lib: introduce the northbound context structure

The new northbound context structure contains information about
the client performing a configuration transaction. This information
will be made available to all configuration callbacks through the
args->context parameter.

The usefulness of this structure comes from the fact that it can be
used as a communication channel (both input and output) between the
northbound callbacks and the northbound clients. This can be done
through its "client_data" field which contains client-specific data.

This should cover some very specific scenarios where a northbound
callback should perform an action only if the configuration change
is coming from a given client. An example would be sending a PCEP
response to a PCE when an SR-TE policy is created or modified
through the PCEP northbound client (for that to happen, the
northbound callbacks need to have access to the PCEP request ID,
which needs to be available).

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

1 files changed, 24 insertions, 8 deletions

diff --git a/lib/northbound_cli.c b/lib/northbound_cli.c
index d4467facaf..544b2434eb 100644
--- a/lib/northbound_cli.c
+++ b/lib/northbound_cli.c
@@ -169,8 +169,12 @@ int nb_cli_apply_changes(struct vty *vty, const char *xpath_base_fmt, ...)
 
 	/* Do an implicit "commit" when using the classic CLI mode. */
 	if (frr_get_cli_mode() == FRR_CLI_CLASSIC) {
-		ret = nb_candidate_commit(vty->candidate_config, NB_CLIENT_CLI,
-					  vty, false, NULL, NULL);
+		struct nb_context context = {};
+
+		context.client = NB_CLIENT_CLI;
+		context.user = vty;
+		ret = nb_candidate_commit(&context, vty->candidate_config,
+					  false, NULL, NULL);
 		if (ret != NB_OK && ret != NB_ERR_NO_CHANGES) {
 			vty_out(vty, "%% Configuration failed: %s.\n\n",
 				nb_err_name(ret));
@@ -217,12 +221,16 @@ void nb_cli_confirmed_commit_clean(struct vty *vty)
 
 int nb_cli_confirmed_commit_rollback(struct vty *vty)
 {
+	struct nb_context context = {};
 	uint32_t transaction_id;
 	int ret;
 
+
 	/* Perform the rollback. */
+	context.client = NB_CLIENT_CLI;
+	context.user = vty;
 	ret = nb_candidate_commit(
-		vty->confirmed_commit_rollback, NB_CLIENT_CLI, vty, true,
+		&context, vty->confirmed_commit_rollback, true,
 		"Rollback to previous configuration - confirmed commit has timed out",
 		&transaction_id);
 	if (ret == NB_OK)
@@ -252,6 +260,7 @@ static int nb_cli_confirmed_commit_timeout(struct thread *thread)
 static int nb_cli_commit(struct vty *vty, bool force,
 			 unsigned int confirmed_timeout, char *comment)
 {
+	struct nb_context context = {};
 	uint32_t transaction_id = 0;
 	int ret;
 
@@ -295,8 +304,10 @@ static int nb_cli_commit(struct vty *vty, bool force,
 				 &vty->t_confirmed_commit_timeout);
 	}
 
-	ret = nb_candidate_commit(vty->candidate_config, NB_CLIENT_CLI, vty,
-				  true, comment, &transaction_id);
+	context.client = NB_CLIENT_CLI;
+	context.user = vty;
+	ret = nb_candidate_commit(&context, vty->candidate_config, true,
+				  comment, &transaction_id);
 
 	/* Map northbound return code to CLI return code. */
 	switch (ret) {
@@ -690,9 +701,12 @@ DEFPY (config_commit_check,
        "Commit changes into the running configuration\n"
        "Check if the configuration changes are valid\n")
 {
+	struct nb_context context = {};
 	int ret;
 
-	ret = nb_candidate_validate(vty->candidate_config);
+	context.client = NB_CLIENT_CLI;
+	context.user = vty;
+	ret = nb_candidate_validate(&context, vty->candidate_config);
 	if (ret != NB_OK) {
 		vty_out(vty,
 			"%% Failed to validate candidate configuration.\n\n");
@@ -1530,6 +1544,7 @@ DEFPY (show_yang_module_translator,
 static int nb_cli_rollback_configuration(struct vty *vty,
 					 uint32_t transaction_id)
 {
+	struct nb_context context = {};
 	struct nb_config *candidate;
 	char comment[80];
 	int ret;
@@ -1544,8 +1559,9 @@ static int nb_cli_rollback_configuration(struct vty *vty,
 	snprintf(comment, sizeof(comment), "Rollback to transaction %u",
 		 transaction_id);
 
-	ret = nb_candidate_commit(candidate, NB_CLIENT_CLI, vty, true, comment,
-				  NULL);
+	context.client = NB_CLIENT_CLI;
+	context.user = vty;
+	ret = nb_candidate_commit(&context, candidate, true, comment, NULL);
 	nb_config_free(candidate);
 	switch (ret) {
 	case NB_OK: