Poor man's visualisation: cope with no BIRD client.

poor_mans_visualisation.py

@@ -13,7 +13,42 @@ if len(sys.argv) > 1:
 with open(ref_topo_file) as ref_file:
 	ref_topo = providers.OspfFileTopologyProvider(ref_file).get_topology()
 
+try:
 	cur_topo = providers.RunningBirdTopologyProvider().get_topology()
+except OSError:
+	# HACK!
+	import traceback as tb
+	tb.print_exc(file=sys.stderr)
+	print(f'Could not get current topology from BIRD,\n'
+		'will load reference one with random omissions\n----', file=sys.stderr)
+	with open(ref_topo_file) as ref_file:
+		cur_topo = providers.OspfFileTopologyProvider(ref_file).get_topology()
+	import random
+	random.seed('birdvisu_demo')
+	# Routers:
+	for _ in range(random.randint(1, 3)):
+		key, router_to_delete = random.choice(list(cur_topo.routers.items()))
+		for l in router_to_delete.links:
+			lk = (l.router.ident, l.network.ident)
+			del cur_topo.links[lk]
+			l.network.links.remove(l)
+		del cur_topo.routers[key]
+	# Networks:
+	for _ in range(random.randint(1, 3)):
+		key, network_to_delete = random.choice(list(cur_topo.networks.items()))
+		for l in network_to_delete.links:
+			lk = (l.router.ident, l.network.ident)
+			del cur_topo.links[lk]
+			l.router.links.remove(l)
+		del cur_topo.networks[key]
+	# Links:
+	for _ in range(random.randint(1, 3)):
+		key, link_to_delete = random.choice(list(cur_topo.links.items()))
+		link_to_delete.router.links.remove(link_to_delete)
+		link_to_delete.network.links.remove(link_to_delete)
+		del cur_topo.links[key]
+
+
 
 # Combine topologies