Adding Dandelion++ support to public networks:

- New flag in NOTIFY_NEW_TRANSACTION to indicate stem mode
  - Stem loops detected in tx_pool.cpp
  - Embargo timeout for a blackhole attack during stem phase

tests/core_tests/chaingen.h

@@ -116,7 +116,8 @@ struct event_visitor_settings
   {
     set_txs_keeped_by_block = 1 << 0,
     set_txs_do_not_relay = 1 << 1,
-    set_local_relay = 1 << 2
+    set_local_relay = 1 << 2,
+    set_txs_stem = 1 << 3
   };
 
   event_visitor_settings(int a_mask = 0)
@@ -548,6 +549,10 @@ public:
     {
       m_tx_relay = cryptonote::relay_method::none;
     }
+    else if (settings.mask & event_visitor_settings::set_txs_stem)
+    {
+      m_tx_relay = cryptonote::relay_method::stem;
+    }
     else
     {
       m_tx_relay = cryptonote::relay_method::fluff;

tests/core_tests/chaingen_main.cpp

@@ -162,6 +162,7 @@ int main(int argc, char* argv[])
     GENERATE_AND_PLAY(txpool_double_spend_norelay);
     GENERATE_AND_PLAY(txpool_double_spend_local);
     GENERATE_AND_PLAY(txpool_double_spend_keyimage);
+    GENERATE_AND_PLAY(txpool_stem_loop);
 
     // Double spend
     GENERATE_AND_PLAY(gen_double_spend_in_tx<false>);

tests/core_tests/tx_pool.cpp

@@ -552,7 +552,6 @@ bool txpool_double_spend_local::generate(std::vector<test_event_entry>& events)
   DO_CALLBACK(events, "mark_no_new");
   events.push_back(tx_0);
   DO_CALLBACK(events, "check_txpool_spent_keys");
-  DO_CALLBACK(events, "mark_timestamp_change");
   DO_CALLBACK(events, "check_unchanged");
   SET_EVENT_VISITOR_SETT(events, 0);
   DO_CALLBACK(events, "timestamp_change_pause");
@@ -580,6 +579,7 @@ bool txpool_double_spend_keyimage::generate(std::vector<test_event_entry>& event
   const std::size_t tx_index1 = events.size();
   MAKE_TX(events, tx_0, miner_account, bob_account, send_amount, blk_0);
 
+  SET_EVENT_VISITOR_SETT(events, event_visitor_settings::set_txs_stem);
   DO_CALLBACK(events, "increase_all_tx_count");
   DO_CALLBACK(events, "check_txpool_spent_keys");
   DO_CALLBACK(events, "mark_timestamp_change");
@@ -611,3 +611,30 @@ bool txpool_double_spend_keyimage::generate(std::vector<test_event_entry>& event
   return true;
 }
 
+bool txpool_stem_loop::generate(std::vector<test_event_entry>& events) const
+{
+  INIT_MEMPOOL_TEST();
+
+  DO_CALLBACK(events, "check_txpool_spent_keys");
+  SET_EVENT_VISITOR_SETT(events, event_visitor_settings::set_txs_stem);
+  DO_CALLBACK(events, "mark_no_new");
+
+  MAKE_TX(events, tx_0, miner_account, bob_account, send_amount, blk_0);
+
+  DO_CALLBACK(events, "increase_all_tx_count");
+  DO_CALLBACK(events, "check_txpool_spent_keys");
+  DO_CALLBACK(events, "mark_timestamp_change");
+  DO_CALLBACK(events, "check_new_hidden");
+  DO_CALLBACK(events, "timestamp_change_pause");
+  events.push_back(tx_0);
+  DO_CALLBACK(events, "increase_broadcasted_tx_count");
+  DO_CALLBACK(events, "check_txpool_spent_keys");
+  DO_CALLBACK(events, "mark_timestamp_change");
+  DO_CALLBACK(events, "check_new_broadcasted");
+  DO_CALLBACK(events, "timestamp_change_pause");
+  DO_CALLBACK(events, "mark_no_new");
+  events.push_back(tx_0);
+  DO_CALLBACK(events, "check_unchanged");
+
+  return true;
+}

tests/core_tests/tx_pool.h

@@ -127,3 +127,12 @@ struct txpool_double_spend_keyimage : txpool_double_spend_base
 
   bool generate(std::vector<test_event_entry>& events) const;
 };
+
+struct txpool_stem_loop : txpool_double_spend_base
+{
+  txpool_stem_loop()
+    : txpool_double_spend_base()
+  {}
+
+  bool generate(std::vector<test_event_entry>& events) const;
+};