removed mutation

p2p/peer.py

@@ -599,14 +599,11 @@ def is_full(self) -> bool:
         return len(self) >= self.max_peers
 
     def is_valid_connection_candidate(self, candidate: Node) -> bool:
-        max_matching_ip = 2
-        matching_ip = 0
-        for peer in self.connected_nodes.values():
-            if candidate.address.ip == peer.remote.address.ip:
-                matching_ip += 1
-            if (matching_ip > max_matching_ip):
-                return False
-        return True
+        # connect to no more then 2 nodes with the same IP
+        nodes_by_ip = groupby(
+            operator.attrgetter('remote.address.ip'), self.connected_nodes.values())
+        matching_ip_nodes = nodes_by_ip.get(candidate.address.ip, [])
+        return len(matching_ip_nodes) <= 2
 
     def get_nodes_to_connect(self) -> Generator[Node, None, None]:
         for node in self.discovery.get_random_nodes(self.max_peers):

p2p/server.py

@@ -355,25 +355,21 @@ async def _receive_handshake(
             inbound=True,
         )
 
-        total_peers_inbound = 0.0
-        total_peers = 0.0
-
-        for current_peers in self.peer_pool.connected_nodes.values():
-            total_peers += 1
-            if current_peers.inbound:
-                total_peers_inbound += 1
-        # make sure to have atleast 1/4 outbound connections
-
         if self.peer_pool.is_full:
             peer.disconnect(DisconnectReason.too_many_peers)
-        elif total_peers > 1 and total_peers_inbound // total_peers > 0.75:
-            peer.disconnect(DisconnectReason.useless_peer)
-        elif not self.peer_pool.is_valid_connection_candidate(peer.remote):
-            peer.disconnect(DisconnectReason.useless_peer)
         else:
-            # We use self.wait() here as a workaround for
-            # https://github.com/ethereum/py-evm/issues/670.
-            await self.wait(self.do_handshake(peer))
+            total_peers = len(self.peer_pool.connected_nodes)
+            inbound_peers = len(
+                [peer for peer in self.peer_pool.connected_nodes.values() if peer.inbound])
+            if total_peers > 1 and inbound_peers / total_peers > 0.75:
+                # make sure to have at least 1/4 outbound connections
+                peer.disconnect(DisconnectReason.useless_peer)
+            elif not self.peer_pool.is_valid_connection_candidate(peer.remote):
+                peer.disconnect(DisconnectReason.useless_peer)
+            else:
+                # We use self.wait() here as a workaround for
+                # https://github.com/ethereum/py-evm/issues/670.
+                await self.wait(self.do_handshake(peer))
 
     async def do_handshake(self, peer: BasePeer) -> None:
         await peer.do_p2p_handshake(),

tests/p2p/test_server.py

@@ -51,6 +51,9 @@ class MockPeerPool():
     def is_valid_connection_candidate(self, node):
         return True
 
+    def __len__(self):
+        return len(self.connected_nodes)
+
 
 def get_server(privkey, address, peer_class):
     base_db = MemoryDB()