diff --git a/src/main/java/org/qortal/block/Block.java b/src/main/java/org/qortal/block/Block.java
index 5f6e1641..798a4f91 100644
--- a/src/main/java/org/qortal/block/Block.java
+++ b/src/main/java/org/qortal/block/Block.java
@@ -1104,6 +1104,10 @@ public class Block {
// Create repository savepoint here so we can rollback to it after testing transactions
repository.setSavepoint();
+ if (this.blockData.getHeight() == 212937)
+ // Apply fix for block 212937 but fix will be rolled back before we exit method
+ Block212937.processFix(this);
+
for (Transaction transaction : this.getTransactions()) {
TransactionData transactionData = transaction.getTransactionData();
@@ -1308,6 +1312,9 @@ public class Block {
// Distribute block rewards, including transaction fees, before transactions processed
processBlockRewards();
+ if (this.blockData.getHeight() == 212937)
+ // Apply fix for block 212937
+ Block212937.processFix(this);
}
// We're about to (test-)process a batch of transactions,
@@ -1542,6 +1549,10 @@ public class Block {
// Invalidate expandedAccounts as they may have changed due to orphaning TRANSFER_PRIVS transactions, etc.
this.cachedExpandedAccounts = null;
+ if (this.blockData.getHeight() == 212937)
+ // Revert fix for block 212937
+ Block212937.orphanFix(this);
+
// Block rewards, including transaction fees, removed after transactions undone
orphanBlockRewards();
diff --git a/src/main/java/org/qortal/block/Block212937.java b/src/main/java/org/qortal/block/Block212937.java
new file mode 100644
index 00000000..a53c9d31
--- /dev/null
+++ b/src/main/java/org/qortal/block/Block212937.java
@@ -0,0 +1,153 @@
+package org.qortal.block;
+
+import java.io.InputStream;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.xml.bind.JAXBContext;
+import javax.xml.bind.JAXBException;
+import javax.xml.bind.UnmarshalException;
+import javax.xml.bind.Unmarshaller;
+import javax.xml.transform.stream.StreamSource;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.eclipse.persistence.jaxb.JAXBContextFactory;
+import org.eclipse.persistence.jaxb.UnmarshallerProperties;
+import org.qortal.data.account.AccountBalanceData;
+import org.qortal.repository.DataException;
+
+/**
+ * Block 212937
+ *
+ * Somehow a node minted a version of block 212937 that contained one transaction:
+ * a PAYMENT transaction that attempted to spend more QORT than that account had as QORT balance.
+ *
+ * This invalid transaction made block 212937 (rightly) invalid to several nodes,
+ * which refused to use that block.
+ * However, it seems there were no other nodes minting an alternative, valid block at that time
+ * and so the chain stalled for several nodes in the network.
+ *
+ * Additionally, the invalid block 212937 affected all new installations, regardless of whether
+ * they synchronized from scratch (block 1) or used an 'official release' bootstrap.
+ *
+ * After lengthy diagnosis, it was discovered that
+ * the invalid transaction seemed to rely on incorrect balances in a corrupted database.
+ * Copies of DB files containing the broken chain were also shared around, exacerbating the problem.
+ *
+ * There were three options:
+ *
+ * - roll back the chain to last known valid block 212936 and re-mint empty blocks to current height
+ * - keep existing chain, but apply database edits at block 212937 to allow current chain to be valid
+ * - attempt to mint an alternative chain, retaining as many valid transactions as possible
+ *
+ *
+ * Option 1 was highly undesirable due to knock-on effects from wiping 700+ transactions, some of which
+ * might have affect cross-chain trades, although there were no cross-chain trade completed during
+ * the decision period.
+ *
+ * Option 3 was essentially a slightly better version of option 1 and rejected for similar reasons.
+ * Attempts at option 3 also rapidly hit cumulative problems with every replacement block due to
+ * differing block timestamps making some transactions, and then even some blocks themselves, invalid.
+ *
+ * This class is the implementation of option 2.
+ *
+ * The change in account balances are relatively small, see block-212937-deltas.json resource
+ * for actual values. These values were obtained by exporting the AccountBalances table from
+ * both versions of the database with chain at block 212936, and then comparing. The values were also
+ * tested by syncing both databases up to block 225500, re-exporting and re-comparing.
+ *
+ * The invalid block 212937 signature is: 2J3GVJjv...qavh6KkQ.
+ *
+ * The invalid transaction in block 212937 is:
+ *
+ *
+ {
+ "amount" : "0.10788294",
+ "approvalStatus" : "NOT_REQUIRED",
+ "blockHeight" : 212937,
+ "creatorAddress" : "QLdw5uabviLJgRGkRiydAFmAtZzxHfNXSs",
+ "fee" : "0.00100000",
+ "recipient" : "QZi1mNHDbiLvsytxTgxDr9nhJe4pNZaWpw",
+ "reference" : "J6JukdTVuXZ3JYbHatfZzwxG2vSiZwVCPDzW5K7PsVQKRj8XZeDtqnkGCGGjaSQZ9bQMtV44ky88NnGM4YBQKU6",
+ "senderPublicKey" : "DBFfbD2M3uh4jPE5PaUcZVvNPfrrJzVB7seeEtBn5SPs",
+ "signature" : "qkitxdCEEnKt8w6wRfFixtErbXsxWE6zG2ESNhpqBdScikV1WxeA6WZTTMJVV4tCeZdBFXw3V1X5NVztv6LirWK",
+ "timestamp" : 1607863074904,
+ "txGroupId" : 0,
+ "type" : "PAYMENT"
+ }
+
+ * Account QLdw5uabviLJgRGkRiydAFmAtZzxHfNXSs attempted to spend 0.10888294 (including fees)
+ * when their QORT balance was really only 0.10886665.
+ *
+ * However, on the broken DB nodes, their balance
+ * seemed to be 0.10890293 which was sufficient to make the transaction valid.
+ */
+public final class Block212937 {
+
+ private static final Logger LOGGER = LogManager.getLogger(Block212937.class);
+ private static final String ACCOUNT_DELTAS_SOURCE = "block-212937-deltas.json";
+
+ private static final List accountDeltas = readAccountDeltas();
+
+ private Block212937() {
+ /* Do not instantiate */
+ }
+
+ @SuppressWarnings("unchecked")
+ private static List readAccountDeltas() {
+ Unmarshaller unmarshaller;
+
+ try {
+ // Create JAXB context aware of classes we need to unmarshal
+ JAXBContext jc = JAXBContextFactory.createContext(new Class[] {
+ AccountBalanceData.class
+ }, null);
+
+ // Create unmarshaller
+ unmarshaller = jc.createUnmarshaller();
+
+ // Set the unmarshaller media type to JSON
+ unmarshaller.setProperty(UnmarshallerProperties.MEDIA_TYPE, "application/json");
+
+ // Tell unmarshaller that there's no JSON root element in the JSON input
+ unmarshaller.setProperty(UnmarshallerProperties.JSON_INCLUDE_ROOT, false);
+ } catch (JAXBException e) {
+ String message = "Failed to setup unmarshaller to read block 212937 deltas";
+ LOGGER.error(message, e);
+ throw new RuntimeException(message, e);
+ }
+
+ ClassLoader classLoader = BlockChain.class.getClassLoader();
+ InputStream in = classLoader.getResourceAsStream(ACCOUNT_DELTAS_SOURCE);
+ StreamSource jsonSource = new StreamSource(in);
+
+ try {
+ // Attempt to unmarshal JSON stream to BlockChain config
+ return (List) unmarshaller.unmarshal(jsonSource, AccountBalanceData.class).getValue();
+ } catch (UnmarshalException e) {
+ String message = "Failed to parse block 212937 deltas";
+ LOGGER.error(message, e);
+ throw new RuntimeException(message, e);
+ } catch (JAXBException e) {
+ String message = "Unexpected JAXB issue while processing block 212937 deltas";
+ LOGGER.error(message, e);
+ throw new RuntimeException(message, e);
+ }
+ }
+
+ public static void processFix(Block block) throws DataException {
+ block.repository.getAccountRepository().modifyAssetBalances(accountDeltas);
+ }
+
+ public static void orphanFix(Block block) throws DataException {
+ // Create inverse deltas
+ List inverseDeltas = accountDeltas.stream()
+ .map(delta -> new AccountBalanceData(delta.getAddress(), delta.getAssetId(), 0 - delta.getBalance()))
+ .collect(Collectors.toList());
+
+ block.repository.getAccountRepository().modifyAssetBalances(inverseDeltas);
+ }
+
+}