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>

1 files changed, 24 insertions, 0 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;
+}