cryptonote: rework block blob size sanity check

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

2 files changed, 24 insertions, 8 deletions

diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index 83d3044f8..5925548d6 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/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;
 }
 //------------------------------------------------------------------
diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index da413bbe2..87cfb27e1 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/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;