net_node: drop connections from banned IPs after looping through connections

This keeps the connections lock just for the time of looping
and adding connectoins to a list, and the dropping happens
after it. This should avoid lengthy delays waiting for the
connections lock.

src/p2p/net_node.inl

@@ -203,15 +203,17 @@ namespace nodetool
     m_blocked_ips[addr] = time(nullptr) + seconds;
 
     // drop any connection to that IP
-    while (!m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
+    std::list<boost::uuids::uuid> conns;
+    m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
     {
       if (cntxt.m_remote_ip == addr)
       {
-        drop_connection(cntxt);
-        return false;
+        conns.push_back(cntxt.m_connection_id);
       }
       return true;
-    }));
+    });
+    for (const auto &c: conns)
+      m_net_server.get_config_object().close(c);
 
     LOG_PRINT_CYAN("IP " << epee::string_tools::get_ip_string_from_int32(addr) << " blocked.", LOG_LEVEL_0);
     return true;