ospfd: add support for suppress_fa

This command will trigger the OSPF forwarding address suppression in
translated type-5 LSAs, causing a NSSA ABR to use 0.0.0.0 as a forwarding
address instead of copying the address from the type-7 LSA

Example: In a topology like: R1 --- R2(ABR) --- R3(ASBR)

R3 is announcing a type-7 LSA that is translated to type-5 by the R2 ABR.
The forwarding address in the type-5 is by default copied from the type-7

    r1# sh ip os da external

                    AS External Link States

      LS age: 6
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000001
      Checksum: 0xcf99
      Length: 36

      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 10.0.23.3    <--- address copied from type-7 lsa
            External Route Tag: 0

    r2# sh ip os database

                    NSSA-external Link States (Area 0.0.0.1 [NSSA])

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.23.3          8 0x80000001 0x431d E2 3.3.3.3/32 [0x0]

                    AS External Link States

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.25.2          0 0x80000001 0xcf99 E2 3.3.3.3/32 [0x0]

    r2# conf t
    r2(config)# router ospf
    r2(config-router)# area 1 nssa suppress-fa
    r2(config-router)# exit
    r2(config)# exit

    r2# sh ip os database

                    NSSA-external Link States (Area 0.0.0.1 [NSSA])

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.23.3         66 0x80000001 0x431d E2 3.3.3.3/32 [0x0]

                    AS External Link States

    Link ID         ADV Router      Age  Seq#       CkSum  Route
    3.3.3.3         10.0.25.2         16 0x80000002 0x0983 E2 3.3.3.3/32 [0x0]

    r1# sh ip os da external

           OSPF Router with ID (11.11.11.11)

                    AS External Link States

      LS age: 34
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000002
      Checksum: 0x0983
      Length: 36

      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 0.0.0.0       <--- address set to 0
            External Route Tag: 0

    r2# conf t
    r2(config)# router ospf
    r2(config-router)# no area 1 nssa suppress-fa
    r2(config-router)# exit

    r1# sh ip os da external

           OSPF Router with ID (11.11.11.11)

                    AS External Link States

      LS age: 1
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000003
      Checksum: 0xcb9b
      Length: 36
      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 0.0.0.0       <--- address set to 0
            External Route Tag: 0

    r2# conf t
    r2(config)# router ospf
    r2(config-router)# no area 1 nssa suppress-fa
    r2(config-router)# exit

    r1# sh ip os da external

           OSPF Router with ID (11.11.11.11)

                    AS External Link States

      LS age: 1
      Options: 0x2  : *|-|-|-|-|-|E|-
      LS Flags: 0x6
      LS Type: AS-external-LSA
      Link State ID: 3.3.3.3 (External Network Number)
      Advertising Router: 10.0.25.2
      LS Seq Number: 80000003
      Checksum: 0xcb9b
      Length: 36

      Network Mask: /32
            Metric Type: 2 (Larger than any link state path)
            TOS: 0
            Metric: 20
            Forward Address: 10.0.23.3    <--- address copied from type-7 lsa
            External Route Tag: 0

Signed-off-by: ckishimo <carles.kishimoto@gmail.com>

ospfd/ospf_abr.c

@@ -675,7 +675,8 @@ static int ospf_abr_translate_nssa(struct ospf_area *area, struct ospf_lsa *lsa)
 		 * originate translated LSA
 		 */
 
-		if (ospf_translated_nssa_originate(area->ospf, lsa) == NULL) {
+		if (ospf_translated_nssa_originate(area->ospf, lsa, old)
+		    == NULL) {
 			if (IS_DEBUG_OSPF_NSSA)
 				zlog_debug(
 					"ospf_abr_translate_nssa(): Could not translate Type-7 for %pI4 to Type-5",

ospfd/ospf_lsa.c

@@ -1765,7 +1765,14 @@ static struct ospf_lsa *ospf_lsa_translated_nssa_new(struct ospf *ospf,
 	/* copy over Type-7 data to new */
 	extnew->e[0].tos = ext->e[0].tos;
 	extnew->e[0].route_tag = ext->e[0].route_tag;
-	extnew->e[0].fwd_addr.s_addr = ext->e[0].fwd_addr.s_addr;
+	if (type7->area->suppress_fa) {
+		extnew->e[0].fwd_addr.s_addr = 0;
+		if (IS_DEBUG_OSPF_NSSA)
+			zlog_debug(
+				"ospf_lsa_translated_nssa_new(): Suppress forwarding address for %pI4",
+				&ei.p.prefix);
+	} else
+		extnew->e[0].fwd_addr.s_addr = ext->e[0].fwd_addr.s_addr;
 	new->data->ls_seqnum = type7->data->ls_seqnum;
 
 	/* add translated flag, checksum and lock new lsa */
@@ -1777,7 +1784,8 @@ static struct ospf_lsa *ospf_lsa_translated_nssa_new(struct ospf *ospf,
 
 /* Originate Translated Type-5 for supplied Type-7 NSSA LSA */
 struct ospf_lsa *ospf_translated_nssa_originate(struct ospf *ospf,
-						struct ospf_lsa *type7)
+						struct ospf_lsa *type7,
+						struct ospf_lsa *type5)
 {
 	struct ospf_lsa *new;
 	struct as_external_lsa *extnew;
@@ -1796,6 +1804,10 @@ struct ospf_lsa *ospf_translated_nssa_originate(struct ospf *ospf,
 
 	extnew = (struct as_external_lsa *)new->data;
 
+	/* Update LSA sequence number from translated Type-5 LSA */
+	if (type5)
+		new->data->ls_seqnum = lsa_seqnum_increment(type5);
+
 	if ((new = ospf_lsa_install(ospf, NULL, new)) == NULL) {
 		flog_warn(EC_OSPF_LSA_INSTALL_FAILURE,
 			  "%s: Could not install LSA id %pI4", __func__,
@@ -1823,6 +1835,8 @@ struct ospf_lsa *ospf_translated_nssa_refresh(struct ospf *ospf,
 					      struct ospf_lsa *type5)
 {
 	struct ospf_lsa *new = NULL;
+	struct as_external_lsa *extold = NULL;
+	uint32_t ls_seqnum = 0;
 
 	/* Sanity checks. */
 	assert(type7 || type5);
@@ -1887,6 +1901,12 @@ struct ospf_lsa *ospf_translated_nssa_refresh(struct ospf *ospf,
 		return NULL;
 	}
 
+	extold = (struct as_external_lsa *)type5->data;
+	if (type7->area->suppress_fa == 1) {
+		if (extold->e[0].fwd_addr.s_addr == 0)
+			ls_seqnum = ntohl(type5->data->ls_seqnum);
+	}
+
 	/* Delete LSA from neighbor retransmit-list. */
 	ospf_ls_retransmit_delete_nbr_as(ospf, type5);
 
@@ -1899,6 +1919,11 @@ struct ospf_lsa *ospf_translated_nssa_refresh(struct ospf *ospf,
 		return NULL;
 	}
 
+	if (type7->area->suppress_fa == 1) {
+		if (extold->e[0].fwd_addr.s_addr == 0)
+			new->data->ls_seqnum = htonl(ls_seqnum + 1);
+	}
+
 	if (!(new = ospf_lsa_install(ospf, NULL, new))) {
 		flog_warn(
 			EC_OSPF_LSA_INSTALL_FAILURE,

ospfd/ospf_lsa.h

@@ -341,11 +341,12 @@ extern char link_info_set(struct stream **s, struct in_addr id,
 
 extern struct in_addr ospf_get_nssa_ip(struct ospf_area *);
 extern int ospf_translated_nssa_compare(struct ospf_lsa *, struct ospf_lsa *);
-extern struct ospf_lsa *ospf_translated_nssa_refresh(struct ospf *,
+extern struct ospf_lsa *ospf_translated_nssa_refresh(struct ospf *ospf,
-						     struct ospf_lsa *,
+						     struct ospf_lsa *type7,
-						     struct ospf_lsa *);
+						     struct ospf_lsa *type5);
-extern struct ospf_lsa *ospf_translated_nssa_originate(struct ospf *,
+extern struct ospf_lsa *ospf_translated_nssa_originate(struct ospf *ospf,
-						       struct ospf_lsa *);
+						       struct ospf_lsa *type7,
+						       struct ospf_lsa *type5);
 extern void ospf_flush_lsa_from_area(struct ospf *ospf, struct in_addr area_id,
 				     int type);
 #endif /* _ZEBRA_OSPF_LSA_H */

ospfd/ospf_vty.c

@@ -1574,6 +1574,58 @@ DEFUN (ospf_area_nssa,
 	return ospf_area_nssa_cmd_handler(vty, argc, argv, 0, 0);
 }
 
+DEFUN(ospf_area_nssa_suppress_fa, ospf_area_nssa_suppress_fa_cmd,
+      "area <A.B.C.D|(0-4294967295)> nssa suppress-fa",
+      "OSPF area parameters\n"
+      "OSPF area ID in IP address format\n"
+      "OSPF area ID as a decimal value\n"
+      "Configure OSPF area as nssa\n"
+      "Suppress forwarding address\n")
+{
+	int idx_ipv4_number = 1;
+	struct in_addr area_id;
+	int format;
+
+	VTY_DECLVAR_INSTANCE_CONTEXT(ospf, ospf);
+	VTY_GET_OSPF_AREA_ID_NO_BB("NSSA", area_id, format,
+				   argv[idx_ipv4_number]->arg);
+
+	ospf_area_display_format_set(ospf, ospf_area_get(ospf, area_id),
+				     format);
+	ospf_area_nssa_suppress_fa_set(ospf, area_id);
+
+	ospf_schedule_abr_task(ospf);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(no_ospf_area_nssa_suppress_fa, no_ospf_area_nssa_suppress_fa_cmd,
+      "no area <A.B.C.D|(0-4294967295)> nssa suppress-fa",
+      NO_STR
+      "OSPF area parameters\n"
+      "OSPF area ID in IP address format\n"
+      "OSPF area ID as a decimal value\n"
+      "Configure OSPF area as nssa\n"
+      "Suppress forwarding address\n")
+{
+	int idx_ipv4_number = 2;
+	struct in_addr area_id;
+	int format;
+
+	VTY_DECLVAR_INSTANCE_CONTEXT(ospf, ospf);
+
+	VTY_GET_OSPF_AREA_ID_NO_BB("nssa", area_id, format,
+				   argv[idx_ipv4_number]->arg);
+
+	ospf_area_display_format_set(ospf, ospf_area_get(ospf, area_id),
+				     format);
+	ospf_area_nssa_suppress_fa_unset(ospf, area_id);
+
+	ospf_schedule_abr_task(ospf);
+
+	return CMD_SUCCESS;
+}
+
 DEFUN (ospf_area_nssa_no_summary,
        ospf_area_nssa_no_summary_cmd,
        "area <A.B.C.D|(0-4294967295)> nssa no-summary",
@@ -11823,6 +11875,10 @@ static int config_write_ospf_area(struct vty *vty, struct ospf *ospf)
 					vty_out(vty,
 						" area %s nssa no-summary\n",
 						buf);
+				if (area->suppress_fa)
+					vty_out(vty,
+						" area %s nssa suppress-fa\n",
+						buf);
 			}
 
 			if (area->default_cost != 1)
@@ -12684,6 +12740,8 @@ void ospf_vty_init(void)
 	install_element(OSPF_NODE, &ospf_area_nssa_translate_cmd);
 	install_element(OSPF_NODE, &ospf_area_nssa_no_summary_cmd);
 	install_element(OSPF_NODE, &no_ospf_area_nssa_no_summary_cmd);
+	install_element(OSPF_NODE, &ospf_area_nssa_suppress_fa_cmd);
+	install_element(OSPF_NODE, &no_ospf_area_nssa_suppress_fa_cmd);
 	install_element(OSPF_NODE, &no_ospf_area_nssa_cmd);
 
 	install_element(OSPF_NODE, &ospf_area_default_cost_cmd);

ospfd/ospfd.c

@@ -1672,6 +1672,7 @@ int ospf_area_nssa_set(struct ospf *ospf, struct in_addr area_id)
 
 		/* set NSSA area defaults */
 		area->no_summary = 0;
+		area->suppress_fa = 0;
 		area->NSSATranslatorRole = OSPF_NSSA_ROLE_CANDIDATE;
 		area->NSSATranslatorState = OSPF_NSSA_TRANSLATE_DISABLED;
 		area->NSSATranslatorStabilityInterval =
@@ -1693,6 +1694,7 @@ int ospf_area_nssa_unset(struct ospf *ospf, struct in_addr area_id, int argc)
 		ospf->anyNSSA--;
 		/* set NSSA area defaults */
 		area->no_summary = 0;
+		area->suppress_fa = 0;
 		area->NSSATranslatorRole = OSPF_NSSA_ROLE_CANDIDATE;
 		area->NSSATranslatorState = OSPF_NSSA_TRANSLATE_DISABLED;
 		area->NSSATranslatorStabilityInterval =
@@ -1708,6 +1710,32 @@ int ospf_area_nssa_unset(struct ospf *ospf, struct in_addr area_id, int argc)
 	return 1;
 }
 
+int ospf_area_nssa_suppress_fa_set(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 0;
+
+	area->suppress_fa = 1;
+
+	return 1;
+}
+
+int ospf_area_nssa_suppress_fa_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 0;
+
+	area->suppress_fa = 0;
+
+	return 1;
+}
+
 int ospf_area_nssa_translator_role_set(struct ospf *ospf,
 				       struct in_addr area_id, int role)
 {

ospfd/ospfd.h

@@ -476,7 +476,7 @@ struct ospf_area {
 	int shortcut_capability; /* Other ABRs agree on S-bit */
 	uint32_t default_cost;   /* StubDefaultCost. */
 	int auth_type;		 /* Authentication type. */
-
+	int suppress_fa;	 /* Suppress forwarding address in NSSA ABR */
 
 	uint8_t NSSATranslatorRole; /* NSSA configured role */
 #define OSPF_NSSA_ROLE_NEVER     0
@@ -668,6 +668,10 @@ extern int ospf_area_no_summary_set(struct ospf *, struct in_addr);
 extern int ospf_area_no_summary_unset(struct ospf *, struct in_addr);
 extern int ospf_area_nssa_set(struct ospf *, struct in_addr);
 extern int ospf_area_nssa_unset(struct ospf *, struct in_addr, int);
+extern int ospf_area_nssa_suppress_fa_set(struct ospf *ospf,
+					  struct in_addr area_id);
+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 *, struct in_addr,
 					      int);
 extern int ospf_area_export_list_set(struct ospf *, struct ospf_area *,