Allow the number of incoming connections to be limited

It was already possible to limit outgoing connections. One might want
to do this on home network connections with high bandwidth but low
usage caps.

4 files changed, 63 insertions, 3 deletions

diff --git a/src/p2p/net_node.cpp b/src/p2p/net_node.cpp
index 121e72392..994941168 100644
--- a/src/p2p/net_node.cpp
+++ b/src/p2p/net_node.cpp
@@ -55,6 +55,7 @@ namespace nodetool
 
     const command_line::arg_descriptor<bool>        arg_no_igd  = {"no-igd", "Disable UPnP port mapping"};
     const command_line::arg_descriptor<int64_t>     arg_out_peers = {"out-peers", "set max number of out peers", -1};
+    const command_line::arg_descriptor<int64_t>     arg_in_peers = {"in-peers", "set max number of in peers", -1};
     const command_line::arg_descriptor<int> arg_tos_flag = {"tos-flag", "set TOS flag", -1};
 
     const command_line::arg_descriptor<int64_t> arg_limit_rate_up = {"limit-rate-up", "set limit-rate-up [kB/s]", -1};
diff --git a/src/p2p/net_node.h b/src/p2p/net_node.h
index 2f26695a2..568c650cc 100644
--- a/src/p2p/net_node.h
+++ b/src/p2p/net_node.h
@@ -81,6 +81,7 @@ namespace nodetool
     node_server(t_payload_net_handler& payload_handler)
       :m_payload_handler(payload_handler),
     m_current_number_of_out_peers(0),
+    m_current_number_of_in_peers(0),
     m_allow_local_ip(false),
     m_hide_my_port(false),
     m_no_igd(false),
@@ -117,8 +118,10 @@ namespace nodetool
     bool log_connections();
     virtual uint64_t get_connections_count();
     size_t get_outgoing_connections_count();
+    size_t get_incoming_connections_count();
     peerlist_manager& get_peerlist_manager(){return m_peerlist;}
     void delete_out_connections(size_t count);
+    void delete_in_connections(size_t count);
     virtual bool block_host(const epee::net_utils::network_address &adress, time_t seconds = P2P_IP_BLOCKTIME);
     virtual bool unblock_host(const epee::net_utils::network_address &address);
     virtual std::map<std::string, time_t> get_blocked_hosts() { CRITICAL_REGION_LOCAL(m_blocked_hosts_lock); return m_blocked_hosts; }
@@ -230,6 +233,7 @@ namespace nodetool
     bool parse_peers_and_add_to_container(const boost::program_options::variables_map& vm, const command_line::arg_descriptor<std::vector<std::string> > & arg, Container& container);
 
     bool set_max_out_peers(const boost::program_options::variables_map& vm, int64_t max);
+    bool set_max_in_peers(const boost::program_options::variables_map& vm, int64_t max);
     bool set_tos_flag(const boost::program_options::variables_map& vm, int limit);
 
     bool set_rate_up_limit(const boost::program_options::variables_map& vm, int64_t limit);
@@ -271,6 +275,7 @@ namespace nodetool
   public:
     config m_config; // TODO was private, add getters?
     std::atomic<unsigned int> m_current_number_of_out_peers;
+    std::atomic<unsigned int> m_current_number_of_in_peers;
 
     void set_save_graph(bool save_graph)
     {
@@ -345,6 +350,7 @@ namespace nodetool
     extern const command_line::arg_descriptor<bool>        arg_no_igd;
     extern const command_line::arg_descriptor<bool>        arg_offline;
     extern const command_line::arg_descriptor<int64_t>     arg_out_peers;
+    extern const command_line::arg_descriptor<int64_t>     arg_in_peers;
     extern const command_line::arg_descriptor<int> arg_tos_flag;
 
     extern const command_line::arg_descriptor<int64_t> arg_limit_rate_up;
diff --git a/src/p2p/net_node.inl b/src/p2p/net_node.inl
index 5f00e97f0..3445674f6 100644
--- a/src/p2p/net_node.inl
+++ b/src/p2p/net_node.inl
@@ -85,6 +85,7 @@ namespace nodetool
     command_line::add_arg(desc, arg_p2p_hide_my_port);
     command_line::add_arg(desc, arg_no_igd);
     command_line::add_arg(desc, arg_out_peers);
+    command_line::add_arg(desc, arg_in_peers);
     command_line::add_arg(desc, arg_tos_flag);
     command_line::add_arg(desc, arg_limit_rate_up);
     command_line::add_arg(desc, arg_limit_rate_down);
@@ -315,6 +316,9 @@ namespace nodetool
     if ( !set_max_out_peers(vm, command_line::get_arg(vm, arg_out_peers) ) )
       return false;
 
+    if ( !set_max_in_peers(vm, command_line::get_arg(vm, arg_in_peers) ) )
+      return false;
+
     if ( !set_tos_flag(vm, command_line::get_arg(vm, arg_tos_flag) ) )
       return false;
 
@@ -565,14 +569,23 @@ namespace nodetool
       while (!is_closing && !m_net_server.is_stop_signal_sent())
       { // main loop of thread
         //number_of_peers = m_net_server.get_config_object().get_connections_count();
-        unsigned int number_of_peers = 0;
+        unsigned int number_of_in_peers = 0;
+        unsigned int number_of_out_peers = 0;
         m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
         {
-          if (!cntxt.m_is_income) ++number_of_peers;
+          if (cntxt.m_is_income)
+          {
+            ++number_of_in_peers;
+          }
+          else
+          {
+            ++number_of_out_peers;
+          }
           return true;
         }); // lambda
 
-        m_current_number_of_out_peers = number_of_peers;
+        m_current_number_of_in_peers = number_of_in_peers;
+        m_current_number_of_out_peers = number_of_out_peers;
 
         boost::this_thread::sleep_for(boost::chrono::seconds(1));
       } // main loop of thread
@@ -1253,6 +1266,20 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
+  size_t node_server<t_payload_net_handler>::get_incoming_connections_count()
+  {
+    size_t count = 0;
+    m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
+    {
+      if(cntxt.m_is_income)
+        ++count;
+      return true;
+    });
+
+    return count;
+  }
+  //-----------------------------------------------------------------------------------
+  template<class t_payload_net_handler>
   bool node_server<t_payload_net_handler>::idle_worker()
   {
     m_peer_handshake_idle_maker_interval.do_call(boost::bind(&node_server<t_payload_net_handler>::peer_sync_idle_maker, this));
@@ -1618,6 +1645,13 @@ namespace nodetool
       return 1;
     }
 
+   if (m_current_number_of_in_peers >= m_config.m_net_config.max_in_connection_count) // in peers limit
+    {
+      LOG_WARNING_CC(context, "COMMAND_HANDSHAKE came, but already have max incoming connections, so dropping this one.");
+      drop_connection(context);
+      return 1;
+    }
+
     if(!m_payload_handler.process_payload_sync_data(arg.payload_data, context, true))
     {
       LOG_WARNING_CC(context, "COMMAND_HANDSHAKE came, but process_payload_sync_data returned false, dropping connection.");
@@ -1787,12 +1821,29 @@ namespace nodetool
   }
 
   template<class t_payload_net_handler>
+  bool node_server<t_payload_net_handler>::set_max_in_peers(const boost::program_options::variables_map& vm, int64_t max)
+  {
+    if(max == -1) {
+      m_config.m_net_config.max_in_connection_count = -1;
+      return true;
+    }
+    m_config.m_net_config.max_in_connection_count = max;
+    return true;
+  }
+
+  template<class t_payload_net_handler>
   void node_server<t_payload_net_handler>::delete_out_connections(size_t count)
   {
     m_net_server.get_config_object().del_out_connections(count);
   }
 
   template<class t_payload_net_handler>
+  void node_server<t_payload_net_handler>::delete_in_connections(size_t count)
+  {
+    m_net_server.get_config_object().del_in_connections(count);
+  }
+
+  template<class t_payload_net_handler>
   bool node_server<t_payload_net_handler>::set_tos_flag(const boost::program_options::variables_map& vm, int flag)
   {
     if(flag==-1){
diff --git a/src/p2p/p2p_protocol_defs.h b/src/p2p/p2p_protocol_defs.h
index 3fa71713d..e793e19b6 100644
--- a/src/p2p/p2p_protocol_defs.h
+++ b/src/p2p/p2p_protocol_defs.h
@@ -132,12 +132,14 @@ namespace nodetool
   {
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(max_out_connection_count)
+      KV_SERIALIZE(max_in_connection_count)
       KV_SERIALIZE(handshake_interval)
       KV_SERIALIZE(packet_max_size)
       KV_SERIALIZE(config_id)
     END_KV_SERIALIZE_MAP()
 
     uint32_t max_out_connection_count;
+    uint32_t max_in_connection_count;
     uint32_t connection_timeout;
     uint32_t ping_connection_timeout;
     uint32_t handshake_interval;