protocol: add a sanity check to the number of block hashes sent

src/cryptonote_config.h

@@ -93,6 +93,7 @@
 
 
 #define BLOCKS_IDS_SYNCHRONIZING_DEFAULT_COUNT          10000  //by default, blocks ids count in synchronizing
+#define BLOCKS_IDS_SYNCHRONIZING_MAX_COUNT              25000  //max blocks ids count in synchronizing
 #define BLOCKS_SYNCHRONIZING_DEFAULT_COUNT_PRE_V4       100    //by default, blocks count in blocks downloading
 #define BLOCKS_SYNCHRONIZING_DEFAULT_COUNT              20     //by default, blocks count in blocks downloading
 #define BLOCKS_SYNCHRONIZING_MAX_COUNT                  2048   //must be a power of 2, greater than 128, equal to SEEDHASH_EPOCH_BLOCKS

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -2442,7 +2442,7 @@ skip:
     }
     MDEBUG(context << "first block hash " << arg.m_block_ids.front() << ", last " << arg.m_block_ids.back());
 
-    if (arg.total_height >= CRYPTONOTE_MAX_BLOCK_NUMBER || arg.m_block_ids.size() >= CRYPTONOTE_MAX_BLOCK_NUMBER)
+    if (arg.total_height >= CRYPTONOTE_MAX_BLOCK_NUMBER || arg.m_block_ids.size() > BLOCKS_IDS_SYNCHRONIZING_MAX_COUNT)
     {
       LOG_ERROR_CCONTEXT("sent wrong NOTIFY_RESPONSE_CHAIN_ENTRY, with total_height=" << arg.total_height << " and block_ids=" << arg.m_block_ids.size());
       drop_connection(context, false, false);