tx_pool: do not accept txes not in a block if they timed out before

This is intended to avoid cases where a timed out tx will be
re-relayed by another peer for which it has not timed out yet,
which would cause the tx to stay in the network's pool for a
long time (until all peers time it out before another one
tries to relay it again).

src/cryptonote_core/tx_pool.cpp

@@ -84,7 +84,15 @@ namespace cryptonote
   //---------------------------------------------------------------------------------
   bool tx_memory_pool::add_tx(const transaction &tx, /*const crypto::hash& tx_prefix_hash,*/ const crypto::hash &id, size_t blob_size, tx_verification_context& tvc, bool kept_by_block, bool relayed, uint8_t version)
   {
-
+    // we do not accept transactions that timed out before, unless they're
+    // kept_by_block
+    if (!kept_by_block && m_timed_out_transactions.find(id) != m_timed_out_transactions.end())
+    {
+      // not clear if we should set that, since verifivation (sic) did not fail before, since
+      // the tx was accepted before timing out.
+      tvc.m_verifivation_failed = true;
+      return false;
+    }
 
     if(!check_inputs_types_supported(tx))
     {
@@ -315,6 +323,7 @@ namespace cryptonote
         {
           m_txs_by_fee.erase(sorted_it);
         }
+        m_timed_out_transactions.insert(it->first);
         auto pit = it++;
         m_transactions.erase(pit);
       }else

src/cryptonote_core/tx_pool.h

@@ -110,7 +110,7 @@ namespace cryptonote
     /*bool flush_pool(const std::strig& folder);
     bool inflate_pool(const std::strig& folder);*/
 
-#define CURRENT_MEMPOOL_ARCHIVE_VER    9
+#define CURRENT_MEMPOOL_ARCHIVE_VER    10
 
     template<class archive_t>
     void serialize(archive_t & a, const unsigned int version)
@@ -120,6 +120,7 @@ namespace cryptonote
       CRITICAL_REGION_LOCAL(m_transactions_lock);
       a & m_transactions;
       a & m_spent_key_images;
+      a & m_timed_out_transactions;
     }
 
     struct tx_details
@@ -162,6 +163,8 @@ namespace cryptonote
 
     sorted_tx_container::iterator find_tx_in_sorted_container(const crypto::hash& id) const;
 
+    std::unordered_set<crypto::hash> m_timed_out_transactions;
+
     //transactions_container m_alternative_transactions;
 
     std::string m_config_folder;