p2p: add --max-connections-per-ip daemon option

Helps daemons behind a proxy get more than one connection.
Defaults to 1 (no change)

3 files changed, 10 insertions, 3 deletions

diff --git a/src/p2p/net_node.cpp b/src/p2p/net_node.cpp
index 8dd551d1e..84cc1581e 100644
--- a/src/p2p/net_node.cpp
+++ b/src/p2p/net_node.cpp
@@ -166,6 +166,7 @@ namespace nodetool
     const command_line::arg_descriptor<bool> arg_pad_transactions = {
       "pad-transactions", "Pad relayed transactions to help defend against traffic volume analysis", false
     };
+    const command_line::arg_descriptor<uint32_t> arg_max_connections_per_ip = {"max-connections-per-ip", "Maximum number of connections allowed from the same IP address", 1};
 
     boost::optional<std::vector<proxy>> get_proxies(boost::program_options::variables_map const& vm)
     {
diff --git a/src/p2p/net_node.h b/src/p2p/net_node.h
index 59a6e5091..db931122e 100644
--- a/src/p2p/net_node.h
+++ b/src/p2p/net_node.h
@@ -258,7 +258,8 @@ namespace nodetool
         m_igd(no_igd),
         m_offline(false),
         is_closing(false),
-        m_network_id()
+        m_network_id(),
+        max_connections(1)
     {}
     virtual ~node_server();
 
@@ -517,6 +518,8 @@ namespace nodetool
     epee::net_utils::ssl_support_t m_ssl_support;
 
     bool m_enable_dns_blocklist;
+
+    uint32_t max_connections;
   };
 
     const int64_t default_limit_up = P2P_DEFAULT_LIMIT_RATE_UP;      // kB/s
@@ -551,6 +554,7 @@ namespace nodetool
     extern const command_line::arg_descriptor<int64_t> arg_limit_rate_down;
     extern const command_line::arg_descriptor<int64_t> arg_limit_rate;
     extern const command_line::arg_descriptor<bool> arg_pad_transactions;
+    extern const command_line::arg_descriptor<uint32_t> arg_max_connections_per_ip;
 }
 
 POP_WARNINGS
diff --git a/src/p2p/net_node.inl b/src/p2p/net_node.inl
index 05af22a7f..63ac2f1bd 100644
--- a/src/p2p/net_node.inl
+++ b/src/p2p/net_node.inl
@@ -131,6 +131,7 @@ namespace nodetool
     command_line::add_arg(desc, arg_limit_rate_down);
     command_line::add_arg(desc, arg_limit_rate);
     command_line::add_arg(desc, arg_pad_transactions);
+    command_line::add_arg(desc, arg_max_connections_per_ip);
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
@@ -615,6 +616,8 @@ namespace nodetool
         return false;
     }
 
+    max_connections = command_line::get_arg(vm, arg_max_connections_per_ip);
+
     return true;
   }
   //-----------------------------------------------------------------------------------
@@ -2846,8 +2849,7 @@ namespace nodetool
     if (address.get_zone() != epee::net_utils::zone::public_)
       return false; // Unable to determine how many connections from host
 
-    const size_t max_connections = 1;
-    size_t count = 0;
+    uint32_t count = 0;
 
     m_network_zones.at(epee::net_utils::zone::public_).m_net_server.get_config_object().foreach_connection([&](const p2p_connection_context& cntxt)
     {