Optional DNS based blocklist

If enabled, pulls IPs to block on blocklist.moneropulse.*, and
blocks then for 8 days (so IPs dropping from the list will
eventually get unblocked, and DNS failures don't result in
instant clearing of the blocklist).

Enable with --enable-dns-blocklist

src/cryptonote_config.h

@@ -197,6 +197,8 @@
 
 #define RPC_CREDITS_PER_HASH_SCALE ((float)(1<<24))
 
+#define DNS_BLOCKLIST_LIFETIME (86400 * 8)
+
 // New constants are intended to go here
 namespace config
 {

src/p2p/net_node.cpp

@@ -149,6 +149,7 @@ namespace nodetool
     const command_line::arg_descriptor<std::string> arg_ban_list = {"ban-list", "Specify ban list file, one IP address per line"};
     const command_line::arg_descriptor<bool> arg_p2p_hide_my_port   =    {"hide-my-port", "Do not announce yourself as peerlist candidate", false, true};
     const command_line::arg_descriptor<bool> arg_no_sync = {"no-sync", "Don't synchronize the blockchain with other peers", false};
+    const command_line::arg_descriptor<bool> arg_enable_dns_blocklist = {"enable-dns-blocklist", "Apply realtime blocklist from DNS", false};
 
     const command_line::arg_descriptor<bool>        arg_no_igd  = {"no-igd", "Disable UPnP port mapping"};
     const command_line::arg_descriptor<std::string> arg_igd = {"igd", "UPnP port mapping (disabled, enabled, delayed)", "delayed"};

src/p2p/net_node.h

@@ -287,7 +287,7 @@ namespace nodetool
     uint32_t get_max_out_public_peers() const;
     void change_max_in_public_peers(size_t count);
     uint32_t get_max_in_public_peers() const;
-    virtual bool block_host(epee::net_utils::network_address address, time_t seconds = P2P_IP_BLOCKTIME);
+    virtual bool block_host(epee::net_utils::network_address address, time_t seconds = P2P_IP_BLOCKTIME, bool add_only = false);
     virtual bool unblock_host(const epee::net_utils::network_address &address);
     virtual bool block_subnet(const epee::net_utils::ipv4_network_subnet &subnet, time_t seconds = P2P_IP_BLOCKTIME);
     virtual bool unblock_subnet(const epee::net_utils::ipv4_network_subnet &subnet);
@@ -369,6 +369,7 @@ namespace nodetool
     bool peer_sync_idle_maker();
     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 update_dns_blocklist();
 
     bool make_new_connection_from_anchor_peerlist(const std::vector<anchor_peerlist_entry>& anchor_peerlist);
     bool make_new_connection_from_peerlist(network_zone& zone, bool use_white_list);
@@ -474,6 +475,7 @@ namespace nodetool
     epee::math_helper::once_a_time_seconds<60*30, false> m_peerlist_store_interval;
     epee::math_helper::once_a_time_seconds<60> m_gray_peerlist_housekeeping_interval;
     epee::math_helper::once_a_time_seconds<3600, false> m_incoming_connections_interval;
+    epee::math_helper::once_a_time_seconds<7000> m_dns_blocklist_interval;
 
     std::list<epee::net_utils::network_address>   m_priority_peers;
     std::vector<epee::net_utils::network_address> m_exclusive_peers;
@@ -512,6 +514,8 @@ namespace nodetool
     cryptonote::network_type m_nettype;
 
     epee::net_utils::ssl_support_t m_ssl_support;
+
+    bool m_enable_dns_blocklist;
   };
 
     const int64_t default_limit_up = P2P_DEFAULT_LIMIT_RATE_UP;      // kB/s
@@ -533,6 +537,7 @@ namespace nodetool
     extern const command_line::arg_descriptor<std::string> arg_ban_list;
     extern const command_line::arg_descriptor<bool> arg_p2p_hide_my_port;
     extern const command_line::arg_descriptor<bool> arg_no_sync;
+    extern const command_line::arg_descriptor<bool> arg_enable_dns_blocklist;
 
     extern const command_line::arg_descriptor<bool>        arg_no_igd;
     extern const command_line::arg_descriptor<std::string> arg_igd;

src/p2p/net_node.inl

@@ -37,6 +37,7 @@
 #include <boost/optional/optional.hpp>
 #include <boost/thread/thread.hpp>
 #include <boost/uuid/uuid_io.hpp>
+#include <boost/algorithm/string.hpp>
 #include <atomic>
 #include <functional>
 #include <limits>
@@ -120,6 +121,7 @@ namespace nodetool
     command_line::add_arg(desc, arg_ban_list);
     command_line::add_arg(desc, arg_p2p_hide_my_port);
     command_line::add_arg(desc, arg_no_sync);
+    command_line::add_arg(desc, arg_enable_dns_blocklist);
     command_line::add_arg(desc, arg_no_igd);
     command_line::add_arg(desc, arg_igd);
     command_line::add_arg(desc, arg_out_peers);
@@ -226,7 +228,7 @@ namespace nodetool
   }
   //-----------------------------------------------------------------------------------
   template<class t_payload_net_handler>
-  bool node_server<t_payload_net_handler>::block_host(epee::net_utils::network_address addr, time_t seconds)
+  bool node_server<t_payload_net_handler>::block_host(epee::net_utils::network_address addr, time_t seconds, bool add_only)
   {
     if(!addr.is_blockable())
       return false;
@@ -240,7 +242,11 @@ namespace nodetool
     else
       limit = now + seconds;
     const std::string host_str = addr.host_str();
-    m_blocked_hosts[host_str] = limit;
+    auto it = m_blocked_hosts.find(host_str);
+    if (it == m_blocked_hosts.end())
+      m_blocked_hosts[host_str] = limit;
+    else if (it->second < limit || !add_only)
+      it->second = limit;
 
     // drop any connection to that address. This should only have to look into
     // the zone related to the connection, but really make sure everything is
@@ -497,6 +503,8 @@ namespace nodetool
     if (command_line::has_arg(vm, arg_no_sync))
       m_payload_handler.set_no_sync(true);
 
+    m_enable_dns_blocklist = command_line::get_arg(vm, arg_enable_dns_blocklist);
+
     if ( !set_max_out_peers(public_zone, command_line::get_arg(vm, arg_out_peers) ) )
       return false;
     else
@@ -1963,6 +1971,52 @@ namespace nodetool
     m_gray_peerlist_housekeeping_interval.do_call(boost::bind(&node_server<t_payload_net_handler>::gray_peerlist_housekeeping, this));
     m_peerlist_store_interval.do_call(boost::bind(&node_server<t_payload_net_handler>::store_config, this));
     m_incoming_connections_interval.do_call(boost::bind(&node_server<t_payload_net_handler>::check_incoming_connections, this));
+    m_dns_blocklist_interval.do_call(boost::bind(&node_server<t_payload_net_handler>::update_dns_blocklist, this));
+    return true;
+  }
+  //-----------------------------------------------------------------------------------
+  template<class t_payload_net_handler>
+  bool node_server<t_payload_net_handler>::update_dns_blocklist()
+  {
+    if (!m_enable_dns_blocklist)
+      return true;
+    if (m_nettype != cryptonote::MAINNET)
+      return true;
+
+    static const std::vector<std::string> dns_urls = {
+      "blocklist.moneropulse.se"
+    , "blocklist.moneropulse.org"
+    , "blocklist.moneropulse.net"
+    , "blocklist.moneropulse.no"
+    , "blocklist.moneropulse.fr"
+    , "blocklist.moneropulse.de"
+    , "blocklist.moneropulse.ch"
+    };
+
+    std::vector<std::string> records;
+    if (!tools::dns_utils::load_txt_records_from_dns(records, dns_urls))
+      return true;
+
+    unsigned good = 0, bad = 0;
+    for (const auto& record : records)
+    {
+      std::vector<std::string> ips;
+      boost::split(ips, record, boost::is_any_of(";"));
+      for (const auto &ip: ips)
+      {
+        const expect<epee::net_utils::network_address> parsed_addr = net::get_network_address(ip, 0);
+        if (!parsed_addr)
+        {
+          MWARNING("Invalid IP address from DNS blocklist: " << ip << " - " << parsed_addr.error());
+          ++bad;
+          continue;
+        }
+        block_host(*parsed_addr, DNS_BLOCKLIST_LIFETIME, true);
+        ++good;
+      }
+    }
+    if (good > 0)
+      MINFO(good << " addresses added to the blocklist");
     return true;
   }
   //-----------------------------------------------------------------------------------

src/p2p/net_node_common.h

@@ -58,7 +58,7 @@ namespace nodetool
     virtual uint64_t get_public_connections_count()=0;
     virtual void for_each_connection(std::function<bool(t_connection_context&, peerid_type, uint32_t)> f)=0;
     virtual bool for_connection(const boost::uuids::uuid&, std::function<bool(t_connection_context&, peerid_type, uint32_t)> f)=0;
-    virtual bool block_host(epee::net_utils::network_address address, time_t seconds = 0)=0;
+    virtual bool block_host(epee::net_utils::network_address address, time_t seconds = 0, bool add_only = false)=0;
     virtual bool unblock_host(const epee::net_utils::network_address &address)=0;
     virtual std::map<std::string, time_t> get_blocked_hosts()=0;
     virtual std::map<epee::net_utils::ipv4_network_subnet, time_t> get_blocked_subnets()=0;
@@ -108,7 +108,7 @@ namespace nodetool
     {
       return false;
     }
-    virtual bool block_host(epee::net_utils::network_address address, time_t seconds)
+    virtual bool block_host(epee::net_utils::network_address address, time_t seconds, bool add_only)
     {
       return true;
     }