Reduce Zenmap's Topology noise by collapsing equivalent 'anonymous' nodes

zenmap/radialnet/util/integration.py

@@ -176,11 +176,21 @@ class TracerouteHostInfo(object):
     hostnames = property(lambda self: self.hostname and [self.hostname] or [])
 
 
+def find_hop_by_ttl(hops, ttl):
+    assert ttl >= 0, "ttl must be non-negative"
+    if ttl == 0: # Same machine (i.e. localhost)
+        return {"ipaddr": "127.0.0.1/8"}
+    for h in hops:
+        if ttl == int(h["ttl"]):
+            return h
+    return None
+
 def make_graph_from_hosts(hosts):
     #hosts = parser.get_root().search_children('host', deep=True)
     graph = Graph()
     nodes = list()
     node_cache = {}
+    invalid_node_cache = {}
 
     # Setting initial reference host
     main_node = NetNode()
@@ -210,13 +220,7 @@ def make_graph_from_hosts(hosts):
             # Getting nodes of host by ttl
             for ttl in range(1, max(ttls) + 1):
                 if ttl in ttls:
-                    # Find a hop by ttl
-                    hop = None
-                    for h in hops:
-                        if ttl == int(h["ttl"]):
-                            hop = h
-                            break
-
+                    hop = find_hop_by_ttl(hops, ttl)
                     node = node_cache.get(hop["ipaddr"])
                     if node is None:
                         node = NetNode()
@@ -245,14 +249,34 @@ def make_graph_from_hosts(hosts):
                     else:
                         graph.set_connection(node, prev_node)
                 else:
-                    node = NetNode()
-                    nodes.append(node)
+                    # Add an "anonymous" node only if there isn't already a node
+                    # equivalent to it (i.e. at same distance from the previous 
+                    # "real" node)
 
-                    node.set_draw_info({"valid": False})
-                    node.set_draw_info(
-                            {"color": (1, 1, 1), "radius": NONE_RADIUS})
+                    pre_hop = None
+                    pre_hop_distance = 0
+                    for i in range(1, ttl + 1):
+                        pre_hop = find_hop_by_ttl(hops, ttl-i)
+                        if pre_hop is not None:
+                            pre_hop_distance = i
+                            break
 
-                    graph.set_connection(node, prev_node)
+                    assert pre_hop is not None, "pre_hop should have become localhost if nothing else"
+
+                    key = (pre_hop["ipaddr"], pre_hop_distance)
+
+                    if key not in invalid_node_cache:
+                        node = NetNode()
+                        nodes.append(node)
+
+                        node.set_draw_info({"valid":False})
+                        node.set_draw_info({"color":(1,1,1), "radius":NONE_RADIUS})
+
+                        graph.set_connection(node, prev_node)
+
+                        invalid_node_cache[key] = node
+
+                    node = invalid_node_cache[key]
 
                 prev_node = node
                 endpoints[host] = node