Add anchor connections

Based on https://eprint.iacr.org/2015/263.pdf 4. Anchor connections.

Peer list serialisation version bumped to 5.

6 files changed, 208 insertions, 18 deletions

diff --git a/src/cryptonote_config.h b/src/cryptonote_config.h
index 97f2f2afc..3f15cee3f 100644
--- a/src/cryptonote_config.h
+++ b/src/cryptonote_config.h
@@ -107,6 +107,7 @@
 #define P2P_DEFAULT_INVOKE_TIMEOUT                      60*2*1000  //2 minutes
 #define P2P_DEFAULT_HANDSHAKE_INVOKE_TIMEOUT            5000       //5 seconds
 #define P2P_DEFAULT_WHITELIST_CONNECTIONS_PERCENT       70
+#define P2P_DEFAULT_ANCHOR_CONNECTIONS_COUNT            2
 
 #define P2P_FAILED_ADDR_FORGET_SECONDS                  (60*60)     //1 hour
 #define P2P_IP_BLOCKTIME                                (60*60*24)  //24 hour
diff --git a/src/p2p/net_node.h b/src/p2p/net_node.h
index 5ed96c00b..51ab9b3f2 100644
--- a/src/p2p/net_node.h
+++ b/src/p2p/net_node.h
@@ -155,6 +155,8 @@ namespace nodetool
       CHAIN_INVOKE_MAP_TO_OBJ_FORCE_CONTEXT(m_payload_handler, typename t_payload_net_handler::connection_context&)
     END_INVOKE_MAP2()
 
+    enum PeerType { anchor = 0, white, gray };
+
     //----------------- commands handlers ----------------------------------------------
     int handle_handshake(int command, typename COMMAND_HANDSHAKE::request& arg, typename COMMAND_HANDSHAKE::response& rsp, p2p_connection_context& context);
     int handle_timed_sync(int command, typename COMMAND_TIMED_SYNC::request& arg, typename COMMAND_TIMED_SYNC::response& rsp, p2p_connection_context& context);
@@ -206,15 +208,17 @@ namespace nodetool
     bool do_handshake_with_peer(peerid_type& pi, p2p_connection_context& context, bool just_take_peerlist = false);
     bool do_peer_timed_sync(const epee::net_utils::connection_context_base& context, peerid_type peer_id);
 
+    bool make_new_connection_from_anchor_peerlist(const std::vector<anchor_peerlist_entry>& anchor_peerlist);
     bool make_new_connection_from_peerlist(bool use_white_list);
-    bool try_to_connect_and_handshake_with_new_peer(const net_address& na, bool just_take_peerlist = false, uint64_t last_seen_stamp = 0, bool white = true);
+    bool try_to_connect_and_handshake_with_new_peer(const net_address& na, bool just_take_peerlist = false, uint64_t last_seen_stamp = 0, PeerType peer_type = white, uint64_t first_seen_stamp = 0);
     size_t get_random_index_with_fixed_probability(size_t max_index);
     bool is_peer_used(const peerlist_entry& peer);
+    bool is_peer_used(const anchor_peerlist_entry& peer);
     bool is_addr_connected(const net_address& peer);
     template<class t_callback>
     bool try_ping(basic_node_data& node_data, p2p_connection_context& context, t_callback cb);
     bool try_get_support_flags(const p2p_connection_context& context, std::function<void(p2p_connection_context&, const uint32_t&)> f);
-    bool make_expected_connections_count(bool white_list, size_t expected_connections);
+    bool make_expected_connections_count(PeerType peer_type, size_t expected_connections);
     void cache_connect_fail_info(const net_address& addr);
     bool is_addr_recently_failed(const net_address& addr);
     bool is_priority_node(const net_address& na);
diff --git a/src/p2p/net_node.inl b/src/p2p/net_node.inl
index 7ab6a4894..568b8208e 100644
--- a/src/p2p/net_node.inl
+++ b/src/p2p/net_node.inl
@@ -847,6 +847,30 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
+  bool node_server<t_payload_net_handler>::is_peer_used(const anchor_peerlist_entry& peer)
+  {
+    if(m_config.m_peer_id == peer.id) {
+        return true;//dont make connections to ourself
+    }
+
+    bool used = false;
+
+    m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
+    {
+      if(cntxt.peer_id == peer.id || (!cntxt.m_is_income && peer.adr.ip == cntxt.m_remote_ip && peer.adr.port == cntxt.m_remote_port))
+      {
+        used = true;
+
+        return false;//stop enumerating
+      }
+
+      return true;
+    });
+
+    return used;
+  }
+  //-----------------------------------------------------------------------------------
+  template<class t_payload_net_handler>
   bool node_server<t_payload_net_handler>::is_addr_connected(const net_address& peer)
   {
     bool connected = false;
@@ -873,7 +897,7 @@ namespace nodetool
   } while(0)
 
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::try_to_connect_and_handshake_with_new_peer(const net_address& na, bool just_take_peerlist, uint64_t last_seen_stamp, bool white)
+  bool node_server<t_payload_net_handler>::try_to_connect_and_handshake_with_new_peer(const net_address& na, bool just_take_peerlist, uint64_t last_seen_stamp, PeerType peer_type, uint64_t first_seen_stamp)
   {
     if (m_current_number_of_out_peers == m_config.m_net_config.connections_count) // out peers limit
     {
@@ -886,7 +910,7 @@ namespace nodetool
       return false;
     }
     MDEBUG("Connecting to " << epee::string_tools::get_ip_string_from_int32(na.ip)  << ":"
-        << epee::string_tools::num_to_string_fast(na.port) << "(white=" << white << ", last_seen: "
+        << epee::string_tools::num_to_string_fast(na.port) << "(peer_type=" << peer_type << ", last_seen: "
         << (last_seen_stamp ? epee::misc_utils::get_time_interval_string(time(NULL) - last_seen_stamp):"never")
         << ")...");
 
@@ -936,6 +960,13 @@ namespace nodetool
     m_peerlist.append_with_peer_white(pe_local);
     //update last seen and push it to peerlist manager
 
+    anchor_peerlist_entry ape = AUTO_VAL_INIT(ape);
+    ape.adr = na;
+    ape.id = pi;
+    ape.first_seen = first_seen_stamp ? first_seen_stamp : time(nullptr);
+
+    m_peerlist.append_with_peer_anchor(ape);
+
     LOG_DEBUG_CC(con, "CONNECTION HANDSHAKED OK.");
     return true;
   }
@@ -1002,6 +1033,41 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
+  bool node_server<t_payload_net_handler>::make_new_connection_from_anchor_peerlist(const std::vector<anchor_peerlist_entry>& anchor_peerlist)
+  {
+    for (const auto& pe: anchor_peerlist) {
+      _note("Considering connecting (out) to peer: " << pe.id << " " << epee::string_tools::get_ip_string_from_int32(pe.adr.ip)  << ":" << boost::lexical_cast<std::string>(pe.adr.port));
+
+      if(is_peer_used(pe)) {
+        _note("Peer is used");
+        continue;
+      }
+
+      if(!is_remote_ip_allowed(pe.adr.ip)) {
+        continue;
+      }
+
+      if(is_addr_recently_failed(pe.adr)) {
+        continue;
+      }
+
+      MDEBUG("Selected peer: " << pe.id << " " << epee::string_tools::get_ip_string_from_int32(pe.adr.ip)
+                               << ":" << boost::lexical_cast<std::string>(pe.adr.port)
+                               << "[peer_type=" << anchor
+                               << "] first_seen: " << epee::misc_utils::get_time_interval_string(time(NULL) - pe.first_seen));
+
+      if(!try_to_connect_and_handshake_with_new_peer(pe.adr, false, 0, anchor, pe.first_seen)) {
+        _note("Handshake failed");
+        continue;
+      }
+
+      return true;
+    }
+
+    return false;
+  }
+  //-----------------------------------------------------------------------------------
+  template<class t_payload_net_handler>
   bool node_server<t_payload_net_handler>::make_new_connection_from_peerlist(bool use_white_list)
   {
     size_t local_peers_count = use_white_list ? m_peerlist.get_white_peers_count():m_peerlist.get_gray_peers_count();
@@ -1045,10 +1111,10 @@ namespace nodetool
 
       MDEBUG("Selected peer: " << pe.id << " " << epee::string_tools::get_ip_string_from_int32(pe.adr.ip)
                     << ":" << boost::lexical_cast<std::string>(pe.adr.port)
-                    << "[white=" << use_white_list
+                    << "[peer_list=" << (use_white_list ? white : gray)
                     << "] last_seen: " << (pe.last_seen ? epee::misc_utils::get_time_interval_string(time(NULL) - pe.last_seen) : "never"));
 
-      if(!try_to_connect_and_handshake_with_new_peer(pe.adr, false, pe.last_seen, use_white_list)) {
+      if(!try_to_connect_and_handshake_with_new_peer(pe.adr, false, pe.last_seen, use_white_list ? white : gray)) {
         _note("Handshake failed");
         continue;
       }
@@ -1095,19 +1161,22 @@ namespace nodetool
     {
       if(conn_count < expected_white_connections)
       {
-        //start from white list
-        if(!make_expected_connections_count(true, expected_white_connections))
+        //start from anchor list
+        if(!make_expected_connections_count(anchor, P2P_DEFAULT_ANCHOR_CONNECTIONS_COUNT))
           return false;
-        //and then do grey list
-        if(!make_expected_connections_count(false, m_config.m_net_config.connections_count))
+        //then do white list
+        if(!make_expected_connections_count(white, expected_white_connections))
+          return false;
+        //then do grey list
+        if(!make_expected_connections_count(gray, m_config.m_net_config.connections_count))
           return false;
       }else
       {
         //start from grey list
-        if(!make_expected_connections_count(false, m_config.m_net_config.connections_count))
+        if(!make_expected_connections_count(gray, m_config.m_net_config.connections_count))
           return false;
         //and then do white list
-        if(!make_expected_connections_count(true, m_config.m_net_config.connections_count))
+        if(!make_expected_connections_count(white, m_config.m_net_config.connections_count))
           return false;
       }
     }
@@ -1116,11 +1185,17 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::make_expected_connections_count(bool white_list, size_t expected_connections)
+  bool node_server<t_payload_net_handler>::make_expected_connections_count(PeerType peer_type, size_t expected_connections)
   {
     if (m_offline)
       return true;
 
+    std::vector<anchor_peerlist_entry> apl;
+
+    if (peer_type == anchor) {
+      m_peerlist.get_and_empty_anchor_peerlist(apl);
+    }
+
     size_t conn_count = get_outgoing_connections_count();
     //add new connections from white peers
     while(conn_count < expected_connections)
@@ -1128,8 +1203,18 @@ namespace nodetool
       if(m_net_server.is_stop_signal_sent())
         return false;
 
-      if(!make_new_connection_from_peerlist(white_list))
+      if (peer_type == anchor && !make_new_connection_from_anchor_peerlist(apl)) {
+        break;
+      }
+
+      if (peer_type == white && !make_new_connection_from_peerlist(true)) {
+        break;
+      }
+
+      if (peer_type == gray && !make_new_connection_from_peerlist(false)) {
         break;
+      }
+
       conn_count = get_outgoing_connections_count();
     }
     return true;
@@ -1611,6 +1696,14 @@ namespace nodetool
   template<class t_payload_net_handler>
   void node_server<t_payload_net_handler>::on_connection_close(p2p_connection_context& context)
   {
+    if (!m_net_server.is_stop_signal_sent() && !context.m_is_income) {
+      nodetool::net_address na = AUTO_VAL_INIT(na);
+      na.ip = context.m_remote_ip;
+      na.port = context.m_remote_port;
+
+      m_peerlist.remove_from_peer_anchor(na);
+    }
+
     MINFO("["<< epee::net_utils::print_connection_context(context) << "] CLOSE CONNECTION");
   }
 
diff --git a/src/p2p/net_peerlist.h b/src/p2p/net_peerlist.h
index c73d6615d..9af3694b6 100644
--- a/src/p2p/net_peerlist.h
+++ b/src/p2p/net_peerlist.h
@@ -54,7 +54,7 @@
 #include "net_peerlist_boost_serialization.h"
 
 
-#define CURRENT_PEERLIST_STORAGE_ARCHIVE_VER    4
+#define CURRENT_PEERLIST_STORAGE_ARCHIVE_VER    5
 
 namespace nodetool
 {
@@ -77,13 +77,15 @@ namespace nodetool
     bool get_gray_peer_by_index(peerlist_entry& p, size_t i);
     bool append_with_peer_white(const peerlist_entry& pr);
     bool append_with_peer_gray(const peerlist_entry& pr);
+    bool append_with_peer_anchor(const anchor_peerlist_entry& ple);
     bool set_peer_just_seen(peerid_type peer, uint32_t ip, uint32_t port);
     bool set_peer_just_seen(peerid_type peer, const net_address& addr);
     bool set_peer_unreachable(const peerlist_entry& pr);
     bool is_ip_allowed(uint32_t ip);
     bool get_random_gray_peer(peerlist_entry& pe);
     bool remove_from_peer_gray(const peerlist_entry& pe);
-
+    bool get_and_empty_anchor_peerlist(std::vector<anchor_peerlist_entry>& apl);
+    bool remove_from_peer_anchor(const net_address& addr);
     
   private:
     struct by_time{};
@@ -145,6 +147,16 @@ namespace nodetool
       boost::multi_index::ordered_non_unique<boost::multi_index::tag<by_time>, boost::multi_index::member<peerlist_entry,int64_t,&peerlist_entry::last_seen> >
       > 
     > peers_indexed_old;
+
+    typedef boost::multi_index_container<
+      anchor_peerlist_entry,
+      boost::multi_index::indexed_by<
+      // access by anchor_peerlist_entry::net_adress
+      boost::multi_index::ordered_unique<boost::multi_index::tag<by_addr>, boost::multi_index::member<anchor_peerlist_entry,net_address,&anchor_peerlist_entry::adr> >,
+      // sort by anchor_peerlist_entry::first_seen
+      boost::multi_index::ordered_non_unique<boost::multi_index::tag<by_time>, boost::multi_index::member<anchor_peerlist_entry,int64_t,&anchor_peerlist_entry::first_seen> >
+      >
+    > anchor_peers_indexed;
   public:    
     
     template <class Archive, class t_version_type>
@@ -161,8 +173,15 @@ namespace nodetool
         peers_indexed_from_old(pio, m_peers_white);
         return;
       }
+
       a & m_peers_white;
       a & m_peers_gray;
+
+      if(ver < 5) {
+        return;
+      }
+
+      a & m_peers_anchor;
     }
 
   private: 
@@ -178,6 +197,7 @@ namespace nodetool
 
     peers_indexed m_peers_gray;
     peers_indexed m_peers_white;
+    anchor_peers_indexed m_peers_anchor;
   };
   //--------------------------------------------------------------------------------------------------
   inline
@@ -398,6 +418,24 @@ namespace nodetool
   }
   //--------------------------------------------------------------------------------------------------
   inline
+  bool peerlist_manager::append_with_peer_anchor(const anchor_peerlist_entry& ple)
+  {
+    TRY_ENTRY();
+
+    CRITICAL_REGION_LOCAL(m_peerlist_lock);
+
+    auto by_addr_it_anchor = m_peers_anchor.get<by_addr>().find(ple.adr);
+
+    if(by_addr_it_anchor == m_peers_anchor.get<by_addr>().end()) {
+      m_peers_anchor.insert(ple);
+    }
+
+    return true;
+
+    CATCH_ENTRY_L0("peerlist_manager::append_with_peer_anchor()", false);
+  }
+  //--------------------------------------------------------------------------------------------------
+  inline
   bool peerlist_manager::get_random_gray_peer(peerlist_entry& pe)
   {
     TRY_ENTRY();
@@ -438,7 +476,46 @@ namespace nodetool
 
     CATCH_ENTRY_L0("peerlist_manager::remove_from_peer_gray()", false);
   }
-    //--------------------------------------------------------------------------------------------------
+  //--------------------------------------------------------------------------------------------------
+  inline
+  bool peerlist_manager::get_and_empty_anchor_peerlist(std::vector<anchor_peerlist_entry>& apl)
+  {
+    TRY_ENTRY();
+
+    CRITICAL_REGION_LOCAL(m_peerlist_lock);
+
+    auto begin = m_peers_anchor.get<by_time>().begin();
+    auto end = m_peers_anchor.get<by_time>().end();
+
+    std::for_each(begin, end, [&apl](const anchor_peerlist_entry &a) {
+      apl.push_back(a);
+    });
+
+    m_peers_anchor.get<by_time>().clear();
+
+    return true;
+
+    CATCH_ENTRY_L0("peerlist_manager::get_and_empty_anchor_peerlist()", false);
+  }
+  //--------------------------------------------------------------------------------------------------
+  inline
+  bool peerlist_manager::remove_from_peer_anchor(const net_address& addr)
+  {
+    TRY_ENTRY();
+
+    CRITICAL_REGION_LOCAL(m_peerlist_lock);
+
+    anchor_peers_indexed::index_iterator<by_addr>::type iterator = m_peers_anchor.get<by_addr>().find(addr);
+
+    if (iterator != m_peers_anchor.get<by_addr>().end()) {
+      m_peers_anchor.erase(iterator);
+    }
+
+    return true;
+
+    CATCH_ENTRY_L0("peerlist_manager::remove_from_peer_anchor()", false);
+  }
+  //--------------------------------------------------------------------------------------------------
 }
 
 BOOST_CLASS_VERSION(nodetool::peerlist_manager, CURRENT_PEERLIST_STORAGE_ARCHIVE_VER)
diff --git a/src/p2p/net_peerlist_boost_serialization.h b/src/p2p/net_peerlist_boost_serialization.h
index d9a11728b..9a0d12c2e 100644
--- a/src/p2p/net_peerlist_boost_serialization.h
+++ b/src/p2p/net_peerlist_boost_serialization.h
@@ -49,6 +49,14 @@ namespace boost
       a & pl.adr;
       a & pl.id;
       a & pl.last_seen;
-    }    
+    }
+
+    template <class Archive, class ver_type>
+    inline void serialize(Archive &a, nodetool::anchor_peerlist_entry& pl, const ver_type ver)
+    {
+      a & pl.adr;
+      a & pl.id;
+      a & pl.first_seen;
+    }
   }
 }
diff --git a/src/p2p/p2p_protocol_defs.h b/src/p2p/p2p_protocol_defs.h
index 6d6ac7b98..dc738d92c 100644
--- a/src/p2p/p2p_protocol_defs.h
+++ b/src/p2p/p2p_protocol_defs.h
@@ -56,6 +56,13 @@ namespace nodetool
     int64_t last_seen;
   };
 
+  struct anchor_peerlist_entry
+  {
+    net_address adr;
+    peerid_type id;
+    int64_t first_seen;
+  };
+
   struct connection_entry
   {
     net_address adr;