IBD Booster: check that booster muhash is empty at final block

Author: theStack

src/validation.cpp

@@ -2758,6 +2758,18 @@ bool Chainstate::ConnectBlock(const CBlock& block, BlockValidationState& state,
             UpdateCoinsIBDBooster(tx, view, pindex->nHeight);
         }
     }
+
+    if (pindex->nHeight == g_ibd_booster_hints.GetFinalBlockHeight()) {
+        if (g_ibd_booster_muhash.IsEmptySet()) {
+            LogInfo("*** IBD Booster: MuHash check at block height %d succeeded. ***\n", pindex->nHeight);
+        } else {
+            // TODO: find a proper way to signal this error; strictly speaking it's not a
+            // block validation error, most likely the given hints data file was invalid
+            state.Invalid(BlockValidationResult::BLOCK_CONSENSUS, "ibd-booster-muhash-not-empty-at-final-block",
+                          "fails the IBD-Booster-MuHash check (should be an empty set!)");
+        }
+    }
+
     const auto time_3{SteadyClock::now()};
     m_chainman.time_connect += time_3 - time_2;
     LogDebug(BCLog::BENCH, "      - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) [%.2fs (%.2fms/blk)]\n", (unsigned)block.vtx.size(),