isisd: Add set-overload on-startup CLI/YANG support

Before:
r1# conf
r1(config)# router isis <area-tag>
r1(config-router)# set-overload-bit
  <cr>
r1(config-router)# end

After:
r1# conf
r1(config)# router isis <area-tag>
r1(config-router)# set-overload-bit
  <cr>
  on-startup  Set overload bit on startup
r1(config-router)# set-overload-bit on-startup
  (0-86400)  Set overload time in seconds
r1(config-router)# set-overload-bit on-startup 300
r1(config-router)# end

Signed-off-by: Isabella de Leon <ideleon@microsoft.com>

7 files changed, 105 insertions, 11 deletions

diff --git a/isisd/isis_cli.c b/isisd/isis_cli.c
index a673cb8c1e..9db867e2c0 100644
--- a/isisd/isis_cli.c
+++ b/isisd/isis_cli.c
@@ -404,7 +404,7 @@ DEFPY_YANG(set_overload_bit, set_overload_bit_cmd, "[no] set-overload-bit",
       "Reset overload bit to accept transit traffic\n"
       "Set overload bit to avoid any transit traffic\n")
 {
-	nb_cli_enqueue_change(vty, "./overload", NB_OP_MODIFY,
+	nb_cli_enqueue_change(vty, "./overload/enabled", NB_OP_MODIFY,
 			      no ? "false" : "true");
 
 	return nb_cli_apply_changes(vty, NULL);
@@ -419,6 +419,42 @@ void cli_show_isis_overload(struct vty *vty, const struct lyd_node *dnode,
 }
 
 /*
+ * XPath: /frr-isisd:isis/instance/overload/on-startup
+ */
+DEFPY_YANG(set_overload_bit_on_startup, set_overload_bit_on_startup_cmd,
+	   "set-overload-bit on-startup (0-86400)$val",
+	   "Set overload bit to avoid any transit traffic\n"
+	   "Set overload bit on startup\n"
+	   "Set overload time in seconds\n")
+{
+	nb_cli_enqueue_change(vty, "./overload/on-startup", NB_OP_MODIFY,
+			      val_str);
+
+	return nb_cli_apply_changes(vty, NULL);
+}
+
+DEFPY_YANG(no_set_overload_bit_on_startup, no_set_overload_bit_on_startup_cmd,
+	   "no set-overload-bit on-startup [(0-86400)$val]",
+	   NO_STR
+	   "Reset overload bit to accept transit traffic\n"
+	   "Set overload bit on startup\n"
+	   "Set overload time in seconds\n")
+{
+	nb_cli_enqueue_change(vty, "./overload/on-startup", NB_OP_DESTROY,
+			      NULL);
+
+	return nb_cli_apply_changes(vty, NULL);
+}
+
+void cli_show_isis_overload_on_startup(struct vty *vty,
+				       const struct lyd_node *dnode,
+				       bool show_defaults)
+{
+	vty_out(vty, " set-overload-bit on-startup %s\n",
+		yang_dnode_get_string(dnode, NULL));
+}
+
+/*
  * XPath: /frr-isisd:isis/instance/attach-send
  */
 DEFPY_YANG(attached_bit_send, attached_bit_send_cmd, "[no] attached-bit send",
@@ -3107,6 +3143,9 @@ void isis_cli_init(void)
 	install_element(ISIS_NODE, &dynamic_hostname_cmd);
 
 	install_element(ISIS_NODE, &set_overload_bit_cmd);
+	install_element(ISIS_NODE, &set_overload_bit_on_startup_cmd);
+	install_element(ISIS_NODE, &no_set_overload_bit_on_startup_cmd);
+
 	install_element(ISIS_NODE, &attached_bit_send_cmd);
 	install_element(ISIS_NODE, &attached_bit_receive_ignore_cmd);
 
diff --git a/isisd/isis_nb.c b/isisd/isis_nb.c
index a2ba33d078..4f4e6dc730 100644
--- a/isisd/isis_nb.c
+++ b/isisd/isis_nb.c
@@ -81,11 +81,18 @@ const struct frr_yang_module_info frr_isisd_info = {
 			},
 		},
 		{
-			.xpath = "/frr-isisd:isis/instance/overload",
+			.xpath = "/frr-isisd:isis/instance/overload/enabled",
 			.cbs = {
 				.cli_show = cli_show_isis_overload,
-				.modify = isis_instance_overload_modify,
-			},
+				.modify = isis_instance_overload_enabled_modify,
+			}
+		},
+		{
+			.xpath = "/frr-isisd:isis/instance/overload/on-startup",
+			.cbs = {
+				.cli_show = cli_show_isis_overload_on_startup,
+				.modify = isis_instance_overload_on_startup_modify,
+			}
 		},
 		{
 			.xpath = "/frr-isisd:isis/instance/metric-style",
diff --git a/isisd/isis_nb.h b/isisd/isis_nb.h
index 00ca8be3b0..a9f2eaea95 100644
--- a/isisd/isis_nb.h
+++ b/isisd/isis_nb.h
@@ -37,7 +37,8 @@ int isis_instance_dynamic_hostname_modify(struct nb_cb_modify_args *args);
 int isis_instance_attached_send_modify(struct nb_cb_modify_args *args);
 int isis_instance_attached_receive_modify(struct nb_cb_modify_args *args);
 int isis_instance_attached_modify(struct nb_cb_modify_args *args);
-int isis_instance_overload_modify(struct nb_cb_modify_args *args);
+int isis_instance_overload_enabled_modify(struct nb_cb_modify_args *args);
+int isis_instance_overload_on_startup_modify(struct nb_cb_modify_args *args);
 int isis_instance_metric_style_modify(struct nb_cb_modify_args *args);
 int isis_instance_purge_originator_modify(struct nb_cb_modify_args *args);
 int isis_instance_lsp_mtu_modify(struct nb_cb_modify_args *args);
@@ -442,6 +443,9 @@ void cli_show_isis_attached_receive(struct vty *vty,
 				    bool show_defaults);
 void cli_show_isis_overload(struct vty *vty, const struct lyd_node *dnode,
 			    bool show_defaults);
+void cli_show_isis_overload_on_startup(struct vty *vty,
+				       const struct lyd_node *dnode,
+				       bool show_defaults);
 void cli_show_isis_metric_style(struct vty *vty, const struct lyd_node *dnode,
 				bool show_defaults);
 void cli_show_isis_area_pwd(struct vty *vty, const struct lyd_node *dnode,
diff --git a/isisd/isis_nb_config.c b/isisd/isis_nb_config.c
index dbe4a017bc..14a66d2568 100644
--- a/isisd/isis_nb_config.c
+++ b/isisd/isis_nb_config.c
@@ -338,9 +338,9 @@ int isis_instance_attached_modify(struct nb_cb_modify_args *args)
 }
 
 /*
- * XPath: /frr-isisd:isis/instance/overload
+ * XPath: /frr-isisd:isis/instance/overload/enabled
  */
-int isis_instance_overload_modify(struct nb_cb_modify_args *args)
+int isis_instance_overload_enabled_modify(struct nb_cb_modify_args *args)
 {
 	struct isis_area *area;
 	bool overload;
@@ -356,6 +356,24 @@ int isis_instance_overload_modify(struct nb_cb_modify_args *args)
 }
 
 /*
+ * XPath: /frr-isisd:isis/instance/overload/on-startup
+ */
+int isis_instance_overload_on_startup_modify(struct nb_cb_modify_args *args)
+{
+	struct isis_area *area;
+	uint32_t overload_time;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	overload_time = yang_dnode_get_uint32(args->dnode, NULL);
+	area = nb_running_get_entry(args->dnode, NULL, true);
+	isis_area_overload_on_startup_set(area, overload_time);
+
+	return NB_OK;
+}
+
+/*
  * XPath: /frr-isisd:isis/instance/metric-style
  */
 int isis_instance_metric_style_modify(struct nb_cb_modify_args *args)
diff --git a/isisd/isisd.c b/isisd/isisd.c
index bce3dbb77b..7a631128a7 100644
--- a/isisd/isisd.c
+++ b/isisd/isisd.c
@@ -3205,6 +3205,15 @@ void isis_area_overload_bit_set(struct isis_area *area, bool overload_bit)
 #endif /* ifndef FABRICD */
 }
 
+void isis_area_overload_on_startup_set(struct isis_area *area,
+				       uint32_t startup_time)
+{
+	if (area->overload_on_startup_time != startup_time)
+		area->overload_on_startup_time = startup_time;
+
+	// TODO: Implement overload on startup functionality
+}
+
 void isis_area_attached_bit_send_set(struct isis_area *area, bool attached_bit)
 {
 
diff --git a/isisd/isisd.h b/isisd/isisd.h
index c313fd9ef7..316f979e1e 100644
--- a/isisd/isisd.h
+++ b/isisd/isisd.h
@@ -181,6 +181,7 @@ struct isis_area {
 	/* are we overloaded? */
 	char overload_bit;
 	uint32_t overload_counter;
+	uint32_t overload_on_startup_time;
 	/* L1/L2 router identifier for inter-area traffic */
 	char attached_bit_send;
 	char attached_bit_rcv_ignore;
@@ -289,6 +290,8 @@ void isis_area_invalidate_routes(struct isis_area *area, int levels);
 void isis_area_verify_routes(struct isis_area *area);
 
 void isis_area_overload_bit_set(struct isis_area *area, bool overload_bit);
+void isis_area_overload_on_startup_set(struct isis_area *area,
+				       uint32_t startup_time);
 void isis_area_attached_bit_send_set(struct isis_area *area, bool attached_bit);
 void isis_area_attached_bit_receive_set(struct isis_area *area,
 					bool attached_bit);
diff --git a/yang/frr-isisd.yang b/yang/frr-isisd.yang
index 0812c86fac..380fce3859 100644
--- a/yang/frr-isisd.yang
+++ b/yang/frr-isisd.yang
@@ -1066,11 +1066,25 @@ module frr-isisd {
           "If true, identify as L1/L2 router for inter-area traffic.";
       }
 
-      leaf overload {
-        type boolean;
-        default "false";
+      container overload {
         description
-          "If true, avoid any transit traffic.";
+          "Overload bit configuration.";
+        leaf enabled {
+          type boolean;
+          default "false";
+          description
+            "If true, avoid any transit traffic.";
+        }
+
+        leaf on-startup {
+          type uint32 {
+            range "0..86400";
+          }
+          units "seconds";
+          default "0";
+          description
+            "The duration the overload bit should be set on startup.";
+        }
       }
 
       leaf metric-style {