From 414158882318898c970297d84d20935f4e4a7bb0 Mon Sep 17 00:00:00 2001
From: Christian Franke <chris@opensourcerouting.org>
Date: Thu, 7 Jun 2018 12:58:42 +0200
Subject: [PATCH] fabricd: add support for completely unnumbered operation

With this commit, fabricd can run without any IPv4 addresses configured
except on loopback. There are two changes to achieve this:

a) If a circuit has no IPv4 address configured, fabricd will resort to
advertise the routers loopback IP in the OpenFabric hellos.

b) All the routes from OpenFabric are sent with ZEBRA_FLAG_ONLINK set,
so that zebra will install them into the fib without checking whether
the nexthop is reachable

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
---
 isisd/fabricd.c    | 24 ++++++++++++++++++++++++
 isisd/fabricd.h    |  1 +
 isisd/isis_pdu.c   | 10 +++++++---
 isisd/isis_zebra.c |  2 ++
 4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/isisd/fabricd.c b/isisd/fabricd.c
index b52f2b554e..7951efe5a1 100644
--- a/isisd/fabricd.c
+++ b/isisd/fabricd.c
@@ -691,3 +691,27 @@ void fabricd_trigger_csnp(struct isis_area *area)
 				      &circuit->t_send_csnp[ISIS_LEVEL2 - 1]);
 	}
 }
+
+struct list *fabricd_ip_addrs(struct isis_circuit *circuit)
+{
+	if (circuit->ip_addrs && listcount(circuit->ip_addrs))
+		return circuit->ip_addrs;
+
+	if (!fabricd || !circuit->area || !circuit->area->circuit_list)
+		return NULL;
+
+	struct listnode *node;
+	struct isis_circuit *c;
+
+	for (ALL_LIST_ELEMENTS_RO(circuit->area->circuit_list, node, c)) {
+		if (c->circ_type != CIRCUIT_T_LOOPBACK)
+			continue;
+
+		if (!c->ip_addrs || !listcount(c->ip_addrs))
+			return NULL;
+
+		return c->ip_addrs;
+	}
+
+	return NULL;
+}
diff --git a/isisd/fabricd.h b/isisd/fabricd.h
index f54c7bf89e..76c182f2d2 100644
--- a/isisd/fabricd.h
+++ b/isisd/fabricd.h
@@ -44,5 +44,6 @@ uint8_t fabricd_tier(struct isis_area *area);
 int fabricd_write_settings(struct isis_area *area, struct vty *vty);
 void fabricd_lsp_flood(struct isis_lsp *lsp);
 void fabricd_trigger_csnp(struct isis_area *area);
+struct list *fabricd_ip_addrs(struct isis_circuit *circuit);
 
 #endif
diff --git a/isisd/isis_pdu.c b/isisd/isis_pdu.c
index fc9ff5143f..88575f5319 100644
--- a/isisd/isis_pdu.c
+++ b/isisd/isis_pdu.c
@@ -679,7 +679,7 @@ static int process_hello(uint8_t pdu_type, struct isis_circuit *circuit,
 		goto out;
 	}
 
-	iih.v4_usable = (circuit->ip_addrs && listcount(circuit->ip_addrs)
+	iih.v4_usable = (fabricd_ip_addrs(circuit)
 			 && iih.tlvs->ipv4_address.count);
 
 	iih.v6_usable = (circuit->ipv6_link && listcount(circuit->ipv6_link)
@@ -1689,8 +1689,12 @@ int send_hello(struct isis_circuit *circuit, int level)
 						     false, false);
 	}
 
-	if (circuit->ip_router && circuit->ip_addrs)
-		isis_tlvs_add_ipv4_addresses(tlvs, circuit->ip_addrs);
+	if (circuit->ip_router) {
+		struct list *circuit_ip_addrs = fabricd_ip_addrs(circuit);
+
+		if (circuit_ip_addrs)
+			isis_tlvs_add_ipv4_addresses(tlvs, circuit_ip_addrs);
+	}
 
 	if (circuit->ipv6_router && circuit->ipv6_link)
 		isis_tlvs_add_ipv6_addresses(tlvs, circuit->ipv6_link);
diff --git a/isisd/isis_zebra.c b/isisd/isis_zebra.c
index 220f131b63..33d8a0f771 100644
--- a/isisd/isis_zebra.c
+++ b/isisd/isis_zebra.c
@@ -261,6 +261,8 @@ static void isis_zebra_route_add_route(struct prefix *prefix,
 		return;
 
 	memset(&api, 0, sizeof(api));
+	if (fabricd)
+		api.flags |= ZEBRA_FLAG_ONLINK;
 	api.vrf_id = VRF_DEFAULT;
 	api.type = PROTO_TYPE;
 	api.safi = SAFI_UNICAST;
-- 
2.39.5