isisd: Add nb command to configure an SRv6 locator

Add a northbound command to configure an SRv6 locator for a specific
IS-IS area.

After configuring a locator, `isis_zebra_srv6_manager_get_locator_chunk`
is called to ask zebra to allocate a chunk from the configured locator.
The allocated chunk will be owned by IS-IS. IS-IS can allocate SIDs from
its chunk.

Currently, we support only one locator per-area. Therefore, before
configuring a locator we unset the previously configured locator, if
there was any.

Signed-off-by: Carmine Scarpitta <carmine.scarpitta@uniroma2.it>

3 files changed, 58 insertions, 0 deletions

diff --git a/isisd/isis_nb.c b/isisd/isis_nb.c
index 4c42d18eb..4fae0836b 100644
--- a/isisd/isis_nb.c
+++ b/isisd/isis_nb.c
@@ -868,6 +868,12 @@ const struct frr_yang_module_info frr_isisd_info = {
 			},
 		},
 		{
+			.xpath = "/frr-isisd:isis/instance/segment-routing-srv6/locator",
+			.cbs = {
+				.modify = isis_instance_segment_routing_srv6_locator_modify,
+			},
+		},
+		{
 			.xpath = "/frr-isisd:isis/instance/mpls/ldp-sync",
 			.cbs = {
 				.cli_show = cli_show_isis_mpls_ldp_sync,
diff --git a/isisd/isis_nb.h b/isisd/isis_nb.h
index 728967700..657c8fb2d 100644
--- a/isisd/isis_nb.h
+++ b/isisd/isis_nb.h
@@ -326,6 +326,8 @@ int isis_instance_segment_routing_srv6_enabled_modify(
 	struct nb_cb_modify_args *args);
 void cli_show_isis_srv6_enabled(struct vty *vty, const struct lyd_node *dnode,
 				bool show_defaults);
+int isis_instance_segment_routing_srv6_locator_modify(
+	struct nb_cb_modify_args *args);
 int isis_instance_mpls_ldp_sync_destroy(struct nb_cb_destroy_args *args);
 int isis_instance_mpls_ldp_sync_create(struct nb_cb_create_args *args);
 int isis_instance_mpls_ldp_sync_holddown_modify(struct nb_cb_modify_args *args);
diff --git a/isisd/isis_nb_config.c b/isisd/isis_nb_config.c
index 3a56c78de..5ec17f393 100644
--- a/isisd/isis_nb_config.c
+++ b/isisd/isis_nb_config.c
@@ -35,6 +35,7 @@
 #include "isisd/isis_adjacency.h"
 #include "isisd/isis_spf.h"
 #include "isisd/isis_spf_private.h"
+#include "isisd/isis_srv6.h"
 #include "isisd/isis_te.h"
 #include "isisd/isis_mt.h"
 #include "isisd/isis_redist.h"
@@ -3478,6 +3479,55 @@ int isis_instance_segment_routing_srv6_enabled_modify(
 }
 
 /*
+ * XPath: /frr-isisd:isis/instance/segment-routing-srv6/locator
+ */
+int isis_instance_segment_routing_srv6_locator_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct isis_area *area;
+	const char *loc_name;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	area = nb_running_get_entry(lyd_parent(lyd_parent(args->dnode)), NULL,
+				    true);
+
+	loc_name = yang_dnode_get_string(args->dnode, NULL);
+
+	if (strncmp(loc_name, area->srv6db.config.srv6_locator_name,
+		    sizeof(area->srv6db.config.srv6_locator_name)) == 0) {
+		snprintf(args->errmsg, args->errmsg_len,
+			 "SRv6 locator %s is already configured", loc_name);
+		return NB_ERR_NO_CHANGES;
+	}
+
+	/* Remove previously configured locator */
+	if (strncmp(area->srv6db.config.srv6_locator_name, "",
+		    sizeof(area->srv6db.config.srv6_locator_name)) != 0) {
+		sr_debug("Unsetting previously configured SRv6 locator");
+		if (!isis_srv6_locator_unset(area)) {
+			zlog_warn("Failed to unset SRv6 locator");
+			return NB_ERR;
+		}
+	}
+
+	strlcpy(area->srv6db.config.srv6_locator_name, loc_name,
+		sizeof(area->srv6db.config.srv6_locator_name));
+
+	sr_debug("Configured SRv6 locator %s for IS-IS area %s", loc_name,
+		 area->area_tag);
+
+	sr_debug("Trying to get a chunk from locator %s for IS-IS area %s",
+		 loc_name, area->area_tag);
+
+	if (isis_zebra_srv6_manager_get_locator_chunk(loc_name) < 0)
+		return NB_ERR;
+
+	return NB_OK;
+}
+
+/*
  * XPath: /frr-isisd:isis/instance/mpls/ldp-sync
  */
 int isis_instance_mpls_ldp_sync_create(struct nb_cb_create_args *args)