temporary fix for block reward dos

ReleaseNotes.txt

@@ -7,7 +7,8 @@ Release notes 0.8.8
 - Fixed a bug with checkpoints behavior
 - UI improvements for daemon
 - Fixed COIN value (10^12)
-- Raised minimum fee to (1/2) * (10^10)
+- Raised minimum fee to 5 * (10^9)
+- Temporary fix for block reward DoS attack
 
 Release notes 0.8.7
 

src/cryptonote_core/tx_pool.cpp

@@ -355,13 +355,35 @@ namespace cryptonote
     total_size = 0;
     fee = 0;
 
-    size_t max_total_size = 2 * median_size - CRYPTONOTE_COINBASE_BLOB_RESERVED_SIZE;
+    size_t max_total_size = 2 * median_size - CRYPTONOTE_COINBASE_BLOB_RESERVED_SIZE; // Max block size
     std::unordered_set<crypto::key_image> k_images;
     BOOST_FOREACH(transactions_container::value_type& tx, m_transactions)
     {
+      // Can not exceed maximum block size
       if (max_total_size < total_size + tx.second.blob_size)
         continue;
 
+      // Check to see if the minimum fee is included
+      if (tx.second.fee < DEFAULT_FEE)
+        continue;
+
+      // Skip transactions that are too large
+      // TODO: Correct upper_transactions_size_limit
+      // such that it is based on median block size;
+      // We need to make a similar patch for
+      // wallet2.h
+      uint64_t upper_transaction_size_limit = ((CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE * 125) / 100) - CRYPTONOTE_COINBASE_BLOB_RESERVED_SIZE;
+      if (tx.second.blob_size > upper_transaction_size_limit)
+        continue;
+
+      // If we've exceeded the penalty free size,
+      // stop including more tx
+      if (total_size > median_size)
+        continue;      
+
+      // Skip transactions that are not ready to be
+      // included into the blockchain or that are
+      // missing key images
       if (!is_transaction_ready_to_go(tx.second) || have_key_images(k_images, tx.second.tx))
         continue;
 

src/wallet/wallet2.h

@@ -102,7 +102,12 @@ namespace tools
     void store();
     cryptonote::account_base& get_account(){return m_account;}
 
-    void init(const std::string& daemon_address = "http://localhost:8080", uint64_t upper_transaction_size_limit = CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE*2 - CRYPTONOTE_COINBASE_BLOB_RESERVED_SIZE);
+    // upper_transaction_size_limit as defined below is set to 
+    // approximately 125% of the fixed minimum allowable penalty
+    // free block size. TODO: fix this so that it actually takes
+    // into account the current median block size rather than
+    // the minimum block size.
+    void init(const std::string& daemon_address = "http://localhost:8080", uint64_t upper_transaction_size_limit = ((CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE * 125) / 100) - CRYPTONOTE_COINBASE_BLOB_RESERVED_SIZE);
     bool deinit();
 
     void stop() { m_run.store(false, std::memory_order_relaxed); }