cryptonote: rework block blob size sanity check

Use the actual block weight limit, assuming that weight is always
greater or equal to size

src/blockchain_db/blockchain_db.h

@@ -1513,6 +1513,20 @@ public:
    */
   virtual bool check_pruning() = 0;
 
+  /**
+   * @brief get the max block size
+   */
+  virtual uint64_t get_max_block_size() = 0;
+
+  /**
+   * @brief add a new max block size
+   *
+   * The max block size will be the maximum of sz and the current block size
+   *
+   * @param: sz the block size
+   */
+
+  virtual void add_max_block_size(uint64_t sz) = 0;
   /**
    * @brief runs a function over all txpool transactions
    *

src/blockchain_db/lmdb/db_lmdb.cpp

@@ -2513,6 +2513,58 @@ std::vector<uint64_t> BlockchainLMDB::get_block_info_64bit_fields(uint64_t start
   return ret;
 }
 
+uint64_t BlockchainLMDB::get_max_block_size()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  TXN_PREFIX_RDONLY();
+  RCURSOR(properties)
+  MDB_val_str(k, "max_block_size");
+  MDB_val v;
+  int result = mdb_cursor_get(m_cur_properties, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    return std::numeric_limits<uint64_t>::max();
+  if (result)
+    throw0(DB_ERROR(lmdb_error("Failed to retrieve max block size: ", result).c_str()));
+  if (v.mv_size != sizeof(uint64_t))
+    throw0(DB_ERROR("Failed to retrieve or create max block size: unexpected value size"));
+  uint64_t max_block_size;
+  memcpy(&max_block_size, v.mv_data, sizeof(max_block_size));
+  TXN_POSTFIX_RDONLY();
+  return max_block_size;
+}
+
+void BlockchainLMDB::add_max_block_size(uint64_t sz)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  mdb_txn_cursors *m_cursors = &m_wcursors;
+
+  CURSOR(properties)
+
+  MDB_val_str(k, "max_block_size");
+  MDB_val v;
+  int result = mdb_cursor_get(m_cur_properties, &k, &v, MDB_SET);
+  if (result && result != MDB_NOTFOUND)
+    throw0(DB_ERROR(lmdb_error("Failed to retrieve max block size: ", result).c_str()));
+  uint64_t max_block_size = 0;
+  if (result == 0)
+  {
+    if (v.mv_size != sizeof(uint64_t))
+      throw0(DB_ERROR("Failed to retrieve or create max block size: unexpected value size"));
+    memcpy(&max_block_size, v.mv_data, sizeof(max_block_size));
+  }
+  if (sz > max_block_size)
+    max_block_size = sz;
+  v.mv_data = (void*)&max_block_size;
+  v.mv_size = sizeof(max_block_size);
+  result = mdb_cursor_put(m_cur_properties, &k, &v, 0);
+  if (result)
+    throw0(DB_ERROR(lmdb_error("Failed to set max_block_size: ", result).c_str()));
+}
+
+
 std::vector<uint64_t> BlockchainLMDB::get_block_weights(uint64_t start_height, size_t count) const
 {
   return get_block_info_64bit_fields(start_height, count, offsetof(mdb_block_info, bi_weight));

src/blockchain_db/lmdb/db_lmdb.h

@@ -400,6 +400,9 @@ private:
 
   std::vector<uint64_t> get_block_info_64bit_fields(uint64_t start_height, size_t count, off_t offset) const;
 
+  uint64_t get_max_block_size();
+  void add_max_block_size(uint64_t sz);
+
   // fix up anything that may be wrong due to past bugs
   virtual void fixup();
 

src/blockchain_db/testdb.h

@@ -149,6 +149,9 @@ public:
   virtual bool update_pruning() { return true; }
   virtual bool check_pruning() { return true; }
   virtual void prune_outputs(uint64_t amount) {}
+
+  virtual uint64_t get_max_block_size() { return 100000000; }
+  virtual void add_max_block_size(uint64_t sz) { }
 };
 
 }

src/cryptonote_basic/cryptonote_basic.h

@@ -422,6 +422,8 @@ namespace cryptonote
       FIELDS(*static_cast<block_header *>(this))
       FIELD(miner_tx)
       FIELD(tx_hashes)
+      if (tx_hashes.size() > CRYPTONOTE_MAX_TX_PER_BLOCK)
+        return false;
     END_SERIALIZE()
   };
 

src/cryptonote_basic/cryptonote_basic_impl.cpp

@@ -76,11 +76,6 @@ namespace cryptonote {
     return CRYPTONOTE_BLOCK_GRANTED_FULL_REWARD_ZONE_V5;
   }
   //-----------------------------------------------------------------------------------------------
-  size_t get_max_block_size()
-  {
-    return CRYPTONOTE_MAX_BLOCK_SIZE;
-  }
-  //-----------------------------------------------------------------------------------------------
   size_t get_max_tx_size()
   {
     return CRYPTONOTE_MAX_TX_SIZE;

src/cryptonote_basic/cryptonote_basic_impl.h

@@ -87,7 +87,6 @@ namespace cryptonote {
   /* Cryptonote helper functions                                          */
   /************************************************************************/
   size_t get_min_block_weight(uint8_t version);
-  size_t get_max_block_size();
   size_t get_max_tx_size();
   bool get_block_reward(size_t median_weight, size_t current_block_weight, uint64_t already_generated_coins, uint64_t &reward, uint8_t version);
   uint8_t get_account_address_checksum(const public_address_outer_blob& bl);

src/cryptonote_config.h

@@ -37,9 +37,9 @@
 #define CRYPTONOTE_DNS_TIMEOUT_MS                       20000
 
 #define CRYPTONOTE_MAX_BLOCK_NUMBER                     500000000
-#define CRYPTONOTE_MAX_BLOCK_SIZE                       500000000  // block header blob limit, never used!
 #define CRYPTONOTE_GETBLOCKTEMPLATE_MAX_BLOCK_SIZE	196608 //size of block (bytes) that is the maximum that miners will produce
-#define CRYPTONOTE_MAX_TX_SIZE                          1000000000
+#define CRYPTONOTE_MAX_TX_SIZE                          1000000
+#define CRYPTONOTE_MAX_TX_PER_BLOCK                     0x10000000
 #define CRYPTONOTE_PUBLIC_ADDRESS_TEXTBLOB_VER          0
 #define CRYPTONOTE_MINED_MONEY_UNLOCK_WINDOW            60
 #define CURRENT_TRANSACTION_VERSION                     2

src/cryptonote_core/blockchain.cpp

@@ -3872,6 +3872,8 @@ bool Blockchain::update_next_cumulative_weight_limit(uint64_t *long_term_effecti
 
   LOG_PRINT_L3("Blockchain::" << __func__);
 
+  m_db->block_txn_start(false);
+
   // when we reach this, the last hf version is not yet written to the db
   const uint64_t db_height = m_db->height();
   const uint8_t hf_version = get_current_hard_fork_version();
@@ -3934,6 +3936,10 @@ bool Blockchain::update_next_cumulative_weight_limit(uint64_t *long_term_effecti
   if (long_term_effective_median_block_weight)
     *long_term_effective_median_block_weight = m_long_term_effective_median_block_weight;
 
+  m_db->add_max_block_size(m_current_block_cumul_weight_limit);
+
+  m_db->block_txn_stop();
+
   return true;
 }
 //------------------------------------------------------------------

src/cryptonote_core/cryptonote_core.cpp

@@ -62,6 +62,9 @@ DISABLE_VS_WARNINGS(4355)
 
 #define BAD_SEMANTICS_TXES_MAX_SIZE 100
 
+// basically at least how many bytes the block itself serializes to without the miner tx
+#define BLOCK_SIZE_SANITY_LEEWAY 100
+
 namespace cryptonote
 {
   const command_line::arg_descriptor<bool, false> arg_testnet_on  = {
@@ -1417,18 +1420,21 @@ namespace cryptonote
   {
     TRY_ENTRY();
 
-    // load json & DNS checkpoints every 10min/hour respectively,
-    // and verify them with respect to what blocks we already have
-    CHECK_AND_ASSERT_MES(update_checkpoints(), false, "One or more checkpoints loaded from json or dns conflicted with existing checkpoints.");
-
     bvc = boost::value_initialized<block_verification_context>();
-    if(block_blob.size() > get_max_block_size())
+
+    if (!check_incoming_block_size(block_blob))
     {
-      LOG_PRINT_L1("WRONG BLOCK BLOB, too big size " << block_blob.size() << ", rejected");
       bvc.m_verifivation_failed = true;
       return false;
     }
 
+    if (((size_t)-1) <= 0xffffffff && block_blob.size() >= 0x3fffffff)
+      MWARNING("This block's size is " << block_blob.size() << ", closing on the 32 bit limit");
+
+    // load json & DNS checkpoints every 10min/hour respectively,
+    // and verify them with respect to what blocks we already have
+    CHECK_AND_ASSERT_MES(update_checkpoints(), false, "One or more checkpoints loaded from json or dns conflicted with existing checkpoints.");
+
     block lb;
     if (!b)
     {
@@ -1452,9 +1458,13 @@ namespace cryptonote
   // block_blob
   bool core::check_incoming_block_size(const blobdata& block_blob) const
   {
-    if(block_blob.size() > get_max_block_size())
+    // note: we assume block weight is always >= block blob size, so we check incoming
+    // blob size against the block weight limit, which acts as a sanity check without
+    // having to parse/weigh first; in fact, since the block blob is the block header
+    // plus the tx hashes, the weight will typically be much larger than the blob size
+    if(block_blob.size() > m_blockchain_storage.get_current_cumulative_block_weight_limit() + BLOCK_SIZE_SANITY_LEEWAY)
     {
-      LOG_PRINT_L1("WRONG BLOCK BLOB, too big size " << block_blob.size() << ", rejected");
+      LOG_PRINT_L1("WRONG BLOCK BLOB, sanity check failed on size " << block_blob.size() << ", rejected");
       return false;
     }
     return true;