Merge pull request #5481

28a7d315 p2p: do not send last_seen timestamp to peers (moneromooo-monero)

src/p2p/net_node.inl

@@ -1955,7 +1955,7 @@ namespace nodetool
     const epee::net_utils::zone zone_type = context.m_remote_address.get_zone();
     network_zone& zone = m_network_zones.at(zone_type);
 
-    zone.m_peerlist.get_peerlist_head(rsp.local_peerlist_new);
+    zone.m_peerlist.get_peerlist_head(rsp.local_peerlist_new, true);
     m_payload_handler.get_payload_sync_data(rsp.payload_data);
 
     /* Tor/I2P nodes receiving connections via forwarding (from tor/i2p daemon)
@@ -2058,7 +2058,7 @@ namespace nodetool
     });
 
     //fill response
-    zone.m_peerlist.get_peerlist_head(rsp.local_peerlist_new);
+    zone.m_peerlist.get_peerlist_head(rsp.local_peerlist_new, true);
     get_local_node_data(rsp.node_data, zone);
     m_payload_handler.get_payload_sync_data(rsp.payload_data);
     LOG_DEBUG_CC(context, "COMMAND_HANDSHAKE");

src/p2p/net_peerlist.h

@@ -102,7 +102,7 @@ namespace nodetool
     size_t get_white_peers_count(){CRITICAL_REGION_LOCAL(m_peerlist_lock); return m_peers_white.size();}
     size_t get_gray_peers_count(){CRITICAL_REGION_LOCAL(m_peerlist_lock); return m_peers_gray.size();}
     bool merge_peerlist(const std::vector<peerlist_entry>& outer_bs);
-    bool get_peerlist_head(std::vector<peerlist_entry>& bs_head, uint32_t depth = P2P_DEFAULT_PEERS_IN_HANDSHAKE);
+    bool get_peerlist_head(std::vector<peerlist_entry>& bs_head, bool anonymize, uint32_t depth = P2P_DEFAULT_PEERS_IN_HANDSHAKE);
     void get_peerlist(std::vector<peerlist_entry>& pl_gray, std::vector<peerlist_entry>& pl_white);
     void get_peerlist(peerlist_types& peers);
     bool get_white_peer_by_index(peerlist_entry& p, size_t i);
@@ -263,23 +263,40 @@ namespace nodetool
   }
   //--------------------------------------------------------------------------------------------------
   inline 
-  bool peerlist_manager::get_peerlist_head(std::vector<peerlist_entry>& bs_head, uint32_t depth)
+  bool peerlist_manager::get_peerlist_head(std::vector<peerlist_entry>& bs_head, bool anonymize, uint32_t depth)
   {
-    
     CRITICAL_REGION_LOCAL(m_peerlist_lock);
     peers_indexed::index<by_time>::type& by_time_index=m_peers_white.get<by_time>();
     uint32_t cnt = 0;
-    bs_head.reserve(depth);
+
+    // picks a random set of peers within the first 120%, rather than a set of the first 100%.
+    // The intent is that if someone asks twice, they can't easily tell:
+    // - this address was not in the first list, but is in the second, so the only way this can be
+    // is if its last_seen was recently reset, so this means the target node recently had a new
+    // connection to that address
+    // - this address was in the first list, and not in the second, which means either the address
+    // was moved to the gray list (if it's not accessibe, which the attacker can check if
+    // the address accepts incoming connections) or it was the oldest to still fit in the 250 items,
+    // so its last_seen is old.
+    const uint32_t pick_depth = anonymize ? depth + depth / 5 : depth;
+    bs_head.reserve(pick_depth);
     for(const peers_indexed::value_type& vl: boost::adaptors::reverse(by_time_index))
     {
-      if(!vl.last_seen)
+      if(cnt++ >= pick_depth)
-        continue;
-
-      if(cnt++ >= depth)
         break;
 
       bs_head.push_back(vl);
     }
+
+    if (anonymize)
+    {
+      std::random_shuffle(bs_head.begin(), bs_head.end());
+      if (bs_head.size() > depth)
+        bs_head.resize(depth);
+      for (auto &e: bs_head)
+        e.last_seen = 0;
+    }
+
     return true;
   }
   //--------------------------------------------------------------------------------------------------

src/p2p/p2p_protocol_defs.h

@@ -81,7 +81,8 @@ namespace nodetool
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(adr)
       KV_SERIALIZE(id)
-      KV_SERIALIZE(last_seen)
+      if (!is_store || this_ref.last_seen != 0)
+        KV_SERIALIZE_OPT(last_seen, (int64_t)0)
       KV_SERIALIZE_OPT(pruning_seed, (uint32_t)0)
       KV_SERIALIZE_OPT(rpc_port, (uint16_t)0)
     END_KV_SERIALIZE_MAP()
@@ -132,7 +133,7 @@ namespace nodetool
       ss << pe.id << "\t" << pe.adr.str() 
         << " \trpc port " << (pe.rpc_port > 0 ? std::to_string(pe.rpc_port) : "-")
         << " \tpruning seed " << pe.pruning_seed 
-        << " \tlast_seen: " << epee::misc_utils::get_time_interval_string(now_time - pe.last_seen) 
+        << " \tlast_seen: " << (pe.last_seen == 0 ? std::string("never") : epee::misc_utils::get_time_interval_string(now_time - pe.last_seen))
         << std::endl;
     }
     return ss.str();