Server full and duplicate handling

- will try to report "Server full" over protocol for 10 extra
connections over limit, instead of simply dropping them
- if connected to the same host inbound and outbound, handle as server
full (prevents duplicate connections)

src/network/bmproto.py

@@ -497,6 +497,20 @@ class BMProto(AdvancedDispatcher, ObjectTracker):
                     return False
             except:
                 pass
+        if not self.isOutbound:
+            # incoming from a peer we're connected to as outbound, or server full
+            # report the same error to counter deanonymisation
+            if state.Peer(self.destination.host, self.peerNode.port) in \
+                network.connectionpool.BMConnectionPool().inboundConnections or \
+                len(network.connectionpool.BMConnectionPool().inboundConnections) + \
+                len(network.connectionpool.BMConnectionPool().outboundConnections) > \
+                BMConfigParser().safeGetInt("bitmessagesettings", "maxtotalconnections") + \
+                BMConfigParser().safeGetInt("bitmessagesettings", "maxbootstrapconnections"):
+                self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
+                    errorText="Server full, please try again later."))
+                logger.debug ("Closed connection to %s due to server full or duplicate inbound/outbound.",
+                    str(self.destination))
+                return False
         if network.connectionpool.BMConnectionPool().isAlreadyConnected(self.nonce):
             self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                 errorText="I'm connected to myself. Closing connection."))

src/network/tcp.py

@@ -292,7 +292,10 @@ class TCPServer(AdvancedDispatcher):
             if len(network.connectionpool.BMConnectionPool().inboundConnections) + \
                 len(network.connectionpool.BMConnectionPool().outboundConnections) > \
                 BMConfigParser().safeGetInt("bitmessagesettings", "maxtotalconnections") + \
-                BMConfigParser().safeGetInt("bitmessagesettings", "maxbootstrapconnections"):
+                BMConfigParser().safeGetInt("bitmessagesettings", "maxbootstrapconnections") + 10:
+                # 10 is a sort of buffer, in between it will go through the version handshake
+                # and return an error to the peer
+                logger.warning("Server full, dropping connection")
                 sock.close()
                 return
             try: