ospfd: implement Type-7 default routes for NSSA areas

Add the "default-information-originate" option to the "area X nssa"
command. That option allows the origination of Type-7 default routes
on NSSA ABRs and ASBRs.

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

doc/user/ospfd.rst

@@ -431,6 +431,16 @@ Areas
     configured not to advertise forwarding addresses into the backbone to direct
     forwarded traffic to the NSSA ABR translator.
 
+.. clicmd:: area A.B.C.D nssa default-information-originate [metric-type (1-2)] [metric (0-16777214)]
+
+.. clicmd:: area (0-4294967295) nssa default-information-originate [metric-type (1-2)] [metric (0-16777214)]
+
+   NSSA ABRs and ASBRs can be configured with the `default-information-originate`
+   option to originate a Type-7 default route into the NSSA area. In the case
+   of NSSA ASBRs, the origination of the default route is conditioned to the
+   existence of a default route in the RIB that wasn't learned via the OSPF
+   protocol.
+
 .. clicmd:: area A.B.C.D default-cost (0-16777215)
 
 

ospfd/ospf_abr.c

@@ -1807,6 +1807,82 @@ static void ospf_abr_announce_non_dna_routers(struct event *thread)
 	OSPF_LOG_DEBUG(IS_DEBUG_OSPF_EVENT, "%s(): Stop", __func__);
 }
 
+static void ospf_abr_nssa_type7_default_create(struct ospf *ospf,
+					       struct ospf_area *area,
+					       struct ospf_lsa *lsa)
+{
+	struct external_info ei;
+
+	if (IS_DEBUG_OSPF_NSSA)
+		zlog_debug(
+			"Announcing Type-7 default route into NSSA area %pI4",
+			&area->area_id);
+
+	/* Prepare the extrenal_info for aggregator */
+	memset(&ei, 0, sizeof(struct external_info));
+	ei.p.family = AF_INET;
+	ei.p.prefixlen = 0;
+	ei.tag = 0;
+	ei.type = 0;
+	ei.instance = ospf->instance;
+
+	/* Compute default route type and metric. */
+	if (area->nssa_default_originate.metric_value != -1)
+		ei.route_map_set.metric =
+			area->nssa_default_originate.metric_value;
+	else
+		ei.route_map_set.metric = DEFAULT_DEFAULT_ALWAYS_METRIC;
+	if (area->nssa_default_originate.metric_type != -1)
+		ei.route_map_set.metric_type =
+			area->nssa_default_originate.metric_type;
+	else
+		ei.route_map_set.metric_type = DEFAULT_METRIC_TYPE;
+
+	if (!lsa)
+		ospf_nssa_lsa_originate(area, &ei);
+	else
+		ospf_nssa_lsa_refresh(area, lsa, &ei);
+}
+
+static void ospf_abr_nssa_type7_default_delete(struct ospf *ospf,
+					       struct ospf_area *area,
+					       struct ospf_lsa *lsa)
+{
+	if (lsa && !CHECK_FLAG(lsa->flags, OSPF_LSA_IN_MAXAGE)) {
+		if (IS_DEBUG_OSPF_NSSA)
+			zlog_debug(
+				"Withdrawing Type-7 default route from area %pI4",
+				&area->area_id);
+
+		ospf_ls_retransmit_delete_nbr_area(area, lsa);
+		ospf_refresher_unregister_lsa(ospf, lsa);
+		ospf_lsa_flush_area(lsa, area);
+	}
+}
+
+/* NSSA Type-7 default route. */
+void ospf_abr_nssa_type7_defaults(struct ospf *ospf)
+{
+	struct ospf_area *area;
+	struct listnode *node;
+
+	for (ALL_LIST_ELEMENTS_RO(ospf->areas, node, area)) {
+		struct in_addr id = {};
+		struct ospf_lsa *lsa;
+
+		lsa = ospf_lsdb_lookup_by_id(area->lsdb, OSPF_AS_NSSA_LSA, id,
+					     area->ospf->router_id);
+		if (area->external_routing == OSPF_AREA_NSSA
+		    && area->nssa_default_originate.enabled
+		    && (IS_OSPF_ABR(ospf)
+			|| (IS_OSPF_ASBR(ospf)
+			    && ospf->nssa_default_import_check.status)))
+			ospf_abr_nssa_type7_default_create(ospf, area, lsa);
+		else
+			ospf_abr_nssa_type7_default_delete(ospf, area, lsa);
+	}
+}
+
 static int ospf_abr_remove_unapproved_translates_apply(struct ospf *ospf,
 						       struct ospf_lsa *lsa)
 {
@@ -2031,6 +2107,11 @@ void ospf_abr_task(struct ospf *ospf)
 			zlog_debug("%s: announce stub defaults", __func__);
 		ospf_abr_announce_stub_defaults(ospf);
 
+		if (IS_DEBUG_OSPF_EVENT)
+			zlog_debug("%s: announce NSSA Type-7 defaults",
+				   __func__);
+		ospf_abr_nssa_type7_defaults(ospf);
+
 		if (ospf->fr_configured) {
 			OSPF_LOG_DEBUG(IS_DEBUG_OSPF_EVENT,
 				       "%s(): announce non-DNArouters",

ospfd/ospf_abr.h

@@ -73,6 +73,7 @@ extern void ospf_schedule_abr_task(struct ospf *);
 
 extern void ospf_abr_announce_network_to_area(struct prefix_ipv4 *, uint32_t,
 					      struct ospf_area *);
+extern void ospf_abr_nssa_type7_defaults(struct ospf *ospf);
 extern void ospf_abr_nssa_check_status(struct ospf *ospf);
 extern void ospf_abr_generate_indication_lsa(struct ospf *ospf,
 					     const struct ospf_area *area);

ospfd/ospf_lsa.c

@@ -1868,8 +1868,7 @@ static struct ospf_lsa *ospf_external_lsa_new(struct ospf *ospf,
 }
 
 /* As Type-7 */
-static void ospf_install_flood_nssa(struct ospf *ospf, struct ospf_lsa *lsa,
+static void ospf_install_flood_nssa(struct ospf *ospf, struct ospf_lsa *lsa)
-				    struct external_info *ei)
 {
 	struct ospf_lsa *new;
 	struct as_external_lsa *extlsa;
@@ -2253,7 +2252,7 @@ struct ospf_lsa *ospf_external_lsa_originate(struct ospf *ospf,
 	    /* stay away from translated LSAs! */
 	    !(CHECK_FLAG(new->flags, OSPF_LSA_LOCAL_XLT)))
 		ospf_install_flood_nssa(
-			ospf, new, ei); /* Install/Flood Type-7 to all NSSAs */
+			ospf, new); /* Install/Flood Type-7 to all NSSAs */
 
 	/* Debug logging. */
 	if (IS_DEBUG_OSPF(lsa, LSA_GENERATE)) {
@@ -2266,6 +2265,100 @@ struct ospf_lsa *ospf_external_lsa_originate(struct ospf *ospf,
 	return new;
 }
 
+/* Originate an NSSA-LSA, install and flood. */
+struct ospf_lsa *ospf_nssa_lsa_originate(struct ospf_area *area,
+					 struct external_info *ei)
+{
+	struct ospf *ospf = area->ospf;
+	struct ospf_lsa *new;
+
+	if (ospf->gr_info.restart_in_progress) {
+		if (IS_DEBUG_OSPF(lsa, LSA_GENERATE))
+			zlog_debug(
+				"LSA[Type7]: Graceful Restart in progress, don't originate");
+		return NULL;
+	}
+
+	if (ospf->router_id.s_addr == INADDR_ANY) {
+		if (IS_DEBUG_OSPF_EVENT)
+			zlog_debug(
+				"LSA[Type7:%pI4]: deferring NSSA-LSA origination, router ID is zero",
+				&ei->p.prefix);
+		return NULL;
+	}
+
+	/* Create new NSSA-LSA instance. */
+	if ((new = ospf_external_lsa_new(ospf, ei, NULL)) == NULL) {
+		if (IS_DEBUG_OSPF_EVENT)
+			zlog_debug(
+				"LSA[Type7:%pI4]: Could not originate NSSA-LSA",
+				&ei->p.prefix);
+		return NULL;
+	}
+	new->data->type = OSPF_AS_NSSA_LSA;
+	new->area = area;
+
+	/* Install newly created LSA into Type-7 LSDB. */
+	ospf_lsa_install(ospf, NULL, new);
+
+	/* Update LSA origination count. */
+	ospf->lsa_originate_count++;
+
+	/* Flooding new LSA */
+	ospf_flood_through_area(area, NULL, new);
+
+	/* Debug logging. */
+	if (IS_DEBUG_OSPF(lsa, LSA_GENERATE)) {
+		zlog_debug("LSA[Type%d:%pI4]: Originate NSSA-LSA %p",
+			   new->data->type, &new->data->id, (void *)new);
+		ospf_lsa_header_dump(new->data);
+	}
+
+	return new;
+}
+
+/* Refresh NSSA-LSA. */
+struct ospf_lsa *ospf_nssa_lsa_refresh(struct ospf_area *area,
+				       struct ospf_lsa *lsa,
+				       struct external_info *ei)
+{
+	struct ospf *ospf = area->ospf;
+	struct ospf_lsa *new;
+
+	/* Delete LSA from neighbor retransmit-list. */
+	ospf_ls_retransmit_delete_nbr_as(ospf, lsa);
+
+	/* Unregister AS-external-LSA from refresh-list. */
+	ospf_refresher_unregister_lsa(ospf, lsa);
+
+	/* Create new NSSA-LSA instance. */
+	if ((new = ospf_external_lsa_new(ospf, ei, NULL)) == NULL) {
+		if (IS_DEBUG_OSPF_EVENT)
+			zlog_debug(
+				"LSA[Type7:%pI4]: Could not originate NSSA-LSA",
+				&ei->p.prefix);
+		return NULL;
+	}
+	new->data->type = OSPF_AS_NSSA_LSA;
+	new->data->ls_seqnum = lsa_seqnum_increment(lsa);
+	new->area = area;
+
+	/* Install newly created LSA into Type-7 LSDB. */
+	ospf_lsa_install(ospf, NULL, new);
+
+	/* Flooding new LSA */
+	ospf_flood_through_area(area, NULL, new);
+
+	/* Debug logging. */
+	if (IS_DEBUG_OSPF(lsa, LSA_GENERATE)) {
+		zlog_debug("LSA[Type%d:%pI4]: NSSA-LSA refresh",
+			   new->data->type, &new->data->id);
+		ospf_lsa_header_dump(new->data);
+	}
+
+	return new;
+}
+
 static struct external_info *ospf_default_external_info(struct ospf *ospf)
 {
 	int type;
@@ -2611,8 +2704,8 @@ struct ospf_lsa *ospf_external_lsa_refresh(struct ospf *ospf,
 
 	/* If any attached NSSA, install as Type-7, flood to all NSSA Areas */
 	if (ospf->anyNSSA && !(CHECK_FLAG(new->flags, OSPF_LSA_LOCAL_XLT)))
-		ospf_install_flood_nssa(ospf, new,
+		ospf_install_flood_nssa(ospf,
-					ei); /* Install/Flood per new rules */
+					new); /* Install/Flood per new rules */
 
 	/* Register self-originated LSA to refresh queue.
 	 * Translated LSAs should not be registered, but refreshed upon

ospfd/ospf_lsa.h

@@ -278,6 +278,11 @@ extern struct in_addr ospf_get_ip_from_ifp(struct ospf_interface *);
 
 extern struct ospf_lsa *ospf_external_lsa_originate(struct ospf *,
 						    struct external_info *);
+extern struct ospf_lsa *ospf_nssa_lsa_originate(struct ospf_area *area,
+						struct external_info *ei);
+extern struct ospf_lsa *ospf_nssa_lsa_refresh(struct ospf_area *area,
+					      struct ospf_lsa *lsa,
+					      struct external_info *ei);
 extern void ospf_external_lsa_rid_change(struct ospf *ospf);
 extern struct ospf_lsa *ospf_lsa_lookup(struct ospf *ospf, struct ospf_area *,
 					uint32_t, struct in_addr,

ospfd/ospf_vty.c

@@ -1438,6 +1438,7 @@ DEFPY (ospf_area_nssa,
        "area <A.B.C.D|(0-4294967295)>$area_str nssa\
          [{\
 	   <translate-candidate|translate-never|translate-always>$translator_role\
+	   |default-information-originate$dflt_originate [{metric (0-16777214)$mval|metric-type (1-2)$mtype}]\
 	   |no-summary$no_summary\
 	   |suppress-fa$suppress_fa\
 	 }]",
@@ -1448,6 +1449,11 @@ DEFPY (ospf_area_nssa,
        "Configure NSSA-ABR for translate election (default)\n"
        "Configure NSSA-ABR to never translate\n"
        "Configure NSSA-ABR to always translate\n"
+       "Originate Type 7 default into NSSA area\n"
+       "OSPF default metric\n"
+       "OSPF metric\n"
+       "OSPF metric type for default routes\n"
+       "Set OSPF External Type 1/2 metrics\n"
        "Do not inject inter-area routes into nssa\n"
        "Suppress forwarding address\n")
 {
@@ -1481,6 +1487,18 @@ DEFPY (ospf_area_nssa,
 						   OSPF_NSSA_ROLE_CANDIDATE);
 	}
 
+	if (dflt_originate) {
+		int metric_type = DEFAULT_METRIC_TYPE;
+
+		if (mval_str == NULL)
+			mval = -1;
+		if (mtype_str)
+			(void)str2metric_type(mtype_str, &metric_type);
+		ospf_area_nssa_default_originate_set(ospf, area_id, mval,
+						     metric_type);
+	} else
+		ospf_area_nssa_default_originate_unset(ospf, area_id);
+
 	if (no_summary)
 		ospf_area_nssa_no_summary_set(ospf, area_id);
 	else
@@ -1504,6 +1522,7 @@ DEFPY (no_ospf_area_nssa,
        "no area <A.B.C.D|(0-4294967295)>$area_str nssa\
          [{\
 	   <translate-candidate|translate-never|translate-always>\
+	   |default-information-originate [{metric (0-16777214)|metric-type (1-2)}]\
 	   |no-summary\
 	   |suppress-fa\
 	 }]",
@@ -1515,6 +1534,11 @@ DEFPY (no_ospf_area_nssa,
        "Configure NSSA-ABR for translate election (default)\n"
        "Configure NSSA-ABR to never translate\n"
        "Configure NSSA-ABR to always translate\n"
+       "Originate Type 7 default into NSSA area\n"
+       "OSPF default metric\n"
+       "OSPF metric\n"
+       "OSPF metric type for default routes\n"
+       "Set OSPF External Type 1/2 metrics\n"
        "Do not inject inter-area routes into nssa\n"
        "Suppress forwarding address\n")
 {
@@ -1527,6 +1551,7 @@ DEFPY (no_ospf_area_nssa,
 	/* Flush the NSSA LSA for the specified area */
 	ospf_flush_lsa_from_area(ospf, area_id, OSPF_AS_NSSA_LSA);
 	ospf_area_no_summary_unset(ospf, area_id);
+	ospf_area_nssa_default_originate_unset(ospf, area_id);
 	ospf_area_nssa_suppress_fa_unset(ospf, area_id);
 	ospf_area_nssa_unset(ospf, area_id);
 
@@ -11872,29 +11897,39 @@ static int config_write_ospf_area(struct vty *vty, struct ospf *ospf)
 					vty_out(vty, " no-summary\n");
 				vty_out(vty, "\n");
 			} else if (area->external_routing == OSPF_AREA_NSSA) {
+				vty_out(vty, " area %s nssa", buf);
+
 				switch (area->NSSATranslatorRole) {
 				case OSPF_NSSA_ROLE_NEVER:
-					vty_out(vty,
+					vty_out(vty, " translate-never");
-						" area %s nssa translate-never\n",
-						buf);
 					break;
 				case OSPF_NSSA_ROLE_ALWAYS:
-					vty_out(vty,
+					vty_out(vty, " translate-always");
-						" area %s nssa translate-always\n",
-						buf);
 					break;
 				case OSPF_NSSA_ROLE_CANDIDATE:
-					vty_out(vty, " area %s nssa \n", buf);
 					break;
 				}
+
+				if (area->nssa_default_originate.enabled) {
+					vty_out(vty,
+						" default-information-originate");
+					if (area->nssa_default_originate
+						    .metric_value
+					    != -1)
+						vty_out(vty, " metric %d",
+							area->nssa_default_originate
+								.metric_value);
+					if (area->nssa_default_originate
+						    .metric_type
+					    != DEFAULT_METRIC_TYPE)
+						vty_out(vty, " metric-type 1");
+				}
+
 				if (area->no_summary)
-					vty_out(vty,
+					vty_out(vty, " no-summary");
-						" area %s nssa no-summary\n",
-						buf);
 				if (area->suppress_fa)
-					vty_out(vty,
+					vty_out(vty, " suppress-fa");
-						" area %s nssa suppress-fa\n",
+				vty_out(vty, "\n");
-						buf);
 			}
 
 			if (area->default_cost != 1)

ospfd/ospf_zebra.c

@@ -20,6 +20,7 @@
 #include "log.h"
 #include "route_opaque.h"
 #include "lib/bfd.h"
+#include "lib/lib_errors.h"
 #include "nexthop.h"
 
 #include "ospfd/ospfd.h"
@@ -1470,6 +1471,61 @@ static int ospf_zebra_read_route(ZAPI_CALLBACK_ARGS)
 	return 0;
 }
 
+void ospf_zebra_import_default_route(struct ospf *ospf, bool unreg)
+{
+	struct prefix prefix = {};
+	int command;
+
+	if (zclient->sock < 0) {
+		if (IS_DEBUG_OSPF(zebra, ZEBRA))
+			zlog_debug("  Not connected to Zebra");
+		return;
+	}
+
+	prefix.family = AF_INET;
+	prefix.prefixlen = 0;
+
+	if (unreg)
+		command = ZEBRA_NEXTHOP_UNREGISTER;
+	else
+		command = ZEBRA_NEXTHOP_REGISTER;
+
+	if (IS_DEBUG_OSPF(zebra, ZEBRA))
+		zlog_debug("%s: sending cmd %s for %pFX (vrf %u)", __func__,
+			   zserv_command_string(command), &prefix,
+			   ospf->vrf_id);
+
+	if (zclient_send_rnh(zclient, command, &prefix, SAFI_UNICAST, false,
+			     true, ospf->vrf_id) == ZCLIENT_SEND_FAILURE)
+		flog_err(EC_LIB_ZAPI_SOCKET, "%s: zclient_send_rnh() failed",
+			 __func__);
+}
+
+static int ospf_zebra_import_check_update(ZAPI_CALLBACK_ARGS)
+{
+	struct ospf *ospf;
+	struct zapi_route nhr;
+	struct prefix matched;
+
+	ospf = ospf_lookup_by_vrf_id(vrf_id);
+	if (ospf == NULL || !IS_OSPF_ASBR(ospf))
+		return 0;
+
+	if (!zapi_nexthop_update_decode(zclient->ibuf, &matched, &nhr)) {
+		zlog_err("%s[%u]: Failure to decode route", __func__,
+			 ospf->vrf_id);
+		return -1;
+	}
+
+	if (matched.family != AF_INET || matched.prefixlen != 0 ||
+	    nhr.type == ZEBRA_ROUTE_OSPF)
+		return 0;
+
+	ospf->nssa_default_import_check.status = !!nhr.nexthop_num;
+	ospf_abr_nssa_type7_defaults(ospf);
+
+	return 0;
+}
 
 int ospf_distribute_list_out_set(struct ospf *ospf, int type, const char *name)
 {
@@ -2132,6 +2188,7 @@ static zclient_handler *const ospf_handlers[] = {
 
 	[ZEBRA_REDISTRIBUTE_ROUTE_ADD] = ospf_zebra_read_route,
 	[ZEBRA_REDISTRIBUTE_ROUTE_DEL] = ospf_zebra_read_route,
+	[ZEBRA_NEXTHOP_UPDATE] = ospf_zebra_import_check_update,
 
 	[ZEBRA_OPAQUE_MESSAGE] = ospf_opaque_msg_handler,
 

ospfd/ospf_zebra.h

@@ -69,6 +69,7 @@ extern int ospf_redistribute_set(struct ospf *, struct ospf_redist *, int,
 				 unsigned short, int, int);
 extern int ospf_redistribute_unset(struct ospf *, int, unsigned short);
 extern int ospf_redistribute_default_set(struct ospf *, int, int, int);
+extern void ospf_zebra_import_default_route(struct ospf *ospf, bool unreg);
 extern int ospf_distribute_list_out_set(struct ospf *, int, const char *);
 extern int ospf_distribute_list_out_unset(struct ospf *, int, const char *);
 extern void ospf_routemap_set(struct ospf_redist *, const char *);

ospfd/ospfd.c

@@ -1774,6 +1774,51 @@ int ospf_area_nssa_translator_role_set(struct ospf *ospf,
 	return 1;
 }
 
+void ospf_area_nssa_default_originate_set(struct ospf *ospf,
+					  struct in_addr area_id, int metric,
+					  int metric_type)
+{
+	struct ospf_area *area;
+
+	area = ospf_area_lookup_by_area_id(ospf, area_id);
+	if (area == NULL)
+		return;
+
+	if (!area->nssa_default_originate.enabled) {
+		area->nssa_default_originate.enabled = true;
+		if (++ospf->nssa_default_import_check.refcnt == 1) {
+			ospf->nssa_default_import_check.status = false;
+			ospf_zebra_import_default_route(ospf, false);
+		}
+	}
+
+	area->nssa_default_originate.metric_value = metric;
+	area->nssa_default_originate.metric_type = metric_type;
+}
+
+void ospf_area_nssa_default_originate_unset(struct ospf *ospf,
+					    struct in_addr area_id)
+{
+	struct ospf_area *area;
+
+	area = ospf_area_lookup_by_area_id(ospf, area_id);
+	if (area == NULL)
+		return;
+
+	if (area->nssa_default_originate.enabled) {
+		area->nssa_default_originate.enabled = false;
+		if (--ospf->nssa_default_import_check.refcnt == 0) {
+			ospf->nssa_default_import_check.status = false;
+			ospf_zebra_import_default_route(ospf, true);
+		}
+		area->nssa_default_originate.metric_value = -1;
+		area->nssa_default_originate.metric_type = -1;
+
+		if (!IS_OSPF_ABR(ospf))
+			ospf_abr_nssa_type7_defaults(ospf);
+	}
+}
+
 int ospf_area_export_list_set(struct ospf *ospf, struct ospf_area *area,
 			      const char *list_name)
 {

ospfd/ospfd.h

@@ -302,6 +302,18 @@ struct ospf {
 
 	int default_metric; /* Default metric for redistribute. */
 
+	/* NSSA default-information-originate */
+	struct {
+		/* # of NSSA areas requesting default information */
+		uint16_t refcnt;
+
+		/*
+		 * Whether a default route known through non-OSPF protocol is
+		 * present in the RIB.
+		 */
+		bool status;
+	} nssa_default_import_check;
+
 #define OSPF_LSA_REFRESHER_GRANULARITY 10
 #define OSPF_LSA_REFRESHER_SLOTS                                               \
 	((OSPF_LS_REFRESH_TIME + OSPF_LS_REFRESH_SHIFT)                        \
@@ -561,6 +573,13 @@ struct ospf_area {
 #define PREFIX_LIST_OUT(A)  (A)->plist_out.list
 #define PREFIX_NAME_OUT(A)  (A)->plist_out.name
 
+	/* NSSA default-information-originate */
+	struct {
+		bool enabled;
+		int metric_type;
+		int metric_value;
+	} nssa_default_originate;
+
 	/* Shortest Path Tree. */
 	struct vertex *spf;
 	struct list *spf_vertex_list;
@@ -704,6 +723,11 @@ extern int ospf_area_nssa_suppress_fa_unset(struct ospf *ospf,
 					    struct in_addr area_id);
 extern int ospf_area_nssa_translator_role_set(struct ospf *ospf,
 					      struct in_addr area_id, int role);
+extern void ospf_area_nssa_default_originate_set(struct ospf *ospf,
+						 struct in_addr area_id,
+						 int metric, int metric_type);
+extern void ospf_area_nssa_default_originate_unset(struct ospf *ospf,
+						   struct in_addr area_id);
 extern int ospf_area_export_list_set(struct ospf *ospf,
 				     struct ospf_area *area_id,
 				     const char *list_name);