Synchronization improvements

Don't attempt to sync, or generate blocks, if we think we're not up to date.

Notify Controller of newly generated block AFTER releasing blockchain lock.

Loads of changes to synchronizer.

Added missing GET_PEERS handling to Controller.onNetworkMessage.

More detailed peer information (last block sig, last generator sig, last block timestamp, ...)
New HEIGHT_V2 network message to help support above.

More, and improved, logging.

Fix for HSQLDB serialization failure caused by trying to save the same new transaction
received by more than one peer/thread simultaneously.

src/main/java/org/qora/block/BlockGenerator.java

@@ -70,12 +70,20 @@ public class BlockGenerator extends Thread {
 				// Sleep for a while
 				try {
 					repository.discardChanges(); // Free repository locks, if any
-					Thread.sleep(1000); // No point sleeping less than this as block timestamp millisecond values must be the same
+					Thread.sleep(1000);
 				} catch (InterruptedException e) {
 					// We've been interrupted - time to exit
 					return;
 				}
 
+				// Don't generate if we don't have enough connected peers as where would the transactions/consensus come from?
+				if (Network.getInstance().getUniqueHandshakedPeers().size() < Settings.getInstance().getMinBlockchainPeers())
+					continue;
+
+				// Don't generate if it looks like we're behind
+				if (!Controller.getInstance().isUpToDate())
+					continue;
+
 				// Check blockchain hasn't changed
 				BlockData lastBlockData = blockRepository.getLastBlock();
 				if (previousBlock == null || !Arrays.equals(previousBlock.getSignature(), lastBlockData.getSignature())) {
@@ -83,10 +91,6 @@ public class BlockGenerator extends Thread {
 					newBlocks.clear();
 				}
 
-				// Don't generate if we don't have enough connected peers as where would the transactions/consensus come from?
-				if (Network.getInstance().getUniqueHandshakedPeers().size() < Settings.getInstance().getMinBlockchainPeers())
-					continue;
-
 				// Do we need to build any potential new blocks?
 				List<ForgingAccountData> forgingAccountsData = repository.getAccountRepository().getForgingAccounts();
 				List<PrivateKeyAccount> forgingAccounts = forgingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getSeed())).collect(Collectors.toList());
@@ -108,7 +112,9 @@ public class BlockGenerator extends Thread {
 
 				// Make sure we're the only thread modifying the blockchain
 				ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-				if (blockchainLock.tryLock())
+				if (blockchainLock.tryLock()) {
+					boolean newBlockGenerated = false;
+
 					generation: try {
 						// Clear repository's "in transaction" state so we don't cause a repository deadlock
 						repository.discardChanges();
@@ -160,7 +166,7 @@ public class BlockGenerator extends Thread {
 							repository.saveChanges();
 
 							// Notify controller
-							Controller.getInstance().onGeneratedBlock(newBlock.getBlockData());
+							newBlockGenerated = true;
 						} catch (DataException e) {
 							// Unable to process block - report and discard
 							LOGGER.error("Unable to process newly generated block?", e);
@@ -169,6 +175,10 @@ public class BlockGenerator extends Thread {
 					} finally {
 						blockchainLock.unlock();
 					}
+
+					if (newBlockGenerated)
+						Controller.getInstance().onGeneratedBlock();
+				}
 			}
 		} catch (DataException e) {
 			LOGGER.warn("Repository issue while running block generator", e);

src/main/java/org/qora/controller/Controller.java

@@ -8,9 +8,11 @@ import java.time.LocalDateTime;
 import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Properties;
 import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Predicate;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -36,6 +38,7 @@ import org.qora.network.message.GetPeersMessage;
 import org.qora.network.message.GetSignaturesMessage;
 import org.qora.network.message.GetSignaturesV2Message;
 import org.qora.network.message.HeightMessage;
+import org.qora.network.message.HeightV2Message;
 import org.qora.network.message.Message;
 import org.qora.network.message.SignaturesMessage;
 import org.qora.network.message.TransactionMessage;
@@ -136,6 +139,16 @@ public class Controller extends Thread {
 		}
 	}
 
+	/** Returns highest block, or null if there's a repository issue */
+	public BlockData getChainTip() {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			return repository.getBlockRepository().getLastBlock();
+		} catch (DataException e) {
+			LOGGER.error("Repository issue when fetching blockchain tip", e);
+			return null;
+		}
+	}
+
 	public ReentrantLock getBlockchainLock() {
 		return this.blockchainLock;
 	}
@@ -222,7 +235,7 @@ public class Controller extends Thread {
 
 		try {
 			while (!isStopping) {
-				Thread.sleep(60 * 1000);
+				Thread.sleep(14 * 1000);
 
 				potentiallySynchronize();
 
@@ -235,31 +248,24 @@ public class Controller extends Thread {
 	}
 
 	private void potentiallySynchronize() {
-		int ourHeight = getChainHeight();
-		if (ourHeight == 0)
-			return;
-
-		// If we have enough peers, potentially synchronize
 		List<Peer> peers = Network.getInstance().getUniqueHandshakedPeers();
+
+		// Check we have enough peers to potentially synchronize
 		if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 			return;
 
 		for(Peer peer : peers)
 			LOGGER.trace(String.format("Peer %s is at height %d", peer, peer.getPeerData().getLastHeight()));
 
-		// Remove peers with unknown, or same, height
+		// Remove peers with unknown height, lower height or same height and same block signature (unless we don't have their block signature)
-		peers.removeIf(peer -> {
+		peers.removeIf(hasShorterBlockchain());
-			Integer peerHeight = peer.getPeerData().getLastHeight();
-			return peerHeight == null;
-		});
 
 		// Remove peers that have "misbehaved" recently
-		peers.removeIf(peer -> {
+		peers.removeIf(hasPeerMisbehaved);
-			Long lastMisbehaved = peer.getPeerData().getLastMisbehaved();
-			return lastMisbehaved != null && lastMisbehaved > NTP.getTime() - MISBEHAVIOUR_COOLOFF;
-		});
 
 		if (!peers.isEmpty()) {
+			int ourHeight = getChainHeight();
+
 			// Pick random peer to sync with
 			int index = new SecureRandom().nextInt(peers.size());
 			Peer peer = peers.get(index);
@@ -294,14 +300,15 @@ public class Controller extends Thread {
 					break;
 
 				case OK:
-					LOGGER.debug(String.format("Synchronized with peer %s", peer));
+				case NOTHING_TO_DO:
+					LOGGER.debug(String.format("Synchronized with peer %s (%s)", peer, syncResult.name()));
 					break;
 			}
 
 			// Broadcast our new height (if changed)
-			int updatedHeight = getChainHeight();
+			BlockData latestBlockData = getChainTip();
-			if (updatedHeight != ourHeight)
+			if (latestBlockData.getHeight() != ourHeight)
-				Network.getInstance().broadcast(recipientPeer -> new HeightMessage(updatedHeight));
+				Network.getInstance().broadcast(recipientPeer -> Network.getInstance().buildHeightMessage(recipientPeer, latestBlockData));
 		}
 	}
 
@@ -365,18 +372,24 @@ public class Controller extends Thread {
 		network.broadcast(peer -> network.buildPeersMessage(peer));
 
 		// Send our current height
-		network.broadcast(peer -> new HeightMessage(this.getChainHeight()));
+		BlockData latestBlockData = getChainTip();
+		network.broadcast(peer -> network.buildHeightMessage(peer, latestBlockData));
 
 		// Request peers lists
 		network.broadcast(peer -> new GetPeersMessage());
 	}
 
-	public void onGeneratedBlock(BlockData newBlockData) {
+	public void onGeneratedBlock() {
-		// XXX we should really be broadcasting the new block sig, not height
+		// Broadcast our new height info
-		// Could even broadcast top two block sigs so that remote peers can see new block references current network-wide last block
+		BlockData latestBlockData = getChainTip();
 
-		// Broadcast our new height
+		Network network = Network.getInstance();
-		Network.getInstance().broadcast(peer -> new HeightMessage(newBlockData.getHeight()));
+		network.broadcast(peer -> network.buildHeightMessage(peer, latestBlockData));
+	}
+
+	public void onNewTransaction(TransactionData transactionData) {
+		// Send round to all peers
+		Network.getInstance().broadcast(peer -> new TransactionMessage(transactionData));
 	}
 
 	public void onNetworkMessage(Peer peer, Message message) {
@@ -387,15 +400,44 @@ public class Controller extends Thread {
 				HeightMessage heightMessage = (HeightMessage) message;
 
 				// Update our record of peer's height
-				peer.getPeerData().setLastHeight(heightMessage.getHeight());
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					PeerData peerData = peer.getPeerData();
+
+					peer.getPeerData().setLastHeight(heightMessage.getHeight());
+
+					repository.getNetworkRepository().save(peerData);
+					repository.saveChanges();
+				} catch (DataException e) {
+					LOGGER.error(String.format("Repository issue while updating height of peer %s", peer), e);
+				}
 
 				break;
 
-			case GET_SIGNATURES:
+			case HEIGHT_V2:
-				try (final Repository repository = RepositoryManager.getRepository()) {
+				HeightV2Message heightV2Message = (HeightV2Message) message;
-					GetSignaturesMessage getSignaturesMessage = (GetSignaturesMessage) message;
-					byte[] parentSignature = getSignaturesMessage.getParentSignature();
 
+				// Update our record for peer's blockchain info
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					PeerData peerData = peer.getPeerData();
+
+					peerData.setLastHeight(heightV2Message.getHeight());
+					peerData.setLastBlockSignature(heightV2Message.getSignature());
+					peerData.setLastBlockTimestamp(heightV2Message.getTimestamp());
+					peerData.setLastBlockGenerator(heightV2Message.getGenerator());
+
+					repository.getNetworkRepository().save(peerData);
+					repository.saveChanges();
+				} catch (DataException e) {
+					LOGGER.error(String.format("Repository issue while updating info of peer %s", peer), e);
+				}
+
+				break;
+
+			case GET_SIGNATURES: {
+				GetSignaturesMessage getSignaturesMessage = (GetSignaturesMessage) message;
+				byte[] parentSignature = getSignaturesMessage.getParentSignature();
+
+				try (final Repository repository = RepositoryManager.getRepository()) {
 					List<byte[]> signatures = new ArrayList<>();
 
 					do {
@@ -411,17 +453,18 @@ public class Controller extends Thread {
 					Message signaturesMessage = new SignaturesMessage(signatures);
 					signaturesMessage.setId(message.getId());
 					if (!peer.sendMessage(signaturesMessage))
-						peer.disconnect();
+						peer.disconnect("failed to send signatures");
 				} catch (DataException e) {
-					LOGGER.error(String.format("Repository issue while responding to %s from peer %s", message.getType().name(), peer), e);
+					LOGGER.error(String.format("Repository issue while sending signatures after %s to peer %s", Base58.encode(parentSignature), peer), e);
 				}
 				break;
+			}
+
+			case GET_SIGNATURES_V2: {
+				GetSignaturesV2Message getSignaturesMessage = (GetSignaturesV2Message) message;
+				byte[] parentSignature = getSignaturesMessage.getParentSignature();
 
-			case GET_SIGNATURES_V2:
 				try (final Repository repository = RepositoryManager.getRepository()) {
-					GetSignaturesV2Message getSignaturesMessage = (GetSignaturesV2Message) message;
-					byte[] parentSignature = getSignaturesMessage.getParentSignature();
-
 					List<byte[]> signatures = new ArrayList<>();
 
 					do {
@@ -437,17 +480,18 @@ public class Controller extends Thread {
 					Message signaturesMessage = new SignaturesMessage(signatures);
 					signaturesMessage.setId(message.getId());
 					if (!peer.sendMessage(signaturesMessage))
-						peer.disconnect();
+						peer.disconnect("failed to send signatures (v2)");
 				} catch (DataException e) {
-					LOGGER.error(String.format("Repository issue while responding to %s from peer %s", message.getType().name(), peer), e);
+					LOGGER.error(String.format("Repository issue while sending V2 signatures after %s to peer %s", Base58.encode(parentSignature), peer), e);
 				}
 				break;
+			}
 
 			case GET_BLOCK:
-				try (final Repository repository = RepositoryManager.getRepository()) {
+				GetBlockMessage getBlockMessage = (GetBlockMessage) message;
-					GetBlockMessage getBlockMessage = (GetBlockMessage) message;
+				byte[] signature = getBlockMessage.getSignature();
-					byte[] signature = getBlockMessage.getSignature();
 
+				try (final Repository repository = RepositoryManager.getRepository()) {
 					BlockData blockData = repository.getBlockRepository().fromSignature(signature);
 					if (blockData == null) {
 						LOGGER.debug(String.format("Ignoring GET_BLOCK request from peer %s for unknown block %s", peer, Base58.encode(signature)));
@@ -460,17 +504,17 @@ public class Controller extends Thread {
 					Message blockMessage = new BlockMessage(block);
 					blockMessage.setId(message.getId());
 					if (!peer.sendMessage(blockMessage))
-						peer.disconnect();
+						peer.disconnect("failed to send block");
 				} catch (DataException e) {
-					LOGGER.error(String.format("Repository issue while responding to %s from peer %s", message.getType().name(), peer), e);
+					LOGGER.error(String.format("Repository issue while send block %s to peer %s", Base58.encode(signature), peer), e);
 				}
 				break;
 
 			case TRANSACTION:
-				try (final Repository repository = RepositoryManager.getRepository()) {
+				TransactionMessage transactionMessage = (TransactionMessage) message;
-					TransactionMessage transactionMessage = (TransactionMessage) message;
+				TransactionData transactionData = transactionMessage.getTransactionData();
 
-					TransactionData transactionData = transactionMessage.getTransactionData();
+				try (final Repository repository = RepositoryManager.getRepository()) {
 					Transaction transaction = Transaction.fromData(repository, transactionData);
 
 					// Check signature
@@ -479,33 +523,40 @@ public class Controller extends Thread {
 						break;
 					}
 
-					// Do we have it already?
+					// Blockchain lock required to prevent multiple threads trying to save the same transaction simultaneously
-					if (repository.getTransactionRepository().exists(transactionData.getSignature())) {
+					ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-						LOGGER.trace(String.format("Ignoring existing TRANSACTION %s from peer %s", Base58.encode(transactionData.getSignature()), peer));
+					blockchainLock.lock();
-						break;
+					try {
-					}
+						// Do we have it already?
+						if (repository.getTransactionRepository().exists(transactionData.getSignature())) {
+							LOGGER.trace(String.format("Ignoring existing TRANSACTION %s from peer %s", Base58.encode(transactionData.getSignature()), peer));
+							break;
+						}
 
-					// Is it valid?
+						// Is it valid?
-					ValidationResult validationResult = transaction.isValidUnconfirmed();
+						ValidationResult validationResult = transaction.isValidUnconfirmed();
-					if (validationResult != ValidationResult.OK) {
+						if (validationResult != ValidationResult.OK) {
-						LOGGER.trace(String.format("Ignoring invalid (%s) TRANSACTION %s from peer %s", validationResult.name(), Base58.encode(transactionData.getSignature()), peer));
+							LOGGER.trace(String.format("Ignoring invalid (%s) TRANSACTION %s from peer %s", validationResult.name(), Base58.encode(transactionData.getSignature()), peer));
-						break;
+							break;
-					}
+						}
 
-					// Seems ok - add to unconfirmed pile
+						// Seems ok - add to unconfirmed pile
-					repository.getTransactionRepository().save(transactionData);
+						repository.getTransactionRepository().save(transactionData);
-					repository.getTransactionRepository().unconfirmTransaction(transactionData);
+						repository.getTransactionRepository().unconfirmTransaction(transactionData);
-					repository.saveChanges();
+						repository.saveChanges();
+					} finally {
+						blockchainLock.unlock();
+					}
 				} catch (DataException e) {
-					LOGGER.error(String.format("Repository issue while responding to %s from peer %s", message.getType().name(), peer), e);
+					LOGGER.error(String.format("Repository issue while processing transaction %s from peer %s", Base58.encode(transactionData.getSignature()), peer), e);
 				}
 				break;
 
 			case GET_BLOCK_SUMMARIES:
-				try (final Repository repository = RepositoryManager.getRepository()) {
+				GetBlockSummariesMessage getBlockSummariesMessage = (GetBlockSummariesMessage) message;
-					GetBlockSummariesMessage getBlockSummariesMessage = (GetBlockSummariesMessage) message;
+				byte[] parentSignature = getBlockSummariesMessage.getParentSignature();
-					byte[] parentSignature = getBlockSummariesMessage.getParentSignature();
 
+				try (final Repository repository = RepositoryManager.getRepository()) {
 					List<BlockSummaryData> blockSummaries = new ArrayList<>();
 
 					int numberRequested = Math.min(Network.MAX_BLOCK_SUMMARIES_PER_REPLY, getBlockSummariesMessage.getNumberRequested());
@@ -524,20 +575,67 @@ public class Controller extends Thread {
 					Message blockSummariesMessage = new BlockSummariesMessage(blockSummaries);
 					blockSummariesMessage.setId(message.getId());
 					if (!peer.sendMessage(blockSummariesMessage))
-						peer.disconnect();
+						peer.disconnect("failed to send block summaries");
 				} catch (DataException e) {
-					LOGGER.error(String.format("Repository issue while responding to %s from peer %s", message.getType().name(), peer), e);
+					LOGGER.error(String.format("Repository issue while sending block summaries after %s to peer %s", Base58.encode(parentSignature), peer), e);
 				}
 				break;
 
+			case GET_PEERS:
+				// Send our known peers
+				if (!peer.sendMessage(Network.getInstance().buildPeersMessage(peer)))
+					peer.disconnect("failed to send peers list");
+				break;
+
 			default:
+				LOGGER.debug(String.format("Unhandled %s message [ID %d] from peer %s", message.getType().name(), message.getId(), peer));
 				break;
 		}
 	}
 
-	public void onNewTransaction(TransactionData transactionData) {
+	// Utilities
-		// Send round to all peers
+
-		Network.getInstance().broadcast(peer -> new TransactionMessage(transactionData));
+	public static final Predicate<Peer> hasPeerMisbehaved = peer -> {
+		Long lastMisbehaved = peer.getPeerData().getLastMisbehaved();
+		return lastMisbehaved != null && lastMisbehaved > NTP.getTime() - MISBEHAVIOUR_COOLOFF;
+	};
+
+	/** True if peer has unknown height, lower height or same height and same block signature (unless we don't have their block signature). */
+	public static Predicate<Peer> hasShorterBlockchain() {
+		BlockData highestBlockData = getInstance().getChainTip();
+		int ourHeight = highestBlockData.getHeight();
+
+		return peer -> {
+			PeerData peerData = peer.getPeerData();
+
+			Integer peerHeight = peerData.getLastHeight();
+			if (peerHeight == null || peerHeight < ourHeight)
+				return true;
+
+			if (peerHeight > ourHeight || peerData.getLastBlockSignature() == null)
+				return false;
+
+			// Remove if signatures match
+			return Arrays.equals(peerData.getLastBlockSignature(), highestBlockData.getSignature());
+		};
+	}
+
+	/** Returns whether we think our node has up-to-date blockchain based on our height info about other peers. */
+	public boolean isUpToDate() {
+		List<Peer> peers = Network.getInstance().getUniqueHandshakedPeers();
+
+		// Check we have enough peers to potentially synchronize/generator
+		if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
+			return false;
+
+		// Remove peers with unknown height, lower height or same height and same block signature (unless we don't have their block signature)
+		peers.removeIf(hasShorterBlockchain());
+
+		// Remove peers that have "misbehaved" recently
+		peers.removeIf(hasPeerMisbehaved);
+
+		// If we have any peers left, then they would be candidates for synchronization therefore we're not up to date.
+		return peers.isEmpty();
 	}
 
 }

src/main/java/org/qora/controller/Synchronizer.java

@@ -9,6 +9,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qora.block.Block;
 import org.qora.block.Block.ValidationResult;
+import org.qora.block.BlockChain;
 import org.qora.block.GenesisBlock;
 import org.qora.data.block.BlockData;
 import org.qora.data.network.BlockSummaryData;
@@ -26,6 +27,7 @@ import org.qora.repository.DataException;
 import org.qora.repository.Repository;
 import org.qora.repository.RepositoryManager;
 import org.qora.transaction.Transaction;
+import org.qora.utils.NTP;
 
 public class Synchronizer {
 
@@ -35,6 +37,8 @@ public class Synchronizer {
 	private static final int MAXIMUM_BLOCK_STEP = 500;
 	private static final int MAXIMUM_HEIGHT_DELTA = 300; // XXX move to blockchain config?
 	private static final int MAXIMUM_COMMON_DELTA = 60; // XXX move to blockchain config?
+	/** Maximum age for our latest block before we consider ditching our fork. */
+	private static final long MAXIMUM_TIP_AGE = BlockChain.getInstance().getMaxBlockTime() * 1000L * 10; // XXX move to blockchain config?
 	private static final int SYNC_BATCH_SIZE = 200;
 
 	private static Synchronizer instance;
@@ -42,7 +46,7 @@ public class Synchronizer {
 	private Repository repository;
 
 	public enum SynchronizationResult {
-		OK, GENESIS_ONLY, NO_COMMON_BLOCK, TOO_FAR_BEHIND, TOO_DIVERGENT, NO_REPLY, INFERIOR_CHAIN, INVALID_DATA, NO_BLOCKCHAIN_LOCK, REPOSITORY_ISSUE;
+		OK, NOTHING_TO_DO, GENESIS_ONLY, NO_COMMON_BLOCK, TOO_FAR_BEHIND, TOO_DIVERGENT, NO_REPLY, INFERIOR_CHAIN, INVALID_DATA, NO_BLOCKCHAIN_LOCK, REPOSITORY_ISSUE;
 	}
 
 	// Constructors
@@ -75,14 +79,16 @@ public class Synchronizer {
 				try (final Repository repository = RepositoryManager.getRepository()) {
 					try {
 						this.repository = repository;
-						final int ourInitialHeight = this.repository.getBlockRepository().getBlockchainHeight();
+						final BlockData ourLatestBlockData = this.repository.getBlockRepository().getLastBlock();
+						final int ourInitialHeight = ourLatestBlockData.getHeight();
 						int ourHeight = ourInitialHeight;
-						final int peerHeight = peer.getPeerData().getLastHeight();
+						int peerHeight = peer.getPeerData().getLastHeight();
 
 						// If peer is at genesis block then peer has no blocks so ignore them for a while
 						if (peerHeight == 1)
 							return SynchronizationResult.GENESIS_ONLY;
 
+						// XXX this may well be obsolete now
 						// If peer is too far behind us then don't them.
 						int minHeight = ourHeight - MAXIMUM_HEIGHT_DELTA;
 						if (peerHeight < minHeight) {
@@ -90,7 +96,12 @@ public class Synchronizer {
 							return SynchronizationResult.TOO_FAR_BEHIND;
 						}
 
-						LOGGER.info(String.format("Synchronizing with peer %s at height %d, our height %d", peer, peerHeight, ourHeight));
+						byte[] peersLastBlockSignature = peer.getPeerData().getLastBlockSignature();
+						byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
+						if (peerHeight == ourHeight && (peersLastBlockSignature == null || !Arrays.equals(peersLastBlockSignature, ourLastBlockSignature)))
+							LOGGER.info(String.format("Synchronizing with peer %s at height %d, our height %d, signatures differ", peer, peerHeight, ourHeight));
+						else
+							LOGGER.info(String.format("Synchronizing with peer %s at height %d, our height %d", peer, peerHeight, ourHeight));
 
 						List<byte[]> signatures = findSignaturesFromCommonBlock(peer, ourHeight);
 						if (signatures == null) {
@@ -104,13 +115,22 @@ public class Synchronizer {
 						LOGGER.debug(String.format("Common block with peer %s is at height %d", peer, commonBlockHeight));
 						signatures.remove(0);
 
+						// If common block height is higher than peer's last reported height
+						// then peer must have a very recent sync. Update our idea of peer's height.
+						if (commonBlockHeight > peerHeight) {
+							LOGGER.debug(String.format("Peer height %d was lower than common block height %d - using higher value", peerHeight, commonBlockHeight));
+							peerHeight = commonBlockHeight;
+						}
+
+						// XXX This may well be obsolete now
 						// If common block is peer's latest block then we simply have the same, or longer, chain to peer, so exit now
 						if (commonBlockHeight == peerHeight) {
 							if (peerHeight == ourHeight)
 								LOGGER.info(String.format("We have the same blockchain as peer %s", peer));
 							else
 								LOGGER.info(String.format("We have the same blockchain as peer %s, but longer", peer));
-							return SynchronizationResult.OK;
+
+							return SynchronizationResult.NOTHING_TO_DO;
 						}
 
 						// If common block is too far behind us then we're on massively different forks so give up.
@@ -121,7 +141,15 @@ public class Synchronizer {
 						}
 
 						// If we have blocks after common block then decide whether we want to sync (lowest block signature wins)
-						for (int height = commonBlockHeight + 1; height <= peerHeight && height <= ourHeight; ++height) {
+						int highestMutualHeight = Math.min(peerHeight, ourHeight);
+
+						// If our latest block is very old, we're very behind and should ditch our fork.
+						if (ourLatestBlockData.getTimestamp() < NTP.getTime() - MAXIMUM_TIP_AGE) {
+							LOGGER.info(String.format("Ditching our chain after height %d as our latest block is very old", commonBlockHeight));
+							highestMutualHeight = commonBlockHeight;
+						}
+
+						for (int height = commonBlockHeight + 1; height <= highestMutualHeight; ++height) {
 							int sigIndex = height - commonBlockHeight - 1;
 
 							// Do we need more signatures?
@@ -268,7 +296,7 @@ public class Synchronizer {
 			testSignature = testBlockData.getSignature();
 
 			// Ask for block signatures since test block's signature
-			LOGGER.trace(String.format("Requesting %d signature%s after our height %d", step, (step != 1 ? "s": ""), testHeight));
+			LOGGER.trace(String.format("Requesting %d signature%s after height %d", step, (step != 1 ? "s": ""), testHeight));
 			blockSignatures = this.getBlockSignatures(peer, testSignature, step);
 
 			if (blockSignatures == null)

src/main/java/org/qora/data/network/PeerData.java

@@ -22,6 +22,9 @@ public class PeerData {
 	private Long lastAttempted;
 	private Long lastConnected;
 	private Integer lastHeight;
+	private byte[] lastBlockSignature;
+	private Long lastBlockTimestamp;
+	private byte[] lastBlockGenerator;
 	private Long lastMisbehaved;
 
 	// Constructors
@@ -30,16 +33,19 @@ public class PeerData {
 	protected PeerData() {
 	}
 
-	public PeerData(PeerAddress peerAddress, Long lastAttempted, Long lastConnected, Integer lastHeight, Long lastMisbehaved) {
+	public PeerData(PeerAddress peerAddress, Long lastAttempted, Long lastConnected, Integer lastHeight, byte[] lastBlockSignature, Long lastBlockTimestamp, byte[] lastBlockGenerator, Long lastMisbehaved) {
 		this.peerAddress = peerAddress;
 		this.lastAttempted = lastAttempted;
 		this.lastConnected = lastConnected;
 		this.lastHeight = lastHeight;
+		this.lastBlockSignature = lastBlockSignature;
+		this.lastBlockTimestamp = lastBlockTimestamp;
+		this.lastBlockGenerator = lastBlockGenerator;
 		this.lastMisbehaved = lastMisbehaved;
 	}
 
 	public PeerData(PeerAddress peerAddress) {
-		this(peerAddress, null, null, null, null);
+		this(peerAddress, null, null, null, null, null, null, null);
 	}
 
 	// Getters / setters
@@ -75,6 +81,30 @@ public class PeerData {
 		this.lastHeight = lastHeight;
 	}
 
+	public byte[] getLastBlockSignature() {
+		return lastBlockSignature;
+	}
+
+	public void setLastBlockSignature(byte[] lastBlockSignature) {
+		this.lastBlockSignature = lastBlockSignature;
+	}
+
+	public Long getLastBlockTimestamp() {
+		return lastBlockTimestamp;
+	}
+
+	public void setLastBlockTimestamp(Long lastBlockTimestamp) {
+		this.lastBlockTimestamp = lastBlockTimestamp;
+	}
+
+	public byte[] getLastBlockGenerator() {
+		return lastBlockGenerator;
+	}
+
+	public void setLastBlockGenerator(byte[] lastBlockGenerator) {
+		this.lastBlockGenerator = lastBlockGenerator;
+	}
+
 	public Long getLastMisbehaved() {
 		return this.lastMisbehaved;
 	}

src/main/java/org/qora/network/Handshake.java

@@ -152,7 +152,7 @@ public enum Handshake {
 			// Drop other inbound peers with the same ID
 			for (Peer otherPeer : Network.getInstance().getConnectedPeers())
 				if (!otherPeer.isOutbound() && otherPeer.getPeerId() != null && Arrays.equals(otherPeer.getPeerId(), peer.getPendingPeerId()))
-					otherPeer.disconnect();
+					otherPeer.disconnect("doppelganger");
 
 			// Tidy up
 			peer.setVerificationCodes(null, null);
@@ -191,13 +191,13 @@ public enum Handshake {
 
 		Message versionMessage = new VersionMessage(buildTimestamp, versionString);
 		if (!peer.sendMessage(versionMessage))
-			peer.disconnect();
+			peer.disconnect("failed to send version");
 	}
 
 	private static void sendMyId(Peer peer) {
 		Message peerIdMessage = new PeerIdMessage(Network.getInstance().getOurPeerId());
 		if (!peer.sendMessage(peerIdMessage))
-			peer.disconnect();
+			peer.disconnect("failed to send peer ID");
 	}
 
 	private static void sendProof(Peer peer) {
@@ -208,7 +208,7 @@ public enum Handshake {
 			// For incoming connections we only need to send a fake proof message as confirmation
 			Message proofMessage = new ProofMessage(peer.getConnectionTimestamp(), 0, 0);
 			if (!peer.sendMessage(proofMessage))
-				peer.disconnect();
+				peer.disconnect("failed to send proof");
 		}
 	}
 
@@ -218,14 +218,14 @@ public enum Handshake {
 		// Send VERIFICATION_CODES to peer
 		Message verificationCodesMessage = new VerificationCodesMessage(peer.getVerificationCodeSent(), peer.getVerificationCodeExpected());
 		if (!otherOutboundPeer.sendMessage(verificationCodesMessage)) {
-			peer.disconnect(); // give up with this peer instead
+			peer.disconnect("failed to send verification codes"); // give up with this peer instead
 			return;
 		}
 
 		// Send PEER_VERIFY to peer
 		Message peerVerifyMessage = new PeerVerifyMessage(peer.getVerificationCodeSent());
 		if (!peer.sendMessage(peerVerifyMessage))
-			peer.disconnect();
+			peer.disconnect("failed to send verification code");
 	}
 
 }

src/main/java/org/qora/network/Network.java

@@ -25,10 +25,12 @@ import java.util.stream.Collectors;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qora.controller.Controller;
+import org.qora.data.block.BlockData;
 import org.qora.data.network.PeerData;
 import org.qora.data.transaction.TransactionData;
 import org.qora.network.message.GetPeersMessage;
 import org.qora.network.message.HeightMessage;
+import org.qora.network.message.HeightV2Message;
 import org.qora.network.message.Message;
 import org.qora.network.message.Message.MessageType;
 import org.qora.network.message.PeerVerifyMessage;
@@ -316,6 +318,7 @@ public class Network extends Thread {
 			newPeer = new Peer(peerData);
 
 			// Update connection attempt info
+			repository.discardChanges();
 			peerData.setLastAttempted(NTP.getTime());
 			repository.getNetworkRepository().save(peerData);
 			repository.saveChanges();
@@ -360,7 +363,7 @@ public class Network extends Thread {
 					return;
 
 				LOGGER.debug(String.format("Unexpected %s message from %s, expected %s", message.getType().name(), peer, handshakeStatus.expectedMessageType));
-				peer.disconnect();
+				peer.disconnect("unexpected message");
 				return;
 			}
 
@@ -369,7 +372,7 @@ public class Network extends Thread {
 			if (newHandshakeStatus == null) {
 				// Handshake failure
 				LOGGER.debug(String.format("Handshake failure with peer %s message %s", peer, message.getType().name()));
-				peer.disconnect();
+				peer.disconnect("handshake failure");
 				return;
 			}
 
@@ -410,7 +413,7 @@ public class Network extends Thread {
 			case PEER_ID:
 			case PROOF:
 				LOGGER.debug(String.format("Unexpected handshaking message %s from peer %s", message.getType().name(), peer));
-				peer.disconnect();
+				peer.disconnect("unexpected handshaking message");
 				return;
 
 			case PING:
@@ -421,7 +424,7 @@ public class Network extends Thread {
 				pongMessage.setId(pingMessage.getId());
 
 				if (!peer.sendMessage(pongMessage))
-					peer.disconnect();
+					peer.disconnect("failed to send ping reply");
 
 				break;
 
@@ -471,7 +474,7 @@ public class Network extends Thread {
 
 		PeerVerifyMessage peerVerifyMessage = new PeerVerifyMessage(peer.getVerificationCodeExpected());
 		if (!peer.sendMessage(peerVerifyMessage)) {
-			peer.disconnect();
+			peer.disconnect("failed to send verification code");
 			return;
 		}
 
@@ -481,13 +484,15 @@ public class Network extends Thread {
 	}
 
 	private void onHandshakeCompleted(Peer peer) {
-		// Do we need extra handshaking because of peer dopplegangers?
+		// Do we need extra handshaking because of peer doppelgangers?
 		if (peer.getPendingPeerId() != null) {
 			peer.setHandshakeStatus(Handshake.PEER_VERIFY);
 			peer.getHandshakeStatus().action(peer);
 			return;
 		}
 
+		LOGGER.debug(String.format("Handshake completed with peer %s", peer));
+
 		// Make a note that we've successfully completed handshake (and when)
 		peer.getPeerData().setLastConnected(NTP.getTime());
 
@@ -495,16 +500,16 @@ public class Network extends Thread {
 		peer.startPings();
 
 		// Send our height
-		Message heightMessage = new HeightMessage(Controller.getInstance().getChainHeight());
+		Message heightMessage = buildHeightMessage(peer, Controller.getInstance().getChainTip());
 		if (!peer.sendMessage(heightMessage)) {
-			peer.disconnect();
+			peer.disconnect("failed to send height/info");
 			return;
 		}
 
 		// Send our peers list
 		Message peersMessage = this.buildPeersMessage(peer);
 		if (!peer.sendMessage(peersMessage))
-			peer.disconnect();
+			peer.disconnect("failed to send peers list");
 
 		// Send our unconfirmed transactions
 		try (final Repository repository = RepositoryManager.getRepository()) {
@@ -513,7 +518,7 @@ public class Network extends Thread {
 			for (TransactionData transactionData : transactions) {
 				Message transactionMessage = new TransactionMessage(transactionData);
 				if (!peer.sendMessage(transactionMessage)) {
-					peer.disconnect();
+					peer.disconnect("failed to send unconfirmed transaction");
 					return;
 				}
 			}
@@ -524,7 +529,7 @@ public class Network extends Thread {
 		// Request their peers list
 		Message getPeersMessage = new GetPeersMessage();
 		if (!peer.sendMessage(getPeersMessage))
-			peer.disconnect();
+			peer.disconnect("failed to request peers list");
 	}
 
 	/** Returns PEERS message made from peers we've connected to recently, and this node's details */
@@ -588,6 +593,16 @@ public class Network extends Thread {
 		}
 	}
 
+	public Message buildHeightMessage(Peer peer, BlockData blockData) {
+		if (peer.getVersion() < 2) {
+			// Legacy height message
+			return new HeightMessage(blockData.getHeight());
+		}
+
+		// HEIGHT_V2 contains way more useful info
+		return new HeightV2Message(blockData.getHeight(), blockData.getSignature(), blockData.getTimestamp(), blockData.getGeneratorPublicKey());
+	}
+
 	// Network-wide calls
 
 	/** Returns list of connected peers that have completed handshaking. */
@@ -712,7 +727,7 @@ public class Network extends Thread {
 			public void run() {
 				for (Peer peer : targetPeers)
 					if (!peer.sendMessage(peerMessage.apply(peer)))
-						peer.disconnect();
+						peer.disconnect("failed to broadcast message");
 			}
 		}
 

src/main/java/org/qora/network/Peer.java

@@ -12,6 +12,7 @@ import java.security.SecureRandom;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Random;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.Executors;
@@ -23,6 +24,7 @@ import org.apache.logging.log4j.Logger;
 import org.qora.controller.Controller;
 import org.qora.data.network.PeerData;
 import org.qora.network.message.Message;
+import org.qora.network.message.Message.MessageException;
 import org.qora.network.message.Message.MessageType;
 import org.qora.settings.Settings;
 import org.qora.network.message.PingMessage;
@@ -236,10 +238,14 @@ public class Peer implements Runnable {
 					Network.getInstance().onMessage(this, message);
 				}
 			}
+		} catch (MessageException e) {
+			LOGGER.debug(String.format("%s, from peer %s", e.getMessage(), this));
+			this.disconnect(e.getMessage());
+		} catch (SocketTimeoutException e) {
+			this.disconnect("timeout");
 		} catch (IOException e) {
-			// Fall-through
+			this.disconnect("I/O error");
 		} finally {
-			this.disconnect();
 			Thread.currentThread().setName("disconnected peer");
 		}
 	}
@@ -262,6 +268,8 @@ public class Peer implements Runnable {
 				this.out.write(message.toBytes());
 				this.out.flush();
 			}
+		} catch (MessageException e) {
+			LOGGER.warn(String.format("Failed to send %s message with ID %d to peer %s: %s", message.getType().name(), message.getId(), this, e.getMessage()));
 		} catch (IOException e) {
 			// Send failure
 			return false;
@@ -329,23 +337,24 @@ public class Peer implements Runnable {
 				long after = System.currentTimeMillis();
 
 				if (message == null || message.getType() != MessageType.PING)
-					peer.disconnect();
+					peer.disconnect("no ping received");
 
 				peer.setLastPing(after - before);
 			}
 		}
-		;
 
-		this.executor.scheduleWithFixedDelay(new Pinger(this), 0, PING_INTERVAL, TimeUnit.MILLISECONDS);
+		Random random = new Random();
+		long initialDelay = random.nextInt(PING_INTERVAL);
+		this.executor.scheduleWithFixedDelay(new Pinger(this), initialDelay, PING_INTERVAL, TimeUnit.MILLISECONDS);
 	}
 
-	public void disconnect() {
+	public void disconnect(String reason) {
 		// Shut down pinger
 		this.executor.shutdownNow();
 
 		// Close socket
 		if (!this.socket.isClosed()) {
-			LOGGER.debug(String.format("Disconnecting peer %s", this));
+			LOGGER.debug(String.format("Disconnecting peer %s: %s", this, reason));
 
 			try {
 				this.socket.close();

src/main/java/org/qora/network/message/HeightV2Message.java

@@ -0,0 +1,83 @@
+package org.qora.network.message;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+
+import org.qora.transform.Transformer;
+import org.qora.transform.block.BlockTransformer;
+
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+
+public class HeightV2Message extends Message {
+
+	private int height;
+	private byte[] signature;
+	private long timestamp;
+	private byte[] generator;
+
+	public HeightV2Message(int height, byte[] signature, long timestamp, byte[] generator) {
+		this(-1, height, signature, timestamp, generator);
+	}
+
+	private HeightV2Message(int id, int height, byte[] signature, long timestamp, byte[] generator) {
+		super(id, MessageType.HEIGHT_V2);
+
+		this.height = height;
+		this.signature = signature;
+		this.timestamp = timestamp;
+		this.generator = generator;
+	}
+
+	public int getHeight() {
+		return this.height;
+	}
+
+	public byte[] getSignature() {
+		return this.signature;
+	}
+
+	public long getTimestamp() {
+		return this.timestamp;
+	}
+
+	public byte[] getGenerator() {
+		return this.generator;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+		int height = bytes.getInt();
+
+		byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
+		bytes.get(signature);
+
+		long timestamp = bytes.getLong();
+
+		byte[] generator = new byte[Transformer.PUBLIC_KEY_LENGTH];
+		bytes.get(generator);
+
+		return new HeightV2Message(id, height, signature, timestamp, generator);
+	}
+
+	@Override
+	protected byte[] toData() {
+		try {
+			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+			bytes.write(Ints.toByteArray(this.height));
+
+			bytes.write(this.signature);
+
+			bytes.write(Longs.toByteArray(this.timestamp));
+
+			bytes.write(this.generator);
+
+			return bytes.toByteArray();
+		} catch (IOException e) {
+			return null;
+		}
+	}
+
+}

src/main/java/org/qora/network/message/Message.java

@@ -27,6 +27,24 @@ public abstract class Message {
 
 	private static final int MAX_DATA_SIZE = 1024 * 1024; // 1MB
 
+	@SuppressWarnings("serial")
+	public static class MessageException extends Exception {
+		public MessageException() {
+		}
+
+		public MessageException(String message) {
+			super(message);
+		}
+
+		public MessageException(String message, Throwable cause) {
+			super(message, cause);
+		}
+
+		public MessageException(Throwable cause) {
+			super(cause);
+		}
+	}
+
 	public enum MessageType {
 		GET_PEERS(1),
 		PEERS(2),
@@ -45,7 +63,8 @@ public abstract class Message {
 		BLOCK_SUMMARIES(15),
 		GET_SIGNATURES_V2(16),
 		PEER_VERIFY(17),
-		VERIFICATION_CODES(18);
+		VERIFICATION_CODES(18),
+		HEIGHT_V2(19);
 
 		public final int value;
 		public final Method fromByteBuffer;
@@ -119,7 +138,7 @@ public abstract class Message {
 		return this.type;
 	}
 
-	public static Message fromStream(DataInputStream in) throws SocketTimeoutException {
+	public static Message fromStream(DataInputStream in) throws MessageException, IOException {
 		try {
 			// Read only enough bytes to cover Message "magic" preamble
 			byte[] messageMagic = new byte[MAGIC_LENGTH];
@@ -127,13 +146,13 @@ public abstract class Message {
 
 			if (!Arrays.equals(messageMagic, Controller.getInstance().getMessageMagic()))
 				// Didn't receive correct Message "magic"
-				return null;
+				throw new MessageException("Received incorrect message 'magic'");
 
 			int typeValue = in.readInt();
 			MessageType messageType = MessageType.valueOf(typeValue);
 			if (messageType == null)
 				// Unrecognised message type
-				return null;
+				throw new MessageException(String.format("Received unknown message type [%d]", typeValue));
 
 			// Find supporting object
 
@@ -144,14 +163,14 @@ public abstract class Message {
 
 				if (id <= 0)
 					// Invalid ID
-					return null;
+					throw new MessageException("Invalid negative ID");
 			}
 
 			int dataSize = in.readInt();
 
 			if (dataSize > MAX_DATA_SIZE)
 				// Too large
-				return null;
+				throw new MessageException(String.format("Declared data length %d larger than max allowed %d", dataSize, MAX_DATA_SIZE));
 
 			byte[] data = null;
 			if (dataSize > 0) {
@@ -164,14 +183,14 @@ public abstract class Message {
 				// Test checksum
 				byte[] actualChecksum = generateChecksum(data);
 				if (!Arrays.equals(expectedChecksum, actualChecksum))
-					return null;
+					throw new MessageException("Message checksum incorrect");
 			}
 
 			return messageType.fromBytes(id, data);
 		} catch (SocketTimeoutException e) {
 			throw e;
 		} catch (IOException e) {
-			return null;
+			throw e;
 		}
 	}
 
@@ -179,7 +198,7 @@ public abstract class Message {
 		return Arrays.copyOfRange(Crypto.digest(data), 0, CHECKSUM_LENGTH);
 	}
 
-	public byte[] toBytes() {
+	public byte[] toBytes() throws MessageException {
 		try {
 			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
 
@@ -198,7 +217,7 @@ public abstract class Message {
 
 			byte[] data = this.toData();
 			if (data == null)
-				return null;
+				throw new MessageException("Missing data payload");
 
 			bytes.write(Ints.toByteArray(data.length));
 
@@ -207,9 +226,12 @@ public abstract class Message {
 				bytes.write(data);
 			}
 
+			if (bytes.size() > MAX_DATA_SIZE)
+				throw new MessageException(String.format("About to send message with length %d larger than allowed %d", bytes.size(), MAX_DATA_SIZE));
+
 			return bytes.toByteArray();
 		} catch (IOException e) {
-			return null;
+			throw new MessageException("Failed to serialize message", e);
 		}
 	}
 

src/main/java/org/qora/repository/hsqldb/HSQLDBDatabaseUpdates.java

@@ -730,6 +730,13 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("CREATE INDEX TransactionParticipantsAddressIndex on TransactionParticipants (participant)");
 					break;
 
+				case 49:
+					// Additional peer information
+					stmt.execute("ALTER TABLE Peers ADD COLUMN last_block_signature BlockSignature BEFORE last_misbehaved");
+					stmt.execute("ALTER TABLE Peers ADD COLUMN last_block_timestamp TIMESTAMP WITH TIME ZONE BEFORE last_misbehaved");
+					stmt.execute("ALTER TABLE Peers ADD COLUMN last_block_generator QoraPublicKey BEFORE last_misbehaved");
+					break;
+
 				default:
 					// nothing to do
 					return false;

src/main/java/org/qora/repository/hsqldb/HSQLDBNetworkRepository.java

@@ -2,9 +2,7 @@ package org.qora.repository.hsqldb;
 
 import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.sql.Timestamp;
 import java.util.ArrayList;
-import java.util.Calendar;
 import java.util.List;
 
 import org.qora.data.network.PeerData;
@@ -22,9 +20,11 @@ public class HSQLDBNetworkRepository implements NetworkRepository {
 
 	@Override
 	public List<PeerData> getAllPeers() throws DataException {
+		String sql = "SELECT address, last_connected, last_attempted, last_height, last_block_signature, last_block_timestamp, last_block_generator, last_misbehaved FROM Peers";
+
 		List<PeerData> peers = new ArrayList<>();
 
-		try (ResultSet resultSet = this.repository.checkedExecute("SELECT address, last_connected, last_attempted, last_height, last_misbehaved FROM Peers")) {
+		try (ResultSet resultSet = this.repository.checkedExecute(sql)) {
 			if (resultSet == null)
 				return peers;
 
@@ -33,20 +33,23 @@ public class HSQLDBNetworkRepository implements NetworkRepository {
 				String address = resultSet.getString(1);
 				PeerAddress peerAddress = PeerAddress.fromString(address);
 
-				Timestamp lastConnectedTimestamp = resultSet.getTimestamp(2, Calendar.getInstance(HSQLDBRepository.UTC));
+				Long lastConnected = HSQLDBRepository.getZonedTimestampMilli(resultSet, 2);
-				Long lastConnected = resultSet.wasNull() ? null : lastConnectedTimestamp.getTime();
 
-				Timestamp lastAttemptedTimestamp = resultSet.getTimestamp(3, Calendar.getInstance(HSQLDBRepository.UTC));
+				Long lastAttempted = HSQLDBRepository.getZonedTimestampMilli(resultSet, 3);
-				Long lastAttempted = resultSet.wasNull() ? null : lastAttemptedTimestamp.getTime();
 
 				Integer lastHeight = resultSet.getInt(4);
 				if (resultSet.wasNull())
 					lastHeight = null;
 
-				Timestamp lastMisbehavedTimestamp = resultSet.getTimestamp(5, Calendar.getInstance(HSQLDBRepository.UTC));
+				byte[] lastBlockSignature = resultSet.getBytes(5);
-				Long lastMisbehaved = resultSet.wasNull() ? null : lastMisbehavedTimestamp.getTime();
 
-				peers.add(new PeerData(peerAddress, lastAttempted, lastConnected, lastHeight, lastMisbehaved));
+				Long lastBlockTimestamp = HSQLDBRepository.getZonedTimestampMilli(resultSet, 6);
+
+				byte[] lastBlockGenerator = resultSet.getBytes(7);
+
+				Long lastMisbehaved = HSQLDBRepository.getZonedTimestampMilli(resultSet, 8);
+
+				peers.add(new PeerData(peerAddress, lastAttempted, lastConnected, lastHeight, lastBlockSignature, lastBlockTimestamp, lastBlockGenerator, lastMisbehaved));
 			} while (resultSet.next());
 
 			return peers;
@@ -61,12 +64,12 @@ public class HSQLDBNetworkRepository implements NetworkRepository {
 	public void save(PeerData peerData) throws DataException {
 		HSQLDBSaver saveHelper = new HSQLDBSaver("Peers");
 
-		Timestamp lastConnected = peerData.getLastConnected() == null ? null : new Timestamp(peerData.getLastConnected());
+		saveHelper.bind("address", peerData.getAddress().toString()).bind("last_connected", HSQLDBRepository.toOffsetDateTime(peerData.getLastConnected()))
-		Timestamp lastAttempted = peerData.getLastAttempted() == null ? null : new Timestamp(peerData.getLastAttempted());
+				.bind("last_attempted", HSQLDBRepository.toOffsetDateTime(peerData.getLastAttempted()))
-		Timestamp lastMisbehaved = peerData.getLastMisbehaved() == null ? null : new Timestamp(peerData.getLastMisbehaved());
+				.bind("last_height", peerData.getLastHeight()).bind("last_block_signature", peerData.getLastBlockSignature())
-
+				.bind("last_block_timestamp", HSQLDBRepository.toOffsetDateTime(peerData.getLastBlockTimestamp()))
-		saveHelper.bind("address", peerData.getAddress().toString()).bind("last_connected", lastConnected).bind("last_attempted", lastAttempted)
+				.bind("last_block_generator", peerData.getLastBlockGenerator())
-				.bind("last_height", peerData.getLastHeight()).bind("last_misbehaved", lastMisbehaved);
+				.bind("last_misbehaved", HSQLDBRepository.toOffsetDateTime(peerData.getLastMisbehaved()));
 
 		try {
 			saveHelper.execute(this.repository);
@@ -92,4 +95,5 @@ public class HSQLDBNetworkRepository implements NetworkRepository {
 			throw new DataException("Unable to delete peers from repository", e);
 		}
 	}
+
 }