perform more complex validations
+        * that depend on the relationship between multiple nodes.
+        *
+        * dnode
+        *    libyang data node associated with the 'pre_validate' callback.
+        */
+       int (*pre_validate)(const struct lyd_node *dnode);
+
        /*
         * Optional configuration callback.
         *