Ban using Peya as a merge-mining parent

src/cryptonote_config.h

@@ -256,6 +256,7 @@
 #define HF_VERSION_EMERGENCY_DIFFICULTY          12
 #define HF_VERSION_MERGE_MINING                  13
 #define HF_VERSION_RESTRICTED_MERGE_MINING       14
+#define HF_VERSION_DISABLE_PEYA_AS_PARENT        15
 
 #define HF_VERSION_REQUIRE_VIEW_TAGS            255
 #define HF_VERSION_ENABLE_CONVERT               255

src/cryptonote_core/blockchain.cpp

@@ -5742,6 +5742,25 @@ leave:
     goto leave;
   }
 
+  if (!bl.aux_header && hf_version >= HF_VERSION_DISABLE_PEYA_AS_PARENT)
+  {
+    std::vector<cryptonote::tx_extra_field> miner_tx_extra_fields;
+    if (!cryptonote::parse_tx_extra(bl.miner_tx.extra, miner_tx_extra_fields))
+    {
+      MERROR_VER("Block with id: " << id << " has invalid miner tx extra while checking parent-side merge-mining tag ban");
+      bvc.m_verifivation_failed = true;
+      goto leave;
+    }
+
+    cryptonote::tx_extra_merge_mining_tag mm_tag;
+    if (cryptonote::find_tx_extra_field_by_type(miner_tx_extra_fields, mm_tag, 0))
+    {
+      MERROR_VER("Block with id: " << id << " carries a parent-side merge mining tag in miner tx after HF_VERSION_DISABLE_PEYA_AS_PARENT");
+      bvc.m_verifivation_failed = true;
+      goto leave;
+    }
+  }
+
   // sanity check basic protocol tx properties;
   if(!prevalidate_protocol_transaction(bl, blockchain_height, hf_version))
   {

src/hardforks/hardforks.cpp

@@ -39,6 +39,9 @@ const hardfork_t mainnet_hard_forks[] = {
   {12, 3, 0, 1341378360 },
   {13, 4, 0, 1341378480 },
   {14, 5, 0, 1341378600 },
+  // Temporary test height for disabling Peya-as-parent via parent-side merge-mining tags.
+  // Before real rollout this should be moved lower to the intended production activation height.
+  {15, 878, 0, 1341482760 },
 };
 const size_t num_mainnet_hard_forks = sizeof(mainnet_hard_forks) / sizeof(mainnet_hard_forks[0]);
 const uint64_t mainnet_hard_fork_version_1_till = 0;
@@ -51,6 +54,9 @@ const hardfork_t testnet_hard_forks[] = {
   {12, 3, 0, 1341378360 },
   {13, 4, 0, 1341378480 },
   {14, 5, 0, 1341378600 },
+  // Temporary test height for disabling Peya-as-parent via parent-side merge-mining tags.
+  // Before real rollout this should be moved lower to the intended production activation height.
+  {15, 878, 0, 1341482760 },
 };
 const size_t num_testnet_hard_forks = sizeof(testnet_hard_forks) / sizeof(testnet_hard_forks[0]);
 const uint64_t testnet_hard_fork_version_1_till = 0;
@@ -63,5 +69,8 @@ const hardfork_t stagenet_hard_forks[] = {
   {12, 3, 0, 1341378360 },
   {13, 4, 0, 1341378480 },
   {14, 5, 0, 1341378600 },
+  // Temporary test height for disabling Peya-as-parent via parent-side merge-mining tags.
+  // Before real rollout this should be moved lower to the intended production activation height.
+  {15, 878, 0, 1341482760 },
 };
 const size_t num_stagenet_hard_forks = sizeof(stagenet_hard_forks) / sizeof(stagenet_hard_forks[0]);