Ask for consensus diffs even from fallback relays

In case you have last epoch's consensus, but your guard has gone away

client.py

@@ -77,7 +77,11 @@ class ClientChannelManager(relay.ChannelManager):
     def get_consensus_from_fallbackrelay(self):
         """Download a fresh consensus from a random fallbackrelay."""
         fb = random.choice(network.thenetwork.getfallbackrelays())
-        self.send_msg(relay.RelayGetConsensusMsg(), fb.netaddr)
+        if self.consensus is not None and \
+                len(self.consensus.consdict['relays']) > 0:
+            self.send_msg(relay.RelayGetConsensusDiffMsg(), fb.netaddr)
+        else:
+            self.send_msg(relay.RelayGetConsensusMsg(), fb.netaddr)
 
     def ensure_guard_vanilla(self):
         """Ensure that we have a channel to a guard (Vanilla Onion
@@ -141,7 +145,7 @@ class ClientChannelManager(relay.ChannelManager):
         received."""
         print("Client %s received msg %s from %s" % (self.myaddr, msg, peeraddr))
         if isinstance(msg, relay.RelayConsensusMsg) or \
-                instance(msg, relay.RelayConsensusDiffMsg):
+                isinstance(msg, relay.RelayConsensusDiffMsg):
             dirauth.Consensus.verify(msg.consensus,
                     network.thenetwork.dirauthkeys(), self.perfstats)
             self.consensus = msg.consensus
@@ -305,10 +309,10 @@ if __name__ == '__main__':
         r = clients[0].channelmgr.consensus.select_weighted_relay(clients[0].channelmgr.consensus_cdf)
         print("relay",r.descdict["addr"])
 
-    #relays[3].terminate()
-    #relaysent += relays[3].perfstats.bytes_sent
-    #relayrecv += relays[3].perfstats.bytes_received
-    #del relays[3]
+    relays[3].terminate()
+    relaysent += relays[3].perfstats.bytes_sent
+    relayrecv += relays[3].perfstats.bytes_received
+    del relays[3]
 
     # Tick the epoch
     network.thenetwork.nextepoch()

relay.py

@@ -566,6 +566,8 @@ class RelayChannelManager(ChannelManager):
                 self.send_msg(RelayRandomHopMsg(msg.ttl-1), nextaddr)
         elif isinstance(msg, RelayGetConsensusMsg):
             self.send_msg(RelayConsensusMsg(self.consensus), peeraddr)
+        elif isinstance(msg, RelayGetConsensusDiffMsg):
+            self.send_msg(RelayConsensusDiffMsg(self.consensus), peeraddr)
         elif isinstance(msg, VanillaCreateCircuitMsg):
             # A new circuit has arrived
             circhandler = channel.new_circuit_with_circid(msg.circid)