From 2d29fdca00ccfa34fa3188b192d7a7d0a9403a4e Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 16 Sep 2022 11:19:10 +0100
Subject: [PATCH 01/50] Allow BTC trades in redeemAll / refundAll, since most
 will now be using ACCTv3.

---
 .../org/qortal/api/resource/CrossChainHtlcResource.java  | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java b/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java
index cf098f53..9f10f781 100644
--- a/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java
+++ b/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java
@@ -373,10 +373,6 @@ public class CrossChainHtlcResource {
 			// Use secret-A to redeem P2SH-A
 
 			Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
-			if (bitcoiny.getClass() == Bitcoin.class) {
-				LOGGER.info("Redeeming a Bitcoin HTLC is not yet supported");
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-			}
 
 			int lockTime = crossChainTradeData.lockTimeA;
 			byte[] redeemScriptA = BitcoinyHTLC.buildScript(crossChainTradeData.partnerForeignPKH, lockTime, crossChainTradeData.creatorForeignPKH, crossChainTradeData.hashOfSecretA);
@@ -599,11 +595,6 @@ public class CrossChainHtlcResource {
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 			Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
-			if (bitcoiny.getClass() == Bitcoin.class) {
-				LOGGER.info("Refunding a Bitcoin HTLC is not yet supported");
-				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
-			}
-
 			int lockTime = tradeBotData.getLockTimeA();
 
 			// We can't refund P2SH-A until lockTime-A has passed

From aff49e6bdf75d64b03bcc2200c921744c9c6eb6a Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 17 Sep 2022 10:30:10 +0100
Subject: [PATCH 02/50] Added support for ARRR refunds via
 /crosschain/htlc/refund/{ataddress} and /crosschain/htlc/refundAll

This could probably be refactored into multiple classes to make the code cleaner, but it is functional for now.
---
 .../api/resource/CrossChainHtlcResource.java  | 74 ++++++++++++++-----
 .../tradebot/PirateChainACCTv3TradeBot.java   |  8 +-
 .../org/qortal/crosschain/PirateChain.java    | 12 +++
 .../qortal/crosschain/PirateChainHTLC.java    | 10 +--
 .../test/crosschain/PirateChainTests.java     |  8 +-
 5 files changed, 75 insertions(+), 37 deletions(-)

diff --git a/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java b/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java
index 9f10f781..664b013a 100644
--- a/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java
+++ b/src/main/java/org/qortal/api/resource/CrossChainHtlcResource.java
@@ -1,5 +1,6 @@
 package org.qortal.api.resource;
 
+import com.google.common.hash.HashCode;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
@@ -538,11 +539,6 @@ public class CrossChainHtlcResource {
 				try {
 					// Determine foreign blockchain receive address for refund
 					Bitcoiny bitcoiny = (Bitcoiny) acct.getBlockchain();
-					if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
-						LOGGER.info("Skipping AT {} because ARRR is currently unsupported", atAddress);
-						continue;
-					}
-
 					String receivingAddress = bitcoiny.getUnusedReceiveAddress(tradeBotData.getForeignKey());
 
 					LOGGER.info("Attempting to refund P2SH balance associated with AT {}...", atAddress);
@@ -585,7 +581,7 @@ public class CrossChainHtlcResource {
 			// If the AT is "finished" then it will have a zero balance
 			// In these cases we should avoid HTLC refunds if tbe QORT haven't been returned to the seller
 			if (atData.getIsFinished() && crossChainTradeData.mode != AcctMode.REFUNDED && crossChainTradeData.mode != AcctMode.CANCELLED) {
-				LOGGER.info(String.format("Skipping AT %s because the QORT has already been redemed", atAddress));
+				LOGGER.info(String.format("Skipping AT %s because the QORT has already been redeemed by the buyer", atAddress));
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 			}
 
@@ -606,15 +602,26 @@ public class CrossChainHtlcResource {
 			if (medianBlockTime <= lockTime)
 				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.FOREIGN_BLOCKCHAIN_TOO_SOON);
 
-			byte[] redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
-			String p2shAddressA = bitcoiny.deriveP2shAddress(redeemScriptA);
-			LOGGER.info(String.format("Refunding P2SH address: %s", p2shAddressA));
-
 			// Fee for redeem/refund is subtracted from P2SH-A balance.
 			long feeTimestamp = calcFeeTimestamp(lockTime, crossChainTradeData.tradeTimeout);
 			long p2shFee = bitcoiny.getP2shFee(feeTimestamp);
 			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
-			BitcoinyHTLC.Status htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+
+			// Create redeem script based on destination chain
+			byte[] redeemScriptA;
+			String p2shAddressA;
+			BitcoinyHTLC.Status htlcStatusA;
+			if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
+				redeemScriptA = PirateChainHTLC.buildScript(tradeBotData.getTradeForeignPublicKey(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+				p2shAddressA = PirateChain.getInstance().deriveP2shAddressBPrefix(redeemScriptA);
+				htlcStatusA = PirateChainHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+			}
+			else {
+				redeemScriptA = BitcoinyHTLC.buildScript(tradeBotData.getTradeForeignPublicKeyHash(), lockTime, crossChainTradeData.creatorForeignPKH, tradeBotData.getHashOfSecret());
+				p2shAddressA = bitcoiny.deriveP2shAddress(redeemScriptA);
+				htlcStatusA = BitcoinyHTLC.determineHtlcStatus(bitcoiny.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+			}
+			LOGGER.info(String.format("Refunding P2SH address: %s", p2shAddressA));
 
 			switch (htlcStatusA) {
 				case UNFUNDED:
@@ -631,18 +638,45 @@ public class CrossChainHtlcResource {
 
 				case FUNDED:{
 					Coin refundAmount = Coin.valueOf(crossChainTradeData.expectedForeignAmount);
-					ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
-					List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddressA);
 
-					// Validate the destination foreign blockchain address
-					Address receiving = Address.fromString(bitcoiny.getNetworkParameters(), receiveAddress);
-					if (receiving.getOutputScriptType() != Script.ScriptType.P2PKH)
-						throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+					if (Objects.equals(bitcoiny.getCurrencyCode(), "ARRR")) {
+						// Pirate Chain custom integration
 
-					Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(bitcoiny.getNetworkParameters(), refundAmount, refundKey,
-							fundingOutputs, redeemScriptA, lockTime, receiving.getHash());
+						PirateChain pirateChain = PirateChain.getInstance();
+						String p2shAddressT3 = pirateChain.deriveP2shAddress(redeemScriptA);
+
+						// Get funding txid
+						String fundingTxidHex = PirateChainHTLC.getUnspentFundingTxid(pirateChain.getBlockchainProvider(), p2shAddressA, minimumAmountA);
+						if (fundingTxidHex == null) {
+							throw new ForeignBlockchainException("Missing funding txid when refunding P2SH");
+						}
+						String fundingTxid58 = Base58.encode(HashCode.fromString(fundingTxidHex).asBytes());
+
+						byte[] privateKey = tradeBotData.getTradePrivateKey();
+						String privateKey58 = Base58.encode(privateKey);
+						String redeemScript58 = Base58.encode(redeemScriptA);
+
+						String txid = PirateChain.getInstance().refundP2sh(p2shAddressT3,
+								receiveAddress, refundAmount.value, redeemScript58, fundingTxid58, lockTime, privateKey58);
+						LOGGER.info("Refund txid: {}", txid);
+					}
+					else {
+						// ElectrumX coins
+
+						ECKey refundKey = ECKey.fromPrivate(tradeBotData.getTradePrivateKey());
+						List<TransactionOutput> fundingOutputs = bitcoiny.getUnspentOutputs(p2shAddressA);
+
+						// Validate the destination foreign blockchain address
+						Address receiving = Address.fromString(bitcoiny.getNetworkParameters(), receiveAddress);
+						if (receiving.getOutputScriptType() != Script.ScriptType.P2PKH)
+							throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
+
+						Transaction p2shRefundTransaction = BitcoinyHTLC.buildRefundTransaction(bitcoiny.getNetworkParameters(), refundAmount, refundKey,
+								fundingOutputs, redeemScriptA, lockTime, receiving.getHash());
+
+						bitcoiny.broadcastTransaction(p2shRefundTransaction);
+					}
 
-					bitcoiny.broadcastTransaction(p2shRefundTransaction);
 					return true;
 				}
 			}
diff --git a/src/main/java/org/qortal/controller/tradebot/PirateChainACCTv3TradeBot.java b/src/main/java/org/qortal/controller/tradebot/PirateChainACCTv3TradeBot.java
index 8f413093..9834df20 100644
--- a/src/main/java/org/qortal/controller/tradebot/PirateChainACCTv3TradeBot.java
+++ b/src/main/java/org/qortal/controller/tradebot/PirateChainACCTv3TradeBot.java
@@ -523,7 +523,7 @@ public class PirateChainACCTv3TradeBot implements AcctTradeBot {
 			long p2shFee = PirateChain.getInstance().getP2shFee(feeTimestamp);
 			final long minimumAmountA = tradeBotData.getForeignAmount() + p2shFee;
 
-			PirateChainHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
+			BitcoinyHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
 
 			switch (htlcStatusA) {
 				case UNFUNDED:
@@ -613,7 +613,7 @@ public class PirateChainACCTv3TradeBot implements AcctTradeBot {
 			long p2shFee = PirateChain.getInstance().getP2shFee(feeTimestamp);
 			long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
 
-			PirateChainHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
+			BitcoinyHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
 
 			switch (htlcStatusA) {
 				case UNFUNDED:
@@ -751,7 +751,7 @@ public class PirateChainACCTv3TradeBot implements AcctTradeBot {
 		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
 		String receivingAddress = Bech32.encode("zs", receivingAccountInfo);
 
-		PirateChainHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
+		BitcoinyHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
 
 		switch (htlcStatusA) {
 			case UNFUNDED:
@@ -822,7 +822,7 @@ public class PirateChainACCTv3TradeBot implements AcctTradeBot {
 		long feeTimestamp = calcFeeTimestamp(lockTimeA, crossChainTradeData.tradeTimeout);
 		long p2shFee = PirateChain.getInstance().getP2shFee(feeTimestamp);
 		long minimumAmountA = crossChainTradeData.expectedForeignAmount + p2shFee;
-		PirateChainHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
+		BitcoinyHTLC.Status htlcStatusA = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmountA);
 
 		switch (htlcStatusA) {
 			case UNFUNDED:
diff --git a/src/main/java/org/qortal/crosschain/PirateChain.java b/src/main/java/org/qortal/crosschain/PirateChain.java
index 97aa07fe..09b37481 100644
--- a/src/main/java/org/qortal/crosschain/PirateChain.java
+++ b/src/main/java/org/qortal/crosschain/PirateChain.java
@@ -4,6 +4,12 @@ import cash.z.wallet.sdk.rpc.CompactFormats;
 import com.google.common.hash.HashCode;
 import com.rust.litewalletjni.LiteWalletJni;
 import org.bitcoinj.core.*;
+import org.bitcoinj.crypto.ChildNumber;
+import org.bitcoinj.crypto.DeterministicKey;
+import org.bitcoinj.script.Script;
+import org.bitcoinj.script.ScriptBuilder;
+import org.bitcoinj.wallet.DeterministicKeyChain;
+import org.bitcoinj.wallet.Wallet;
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -352,6 +358,12 @@ public class PirateChain extends Bitcoiny {
 		}
 	}
 
+	public String getUnusedReceiveAddress(String key58) throws ForeignBlockchainException {
+		// For now, return the main wallet address
+		// FUTURE: generate an unused one
+		return this.getWalletAddress(key58);
+	}
+
 	public String sendCoins(PirateChainSendRequest pirateChainSendRequest) throws ForeignBlockchainException {
 		PirateChainWalletController walletController = PirateChainWalletController.getInstance();
 		walletController.initWithEntropy58(pirateChainSendRequest.entropy58);
diff --git a/src/main/java/org/qortal/crosschain/PirateChainHTLC.java b/src/main/java/org/qortal/crosschain/PirateChainHTLC.java
index f28897dc..17f7ad74 100644
--- a/src/main/java/org/qortal/crosschain/PirateChainHTLC.java
+++ b/src/main/java/org/qortal/crosschain/PirateChainHTLC.java
@@ -3,25 +3,17 @@ package org.qortal.crosschain;
 import com.google.common.hash.HashCode;
 import com.google.common.primitives.Bytes;
 import org.bitcoinj.core.*;
-import org.bitcoinj.core.Transaction.SigHash;
-import org.bitcoinj.crypto.TransactionSignature;
 import org.bitcoinj.script.Script;
-import org.bitcoinj.script.ScriptBuilder;
 import org.bitcoinj.script.ScriptChunk;
-import org.bitcoinj.script.ScriptOpCodes;
 import org.qortal.crypto.Crypto;
 import org.qortal.utils.Base58;
 import org.qortal.utils.BitTwiddling;
 
 import java.util.*;
-import java.util.function.Function;
+import static org.qortal.crosschain.BitcoinyHTLC.Status;
 
 public class PirateChainHTLC {
 
-	public enum Status {
-		UNFUNDED, FUNDING_IN_PROGRESS, FUNDED, REDEEM_IN_PROGRESS, REDEEMED, REFUND_IN_PROGRESS, REFUNDED
-	}
-
 	public static final int SECRET_LENGTH = 32;
 	public static final int MIN_LOCKTIME = 1500000000;
 
diff --git a/src/test/java/org/qortal/test/crosschain/PirateChainTests.java b/src/test/java/org/qortal/test/crosschain/PirateChainTests.java
index d203cf5e..9502e45a 100644
--- a/src/test/java/org/qortal/test/crosschain/PirateChainTests.java
+++ b/src/test/java/org/qortal/test/crosschain/PirateChainTests.java
@@ -20,7 +20,7 @@ import java.util.Arrays;
 import java.util.List;
 
 import static org.junit.Assert.*;
-import static org.qortal.crosschain.PirateChainHTLC.Status.*;
+import static org.qortal.crosschain.BitcoinyHTLC.Status.*;
 
 public class PirateChainTests extends Common {
 
@@ -121,7 +121,7 @@ public class PirateChainTests extends Common {
 		String p2shAddress = "ba6Q5HWrWtmfU2WZqQbrFdRYsafA45cUAt";
 		long p2shFee = 10000;
 		final long minimumAmount = 10000 + p2shFee;
-		PirateChainHTLC.Status htlcStatus = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
+		BitcoinyHTLC.Status htlcStatus = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
 		assertEquals(FUNDED, htlcStatus);
 	}
 
@@ -130,7 +130,7 @@ public class PirateChainTests extends Common {
 		String p2shAddress = "bYZrzSSgGp8aEGvihukoMGU8sXYrx19Wka";
 		long p2shFee = 10000;
 		final long minimumAmount = 10000 + p2shFee;
-		PirateChainHTLC.Status htlcStatus = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
+		BitcoinyHTLC.Status htlcStatus = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
 		assertEquals(REDEEMED, htlcStatus);
 	}
 
@@ -139,7 +139,7 @@ public class PirateChainTests extends Common {
 		String p2shAddress = "bE49izfVxz8odhu8c2BcUaVFUnt7NLFRgv";
 		long p2shFee = 10000;
 		final long minimumAmount = 10000 + p2shFee;
-		PirateChainHTLC.Status htlcStatus = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
+		BitcoinyHTLC.Status htlcStatus = PirateChainHTLC.determineHtlcStatus(pirateChain.getBlockchainProvider(), p2shAddress, minimumAmount);
 		assertEquals(REFUNDED, htlcStatus);
 	}
 

From 791a9b78ec7abd3765202e46c2a694b5bdf9e123 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 17 Sep 2022 10:36:25 +0100
Subject: [PATCH 03/50] Added support for Pirate Chain wallets on FreeBSD.

---
 .../org/qortal/controller/PirateChainWalletController.java    | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/qortal/controller/PirateChainWalletController.java b/src/main/java/org/qortal/controller/PirateChainWalletController.java
index 931850db..1eac4b3a 100644
--- a/src/main/java/org/qortal/controller/PirateChainWalletController.java
+++ b/src/main/java/org/qortal/controller/PirateChainWalletController.java
@@ -238,10 +238,10 @@ public class PirateChainWalletController extends Thread {
         if (osName.equals("Mac OS X") && osArchitecture.equals("x86_64")) {
             return "librust-macos-x86_64.dylib";
         }
-        else if (osName.equals("Linux") && osArchitecture.equals("aarch64")) {
+        else if ((osName.equals("Linux") || osName.equals("FreeBSD")) && osArchitecture.equals("aarch64")) {
             return "librust-linux-aarch64.so";
         }
-        else if (osName.equals("Linux") && osArchitecture.equals("amd64")) {
+        else if ((osName.equals("Linux") || osName.equals("FreeBSD")) && osArchitecture.equals("amd64")) {
             return "librust-linux-x86_64.so";
         }
         else if (osName.contains("Windows") && osArchitecture.equals("amd64")) {

From 858269f6cb79275a2a19a7993a0480b3d64f5481 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 17 Sep 2022 12:21:56 +0100
Subject: [PATCH 04/50] ChatTransaction MAX_DATA_SIZE increased from 256 to
 1024 bytes, to allow for new UI features.

---
 src/main/java/org/qortal/transaction/ChatTransaction.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/transaction/ChatTransaction.java b/src/main/java/org/qortal/transaction/ChatTransaction.java
index 2671c209..9cccd42a 100644
--- a/src/main/java/org/qortal/transaction/ChatTransaction.java
+++ b/src/main/java/org/qortal/transaction/ChatTransaction.java
@@ -26,7 +26,7 @@ public class ChatTransaction extends Transaction {
 	private ChatTransactionData chatTransactionData;
 
 	// Other useful constants
-	public static final int MAX_DATA_SIZE = 256;
+	public static final int MAX_DATA_SIZE = 1024;
 	public static final int POW_BUFFER_SIZE = 8 * 1024 * 1024; // bytes
 	public static final int POW_DIFFICULTY_WITH_QORT = 8; // leading zero bits
 	public static final int POW_DIFFICULTY_NO_QORT = 12; // leading zero bits

From 02ac6dd8c1dd8a3429d6a9fd715a63fd0818444f Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 17 Sep 2022 13:28:32 +0100
Subject: [PATCH 05/50] Added GET /chat/message/{signature} endpoint.

This will ease the transition to a Q-Chat protocol, where chat messages will no longer be regular transactions.
---
 .../org/qortal/api/resource/ChatResource.java | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/main/java/org/qortal/api/resource/ChatResource.java b/src/main/java/org/qortal/api/resource/ChatResource.java
index be8bd7d7..79e479b1 100644
--- a/src/main/java/org/qortal/api/resource/ChatResource.java
+++ b/src/main/java/org/qortal/api/resource/ChatResource.java
@@ -99,6 +99,38 @@ public class ChatResource {
 		}
 	}
 
+	@GET
+	@Path("/message/{signature}")
+	@Operation(
+			summary = "Find chat message by signature",
+			responses = {
+					@ApiResponse(
+							description = "CHAT message",
+							content = @Content(
+										schema = @Schema(
+												implementation = ChatMessage.class
+										)
+							)
+					)
+			}
+	)
+	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.REPOSITORY_ISSUE})
+	public ChatMessage getMessageBySignature(@QueryParam("signature") String signature58) {
+		byte[] signature = Base58.decode(signature58);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			ChatTransactionData chatTransactionData = (ChatTransactionData) repository.getTransactionRepository().fromSignature(signature);
+			if (chatTransactionData == null) {
+				throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Message not found");
+			}
+
+			return repository.getChatRepository().toChatMessage(chatTransactionData);
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 	@GET
 	@Path("/active/{address}")
 	@Operation(

From 5017072f6c00c91c50825ae4dc1e8a0c48f1d308 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 17 Sep 2022 13:50:04 +0100
Subject: [PATCH 06/50] Use path parameter instead of query string.

---
 src/main/java/org/qortal/api/resource/ChatResource.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/api/resource/ChatResource.java b/src/main/java/org/qortal/api/resource/ChatResource.java
index 79e479b1..0bbd1951 100644
--- a/src/main/java/org/qortal/api/resource/ChatResource.java
+++ b/src/main/java/org/qortal/api/resource/ChatResource.java
@@ -115,7 +115,7 @@ public class ChatResource {
 			}
 	)
 	@ApiErrors({ApiError.INVALID_CRITERIA, ApiError.INVALID_ADDRESS, ApiError.REPOSITORY_ISSUE})
-	public ChatMessage getMessageBySignature(@QueryParam("signature") String signature58) {
+	public ChatMessage getMessageBySignature(@PathParam("signature") String signature58) {
 		byte[] signature = Base58.decode(signature58);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {

From 64ef8ab8633a584c4a57108274091961a391a7fe Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 19 Sep 2022 16:36:39 +0100
Subject: [PATCH 07/50] OnlineAccountsV3Message.MIN_PEER_VERSION set to 3.6.0

---
 .../org/qortal/network/message/OnlineAccountsV3Message.java     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/network/message/OnlineAccountsV3Message.java b/src/main/java/org/qortal/network/message/OnlineAccountsV3Message.java
index 0c5f6730..d554d96c 100644
--- a/src/main/java/org/qortal/network/message/OnlineAccountsV3Message.java
+++ b/src/main/java/org/qortal/network/message/OnlineAccountsV3Message.java
@@ -20,7 +20,7 @@ import java.util.Map;
  */
 public class OnlineAccountsV3Message extends Message {
 
-	public static final long MIN_PEER_VERSION = 0x300050001L; // 3.5.1
+	public static final long MIN_PEER_VERSION = 0x300060000L; // 3.6.0
 
 	private List<OnlineAccountData> onlineAccounts;
 

From 952c51ab2526e21ef15bfd97c9029b94afe76408 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 19 Sep 2022 17:27:07 +0100
Subject: [PATCH 08/50] QORA / block reward adjustments set to activate at
 height 1010000

---
 src/main/resources/blockchain.json | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/resources/blockchain.json b/src/main/resources/blockchain.json
index 8d1600ed..fad81ab5 100644
--- a/src/main/resources/blockchain.json
+++ b/src/main/resources/blockchain.json
@@ -56,7 +56,7 @@
 	],
 	"qoraHoldersShareByHeight": [
 		{ "height": 1, "share": 0.20 },
-		{ "height": 9999999, "share": 0.01 }
+		{ "height": 1010000, "share": 0.01 }
 	],
 	"qoraPerQortReward": 250,
 	"minAccountsToActivateShareBin": 30,
@@ -75,7 +75,7 @@
 		"atFindNextTransactionFix": 275000,
 		"newBlockSigHeight": 320000,
 		"shareBinFix": 399000,
-		"sharesByLevelV2Height": 9999999,
+		"sharesByLevelV2Height": 1010000,
 		"rewardShareLimitTimestamp": 1657382400000,
 		"calcChainWeightTimestamp": 1620579600000,
 		"transactionV5Timestamp": 1642176000000,

From b99b1f5d5766b25f995590d40643980b2006e05e Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 19 Sep 2022 17:29:26 +0100
Subject: [PATCH 09/50] Bump version to 3.6.0

---
 pom.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pom.xml b/pom.xml
index 22017136..e045e0f4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.5.0</version>
+	<version>3.6.0</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>

From 84d42b93e15ae478672e7fe81602f7ba542bd08e Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Tue, 20 Sep 2022 08:50:37 +0100
Subject: [PATCH 10/50] Reordered code in Block.mint() to fix potential issue
 after mempow activates.

---
 src/main/java/org/qortal/block/Block.java | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/main/java/org/qortal/block/Block.java b/src/main/java/org/qortal/block/Block.java
index e0581e7d..bdae83c2 100644
--- a/src/main/java/org/qortal/block/Block.java
+++ b/src/main/java/org/qortal/block/Block.java
@@ -368,16 +368,17 @@ public class Block {
 
 		// Fetch our list of online accounts
 		List<OnlineAccountData> onlineAccounts = OnlineAccountsManager.getInstance().getOnlineAccounts(onlineAccountsTimestamp);
-		if (onlineAccounts.isEmpty()) {
-			LOGGER.error("No online accounts - not even our own?");
-			return null;
-		}
 
 		// If mempow is active, remove any legacy accounts that are missing a nonce
 		if (timestamp >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
 			onlineAccounts.removeIf(a -> a.getNonce() == null || a.getNonce() < 0);
 		}
 
+		if (onlineAccounts.isEmpty()) {
+			LOGGER.error("No online accounts - not even our own?");
+			return null;
+		}
+
 		// Load sorted list of reward share public keys into memory, so that the indexes can be obtained.
 		// This is up to 100x faster than querying each index separately. For 4150 reward share keys, it
 		// was taking around 5000ms to query individually, vs 50ms using this approach.

From 951c85faf1b743cf5de9da21bb819c71b17449b4 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Tue, 20 Sep 2022 22:26:30 +0100
Subject: [PATCH 11/50] Fixed bug causing error 500 in some cases.

---
 .../org/qortal/data/arbitrary/ArbitraryResourceMetadata.java | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/data/arbitrary/ArbitraryResourceMetadata.java b/src/main/java/org/qortal/data/arbitrary/ArbitraryResourceMetadata.java
index 75b5a4d8..e2bcaf56 100644
--- a/src/main/java/org/qortal/data/arbitrary/ArbitraryResourceMetadata.java
+++ b/src/main/java/org/qortal/data/arbitrary/ArbitraryResourceMetadata.java
@@ -24,7 +24,10 @@ public class ArbitraryResourceMetadata {
         this.description = description;
         this.tags = tags;
         this.category = category;
-        this.categoryName = category.getName();
+
+        if (category != null) {
+            this.categoryName = category.getName();
+        }
     }
 
     public static ArbitraryResourceMetadata fromTransactionMetadata(ArbitraryDataTransactionMetadata transactionMetadata) {

From 49d83650f4c202a64b1883a0240cba6884002a00 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 23 Sep 2022 15:25:44 +0100
Subject: [PATCH 12/50] Removed online accounts V2 and V1 messaging, as the V3
 format will soon be required due to the nonce values.

---
 .../org/qortal/controller/Controller.java     |  11 +-
 .../controller/OnlineAccountsManager.java     | 157 +-----------------
 2 files changed, 6 insertions(+), 162 deletions(-)

diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index 4ff08e15..f6711991 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -1232,19 +1232,10 @@ public class Controller extends Thread {
 				break;
 
 			case GET_ONLINE_ACCOUNTS:
-				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsMessage(peer, message);
-				break;
-
 			case ONLINE_ACCOUNTS:
-				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsMessage(peer, message);
-				break;
-
 			case GET_ONLINE_ACCOUNTS_V2:
-				OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsV2Message(peer, message);
-				break;
-
 			case ONLINE_ACCOUNTS_V2:
-				OnlineAccountsManager.getInstance().onNetworkOnlineAccountsV2Message(peer, message);
+				// No longer supported - to be eventually removed
 				break;
 
 			case GET_ONLINE_ACCOUNTS_V3:
diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 254d6168..b4bfab12 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -55,12 +55,8 @@ public class OnlineAccountsManager {
 
     private static final long ONLINE_ACCOUNTS_QUEUE_INTERVAL = 100L; //ms
     private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
-    private static final long ONLINE_ACCOUNTS_LEGACY_BROADCAST_INTERVAL = 60 * 1000L; // ms
     private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 5 * 1000L; // ms
 
-    private static final long ONLINE_ACCOUNTS_V2_PEER_VERSION = 0x0300020000L; // v3.2.0
-    private static final long ONLINE_ACCOUNTS_V3_PEER_VERSION = 0x0300040000L; // v3.4.0
-
     // MemoryPoW
     public final int POW_BUFFER_SIZE = 1 * 1024 * 1024; // bytes
     public int POW_DIFFICULTY = 18; // leading zero bits
@@ -125,9 +121,7 @@ public class OnlineAccountsManager {
         // Send our online accounts
         executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
 
-        // Request online accounts from peers (legacy)
-        executor.scheduleAtFixedRate(this::requestLegacyRemoteOnlineAccounts, ONLINE_ACCOUNTS_LEGACY_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_LEGACY_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
-        // Request online accounts from peers (V3+)
+        // Request online accounts from peers
         executor.scheduleAtFixedRate(this::requestRemoteOnlineAccounts, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
 
         // Process import queue
@@ -399,30 +393,7 @@ public class OnlineAccountsManager {
     }
 
     /**
-     * Request data from other peers. (Pre-V3)
-     */
-    private void requestLegacyRemoteOnlineAccounts() {
-        final Long now = NTP.getTime();
-        if (now == null)
-            return;
-
-        // Don't bother if we're not up to date
-        if (!Controller.getInstance().isUpToDate())
-            return;
-
-        List<OnlineAccountData> mergedOnlineAccounts = Set.copyOf(this.currentOnlineAccounts.values()).stream().flatMap(Set::stream).collect(Collectors.toList());
-
-        Message messageV2 = new GetOnlineAccountsV2Message(mergedOnlineAccounts);
-
-        Network.getInstance().broadcast(peer ->
-                peer.getPeersVersion() < ONLINE_ACCOUNTS_V3_PEER_VERSION
-                        ? messageV2
-                        : null
-        );
-    }
-
-    /**
-     * Request data from other peers. V3+
+     * Request data from other peers
      */
     private void requestRemoteOnlineAccounts() {
         final Long now = NTP.getTime();
@@ -435,11 +406,7 @@ public class OnlineAccountsManager {
 
         Message messageV3 = new GetOnlineAccountsV3Message(currentOnlineAccountsHashes);
 
-        Network.getInstance().broadcast(peer ->
-                peer.getPeersVersion() >= ONLINE_ACCOUNTS_V3_PEER_VERSION
-                        ? messageV3
-                        : null
-        );
+        Network.getInstance().broadcast(peer -> messageV3);
     }
 
     /**
@@ -579,17 +546,7 @@ public class OnlineAccountsManager {
         if (!hasInfoChanged)
             return false;
 
-        Message messageV1 = new OnlineAccountsMessage(ourOnlineAccounts);
-        Message messageV2 = new OnlineAccountsV2Message(ourOnlineAccounts);
-        Message messageV3 = new OnlineAccountsV3Message(ourOnlineAccounts);
-
-        Network.getInstance().broadcast(peer ->
-                peer.getPeersVersion() >= OnlineAccountsV3Message.MIN_PEER_VERSION
-                        ? messageV3
-                        : peer.getPeersVersion() >= ONLINE_ACCOUNTS_V2_PEER_VERSION
-                        ? messageV2
-                        : messageV1
-        );
+        Network.getInstance().broadcast(peer -> new OnlineAccountsV3Message(ourOnlineAccounts));
 
         LOGGER.debug("Broadcasted {} online account{} with timestamp {}", ourOnlineAccounts.size(), (ourOnlineAccounts.size() != 1 ? "s" : ""), onlineAccountsTimestamp);
 
@@ -767,106 +724,6 @@ public class OnlineAccountsManager {
 
     // Network handlers
 
-    public void onNetworkGetOnlineAccountsMessage(Peer peer, Message message) {
-        GetOnlineAccountsMessage getOnlineAccountsMessage = (GetOnlineAccountsMessage) message;
-
-        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
-
-        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
-        List<OnlineAccountData> accountsToSend = Set.copyOf(this.currentOnlineAccounts.values()).stream().flatMap(Set::stream).collect(Collectors.toList());
-        int prefilterSize = accountsToSend.size();
-
-        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
-        while (iterator.hasNext()) {
-            OnlineAccountData onlineAccountData = iterator.next();
-
-            for (OnlineAccountData excludeAccountData : excludeAccounts) {
-                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
-                    iterator.remove();
-                    break;
-                }
-            }
-        }
-
-        if (accountsToSend.isEmpty())
-            return;
-
-        Message onlineAccountsMessage = new OnlineAccountsMessage(accountsToSend);
-        peer.sendMessage(onlineAccountsMessage);
-
-        LOGGER.debug("Sent {} of our {} online accounts to {}", accountsToSend.size(), prefilterSize, peer);
-    }
-
-    public void onNetworkOnlineAccountsMessage(Peer peer, Message message) {
-        OnlineAccountsMessage onlineAccountsMessage = (OnlineAccountsMessage) message;
-
-        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-        LOGGER.debug("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
-
-        int importCount = 0;
-
-        // Add any online accounts to the queue that aren't already present
-        for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
-            boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
-
-            if (isNewEntry)
-                importCount++;
-        }
-
-        if (importCount > 0)
-            LOGGER.debug("Added {} online accounts to queue", importCount);
-    }
-
-    public void onNetworkGetOnlineAccountsV2Message(Peer peer, Message message) {
-        GetOnlineAccountsV2Message getOnlineAccountsMessage = (GetOnlineAccountsV2Message) message;
-
-        List<OnlineAccountData> excludeAccounts = getOnlineAccountsMessage.getOnlineAccounts();
-
-        // Send online accounts info, excluding entries with matching timestamp & public key from excludeAccounts
-        List<OnlineAccountData> accountsToSend = Set.copyOf(this.currentOnlineAccounts.values()).stream().flatMap(Set::stream).collect(Collectors.toList());
-        int prefilterSize = accountsToSend.size();
-
-        Iterator<OnlineAccountData> iterator = accountsToSend.iterator();
-        while (iterator.hasNext()) {
-            OnlineAccountData onlineAccountData = iterator.next();
-
-            for (OnlineAccountData excludeAccountData : excludeAccounts) {
-                if (onlineAccountData.getTimestamp() == excludeAccountData.getTimestamp() && Arrays.equals(onlineAccountData.getPublicKey(), excludeAccountData.getPublicKey())) {
-                    iterator.remove();
-                    break;
-                }
-            }
-        }
-
-        if (accountsToSend.isEmpty())
-            return;
-
-        Message onlineAccountsMessage = new OnlineAccountsV2Message(accountsToSend);
-        peer.sendMessage(onlineAccountsMessage);
-
-        LOGGER.debug("Sent {} of our {} online accounts to {}", accountsToSend.size(), prefilterSize, peer);
-    }
-
-    public void onNetworkOnlineAccountsV2Message(Peer peer, Message message) {
-        OnlineAccountsV2Message onlineAccountsMessage = (OnlineAccountsV2Message) message;
-
-        List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-        LOGGER.debug("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
-
-        int importCount = 0;
-
-        // Add any online accounts to the queue that aren't already present
-        for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
-            boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
-
-            if (isNewEntry)
-                importCount++;
-        }
-
-        if (importCount > 0)
-            LOGGER.debug("Added {} online accounts to queue", importCount);
-    }
-
     public void onNetworkGetOnlineAccountsV3Message(Peer peer, Message message) {
         GetOnlineAccountsV3Message getOnlineAccountsMessage = (GetOnlineAccountsV3Message) message;
 
@@ -920,11 +777,7 @@ public class OnlineAccountsManager {
             }
         }
 
-        peer.sendMessage(
-                peer.getPeersVersion() >= OnlineAccountsV3Message.MIN_PEER_VERSION ?
-                        new OnlineAccountsV3Message(outgoingOnlineAccounts) :
-                        new OnlineAccountsV2Message(outgoingOnlineAccounts)
-        );
+        peer.sendMessage(new OnlineAccountsV3Message(outgoingOnlineAccounts));
 
         LOGGER.debug("Sent {} online accounts to {}", outgoingOnlineAccounts.size(), peer);
     }

From 84a16157d1e7407718b4439d9e1e1afdc629f108 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 23 Sep 2022 18:02:46 +0100
Subject: [PATCH 13/50] Don't add online accounts to the import queue if they
 are already validated

---
 .../java/org/qortal/controller/OnlineAccountsManager.java   | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index b4bfab12..eaf12db3 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -792,6 +792,12 @@ public class OnlineAccountsManager {
 
         // Add any online accounts to the queue that aren't already present
         for (OnlineAccountData onlineAccountData : peersOnlineAccounts) {
+
+            Set<OnlineAccountData> onlineAccounts = this.currentOnlineAccounts.computeIfAbsent(onlineAccountData.getTimestamp(), k -> ConcurrentHashMap.newKeySet());
+            if (onlineAccounts.contains(onlineAccountData))
+                // We have already validated this online account
+                continue;
+
             boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
 
             if (isNewEntry)

From 99858f378100ee8dea6103f1aed6d15219f730d7 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 23 Sep 2022 18:28:41 +0100
Subject: [PATCH 14/50] Wait 30 seconds after the node starts before computing
 our online accounts.

This allows some time for initial online account lists to be retrieved, and reduces the chances of the same nonce being computed twice.
---
 .../controller/OnlineAccountsManager.java       | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index eaf12db3..39ce8a85 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -57,6 +57,8 @@ public class OnlineAccountsManager {
     private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
     private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 5 * 1000L; // ms
 
+    private static final long INITIAL_SLEEP_INTERVAL = 30 * 1000L;
+
     // MemoryPoW
     public final int POW_BUFFER_SIZE = 1 * 1024 * 1024; // bytes
     public int POW_DIFFICULTY = 18; // leading zero bits
@@ -118,14 +120,23 @@ public class OnlineAccountsManager {
         // Expire old online accounts signatures
         executor.scheduleAtFixedRate(this::expireOldOnlineAccounts, ONLINE_ACCOUNTS_TASKS_INTERVAL, ONLINE_ACCOUNTS_TASKS_INTERVAL, TimeUnit.MILLISECONDS);
 
-        // Send our online accounts
-        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
-
         // Request online accounts from peers
         executor.scheduleAtFixedRate(this::requestRemoteOnlineAccounts, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
 
         // Process import queue
         executor.scheduleWithFixedDelay(this::processOnlineAccountsImportQueue, ONLINE_ACCOUNTS_QUEUE_INTERVAL, ONLINE_ACCOUNTS_QUEUE_INTERVAL, TimeUnit.MILLISECONDS);
+
+        // Sleep for some time before scheduling sendOurOnlineAccountsInfo()
+        // This allows some time for initial online account lists to be retrieved, and
+        // reduces the chances of the same nonce being computed twice
+        try {
+            Thread.sleep(INITIAL_SLEEP_INTERVAL);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        // Send our online accounts
+        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
     }
 
     public void shutdown() {

From 6d9e6e8d4c89582ffad23c1094b6a8e3aee91116 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 23 Sep 2022 18:46:01 +0100
Subject: [PATCH 15/50] Allow duplicate variations of each OnlineAccountData in
 the import queue, but don't allow two entries that match exactly.

---
 .../controller/OnlineAccountsManager.java     | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 39ce8a85..f770bc3a 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -66,7 +66,7 @@ public class OnlineAccountsManager {
     private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(4, new NamedThreadFactory("OnlineAccounts"));
     private volatile boolean isStopping = false;
 
-    private final Set<OnlineAccountData> onlineAccountsImportQueue = ConcurrentHashMap.newKeySet();
+    private final List<OnlineAccountData> onlineAccountsImportQueue = Collections.synchronizedList(new ArrayList<>());
 
     /**
      * Cache of 'current' online accounts, keyed by timestamp
@@ -184,9 +184,12 @@ public class OnlineAccountsManager {
 
         LOGGER.debug("Processing online accounts import queue (size: {})", this.onlineAccountsImportQueue.size());
 
+        // Take a copy of onlineAccountsImportQueue so we can safely remove whilst iterating
+        List<OnlineAccountData> onlineAccountsImportQueueCopy = new ArrayList<>(this.onlineAccountsImportQueue);
+
         Set<OnlineAccountData> onlineAccountsToAdd = new HashSet<>();
         try (final Repository repository = RepositoryManager.getRepository()) {
-            for (OnlineAccountData onlineAccountData : this.onlineAccountsImportQueue) {
+            for (OnlineAccountData onlineAccountData : onlineAccountsImportQueueCopy) {
                 if (isStopping)
                     return;
 
@@ -207,6 +210,19 @@ public class OnlineAccountsManager {
         }
     }
 
+    private boolean importQueueContainsExactMatch(OnlineAccountData acc) {
+        // Check if an item exists where all properties match exactly
+        // This is needed because signature and nonce are not compared in OnlineAccountData.equals()
+        synchronized (onlineAccountsImportQueue) {
+            return onlineAccountsImportQueue.stream().anyMatch(otherAcc ->
+                    acc.getTimestamp() == otherAcc.getTimestamp() &&
+                            Arrays.equals(acc.getPublicKey(), otherAcc.getPublicKey()) &&
+                            acc.getNonce() == otherAcc.getNonce() &&
+                            Arrays.equals(acc.getSignature(), otherAcc.getSignature())
+            );
+        }
+    }
+
     /**
      * Check if supplied onlineAccountData is superior (i.e. has a nonce value) than existing record.
      * Two entries are considered equal even if the nonce differs, to prevent multiple variations
@@ -809,6 +825,10 @@ public class OnlineAccountsManager {
                 // We have already validated this online account
                 continue;
 
+            if (this.importQueueContainsExactMatch(onlineAccountData))
+                // Identical online account data already present in queue
+                continue;
+
             boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
 
             if (isNewEntry)

From ea4f4d949bdefac88736207b84b16a4d2229412d Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 23 Sep 2022 19:45:59 +0100
Subject: [PATCH 16/50] When validating online accounts, enforce mempow if the
 online account's timestamp is after the feature trigger.

---
 .../java/org/qortal/controller/OnlineAccountsManager.java | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index f770bc3a..4d1ab561 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -325,8 +325,9 @@ public class OnlineAccountsManager {
             return false;
         }
 
-        // Validate mempow if feature trigger is active
-        if (now >= BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp()) {
+        // Validate mempow if feature trigger is active (or if online account's timestamp is past the trigger timestamp)
+        long memoryPoWStartTimestamp = BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp();
+        if (now >= memoryPoWStartTimestamp || onlineAccountTimestamp >= memoryPoWStartTimestamp) {
             if (!getInstance().verifyMemoryPoW(onlineAccountData, now)) {
                 LOGGER.trace(() -> String.format("Rejecting online reward-share for account %s due to invalid PoW nonce", mintingAccount.getAddress()));
                 return false;
@@ -628,7 +629,8 @@ public class OnlineAccountsManager {
     }
 
     public boolean verifyMemoryPoW(OnlineAccountData onlineAccountData, Long timestamp) {
-        if (!isMemoryPoWActive(timestamp)) {
+        long memoryPoWStartTimestamp = BlockChain.getInstance().getOnlineAccountsMemoryPoWTimestamp();
+        if (timestamp < memoryPoWStartTimestamp && onlineAccountData.getTimestamp() < memoryPoWStartTimestamp) {
             // Not active yet, so treat it as valid
             return true;
         }

From c7cf33ef7838bf96777af0e3fab77e67c4e6cf1c Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 10:23:55 +0100
Subject: [PATCH 17/50] Set hasOurOnlineAccounts to true if one of our accounts
 is found before signing.

---
 src/main/java/org/qortal/controller/OnlineAccountsManager.java | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 4d1ab561..32d0a47a 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -517,6 +517,8 @@ public class OnlineAccountsManager {
             Set<OnlineAccountData> onlineAccounts = this.currentOnlineAccounts.computeIfAbsent(onlineAccountsTimestamp, k -> ConcurrentHashMap.newKeySet());
             boolean alreadyExists = onlineAccounts.stream().anyMatch(a -> Arrays.equals(a.getPublicKey(), publicKey));
             if (alreadyExists) {
+                this.hasOurOnlineAccounts = true;
+
                 if (remaining > 0) {
                     // Move on to next account
                     continue;

From 174a779e4cd9bc692ef1ef8ecc03edb20206cc04 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 10:56:52 +0100
Subject: [PATCH 18/50] Add accounts from the import queue individually, and
 then skip future duplicates before unnecessarily validating them again.

This closes a gap where accounts would be moved from onlineAccountsImportQueue to onlineAccountsToAdd, but not yet imported. During this time, there was nothing to stop them from being added to the import queue again, causing duplicate validations.
---
 .../controller/OnlineAccountsManager.java       | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 32d0a47a..de8cfb12 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -193,9 +193,17 @@ public class OnlineAccountsManager {
                 if (isStopping)
                     return;
 
+                // Skip this account if it's already validated
+                Set<OnlineAccountData> onlineAccounts = this.currentOnlineAccounts.computeIfAbsent(onlineAccountData.getTimestamp(), k -> ConcurrentHashMap.newKeySet());
+                if (onlineAccounts.contains(onlineAccountData)) {
+                    // We have already validated this online account
+                    onlineAccountsImportQueue.remove(onlineAccountData);
+                    continue;
+                }
+
                 boolean isValid = this.isValidCurrentAccount(repository, onlineAccountData);
                 if (isValid)
-                    onlineAccountsToAdd.add(onlineAccountData);
+                    addAccounts(Arrays.asList(onlineAccountData));
 
                 // Remove from queue
                 onlineAccountsImportQueue.remove(onlineAccountData);
@@ -203,11 +211,6 @@ public class OnlineAccountsManager {
         } catch (DataException e) {
             LOGGER.error("Repository issue while verifying online accounts", e);
         }
-
-        if (!onlineAccountsToAdd.isEmpty()) {
-            LOGGER.debug("Merging {} validated online accounts from import queue", onlineAccountsToAdd.size());
-            addAccounts(onlineAccountsToAdd);
-        }
     }
 
     private boolean importQueueContainsExactMatch(OnlineAccountData acc) {
@@ -381,7 +384,7 @@ public class OnlineAccountsManager {
             }
         }
 
-        LOGGER.debug(String.format("we have online accounts for timestamps: %s", String.join(", ", this.currentOnlineAccounts.keySet().stream().map(l -> Long.toString(l)).collect(Collectors.joining(", ")))));
+        LOGGER.trace(String.format("we have online accounts for timestamps: %s", String.join(", ", this.currentOnlineAccounts.keySet().stream().map(l -> Long.toString(l)).collect(Collectors.joining(", ")))));
 
         return true;
     }

From 5b81b30974b4fba01bbf796e45d2bb4bbdd7b185 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 13:02:27 +0100
Subject: [PATCH 19/50] Modified online accounts request interval, and
 introduced bursting.

It will now request online accounts every 1 minute instead of every 5 seconds, except for the first 5 minutes following a new online accounts timestamp, in which it will request every 5 seconds (referred to as the "burst" interval). It will also use the burst interval for the first 5 minutes after the node starts.

This is based on the idea that most online accounts arrive soon after a new timestamp begins, and so there is no need to request accounts so frequently after that. This should reduce data usage by a significant amount.

Once mempow is fully rolled out, the "burst" feature can be reduced or removed, since online accounts will be sent ahead of time, generally 15-30 mins prior to the new online accounts timestamp becoming active.
---
 .../org/qortal/controller/Controller.java     |  4 +++
 .../controller/OnlineAccountsManager.java     | 31 ++++++++++++++++---
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index f6711991..8e1dfd8a 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -317,6 +317,10 @@ public class Controller extends Thread {
 		}
 	}
 
+	public static long uptime() {
+		return System.currentTimeMillis() - Controller.startTime;
+	}
+
 	/** Returns highest block, or null if it's not available. */
 	public BlockData getChainTip() {
 		synchronized (this.latestBlocks) {
diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index de8cfb12..a0f4db68 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -55,7 +55,12 @@ public class OnlineAccountsManager {
 
     private static final long ONLINE_ACCOUNTS_QUEUE_INTERVAL = 100L; //ms
     private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
-    private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 5 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_COMPUTE_INTERVAL = 5 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 60 * 1000L; // ms
+    // After switching to a new online timestamp, we "burst" the online accounts requests
+    // at an increased interval for a specified amount of time
+    private static final long ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL = 5 * 1000L; // ms
+    private static final long ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH = 5 * 60 * 1000L; // ms
 
     private static final long INITIAL_SLEEP_INTERVAL = 30 * 1000L;
 
@@ -83,6 +88,8 @@ public class OnlineAccountsManager {
      */
     private final SortedMap<Long, Set<OnlineAccountData>> latestBlocksOnlineAccounts = new ConcurrentSkipListMap<>();
 
+    private long lastOnlineAccountsRequest = 0;
+
     private boolean hasOurOnlineAccounts = false;
 
     public static long getOnlineTimestampModulus() {
@@ -121,7 +128,7 @@ public class OnlineAccountsManager {
         executor.scheduleAtFixedRate(this::expireOldOnlineAccounts, ONLINE_ACCOUNTS_TASKS_INTERVAL, ONLINE_ACCOUNTS_TASKS_INTERVAL, TimeUnit.MILLISECONDS);
 
         // Request online accounts from peers
-        executor.scheduleAtFixedRate(this::requestRemoteOnlineAccounts, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
+        executor.scheduleAtFixedRate(this::requestRemoteOnlineAccounts, ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL, TimeUnit.MILLISECONDS);
 
         // Process import queue
         executor.scheduleWithFixedDelay(this::processOnlineAccountsImportQueue, ONLINE_ACCOUNTS_QUEUE_INTERVAL, ONLINE_ACCOUNTS_QUEUE_INTERVAL, TimeUnit.MILLISECONDS);
@@ -136,7 +143,7 @@ public class OnlineAccountsManager {
         }
 
         // Send our online accounts
-        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, ONLINE_ACCOUNTS_BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
+        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, TimeUnit.MILLISECONDS);
     }
 
     public void shutdown() {
@@ -435,8 +442,24 @@ public class OnlineAccountsManager {
         if (!Controller.getInstance().isUpToDate())
             return;
 
-        Message messageV3 = new GetOnlineAccountsV3Message(currentOnlineAccountsHashes);
+        long onlineAccountsTimestamp = getCurrentOnlineAccountTimestamp();
+        if (now - onlineAccountsTimestamp >= ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH) {
+            // New online timestamp started more than 5 mins ago - we probably don't need to request so frequently
 
+            if (Controller.uptime() < ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH) {
+                // The node recently started up, so we should request at the burst interval
+                // This could allow accounts to move around the network more easily when an auto update is occurring
+            }
+            else if (now - lastOnlineAccountsRequest < ONLINE_ACCOUNTS_BROADCAST_INTERVAL) {
+                // We already requested online accounts in the last minute, so no need to request again
+                return;
+            }
+        }
+
+        LOGGER.info("Requesting online accounts via broadcast...");
+
+        lastOnlineAccountsRequest = now;
+        Message messageV3 = new GetOnlineAccountsV3Message(currentOnlineAccountsHashes);
         Network.getInstance().broadcast(peer -> messageV3);
     }
 

From 863a5eff9735671f24f72a03fafc9fb41886bd88 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 13:11:28 +0100
Subject: [PATCH 20/50] Moved various online accounts logs to TRACE level, to
 make it easier to monitor the queue processing when in DEBUG.

---
 .../org/qortal/controller/OnlineAccountsManager.java | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index a0f4db68..40192876 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -365,7 +365,7 @@ public class OnlineAccountsManager {
         for (var entry : hashesToRebuild.entrySet()) {
             Long timestamp = entry.getKey();
 
-            LOGGER.debug(() -> String.format("Rehashing for timestamp %d and leading bytes %s",
+            LOGGER.trace(() -> String.format("Rehashing for timestamp %d and leading bytes %s",
                             timestamp,
                             entry.getValue().stream().sorted(Byte::compareUnsigned).map(leadingByte -> String.format("%02x", leadingByte)).collect(Collectors.joining(", "))
                     )
@@ -456,7 +456,7 @@ public class OnlineAccountsManager {
             }
         }
 
-        LOGGER.info("Requesting online accounts via broadcast...");
+        LOGGER.debug("Requesting online accounts via broadcast...");
 
         lastOnlineAccountsRequest = now;
         Message messageV3 = new GetOnlineAccountsV3Message(currentOnlineAccountsHashes);
@@ -801,7 +801,7 @@ public class OnlineAccountsManager {
                 Set<OnlineAccountData> timestampsOnlineAccounts = this.currentOnlineAccounts.getOrDefault(timestamp, Collections.emptySet());
                 outgoingOnlineAccounts.addAll(timestampsOnlineAccounts);
 
-                LOGGER.debug(() -> String.format("Going to send all %d online accounts for timestamp %d", timestampsOnlineAccounts.size(), timestamp));
+                LOGGER.trace(() -> String.format("Going to send all %d online accounts for timestamp %d", timestampsOnlineAccounts.size(), timestamp));
             } else {
                 // Quick cache of which leading bytes to send so we only have to filter once
                 Set<Byte> outgoingLeadingBytes = new HashSet<>();
@@ -825,7 +825,7 @@ public class OnlineAccountsManager {
                         .forEach(outgoingOnlineAccounts::add);
 
                 if (outgoingOnlineAccounts.size() > beforeAddSize)
-                    LOGGER.debug(String.format("Going to send %d online accounts for timestamp %d and leading bytes %s",
+                    LOGGER.trace(String.format("Going to send %d online accounts for timestamp %d and leading bytes %s",
                             outgoingOnlineAccounts.size() - beforeAddSize,
                             timestamp,
                             outgoingLeadingBytes.stream().sorted(Byte::compareUnsigned).map(leadingByte -> String.format("%02x", leadingByte)).collect(Collectors.joining(", "))
@@ -836,14 +836,14 @@ public class OnlineAccountsManager {
 
         peer.sendMessage(new OnlineAccountsV3Message(outgoingOnlineAccounts));
 
-        LOGGER.debug("Sent {} online accounts to {}", outgoingOnlineAccounts.size(), peer);
+        LOGGER.trace("Sent {} online accounts to {}", outgoingOnlineAccounts.size(), peer);
     }
 
     public void onNetworkOnlineAccountsV3Message(Peer peer, Message message) {
         OnlineAccountsV3Message onlineAccountsMessage = (OnlineAccountsV3Message) message;
 
         List<OnlineAccountData> peersOnlineAccounts = onlineAccountsMessage.getOnlineAccounts();
-        LOGGER.debug("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
+        LOGGER.trace("Received {} online accounts from {}", peersOnlineAccounts.size(), peer);
 
         int importCount = 0;
 

From 94cdc10151669c92b7daedbce43e47c5212a01d8 Mon Sep 17 00:00:00 2001
From: catbref <misc-github@talk2dom.com>
Date: Tue, 31 May 2022 21:06:34 +0100
Subject: [PATCH 21/50] Initial work on BLOCK_SUMMARIES_V2, part of a bigger
 arc to improve synchronization.

Touches quite a few files because:

* Deprecate HEIGHT_V2 because it doesn't contain enough info to be fully useful during sync.
Newer peers will re-use BLOCK_SUMMARIES_V2.

* For newer peers, instead of sending / broadcasting HEIGHT_V2,
send top N block summaries instead, to avoid requests for minor reorgs.

* When responding to GET_BLOCK, and we don't actually have the requested block,
we currently send an empty BLOCK_SUMMARIES message instead of not responding,
which would cause a slow timeout in Synchronizer.

This pattern has spread to other network message response code,
so now we introduce a generic 'unknown' message type for all these cases.

* Remove PeerChainTipData class entirely and re-use BlockSummaryData instead.

* Each Peer instance used to hold PeerChainTipData - essentially single latest block summary - but now holds a List of latest block summaries.

* PeerChainTipData getter/setter methods modified for compatibility at this point in time.

* Repository methods that return BlockSummaryData (or lists of) now try to fully populate them,
including newly added block reference field.

* Re-worked Peer.canUseCommonBlockData() to be more readable

* Cherry-picked patch to Message.fromByteBuffer() to pass an empty, read-only ByteBuffer to subclass fromByteBuffer() methods, instead of null.
This allows natural use of BufferUnderflowException if a subclass tries to use read(), or hasRemaining(), etc. from an empty data-payload message.
Previously this could have caused an NPE.
---
 .../org/qortal/api/model/ConnectedPeer.java   |  10 +-
 .../org/qortal/controller/BlockMinter.java    |  16 +--
 .../org/qortal/controller/Controller.java     | 102 +++++++++++------
 .../org/qortal/controller/Synchronizer.java   |  44 ++++----
 .../arbitrary/ArbitraryDataFileManager.java   |   7 +-
 .../qortal/data/block/BlockSummaryData.java   |  24 +++-
 .../qortal/data/block/CommonBlockData.java    |   8 +-
 .../qortal/data/network/PeerChainTipData.java |  37 -------
 src/main/java/org/qortal/network/Network.java |  62 +++++++++--
 src/main/java/org/qortal/network/Peer.java    |  66 ++++++-----
 .../message/BlockSummariesV2Message.java      | 104 ++++++++++++++++++
 .../message/GenericUnknownMessage.java        |  23 ++++
 .../qortal/network/message/MessageType.java   |   2 +
 .../hsqldb/HSQLDBBlockArchiveRepository.java  |   8 +-
 .../hsqldb/HSQLDBBlockRepository.java         |  13 ++-
 15 files changed, 367 insertions(+), 159 deletions(-)
 delete mode 100644 src/main/java/org/qortal/data/network/PeerChainTipData.java
 create mode 100644 src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
 create mode 100644 src/main/java/org/qortal/network/message/GenericUnknownMessage.java

diff --git a/src/main/java/org/qortal/api/model/ConnectedPeer.java b/src/main/java/org/qortal/api/model/ConnectedPeer.java
index 21bfc1f9..3d383321 100644
--- a/src/main/java/org/qortal/api/model/ConnectedPeer.java
+++ b/src/main/java/org/qortal/api/model/ConnectedPeer.java
@@ -1,7 +1,7 @@
 package org.qortal.api.model;
 
 import io.swagger.v3.oas.annotations.media.Schema;
-import org.qortal.data.network.PeerChainTipData;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.Handshake;
 import org.qortal.network.Peer;
@@ -63,11 +63,11 @@ public class ConnectedPeer {
             this.age = "connecting...";
         }
 
-        PeerChainTipData peerChainTipData = peer.getChainTipData();
+        BlockSummaryData peerChainTipData = peer.getChainTipData();
         if (peerChainTipData != null) {
-            this.lastHeight = peerChainTipData.getLastHeight();
-            this.lastBlockSignature = peerChainTipData.getLastBlockSignature();
-            this.lastBlockTimestamp = peerChainTipData.getLastBlockTimestamp();
+            this.lastHeight = peerChainTipData.getHeight();
+            this.lastBlockSignature = peerChainTipData.getSignature();
+            this.lastBlockTimestamp = peerChainTipData.getTimestamp();
         }
     }
 
diff --git a/src/main/java/org/qortal/controller/BlockMinter.java b/src/main/java/org/qortal/controller/BlockMinter.java
index 343ab4af..a07d37fe 100644
--- a/src/main/java/org/qortal/controller/BlockMinter.java
+++ b/src/main/java/org/qortal/controller/BlockMinter.java
@@ -26,6 +26,9 @@ import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
+import org.qortal.network.message.BlockSummariesV2Message;
+import org.qortal.network.message.HeightV2Message;
+import org.qortal.network.message.Message;
 import org.qortal.repository.BlockRepository;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
@@ -431,16 +434,9 @@ public class BlockMinter extends Thread {
 						blockchainLock.unlock();
 					}
 
-					if (newBlockMinted) {
-						// Broadcast our new chain to network
-						BlockData newBlockData = newBlock.getBlockData();
-
-						Network network = Network.getInstance();
-						network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newBlockData));
-					}
-				} catch (InterruptedException e) {
-					// We've been interrupted - time to exit
-					return;
+				if (newBlockMinted) {
+					// Broadcast our new chain to network
+					Network.getInstance().broadcastOurChain();
 				}
 			}
 		} catch (DataException e) {
diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index 8e1dfd8a..ce994757 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -45,7 +45,6 @@ import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.naming.NameData;
-import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.ChatTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -731,25 +730,25 @@ public class Controller extends Thread {
 
 	public static final Predicate<Peer> hasNoRecentBlock = peer -> {
 		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-		return peerChainTipData == null || peerChainTipData.getLastBlockTimestamp() == null || peerChainTipData.getLastBlockTimestamp() < minLatestBlockTimestamp;
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
+		return peerChainTipData == null || peerChainTipData.getTimestamp() == null || peerChainTipData.getTimestamp() < minLatestBlockTimestamp;
 	};
 
 	public static final Predicate<Peer> hasNoOrSameBlock = peer -> {
 		final BlockData latestBlockData = getInstance().getChainTip();
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || Arrays.equals(latestBlockData.getSignature(), peerChainTipData.getLastBlockSignature());
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
+		return peerChainTipData == null || peerChainTipData.getSignature() == null || Arrays.equals(latestBlockData.getSignature(), peerChainTipData.getSignature());
 	};
 
 	public static final Predicate<Peer> hasOnlyGenesisBlock = peer -> {
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
-		return peerChainTipData == null || peerChainTipData.getLastHeight() == null || peerChainTipData.getLastHeight() == 1;
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
+		return peerChainTipData == null || peerChainTipData.getHeight() == 1;
 	};
 
 	public static final Predicate<Peer> hasInferiorChainTip = peer -> {
-		final PeerChainTipData peerChainTipData = peer.getChainTipData();
+		final BlockSummaryData peerChainTipData = peer.getChainTipData();
 		final List<ByteArray> inferiorChainTips = Synchronizer.getInstance().inferiorChainSignatures;
-		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(ByteArray.wrap(peerChainTipData.getLastBlockSignature()));
+		return peerChainTipData == null || peerChainTipData.getSignature() == null || inferiorChainTips.contains(ByteArray.wrap(peerChainTipData.getSignature()));
 	};
 
 	public static final Predicate<Peer> hasOldVersion = peer -> {
@@ -1011,8 +1010,7 @@ public class Controller extends Thread {
 		network.broadcast(peer -> peer.isOutbound() ? network.buildPeersMessage(peer) : new GetPeersMessage());
 
 		// Send our current height
-		BlockData latestBlockData = getChainTip();
-		network.broadcast(peer -> network.buildHeightMessage(peer, latestBlockData));
+		network.broadcastOurChain();
 
 		// Request unconfirmed transaction signatures, but only if we're up-to-date.
 		// If we're NOT up-to-date then priority is synchronizing first
@@ -1219,6 +1217,10 @@ public class Controller extends Thread {
 				onNetworkHeightV2Message(peer, message);
 				break;
 
+			case BLOCK_SUMMARIES_V2:
+				onNetworkBlockSummariesV2Message(peer, message);
+				break;
+
 			case GET_TRANSACTION:
 				TransactionImporter.getInstance().onNetworkGetTransactionMessage(peer, message);
 				break;
@@ -1373,8 +1375,10 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer's synchronizer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'block unknown' response to peer %s for GET_BLOCK request for unknown block %s", peer, Base58.encode(signature)));
 
-				// We'll send empty block summaries message as it's very short
-				Message blockUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message blockUnknownMessage = peer.getPeersVersion() >= GenericUnknownMessage.MINIMUM_PEER_VERSION
+						? new GenericUnknownMessage()
+						: new BlockSummariesMessage(Collections.emptyList());
 				blockUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(blockUnknownMessage))
 					peer.disconnect("failed to send block-unknown response");
@@ -1423,11 +1427,15 @@ public class Controller extends Thread {
 		this.stats.getBlockSummariesStats.requests.incrementAndGet();
 
 		// If peer's parent signature matches our latest block signature
-		// then we can short-circuit with an empty response
+		// then we have no blocks after that and can short-circuit with an empty response
 		BlockData chainTip = getChainTip();
 		if (chainTip != null && Arrays.equals(parentSignature, chainTip.getSignature())) {
-			Message blockSummariesMessage = new BlockSummariesMessage(Collections.emptyList());
+			Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+					? new BlockSummariesV2Message(Collections.emptyList())
+					: new BlockSummariesMessage(Collections.emptyList());
+
 			blockSummariesMessage.setId(message.getId());
+
 			if (!peer.sendMessage(blockSummariesMessage))
 				peer.disconnect("failed to send block summaries");
 
@@ -1483,7 +1491,9 @@ public class Controller extends Thread {
 				this.stats.getBlockSummariesStats.fullyFromCache.incrementAndGet();
 		}
 
-		Message blockSummariesMessage = new BlockSummariesMessage(blockSummaries);
+		Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+				? new BlockSummariesV2Message(blockSummaries)
+				: new BlockSummariesMessage(blockSummaries);
 		blockSummariesMessage.setId(message.getId());
 		if (!peer.sendMessage(blockSummariesMessage))
 			peer.disconnect("failed to send block summaries");
@@ -1558,18 +1568,48 @@ public class Controller extends Thread {
 			// If peer is inbound and we've not updated their height
 			// then this is probably their initial HEIGHT_V2 message
 			// so they need a corresponding HEIGHT_V2 message from us
-			if (!peer.isOutbound() && (peer.getChainTipData() == null || peer.getChainTipData().getLastHeight() == null))
-				peer.sendMessage(Network.getInstance().buildHeightMessage(peer, getChainTip()));
+			if (!peer.isOutbound() && peer.getChainTipData() == null) {
+				Message responseMessage = Network.getInstance().buildHeightOrChainTipInfo(peer);
+
+				if (responseMessage == null || !peer.sendMessage(responseMessage)) {
+					peer.disconnect("failed to send our chain tip info");
+					return;
+				}
+			}
 		}
 
 		// Update peer chain tip data
-		PeerChainTipData newChainTipData = new PeerChainTipData(heightV2Message.getHeight(), heightV2Message.getSignature(), heightV2Message.getTimestamp(), heightV2Message.getMinterPublicKey());
+		BlockSummaryData newChainTipData = new BlockSummaryData(heightV2Message.getHeight(), heightV2Message.getSignature(), heightV2Message.getMinterPublicKey(), heightV2Message.getTimestamp());
 		peer.setChainTipData(newChainTipData);
 
 		// Potentially synchronize
 		Synchronizer.getInstance().requestSync();
 	}
 
+	private void onNetworkBlockSummariesV2Message(Peer peer, Message message) {
+		BlockSummariesV2Message blockSummariesV2Message = (BlockSummariesV2Message) message;
+
+		if (!Settings.getInstance().isLite()) {
+			// If peer is inbound and we've not updated their height
+			// then this is probably their initial BLOCK_SUMMARIES_V2 message
+			// so they need a corresponding BLOCK_SUMMARIES_V2 message from us
+			if (!peer.isOutbound() && peer.getChainTipData() == null) {
+				Message responseMessage = Network.getInstance().buildHeightOrChainTipInfo(peer);
+
+				if (responseMessage == null || !peer.sendMessage(responseMessage)) {
+					peer.disconnect("failed to send our chain tip info");
+					return;
+				}
+			}
+		}
+
+		// Update peer chain tip data
+		peer.setChainTipSummaries(blockSummariesV2Message.getBlockSummaries());
+
+		// Potentially synchronize
+		Synchronizer.getInstance().requestSync();
+	}
+
 	private void onNetworkGetAccountMessage(Peer peer, Message message) {
 		GetAccountMessage getAccountMessage = (GetAccountMessage) message;
 		String address = getAccountMessage.getAddress();
@@ -1585,8 +1625,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT request for unknown account %s", peer, address));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1621,8 +1661,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_BALANCE request for unknown account %s and asset ID %d", peer, address, assetId));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1665,8 +1705,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_TRANSACTIONS request for unknown account %s", peer, address));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1702,8 +1742,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'account unknown' response to peer %s for GET_ACCOUNT_NAMES request for unknown account %s", peer, address));
 
-				// We'll send empty block summaries message as it's very short
-				Message accountUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
 				accountUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(accountUnknownMessage))
 					peer.disconnect("failed to send account-unknown response");
@@ -1737,8 +1777,8 @@ public class Controller extends Thread {
 				// Send valid, yet unexpected message type in response, so peer doesn't have to wait for timeout
 				LOGGER.debug(() -> String.format("Sending 'name unknown' response to peer %s for GET_NAME request for unknown name %s", peer, name));
 
-				// We'll send empty block summaries message as it's very short
-				Message nameUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+				// Send generic 'unknown' message as it's very short
+				Message nameUnknownMessage = new GenericUnknownMessage();
 				nameUnknownMessage.setId(message.getId());
 				if (!peer.sendMessage(nameUnknownMessage))
 					peer.disconnect("failed to send name-unknown response");
@@ -1786,14 +1826,14 @@ public class Controller extends Thread {
 				continue;
 			}
 
-			final PeerChainTipData peerChainTipData = peer.getChainTipData();
+			BlockSummaryData peerChainTipData = peer.getChainTipData();
 			if (peerChainTipData == null) {
 				iterator.remove();
 				continue;
 			}
 
 			// Disregard peers that don't have a recent block
-			if (peerChainTipData.getLastBlockTimestamp() == null || peerChainTipData.getLastBlockTimestamp() < minLatestBlockTimestamp) {
+			if (peerChainTipData.getTimestamp() == null || peerChainTipData.getTimestamp() < minLatestBlockTimestamp) {
 				iterator.remove();
 				continue;
 			}
diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index 74a4a785..a6fbfe71 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -19,7 +19,6 @@ import org.qortal.block.BlockChain;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.block.CommonBlockData;
-import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.transaction.RewardShareTransactionData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.event.Event;
@@ -282,7 +281,7 @@ public class Synchronizer extends Thread {
 		BlockData priorChainTip = Controller.getInstance().getChainTip();
 
 		synchronized (this.syncLock) {
-			this.syncPercent = (priorChainTip.getHeight() * 100) / peer.getChainTipData().getLastHeight();
+			this.syncPercent = (priorChainTip.getHeight() * 100) / peer.getChainTipData().getHeight();
 
 			// Only update SysTray if we're potentially changing height
 			if (this.syncPercent < 100) {
@@ -312,7 +311,7 @@ public class Synchronizer extends Thread {
 
 				case INFERIOR_CHAIN: {
 					// Update our list of inferior chain tips
-					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getLastBlockSignature());
+					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getSignature());
 					if (!inferiorChainSignatures.contains(inferiorChainSignature))
 						inferiorChainSignatures.add(inferiorChainSignature);
 
@@ -320,7 +319,8 @@ public class Synchronizer extends Thread {
 					LOGGER.debug(() -> String.format("Refused to synchronize with peer %s (%s)", peer, syncResult.name()));
 
 					// Notify peer of our superior chain
-					if (!peer.sendMessage(Network.getInstance().buildHeightMessage(peer, priorChainTip)))
+					Message message = Network.getInstance().buildHeightOrChainTipInfo(peer);
+					if (message == null || !peer.sendMessage(message))
 						peer.disconnect("failed to notify peer of our superior chain");
 					break;
 				}
@@ -341,7 +341,7 @@ public class Synchronizer extends Thread {
 					// fall-through...
 				case NOTHING_TO_DO: {
 					// Update our list of inferior chain tips
-					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getLastBlockSignature());
+					ByteArray inferiorChainSignature = ByteArray.wrap(peer.getChainTipData().getSignature());
 					if (!inferiorChainSignatures.contains(inferiorChainSignature))
 						inferiorChainSignatures.add(inferiorChainSignature);
 
@@ -369,8 +369,7 @@ public class Synchronizer extends Thread {
 				// Reset our cache of inferior chains
 				inferiorChainSignatures.clear();
 
-				Network network = Network.getInstance();
-				network.broadcast(broadcastPeer -> network.buildHeightMessage(broadcastPeer, newChainTip));
+				Network.getInstance().broadcastOurChain();
 
 				EventBus.INSTANCE.notify(new NewChainTipEvent(priorChainTip, newChainTip));
 			}
@@ -513,13 +512,13 @@ public class Synchronizer extends Thread {
 			final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 			final int ourInitialHeight = ourLatestBlockData.getHeight();
 
-			PeerChainTipData peerChainTipData = peer.getChainTipData();
-			int peerHeight = peerChainTipData.getLastHeight();
-			byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
+			BlockSummaryData peerChainTipData = peer.getChainTipData();
+			int peerHeight = peerChainTipData.getHeight();
+			byte[] peersLastBlockSignature = peerChainTipData.getSignature();
 
 			byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
 			LOGGER.debug(String.format("Fetching summaries from peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
-					peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
+					peerHeight, Base58.encode(peersLastBlockSignature), peerChainTipData.getTimestamp(),
 					ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
 
 			List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
@@ -637,9 +636,9 @@ public class Synchronizer extends Thread {
 							return peers;
 
 						// Count the number of blocks this peer has beyond our common block
-						final PeerChainTipData peerChainTipData = peer.getChainTipData();
-						final int peerHeight = peerChainTipData.getLastHeight();
-						final byte[] peerLastBlockSignature = peerChainTipData.getLastBlockSignature();
+						final BlockSummaryData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getHeight();
+						final byte[] peerLastBlockSignature = peerChainTipData.getSignature();
 						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 						// Limit the number of blocks we are comparing. FUTURE: we could request more in batches, but there may not be a case when this is needed
 						int summariesRequired = Math.min(peerAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
@@ -727,8 +726,9 @@ public class Synchronizer extends Thread {
 
 					LOGGER.debug(String.format("Listing peers with common block %.8s...", Base58.encode(commonBlockSummary.getSignature())));
 					for (Peer peer : peersSharingCommonBlock) {
-						final int peerHeight = peer.getChainTipData().getLastHeight();
-						final Long peerLastBlockTimestamp = peer.getChainTipData().getLastBlockTimestamp();
+						BlockSummaryData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getHeight();
+						final Long peerLastBlockTimestamp = peerChainTipData.getTimestamp();
 						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 						final CommonBlockData peerCommonBlockData = peer.getCommonBlockData();
 
@@ -825,7 +825,7 @@ public class Synchronizer extends Thread {
 		// Calculate the length of the shortest peer chain sharing this common block
 		int minChainLength = 0;
 		for (Peer peer : peersSharingCommonBlock) {
-			final int peerHeight = peer.getChainTipData().getLastHeight();
+			final int peerHeight = peer.getChainTipData().getHeight();
 			final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 
 			if (peerAdditionalBlocksAfterCommonBlock < minChainLength || minChainLength == 0)
@@ -933,13 +933,13 @@ public class Synchronizer extends Thread {
 					final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 					final int ourInitialHeight = ourLatestBlockData.getHeight();
 
-					PeerChainTipData peerChainTipData = peer.getChainTipData();
-					int peerHeight = peerChainTipData.getLastHeight();
-					byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
+					BlockSummaryData peerChainTipData = peer.getChainTipData();
+					int peerHeight = peerChainTipData.getHeight();
+					byte[] peersLastBlockSignature = peerChainTipData.getSignature();
 
 					byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
 					String syncString = String.format("Synchronizing with peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
-							peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
+							peerHeight, Base58.encode(peersLastBlockSignature), peerChainTipData.getTimestamp(),
 							ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp());
 					LOGGER.info(syncString);
 
@@ -1313,7 +1313,7 @@ public class Synchronizer extends Thread {
 			// Final check to make sure the peer isn't out of date (except for when we're in recovery mode)
 			if (!recoveryMode && peer.getChainTipData() != null) {
 				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
-				final Long peerLastBlockTimestamp = peer.getChainTipData().getLastBlockTimestamp();
+				final Long peerLastBlockTimestamp = peer.getChainTipData().getTimestamp();
 				if (peerLastBlockTimestamp == null || peerLastBlockTimestamp < minLatestBlockTimestamp) {
 					LOGGER.info(String.format("Peer %s is out of date, so abandoning sync attempt", peer));
 					return SynchronizationResult.CHAIN_TIP_TOO_OLD;
diff --git a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileManager.java b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileManager.java
index 22cf4144..30b0fcca 100644
--- a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileManager.java
+++ b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileManager.java
@@ -595,9 +595,10 @@ public class ArbitraryDataFileManager extends Thread {
                 // Send valid, yet unexpected message type in response, so peer's synchronizer doesn't have to wait for timeout
                 LOGGER.debug(String.format("Sending 'file unknown' response to peer %s for GET_FILE request for unknown file %s", peer, arbitraryDataFile));
 
-                // We'll send empty block summaries message as it's very short
-                // TODO: use a different message type here
-                Message fileUnknownMessage = new BlockSummariesMessage(Collections.emptyList());
+                // Send generic 'unknown' message as it's very short
+                Message fileUnknownMessage = peer.getPeersVersion() >= GenericUnknownMessage.MINIMUM_PEER_VERSION
+                        ? new GenericUnknownMessage()
+                        : new BlockSummariesMessage(Collections.emptyList());
                 fileUnknownMessage.setId(message.getId());
                 if (!peer.sendMessage(fileUnknownMessage)) {
                     LOGGER.debug("Couldn't sent file-unknown response");
diff --git a/src/main/java/org/qortal/data/block/BlockSummaryData.java b/src/main/java/org/qortal/data/block/BlockSummaryData.java
index 2167f0f0..57e29d0d 100644
--- a/src/main/java/org/qortal/data/block/BlockSummaryData.java
+++ b/src/main/java/org/qortal/data/block/BlockSummaryData.java
@@ -11,11 +11,12 @@ public class BlockSummaryData {
 	private int height;
 	private byte[] signature;
 	private byte[] minterPublicKey;
-	private int onlineAccountsCount;
 
 	// Optional, set during construction
+	private Integer onlineAccountsCount;
 	private Long timestamp;
 	private Integer transactionCount;
+	private byte[] reference;
 
 	// Optional, set after construction
 	private Integer minterLevel;
@@ -25,6 +26,15 @@ public class BlockSummaryData {
 	protected BlockSummaryData() {
 	}
 
+	/** Constructor typically populated with fields from HeightV2Message */
+	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, long timestamp) {
+		this.height = height;
+		this.signature = signature;
+		this.minterPublicKey = minterPublicKey;
+		this.timestamp = timestamp;
+	}
+
+	/** Constructor typically populated with fields from BlockSummariesMessage */
 	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, int onlineAccountsCount) {
 		this.height = height;
 		this.signature = signature;
@@ -32,13 +42,16 @@ public class BlockSummaryData {
 		this.onlineAccountsCount = onlineAccountsCount;
 	}
 
-	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, int onlineAccountsCount, long timestamp, int transactionCount) {
+	/** Constructor typically populated with fields from BlockSummariesV2Message */
+	public BlockSummaryData(int height, byte[] signature, byte[] minterPublicKey, Integer onlineAccountsCount,
+							Long timestamp, Integer transactionCount, byte[] reference) {
 		this.height = height;
 		this.signature = signature;
 		this.minterPublicKey = minterPublicKey;
 		this.onlineAccountsCount = onlineAccountsCount;
 		this.timestamp = timestamp;
 		this.transactionCount = transactionCount;
+		this.reference = reference;
 	}
 
 	public BlockSummaryData(BlockData blockData) {
@@ -49,6 +62,7 @@ public class BlockSummaryData {
 
 		this.timestamp = blockData.getTimestamp();
 		this.transactionCount = blockData.getTransactionCount();
+		this.reference = blockData.getReference();
 	}
 
 	// Getters / setters
@@ -65,7 +79,7 @@ public class BlockSummaryData {
 		return this.minterPublicKey;
 	}
 
-	public int getOnlineAccountsCount() {
+	public Integer getOnlineAccountsCount() {
 		return this.onlineAccountsCount;
 	}
 
@@ -77,6 +91,10 @@ public class BlockSummaryData {
 		return this.transactionCount;
 	}
 
+	public byte[] getReference() {
+		return this.reference;
+	}
+
 	public Integer getMinterLevel() {
 		return this.minterLevel;
 	}
diff --git a/src/main/java/org/qortal/data/block/CommonBlockData.java b/src/main/java/org/qortal/data/block/CommonBlockData.java
index dd502df7..37e9649b 100644
--- a/src/main/java/org/qortal/data/block/CommonBlockData.java
+++ b/src/main/java/org/qortal/data/block/CommonBlockData.java
@@ -1,7 +1,5 @@
 package org.qortal.data.block;
 
-import org.qortal.data.network.PeerChainTipData;
-
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import java.math.BigInteger;
@@ -14,14 +12,14 @@ public class CommonBlockData {
 	private BlockSummaryData commonBlockSummary = null;
 	private List<BlockSummaryData> blockSummariesAfterCommonBlock = null;
 	private BigInteger chainWeight = null;
-	private PeerChainTipData chainTipData = null;
+	private BlockSummaryData chainTipData = null;
 
 	// Constructors
 
 	protected CommonBlockData() {
 	}
 
-	public CommonBlockData(BlockSummaryData commonBlockSummary, PeerChainTipData chainTipData) {
+	public CommonBlockData(BlockSummaryData commonBlockSummary, BlockSummaryData chainTipData) {
 		this.commonBlockSummary = commonBlockSummary;
 		this.chainTipData = chainTipData;
 	}
@@ -49,7 +47,7 @@ public class CommonBlockData {
 		this.chainWeight = chainWeight;
 	}
 
-	public PeerChainTipData getChainTipData() {
+	public BlockSummaryData getChainTipData() {
 		return this.chainTipData;
 	}
 
diff --git a/src/main/java/org/qortal/data/network/PeerChainTipData.java b/src/main/java/org/qortal/data/network/PeerChainTipData.java
deleted file mode 100644
index d8dbbad4..00000000
--- a/src/main/java/org/qortal/data/network/PeerChainTipData.java
+++ /dev/null
@@ -1,37 +0,0 @@
-package org.qortal.data.network;
-
-public class PeerChainTipData {
-
-	/** Latest block height as reported by peer. */
-	private Integer lastHeight;
-	/** Latest block signature as reported by peer. */
-	private byte[] lastBlockSignature;
-	/** Latest block timestamp as reported by peer. */
-	private Long lastBlockTimestamp;
-	/** Latest block minter public key as reported by peer. */
-	private byte[] lastBlockMinter;
-
-	public PeerChainTipData(Integer lastHeight, byte[] lastBlockSignature, Long lastBlockTimestamp, byte[] lastBlockMinter) {
-		this.lastHeight = lastHeight;
-		this.lastBlockSignature = lastBlockSignature;
-		this.lastBlockTimestamp = lastBlockTimestamp;
-		this.lastBlockMinter = lastBlockMinter;
-	}
-
-	public Integer getLastHeight() {
-		return this.lastHeight;
-	}
-
-	public byte[] getLastBlockSignature() {
-		return this.lastBlockSignature;
-	}
-
-	public Long getLastBlockTimestamp() {
-		return this.lastBlockTimestamp;
-	}
-
-	public byte[] getLastBlockMinter() {
-		return this.lastBlockMinter;
-	}
-
-}
diff --git a/src/main/java/org/qortal/network/Network.java b/src/main/java/org/qortal/network/Network.java
index 57073e99..8aac68f0 100644
--- a/src/main/java/org/qortal/network/Network.java
+++ b/src/main/java/org/qortal/network/Network.java
@@ -11,6 +11,7 @@ import org.qortal.controller.arbitrary.ArbitraryDataFileListManager;
 import org.qortal.controller.arbitrary.ArbitraryDataManager;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.block.BlockData;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.network.PeerData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.network.message.*;
@@ -90,6 +91,8 @@ public class Network {
 
     private static final long DISCONNECTION_CHECK_INTERVAL = 10 * 1000L; // milliseconds
 
+    private static final int BROADCAST_CHAIN_TIP_DEPTH = 7; // Just enough to fill a SINGLE TCP packet (~1440 bytes)
+
     // Generate our node keys / ID
     private final Ed25519PrivateKeyParameters edPrivateKeyParams = new Ed25519PrivateKeyParameters(new SecureRandom());
     private final Ed25519PublicKeyParameters edPublicKeyParams = edPrivateKeyParams.generatePublicKey();
@@ -1087,10 +1090,16 @@ public class Network {
 
         if (peer.isOutbound()) {
             if (!Settings.getInstance().isLite()) {
-                // Send our height
-                Message heightMessage = buildHeightMessage(peer, Controller.getInstance().getChainTip());
-                if (!peer.sendMessage(heightMessage)) {
-                    peer.disconnect("failed to send height/info");
+                // Send our height / chain tip info
+                Message message = this.buildHeightOrChainTipInfo(peer);
+
+                if (message == null) {
+                    peer.disconnect("Couldn't build our chain tip info");
+                    return;
+                }
+
+                if (!peer.sendMessage(message)) {
+                    peer.disconnect("failed to send height / chain tip info");
                     return;
                 }
             }
@@ -1164,10 +1173,47 @@ public class Network {
         return new PeersV2Message(peerAddresses);
     }
 
-    public Message buildHeightMessage(Peer peer, BlockData blockData) {
-        // HEIGHT_V2 contains way more useful info
-        return new HeightV2Message(blockData.getHeight(), blockData.getSignature(),
-                blockData.getTimestamp(), blockData.getMinterPublicKey());
+    /** Builds either (legacy) HeightV2Message or (newer) BlockSummariesV2Message, depending on peer version.
+     *
+     *  @return Message, or null if DataException was thrown.
+     */
+    public Message buildHeightOrChainTipInfo(Peer peer) {
+        if (peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION) {
+            int latestHeight = Controller.getInstance().getChainHeight();
+
+            try (final Repository repository = RepositoryManager.getRepository()) {
+                List<BlockSummaryData> latestBlockSummaries = repository.getBlockRepository().getBlockSummaries(latestHeight - BROADCAST_CHAIN_TIP_DEPTH, latestHeight);
+                return new BlockSummariesV2Message(latestBlockSummaries);
+            } catch (DataException e) {
+                return null;
+            }
+        } else {
+            // For older peers
+            BlockData latestBlockData = Controller.getInstance().getChainTip();
+            return new HeightV2Message(latestBlockData.getHeight(), latestBlockData.getSignature(),
+                    latestBlockData.getTimestamp(), latestBlockData.getMinterPublicKey());
+        }
+    }
+
+    public void broadcastOurChain() {
+        BlockData latestBlockData = Controller.getInstance().getChainTip();
+        int latestHeight = latestBlockData.getHeight();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            List<BlockSummaryData> latestBlockSummaries = repository.getBlockRepository().getBlockSummaries(latestHeight - BROADCAST_CHAIN_TIP_DEPTH, latestHeight);
+            Message latestBlockSummariesMessage = new BlockSummariesV2Message(latestBlockSummaries);
+
+            // For older peers
+            Message heightMessage = new HeightV2Message(latestBlockData.getHeight(), latestBlockData.getSignature(),
+                    latestBlockData.getTimestamp(), latestBlockData.getMinterPublicKey());
+
+            Network.getInstance().broadcast(broadcastPeer -> broadcastPeer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+                    ? latestBlockSummariesMessage
+                    : heightMessage
+            );
+        } catch (DataException e) {
+            LOGGER.warn("Couldn't broadcast our chain tip info", e);
+        }
     }
 
     public Message buildNewTransactionMessage(Peer peer, TransactionData transactionData) {
diff --git a/src/main/java/org/qortal/network/Peer.java b/src/main/java/org/qortal/network/Peer.java
index cac0ccc9..a187d29b 100644
--- a/src/main/java/org/qortal/network/Peer.java
+++ b/src/main/java/org/qortal/network/Peer.java
@@ -6,8 +6,8 @@ import com.google.common.net.InetAddresses;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.controller.Controller;
+import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.block.CommonBlockData;
-import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.message.ChallengeMessage;
 import org.qortal.network.message.Message;
@@ -148,7 +148,7 @@ public class Peer {
     /**
      * Latest block info as reported by peer.
      */
-    private PeerChainTipData peersChainTipData;
+    private List<BlockSummaryData> peersChainTipData = Collections.emptyList();
 
     /**
      * Our common block with this peer
@@ -353,28 +353,34 @@ public class Peer {
         }
     }
 
-    public PeerChainTipData getChainTipData() {
-        synchronized (this.peerInfoLock) {
-            return this.peersChainTipData;
-        }
+    public BlockSummaryData getChainTipData() {
+        List<BlockSummaryData> chainTipSummaries = this.peersChainTipData;
+
+        if (chainTipSummaries.isEmpty())
+            return null;
+
+        // Return last entry, which should have greatest height
+        return chainTipSummaries.get(chainTipSummaries.size() - 1);
     }
 
-    public void setChainTipData(PeerChainTipData chainTipData) {
-        synchronized (this.peerInfoLock) {
-            this.peersChainTipData = chainTipData;
-        }
+    public void setChainTipData(BlockSummaryData chainTipData) {
+        this.peersChainTipData = Collections.singletonList(chainTipData);
+    }
+
+    public List<BlockSummaryData> getChainTipSummaries() {
+        return this.peersChainTipData;
+    }
+
+    public void setChainTipSummaries(List<BlockSummaryData> chainTipSummaries) {
+        this.peersChainTipData = List.copyOf(chainTipSummaries);
     }
 
     public CommonBlockData getCommonBlockData() {
-        synchronized (this.peerInfoLock) {
-            return this.commonBlockData;
-        }
+        return this.commonBlockData;
     }
 
     public void setCommonBlockData(CommonBlockData commonBlockData) {
-        synchronized (this.peerInfoLock) {
-            this.commonBlockData = commonBlockData;
-        }
+        this.commonBlockData = commonBlockData;
     }
 
     public boolean isSyncInProgress() {
@@ -904,20 +910,22 @@ public class Peer {
     // Common block data
 
     public boolean canUseCachedCommonBlockData() {
-        PeerChainTipData peerChainTipData = this.getChainTipData();
-        CommonBlockData commonBlockData = this.getCommonBlockData();
+        BlockSummaryData peerChainTipData = this.getChainTipData();
+        if (peerChainTipData == null || peerChainTipData.getSignature() == null)
+            return false;
 
-        if (peerChainTipData != null && commonBlockData != null) {
-            PeerChainTipData commonBlockChainTipData = commonBlockData.getChainTipData();
-            if (peerChainTipData.getLastBlockSignature() != null && commonBlockChainTipData != null
-                    && commonBlockChainTipData.getLastBlockSignature() != null) {
-                if (Arrays.equals(peerChainTipData.getLastBlockSignature(),
-                        commonBlockChainTipData.getLastBlockSignature())) {
-                    return true;
-                }
-            }
-        }
-        return false;
+        CommonBlockData commonBlockData = this.getCommonBlockData();
+        if (commonBlockData == null)
+            return false;
+
+        BlockSummaryData commonBlockChainTipData = commonBlockData.getChainTipData();
+        if (commonBlockChainTipData == null || commonBlockChainTipData.getSignature() == null)
+            return false;
+
+        if (!Arrays.equals(peerChainTipData.getSignature(), commonBlockChainTipData.getSignature()))
+            return false;
+
+        return true;
     }
 
 
diff --git a/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java b/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
new file mode 100644
index 00000000..96c661a4
--- /dev/null
+++ b/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
@@ -0,0 +1,104 @@
+package org.qortal.network.message;
+
+import com.google.common.primitives.Ints;
+import com.google.common.primitives.Longs;
+import org.qortal.data.block.BlockSummaryData;
+import org.qortal.transform.Transformer;
+import org.qortal.transform.block.BlockTransformer;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BlockSummariesV2Message extends Message {
+
+	public static final long MINIMUM_PEER_VERSION = 0x03000400cbL;
+
+	private static final int BLOCK_SUMMARY_V2_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH /* block signature */
+			+ Transformer.PUBLIC_KEY_LENGTH /* minter public key */
+			+ Transformer.INT_LENGTH /* online accounts count */
+			+ Transformer.LONG_LENGTH /* block timestamp */
+			+ Transformer.INT_LENGTH /* transactions count */
+			+ BlockTransformer.BLOCK_SIGNATURE_LENGTH; /* block reference */
+
+	private List<BlockSummaryData> blockSummaries;
+
+	public BlockSummariesV2Message(List<BlockSummaryData> blockSummaries) {
+		super(MessageType.BLOCK_SUMMARIES_V2);
+
+		// Shortcut for when there are no summaries
+		if (blockSummaries.isEmpty()) {
+			this.dataBytes = Message.EMPTY_DATA_BYTES;
+			return;
+		}
+
+		ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+		try {
+			// First summary's height
+			bytes.write(Ints.toByteArray(blockSummaries.get(0).getHeight()));
+
+			for (BlockSummaryData blockSummary : blockSummaries) {
+				bytes.write(blockSummary.getSignature());
+				bytes.write(blockSummary.getMinterPublicKey());
+				bytes.write(Ints.toByteArray(blockSummary.getOnlineAccountsCount()));
+				bytes.write(Longs.toByteArray(blockSummary.getTimestamp()));
+				bytes.write(Ints.toByteArray(blockSummary.getTransactionCount()));
+				bytes.write(blockSummary.getReference());
+			}
+		} catch (IOException e) {
+			throw new AssertionError("IOException shouldn't occur with ByteArrayOutputStream");
+		}
+
+		this.dataBytes = bytes.toByteArray();
+		this.checksumBytes = Message.generateChecksum(this.dataBytes);
+	}
+
+	private BlockSummariesV2Message(int id, List<BlockSummaryData> blockSummaries) {
+		super(id, MessageType.BLOCK_SUMMARIES_V2);
+
+		this.blockSummaries = blockSummaries;
+	}
+
+	public List<BlockSummaryData> getBlockSummaries() {
+		return this.blockSummaries;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		int height = bytes.getInt();
+
+		// Expecting bytes remaining to be exact multiples of BLOCK_SUMMARY_V2_LENGTH
+		if (bytes.remaining() % BLOCK_SUMMARY_V2_LENGTH != 0)
+			throw new BufferUnderflowException();
+
+		List<BlockSummaryData> blockSummaries = new ArrayList<>();
+		while (bytes.hasRemaining()) {
+			byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
+			bytes.get(signature);
+
+			byte[] minterPublicKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+			bytes.get(minterPublicKey);
+
+			int onlineAccountsCount = bytes.getInt();
+
+			long timestamp = bytes.getLong();
+
+			int transactionsCount = bytes.getInt();
+
+			byte[] reference = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
+			bytes.get(reference);
+
+			BlockSummaryData blockSummary = new BlockSummaryData(height, signature, minterPublicKey,
+					onlineAccountsCount, timestamp, transactionsCount, reference);
+			blockSummaries.add(blockSummary);
+
+			height++;
+		}
+
+		return new BlockSummariesV2Message(id, blockSummaries);
+	}
+
+}
diff --git a/src/main/java/org/qortal/network/message/GenericUnknownMessage.java b/src/main/java/org/qortal/network/message/GenericUnknownMessage.java
new file mode 100644
index 00000000..15faaa1b
--- /dev/null
+++ b/src/main/java/org/qortal/network/message/GenericUnknownMessage.java
@@ -0,0 +1,23 @@
+package org.qortal.network.message;
+
+import java.nio.ByteBuffer;
+
+public class GenericUnknownMessage extends Message {
+
+    public static final long MINIMUM_PEER_VERSION = 0x03000400cbL;
+
+    public GenericUnknownMessage() {
+        super(MessageType.GENERIC_UNKNOWN);
+
+        this.dataBytes = EMPTY_DATA_BYTES;
+    }
+
+    private GenericUnknownMessage(int id) {
+        super(id, MessageType.GENERIC_UNKNOWN);
+    }
+
+    public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+        return new GenericUnknownMessage(id);
+    }
+
+}
diff --git a/src/main/java/org/qortal/network/message/MessageType.java b/src/main/java/org/qortal/network/message/MessageType.java
index 087e7fbf..4dd4a3c8 100644
--- a/src/main/java/org/qortal/network/message/MessageType.java
+++ b/src/main/java/org/qortal/network/message/MessageType.java
@@ -21,6 +21,7 @@ public enum MessageType {
     HEIGHT_V2(10, HeightV2Message::fromByteBuffer),
     PING(11, PingMessage::fromByteBuffer),
     PONG(12, PongMessage::fromByteBuffer),
+    GENERIC_UNKNOWN(13, GenericUnknownMessage::fromByteBuffer),
 
     // Requesting data
     PEERS_V2(20, PeersV2Message::fromByteBuffer),
@@ -41,6 +42,7 @@ public enum MessageType {
 
     BLOCK_SUMMARIES(70, BlockSummariesMessage::fromByteBuffer),
     GET_BLOCK_SUMMARIES(71, GetBlockSummariesMessage::fromByteBuffer),
+    BLOCK_SUMMARIES_V2(72, BlockSummariesV2Message::fromByteBuffer),
 
     ONLINE_ACCOUNTS(80, OnlineAccountsMessage::fromByteBuffer),
     GET_ONLINE_ACCOUNTS(81, GetOnlineAccountsMessage::fromByteBuffer),
diff --git a/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockArchiveRepository.java b/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockArchiveRepository.java
index cc7e1611..c3c5638a 100644
--- a/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockArchiveRepository.java
+++ b/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockArchiveRepository.java
@@ -143,13 +143,17 @@ public class HSQLDBBlockArchiveRepository implements BlockArchiveRepository {
                 byte[] blockMinterPublicKey = resultSet.getBytes(3);
 
                 // Fetch additional info from the archive itself
-                int onlineAccountsCount = 0;
+                Integer onlineAccountsCount = null;
+                Long timestamp = null;
+                Integer transactionCount = null;
+                byte[] reference = null;
+
                 BlockData blockData = this.fromSignature(signature);
                 if (blockData != null) {
                     onlineAccountsCount = blockData.getOnlineAccountsCount();
                 }
 
-                BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount);
+                BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount, timestamp, transactionCount, reference);
                 blockSummaries.add(blockSummary);
             } while (resultSet.next());
 
diff --git a/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockRepository.java b/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockRepository.java
index b8238085..f38d549c 100644
--- a/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockRepository.java
+++ b/src/main/java/org/qortal/repository/hsqldb/HSQLDBBlockRepository.java
@@ -297,7 +297,7 @@ public class HSQLDBBlockRepository implements BlockRepository {
 	@Override
 	public List<BlockSummaryData> getBlockSummariesBySigner(byte[] signerPublicKey, Integer limit, Integer offset, Boolean reverse) throws DataException {
 		StringBuilder sql = new StringBuilder(512);
-		sql.append("SELECT signature, height, Blocks.minter, online_accounts_count FROM ");
+		sql.append("SELECT signature, height, Blocks.minter, online_accounts_count, minted_when, transaction_count, Blocks.reference FROM ");
 
 		// List of minter account's public key and reward-share public keys with minter's public key
 		sql.append("(SELECT * FROM (VALUES (CAST(? AS QortalPublicKey))) UNION (SELECT reward_share_public_key FROM RewardShares WHERE minter_public_key = ?)) AS PublicKeys (public_key) ");
@@ -322,8 +322,12 @@ public class HSQLDBBlockRepository implements BlockRepository {
 				int height = resultSet.getInt(2);
 				byte[] blockMinterPublicKey = resultSet.getBytes(3);
 				int onlineAccountsCount = resultSet.getInt(4);
+				long timestamp = resultSet.getLong(5);
+				int transactionCount = resultSet.getInt(6);
+				byte[] reference = resultSet.getBytes(7);
 
-				BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount);
+				BlockSummaryData blockSummary = new BlockSummaryData(height, signature, blockMinterPublicKey, onlineAccountsCount,
+						timestamp, transactionCount, reference);
 				blockSummaries.add(blockSummary);
 			} while (resultSet.next());
 
@@ -355,7 +359,7 @@ public class HSQLDBBlockRepository implements BlockRepository {
 
 	@Override
 	public List<BlockSummaryData> getBlockSummaries(int firstBlockHeight, int lastBlockHeight) throws DataException {
-		String sql = "SELECT signature, height, minter, online_accounts_count, minted_when, transaction_count "
+		String sql = "SELECT signature, height, minter, online_accounts_count, minted_when, transaction_count, reference "
 				+ "FROM Blocks WHERE height BETWEEN ? AND ?";
 
 		List<BlockSummaryData> blockSummaries = new ArrayList<>();
@@ -371,9 +375,10 @@ public class HSQLDBBlockRepository implements BlockRepository {
 				int onlineAccountsCount = resultSet.getInt(4);
 				long timestamp = resultSet.getLong(5);
 				int transactionCount = resultSet.getInt(6);
+				byte[] reference = resultSet.getBytes(7);
 
 				BlockSummaryData blockSummary = new BlockSummaryData(height, signature, minterPublicKey, onlineAccountsCount,
-						timestamp, transactionCount);
+						timestamp, transactionCount, reference);
 				blockSummaries.add(blockSummary);
 			} while (resultSet.next());
 

From e80dd31fb4a9ccfb960218561fcc242234801bb2 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 13:53:27 +0100
Subject: [PATCH 22/50] BlockSummariesV2Message.MINIMUM_PEER_VERSION set to
 3.6.1

---
 .../org/qortal/network/message/BlockSummariesV2Message.java     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java b/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
index 96c661a4..6ed6c8aa 100644
--- a/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
+++ b/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
@@ -15,7 +15,7 @@ import java.util.List;
 
 public class BlockSummariesV2Message extends Message {
 
-	public static final long MINIMUM_PEER_VERSION = 0x03000400cbL;
+	public static final long MINIMUM_PEER_VERSION = 0x0300060001L;
 
 	private static final int BLOCK_SUMMARY_V2_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH /* block signature */
 			+ Transformer.PUBLIC_KEY_LENGTH /* minter public key */

From 7a60f713ead6bded0062a026af4cc147cb1a952d Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 14:35:02 +0100
Subject: [PATCH 23/50] Fixed error in rebase.

---
 src/main/java/org/qortal/controller/BlockMinter.java | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/BlockMinter.java b/src/main/java/org/qortal/controller/BlockMinter.java
index a07d37fe..100e74db 100644
--- a/src/main/java/org/qortal/controller/BlockMinter.java
+++ b/src/main/java/org/qortal/controller/BlockMinter.java
@@ -434,9 +434,14 @@ public class BlockMinter extends Thread {
 						blockchainLock.unlock();
 					}
 
-				if (newBlockMinted) {
-					// Broadcast our new chain to network
-					Network.getInstance().broadcastOurChain();
+					if (newBlockMinted) {
+						// Broadcast our new chain to network
+						Network.getInstance().broadcastOurChain();
+					}
+
+				} catch (InterruptedException e) {
+					// We've been interrupted - time to exit
+					return;
 				}
 			}
 		} catch (DataException e) {

From d2ebb215e605709a498170d100d0bc57a4b01ed4 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 14:36:49 +0100
Subject: [PATCH 24/50] Fixed Synchronizer.getBlockSummaries() which was
 expecting BLOCK_SUMMARIES, but updated peers send BLOCK_SUMMARIES_V2

---
 .../java/org/qortal/controller/Synchronizer.java    | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index a6fbfe71..a8d91f52 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -1553,12 +1553,19 @@ public class Synchronizer extends Thread {
 		Message getBlockSummariesMessage = new GetBlockSummariesMessage(parentSignature, numberRequested);
 
 		Message message = peer.getResponse(getBlockSummariesMessage);
-		if (message == null || message.getType() != MessageType.BLOCK_SUMMARIES)
+		if (message == null)
 			return null;
 
-		BlockSummariesMessage blockSummariesMessage = (BlockSummariesMessage) message;
+		if (message.getType() == MessageType.BLOCK_SUMMARIES) {
+			BlockSummariesMessage blockSummariesMessage = (BlockSummariesMessage) message;
+			return blockSummariesMessage.getBlockSummaries();
+		}
+		else if (message.getType() == MessageType.BLOCK_SUMMARIES_V2) {
+			BlockSummariesV2Message blockSummariesMessage = (BlockSummariesV2Message) message;
+			return blockSummariesMessage.getBlockSummaries();
+		}
 
-		return blockSummariesMessage.getBlockSummaries();
+		return null;
 	}
 
 	private List<byte[]> getBlockSignatures(Peer peer, byte[] parentSignature, int numberRequested) throws InterruptedException {

From 309f27a6b83a6745583a887b5150d790a43bdcf3 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 15:21:01 +0100
Subject: [PATCH 25/50] Moved error to debug, as we now get a burst of these
 soon after startup, due to commit 99858f3.

This also shows that commit 99858f3 now prevents a block candidate with a very small number of online accounts being built immediately after startup.
---
 src/main/java/org/qortal/block/Block.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/block/Block.java b/src/main/java/org/qortal/block/Block.java
index bdae83c2..07c7db6f 100644
--- a/src/main/java/org/qortal/block/Block.java
+++ b/src/main/java/org/qortal/block/Block.java
@@ -375,7 +375,7 @@ public class Block {
 		}
 
 		if (onlineAccounts.isEmpty()) {
-			LOGGER.error("No online accounts - not even our own?");
+			LOGGER.debug("No online accounts - not even our own?");
 			return null;
 		}
 

From 5c746f0bd90fc5aa8de6a5800608bd21e84164d9 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 15:48:45 +0100
Subject: [PATCH 26/50] Fixed bug which required a node to hold local trade
 presences before it would request any.

This caused large gaps with no presence data. They are removed when they expire, causing the local count to drop to zero, and the node would only start requesting them again once a peer had pushed one or more entries proactively.
---
 src/main/java/org/qortal/controller/tradebot/TradeBot.java | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/tradebot/TradeBot.java b/src/main/java/org/qortal/controller/tradebot/TradeBot.java
index c7ae1db3..85e594fa 100644
--- a/src/main/java/org/qortal/controller/tradebot/TradeBot.java
+++ b/src/main/java/org/qortal/controller/tradebot/TradeBot.java
@@ -468,9 +468,6 @@ public class TradeBot implements Listener {
 
 		List<TradePresenceData> safeTradePresences = List.copyOf(this.safeAllTradePresencesByPubkey.values());
 
-		if (safeTradePresences.isEmpty())
-			return;
-
 		LOGGER.debug("Broadcasting all {} known trade presences. Next broadcast timestamp: {}",
 				safeTradePresences.size(), nextTradePresenceBroadcastTimestamp
 		);

From 4681218416c86e841dc2afa58436c9166ab46bae Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sat, 24 Sep 2022 15:49:29 +0100
Subject: [PATCH 27/50] Include total count in debug trade presence logging

---
 src/main/java/org/qortal/controller/tradebot/TradeBot.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/controller/tradebot/TradeBot.java b/src/main/java/org/qortal/controller/tradebot/TradeBot.java
index 85e594fa..5880f561 100644
--- a/src/main/java/org/qortal/controller/tradebot/TradeBot.java
+++ b/src/main/java/org/qortal/controller/tradebot/TradeBot.java
@@ -634,7 +634,7 @@ public class TradeBot implements Listener {
 		}
 
 		if (newCount > 0) {
-			LOGGER.debug("New trade presences: {}", newCount);
+			LOGGER.debug("New trade presences: {}, all trade presences: {}", newCount, allTradePresencesByPubkey.size());
 			rebuildSafeAllTradePresences();
 		}
 	}

From aa9da45c01657e218a9f249497cc8c25e164d0f5 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 11:37:07 +0100
Subject: [PATCH 28/50] Added optional filtering by reference in GET
 /chat/messages

---
 src/main/java/org/qortal/api/resource/ChatResource.java    | 6 ++++++
 .../org/qortal/api/websocket/ChatMessagesWebSocket.java    | 2 ++
 src/main/java/org/qortal/repository/ChatRepository.java    | 2 +-
 .../org/qortal/repository/hsqldb/HSQLDBChatRepository.java | 7 ++++++-
 4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/qortal/api/resource/ChatResource.java b/src/main/java/org/qortal/api/resource/ChatResource.java
index 0bbd1951..ee2a8599 100644
--- a/src/main/java/org/qortal/api/resource/ChatResource.java
+++ b/src/main/java/org/qortal/api/resource/ChatResource.java
@@ -69,6 +69,7 @@ public class ChatResource {
 	public List<ChatMessage> searchChat(@QueryParam("before") Long before, @QueryParam("after") Long after,
 			@QueryParam("txGroupId") Integer txGroupId,
 			@QueryParam("involving") List<String> involvingAddresses,
+			@QueryParam("reference") String reference,
 			@Parameter(ref = "limit") @QueryParam("limit") Integer limit,
 			@Parameter(ref = "offset") @QueryParam("offset") Integer offset,
 			@Parameter(ref = "reverse") @QueryParam("reverse") Boolean reverse) {
@@ -87,11 +88,16 @@ public class ChatResource {
 		if (after != null && after < 1500000000000L)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
+		byte[] referenceBytes = null;
+		if (reference != null)
+			referenceBytes = Base58.decode(reference);
+
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			return repository.getChatRepository().getMessagesMatchingCriteria(
 					before,
 					after,
 					txGroupId,
+					referenceBytes,
 					involvingAddresses,
 					limit, offset, reverse);
 		} catch (DataException e) {
diff --git a/src/main/java/org/qortal/api/websocket/ChatMessagesWebSocket.java b/src/main/java/org/qortal/api/websocket/ChatMessagesWebSocket.java
index 3dc2d494..9760b7f0 100644
--- a/src/main/java/org/qortal/api/websocket/ChatMessagesWebSocket.java
+++ b/src/main/java/org/qortal/api/websocket/ChatMessagesWebSocket.java
@@ -46,6 +46,7 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 						null,
 						txGroupId,
 						null,
+						null,
 						null, null, null);
 
 				sendMessages(session, chatMessages);
@@ -72,6 +73,7 @@ public class ChatMessagesWebSocket extends ApiWebSocket {
 					null,
 					null,
 					null,
+					null,
 					involvingAddresses,
 					null, null, null);
 
diff --git a/src/main/java/org/qortal/repository/ChatRepository.java b/src/main/java/org/qortal/repository/ChatRepository.java
index cd4b9a8f..2ecd8a34 100644
--- a/src/main/java/org/qortal/repository/ChatRepository.java
+++ b/src/main/java/org/qortal/repository/ChatRepository.java
@@ -14,7 +14,7 @@ public interface ChatRepository {
 	 * Expects EITHER non-null txGroupID OR non-null sender and recipient addresses.
 	 */
 	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after,
-			Integer txGroupId, List<String> involving,
+			Integer txGroupId, byte[] reference, List<String> involving,
 			Integer limit, Integer offset, Boolean reverse) throws DataException;
 
 	public ChatMessage toChatMessage(ChatTransactionData chatTransactionData) throws DataException;
diff --git a/src/main/java/org/qortal/repository/hsqldb/HSQLDBChatRepository.java b/src/main/java/org/qortal/repository/hsqldb/HSQLDBChatRepository.java
index 2972e9f2..2f570686 100644
--- a/src/main/java/org/qortal/repository/hsqldb/HSQLDBChatRepository.java
+++ b/src/main/java/org/qortal/repository/hsqldb/HSQLDBChatRepository.java
@@ -23,7 +23,7 @@ public class HSQLDBChatRepository implements ChatRepository {
 	}
 
 	@Override
-	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after, Integer txGroupId,
+	public List<ChatMessage> getMessagesMatchingCriteria(Long before, Long after, Integer txGroupId, byte[] referenceBytes,
 			List<String> involving, Integer limit, Integer offset, Boolean reverse)
 			throws DataException {
 		// Check args meet expectations
@@ -57,6 +57,11 @@ public class HSQLDBChatRepository implements ChatRepository {
 			bindParams.add(after);
 		}
 
+		if (referenceBytes != null) {
+			whereClauses.add("reference = ?");
+			bindParams.add(referenceBytes);
+		}
+
 		if (txGroupId != null) {
 			whereClauses.add("tx_group_id = " + txGroupId); // int safe to use literally
 			whereClauses.add("recipient IS NULL");

From 5989473c8a9bd2c09134e46a262878ef8b286ad3 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 12:06:14 +0100
Subject: [PATCH 29/50] Revert "Allow duplicate variations of each
 OnlineAccountData in the import queue, but don't allow two entries that match
 exactly."

This reverts commit 6d9e6e8d4c89582ffad23c1094b6a8e3aee91116.
---
 .../controller/OnlineAccountsManager.java     | 24 ++-----------------
 1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 40192876..47d8cf1b 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -71,7 +71,7 @@ public class OnlineAccountsManager {
     private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(4, new NamedThreadFactory("OnlineAccounts"));
     private volatile boolean isStopping = false;
 
-    private final List<OnlineAccountData> onlineAccountsImportQueue = Collections.synchronizedList(new ArrayList<>());
+    private final Set<OnlineAccountData> onlineAccountsImportQueue = ConcurrentHashMap.newKeySet();
 
     /**
      * Cache of 'current' online accounts, keyed by timestamp
@@ -191,12 +191,9 @@ public class OnlineAccountsManager {
 
         LOGGER.debug("Processing online accounts import queue (size: {})", this.onlineAccountsImportQueue.size());
 
-        // Take a copy of onlineAccountsImportQueue so we can safely remove whilst iterating
-        List<OnlineAccountData> onlineAccountsImportQueueCopy = new ArrayList<>(this.onlineAccountsImportQueue);
-
         Set<OnlineAccountData> onlineAccountsToAdd = new HashSet<>();
         try (final Repository repository = RepositoryManager.getRepository()) {
-            for (OnlineAccountData onlineAccountData : onlineAccountsImportQueueCopy) {
+            for (OnlineAccountData onlineAccountData : this.onlineAccountsImportQueue) {
                 if (isStopping)
                     return;
 
@@ -220,19 +217,6 @@ public class OnlineAccountsManager {
         }
     }
 
-    private boolean importQueueContainsExactMatch(OnlineAccountData acc) {
-        // Check if an item exists where all properties match exactly
-        // This is needed because signature and nonce are not compared in OnlineAccountData.equals()
-        synchronized (onlineAccountsImportQueue) {
-            return onlineAccountsImportQueue.stream().anyMatch(otherAcc ->
-                    acc.getTimestamp() == otherAcc.getTimestamp() &&
-                            Arrays.equals(acc.getPublicKey(), otherAcc.getPublicKey()) &&
-                            acc.getNonce() == otherAcc.getNonce() &&
-                            Arrays.equals(acc.getSignature(), otherAcc.getSignature())
-            );
-        }
-    }
-
     /**
      * Check if supplied onlineAccountData is superior (i.e. has a nonce value) than existing record.
      * Two entries are considered equal even if the nonce differs, to prevent multiple variations
@@ -855,10 +839,6 @@ public class OnlineAccountsManager {
                 // We have already validated this online account
                 continue;
 
-            if (this.importQueueContainsExactMatch(onlineAccountData))
-                // Identical online account data already present in queue
-                continue;
-
             boolean isNewEntry = onlineAccountsImportQueue.add(onlineAccountData);
 
             if (isNewEntry)

From 765416db71a1b3dd986a108dbfd31713d3004016 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 12:26:00 +0100
Subject: [PATCH 30/50] Yet another attempt to optimize the online accounts
 import queue processing.

The main difference here is that we now remove items from the onlineAccountsImportQueue in a batch, _after_ they have been imported. This prevents duplicates from being added to the queue in the previous time gap between them being removed and imported.
---
 .../qortal/controller/OnlineAccountsManager.java    | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 47d8cf1b..6fa69a89 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -207,13 +207,20 @@ public class OnlineAccountsManager {
 
                 boolean isValid = this.isValidCurrentAccount(repository, onlineAccountData);
                 if (isValid)
-                    addAccounts(Arrays.asList(onlineAccountData));
+                    onlineAccountsToAdd.add(onlineAccountData);
 
-                // Remove from queue
-                onlineAccountsImportQueue.remove(onlineAccountData);
+                // Don't remove from the queue yet - we'll do this at the end of the process
+                // This prevents duplicates being added to the queue whilst it's being processed
             }
         } catch (DataException e) {
             LOGGER.error("Repository issue while verifying online accounts", e);
+
+        } finally {
+            if (!onlineAccountsToAdd.isEmpty()) {
+                LOGGER.debug("Merging {} validated online accounts from import queue", onlineAccountsToAdd.size());
+                addAccounts(onlineAccountsToAdd);
+                onlineAccountsImportQueue.removeAll(onlineAccountsToAdd);
+            }
         }
     }
 

From 1bb8f1b6d2d68032e02eb05aba6b49e6258f09b9 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 12:36:00 +0100
Subject: [PATCH 31/50] Fixed bug in last commit.

We need to track items to remove separately from items to add, otherwise invalid accounts remain in the queue.
---
 .../java/org/qortal/controller/OnlineAccountsManager.java     | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 6fa69a89..686ef514 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -192,6 +192,7 @@ public class OnlineAccountsManager {
         LOGGER.debug("Processing online accounts import queue (size: {})", this.onlineAccountsImportQueue.size());
 
         Set<OnlineAccountData> onlineAccountsToAdd = new HashSet<>();
+        Set<OnlineAccountData> onlineAccountsToRemove = new HashSet<>();
         try (final Repository repository = RepositoryManager.getRepository()) {
             for (OnlineAccountData onlineAccountData : this.onlineAccountsImportQueue) {
                 if (isStopping)
@@ -211,6 +212,7 @@ public class OnlineAccountsManager {
 
                 // Don't remove from the queue yet - we'll do this at the end of the process
                 // This prevents duplicates being added to the queue whilst it's being processed
+                onlineAccountsToRemove.add(onlineAccountData);
             }
         } catch (DataException e) {
             LOGGER.error("Repository issue while verifying online accounts", e);
@@ -219,7 +221,7 @@ public class OnlineAccountsManager {
             if (!onlineAccountsToAdd.isEmpty()) {
                 LOGGER.debug("Merging {} validated online accounts from import queue", onlineAccountsToAdd.size());
                 addAccounts(onlineAccountsToAdd);
-                onlineAccountsImportQueue.removeAll(onlineAccountsToAdd);
+                onlineAccountsImportQueue.removeAll(onlineAccountsToRemove);
             }
         }
     }

From a9721bab3d735ad376d5296f29833002dcd0e742 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 18:39:56 +0100
Subject: [PATCH 32/50] Fixed issue causing startup of various components to be
 delayed by 30 seconds.

---
 .../org/qortal/controller/OnlineAccountsManager.java  | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 686ef514..2644fa66 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -133,17 +133,10 @@ public class OnlineAccountsManager {
         // Process import queue
         executor.scheduleWithFixedDelay(this::processOnlineAccountsImportQueue, ONLINE_ACCOUNTS_QUEUE_INTERVAL, ONLINE_ACCOUNTS_QUEUE_INTERVAL, TimeUnit.MILLISECONDS);
 
-        // Sleep for some time before scheduling sendOurOnlineAccountsInfo()
+        // Send our online accounts (using increased initial delay)
         // This allows some time for initial online account lists to be retrieved, and
         // reduces the chances of the same nonce being computed twice
-        try {
-            Thread.sleep(INITIAL_SLEEP_INTERVAL);
-        } catch (InterruptedException e) {
-            throw new RuntimeException(e);
-        }
-
-        // Send our online accounts
-        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, TimeUnit.MILLISECONDS);
+        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, INITIAL_SLEEP_INTERVAL, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, TimeUnit.MILLISECONDS);
     }
 
     public void shutdown() {

From 3890fa849072a5c5d28f265d4235ed32936840d1 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 18:46:33 +0100
Subject: [PATCH 33/50] Renamed constant for consistency

---
 .../java/org/qortal/controller/OnlineAccountsManager.java   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/qortal/controller/OnlineAccountsManager.java b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
index 2644fa66..ff20a8d0 100644
--- a/src/main/java/org/qortal/controller/OnlineAccountsManager.java
+++ b/src/main/java/org/qortal/controller/OnlineAccountsManager.java
@@ -53,7 +53,7 @@ public class OnlineAccountsManager {
      */
     private static final int MAX_BLOCKS_CACHED_ONLINE_ACCOUNTS = 3;
 
-    private static final long ONLINE_ACCOUNTS_QUEUE_INTERVAL = 100L; //ms
+    private static final long ONLINE_ACCOUNTS_QUEUE_INTERVAL = 100L; // ms
     private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
     private static final long ONLINE_ACCOUNTS_COMPUTE_INTERVAL = 5 * 1000L; // ms
     private static final long ONLINE_ACCOUNTS_BROADCAST_INTERVAL = 60 * 1000L; // ms
@@ -62,7 +62,7 @@ public class OnlineAccountsManager {
     private static final long ONLINE_ACCOUNTS_BROADCAST_BURST_INTERVAL = 5 * 1000L; // ms
     private static final long ONLINE_ACCOUNTS_BROADCAST_BURST_LENGTH = 5 * 60 * 1000L; // ms
 
-    private static final long INITIAL_SLEEP_INTERVAL = 30 * 1000L;
+    private static final long ONLINE_ACCOUNTS_COMPUTE_INITIAL_SLEEP_INTERVAL = 30 * 1000L; // ms
 
     // MemoryPoW
     public final int POW_BUFFER_SIZE = 1 * 1024 * 1024; // bytes
@@ -136,7 +136,7 @@ public class OnlineAccountsManager {
         // Send our online accounts (using increased initial delay)
         // This allows some time for initial online account lists to be retrieved, and
         // reduces the chances of the same nonce being computed twice
-        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, INITIAL_SLEEP_INTERVAL, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, TimeUnit.MILLISECONDS);
+        executor.scheduleAtFixedRate(this::sendOurOnlineAccountsInfo, ONLINE_ACCOUNTS_COMPUTE_INITIAL_SLEEP_INTERVAL, ONLINE_ACCOUNTS_COMPUTE_INTERVAL, TimeUnit.MILLISECONDS);
     }
 
     public void shutdown() {

From 7080b55aacd69138fed21ab8e3370e5088a20b59 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 25 Sep 2022 19:43:56 +0100
Subject: [PATCH 34/50] Reintroduced initial sleep period in block archiver.

---
 .../java/org/qortal/controller/repository/BlockArchiver.java    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/controller/repository/BlockArchiver.java b/src/main/java/org/qortal/controller/repository/BlockArchiver.java
index 8757bf32..63d61ef8 100644
--- a/src/main/java/org/qortal/controller/repository/BlockArchiver.java
+++ b/src/main/java/org/qortal/controller/repository/BlockArchiver.java
@@ -16,7 +16,7 @@ public class BlockArchiver implements Runnable {
 
 	private static final Logger LOGGER = LogManager.getLogger(BlockArchiver.class);
 
-	private static final long INITIAL_SLEEP_PERIOD = 0L; // TODO: 5 * 60 * 1000L + 1234L; // ms
+	private static final long INITIAL_SLEEP_PERIOD = 5 * 60 * 1000L + 1234L; // ms
 
 	public void run() {
 		Thread.currentThread().setName("Block archiver");

From c35c7180d4c15438ca1db2129c03df563fdd24cc Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 3 Oct 2022 10:58:47 +0100
Subject: [PATCH 35/50] Return empty levels in GET /addresses/online/levels

---
 src/main/java/org/qortal/api/resource/AddressesResource.java | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/main/java/org/qortal/api/resource/AddressesResource.java b/src/main/java/org/qortal/api/resource/AddressesResource.java
index 4de8d908..468b90a8 100644
--- a/src/main/java/org/qortal/api/resource/AddressesResource.java
+++ b/src/main/java/org/qortal/api/resource/AddressesResource.java
@@ -205,6 +205,10 @@ public class AddressesResource {
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			List<OnlineAccountLevel> onlineAccountLevels = new ArrayList<>();
 
+			// Prepopulate all levels
+			for (int i=0; i<=10; i++)
+				onlineAccountLevels.add(new OnlineAccountLevel(i, 0));
+
 			for (OnlineAccountData onlineAccountData : onlineAccounts) {
 				try {
 					final int minterLevel = Account.getRewardShareEffectiveMintingLevelIncludingLevelZero(repository, onlineAccountData.getPublicKey());

From 1233ba670300c9e6b6b831a034613c5325346120 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Tue, 4 Oct 2022 20:08:30 +0100
Subject: [PATCH 36/50] Bump version to 3.6.1

---
 pom.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pom.xml b/pom.xml
index e045e0f4..3be7fff3 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.6.0</version>
+	<version>3.6.1</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>

From 10b0f0a0549094a82be158efe88d6a1b18de2fd7 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Wed, 5 Oct 2022 15:29:29 +0100
Subject: [PATCH 37/50] Catch JSON exceptions in PirateChainWalletController.

This could prevent additional wallets from being initialized if connection was lost while syncing an existing one.
---
 .../PirateChainWalletController.java           | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/qortal/controller/PirateChainWalletController.java b/src/main/java/org/qortal/controller/PirateChainWalletController.java
index 1eac4b3a..333c2cda 100644
--- a/src/main/java/org/qortal/controller/PirateChainWalletController.java
+++ b/src/main/java/org/qortal/controller/PirateChainWalletController.java
@@ -4,6 +4,7 @@ import com.rust.litewalletjni.LiteWalletJni;
 import org.apache.commons.io.FileUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.json.JSONException;
 import org.json.JSONObject;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.arbitrary.ArbitraryDataReader;
@@ -99,14 +100,19 @@ public class PirateChainWalletController extends Thread {
                 LOGGER.debug("Syncing Pirate Chain wallet...");
                 String response = LiteWalletJni.execute("sync", "");
                 LOGGER.debug("sync response: {}", response);
-                JSONObject json = new JSONObject(response);
-                if (json.has("result")) {
-                    String result = json.getString("result");
 
-                    // We may have to set wallet to ready if this is the first ever successful sync
-                    if (Objects.equals(result, "success")) {
-                        this.currentWallet.setReady(true);
+                try {
+                    JSONObject json = new JSONObject(response);
+                    if (json.has("result")) {
+                        String result = json.getString("result");
+
+                        // We may have to set wallet to ready if this is the first ever successful sync
+                        if (Objects.equals(result, "success")) {
+                            this.currentWallet.setReady(true);
+                        }
                     }
+                } catch (JSONException e) {
+                    LOGGER.info("Unable to interpret JSON", e);
                 }
 
                 // Rate limit sync attempts

From fdd95eac563beb860797bdb888a6abb98f0cf0c9 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 7 Oct 2022 11:05:24 +0100
Subject: [PATCH 38/50] Limit to 240 blocks in syncToPeerChain().

Should fix OutOfMemoryException often seen when syncing from 1000+ blocks behind the chain tip.
---
 src/main/java/org/qortal/controller/Synchronizer.java | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index a8d91f52..0fe9a56b 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -1246,7 +1246,14 @@ public class Synchronizer extends Thread {
 		int numberSignaturesRequired = additionalPeerBlocksAfterCommonBlock - peerBlockSignatures.size();
 
 		int retryCount = 0;
-		while (height < peerHeight) {
+
+		// Keep fetching blocks from peer until we reach their tip, or reach a count of MAXIMUM_COMMON_DELTA blocks.
+		// We need to limit the total number, otherwise too much can be loaded into memory, causing an
+		// OutOfMemoryException. This is common when syncing from 1000+ blocks behind the chain tip, after starting
+		// from a small fork that didn't become part of the main chain. This causes the entire sync process to
+		// use syncToPeerChain(), resulting in potentially thousands of blocks being held in memory if the limit
+		// below isn't applied.
+		while (height < peerHeight && peerBlocks.size() <= MAXIMUM_COMMON_DELTA) {
 			if (Controller.isStopping())
 				return SynchronizationResult.SHUTTING_DOWN;
 

From 8cedf618f45a5d1ab24633e9b32972e663c3dcdd Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 7 Oct 2022 14:46:09 +0100
Subject: [PATCH 39/50] Skip GET_BLOCK_SUMMARIES requests if it can already be
 fulfilled entirely from the peer's chain tip block summaries cache.

Loading from the cache should speed up sync decisions, particularly when choose which peer to sync from. The greater the number of connected peers, the more significant this optimization will be. It should also reduce wasted network requests and data usage.

Adding this check prior to making a network request is a simple way to introduce the new cached summaries from BLOCK_SUMMARIES_V2 without having to rewrite a lot of the complex sync / peer comparison logic. Longer term we may want to rewrite that logic to read from the cache directly, but it doesn't make sense to introduce that level of risk at this point time, especially as the Synchronizer may be rewritten soon to prefer longer chains.

Even so, this is still quite a high risk commit so lots of testing will be needed.
---
 .../org/qortal/controller/Synchronizer.java   | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index 0fe9a56b..dc70db2a 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -8,6 +8,7 @@ import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -1556,7 +1557,41 @@ public class Synchronizer extends Thread {
 		return SynchronizationResult.OK;
 	}
 
+	private List<BlockSummaryData> getBlockSummariesFromCache(Peer peer, byte[] parentSignature, int numberRequested) {
+		List<BlockSummaryData> peerSummaries = peer.getChainTipSummaries();
+		if (peerSummaries == null)
+			return null;
+
+		// Check if the requested parent block exists in peer's summaries cache
+		int parentIndex = IntStream.range(0, peerSummaries.size()).filter(i -> Arrays.equals(peerSummaries.get(i).getSignature(), parentSignature)).findFirst().orElse(-1);
+		if (parentIndex < 0)
+			return null;
+
+		// Peer's summaries contains the requested parent, so return summaries after that
+		// Make sure we have at least one block after the parent block
+		int summariesAvailable = peerSummaries.size() - parentIndex - 1;
+		if (summariesAvailable <= 0)
+			return null;
+
+		// Don't try and return more summaries than we have, or more than were requested
+		int summariesToReturn = Math.min(numberRequested, summariesAvailable);
+		int startIndex = parentIndex + 1;
+		int endIndex = startIndex + summariesToReturn - 1;
+		if (endIndex > peerSummaries.size() - 1)
+			return null;
+
+		LOGGER.trace("Serving {} block summaries from cache", summariesToReturn);
+		return peerSummaries.subList(startIndex, endIndex);
+	}
+
 	private List<BlockSummaryData> getBlockSummaries(Peer peer, byte[] parentSignature, int numberRequested) throws InterruptedException {
+		// We might be able to shortcut the response if we already have the summaries in the peer's chain tip data
+		List<BlockSummaryData> cachedSummaries = this.getBlockSummariesFromCache(peer, parentSignature, numberRequested);
+		if (cachedSummaries != null && !cachedSummaries.isEmpty())
+			return cachedSummaries;
+
+		LOGGER.trace("Requesting {} block summaries from peer {}", numberRequested, peer);
+
 		Message getBlockSummariesMessage = new GetBlockSummariesMessage(parentSignature, numberRequested);
 
 		Message message = peer.getResponse(getBlockSummariesMessage);

From 0088ba8485a73c723a9ea4555e0435d42df20a3f Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Fri, 7 Oct 2022 14:47:46 +0100
Subject: [PATCH 40/50] Reduce INITIAL_BLOCK_STEP from 8 to 7.

This allows the first pass to always be served from the peer's cache of 8 summaries. This allows a maximum of 7 to be returned, because the 8th spot is needed for the parent block's signature.
---
 src/main/java/org/qortal/controller/Synchronizer.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index dc70db2a..ccb3dfdd 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -44,7 +44,7 @@ public class Synchronizer extends Thread {
 	private static final int SYNC_BATCH_SIZE = 1000; // XXX move to Settings?
 
 	/** Initial jump back of block height when searching for common block with peer */
-	private static final int INITIAL_BLOCK_STEP = 8;
+	private static final int INITIAL_BLOCK_STEP = 7;
 	/** Maximum jump back of block height when searching for common block with peer */
 	private static final int MAXIMUM_BLOCK_STEP = 128;
 

From 3a18599d8511833872cbd46d3c23e4b3ff81ddf4 Mon Sep 17 00:00:00 2001
From: Nuc1eoN <2538022+Nuc1eoN@users.noreply.github.com>
Date: Fri, 7 Oct 2022 23:35:35 +0200
Subject: [PATCH 41/50] Mark start/stop scripts as executables

The `start.sh` & `stop.sh` scripts have already been marked as executables in the source folder... But since we have only piped their contents, we need to set correct file permissions again.
---
 tools/build-zip.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/build-zip.sh b/tools/build-zip.sh
index b52b5da7..f423bca1 100755
--- a/tools/build-zip.sh
+++ b/tools/build-zip.sh
@@ -58,6 +58,9 @@ git show HEAD:log4j2.properties > ${build_dir}/log4j2.properties
 git show HEAD:start.sh > ${build_dir}/start.sh
 git show HEAD:stop.sh > ${build_dir}/stop.sh
 
+chmod +x ${build_dir}/start.sh
+chmod +x ${build_dir}/stop.sh
+
 printf "{\n}\n" > ${build_dir}/settings.json
 
 gtouch -d ${commit_ts%%+??:??} ${build_dir} ${build_dir}/*

From 77d60fc33f8171363d58d037044a7bac4ae4152d Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 9 Oct 2022 14:11:28 +0100
Subject: [PATCH 42/50] Revert "Skip GET_BLOCK_SUMMARIES requests if it can
 already be fulfilled entirely from the peer's chain tip block summaries
 cache."

This reverts commit 8cedf618f45a5d1ab24633e9b32972e663c3dcdd.
---
 .../org/qortal/controller/Synchronizer.java   | 35 -------------------
 1 file changed, 35 deletions(-)

diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index ccb3dfdd..e4419249 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -8,7 +8,6 @@ import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
-import java.util.stream.IntStream;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -1557,41 +1556,7 @@ public class Synchronizer extends Thread {
 		return SynchronizationResult.OK;
 	}
 
-	private List<BlockSummaryData> getBlockSummariesFromCache(Peer peer, byte[] parentSignature, int numberRequested) {
-		List<BlockSummaryData> peerSummaries = peer.getChainTipSummaries();
-		if (peerSummaries == null)
-			return null;
-
-		// Check if the requested parent block exists in peer's summaries cache
-		int parentIndex = IntStream.range(0, peerSummaries.size()).filter(i -> Arrays.equals(peerSummaries.get(i).getSignature(), parentSignature)).findFirst().orElse(-1);
-		if (parentIndex < 0)
-			return null;
-
-		// Peer's summaries contains the requested parent, so return summaries after that
-		// Make sure we have at least one block after the parent block
-		int summariesAvailable = peerSummaries.size() - parentIndex - 1;
-		if (summariesAvailable <= 0)
-			return null;
-
-		// Don't try and return more summaries than we have, or more than were requested
-		int summariesToReturn = Math.min(numberRequested, summariesAvailable);
-		int startIndex = parentIndex + 1;
-		int endIndex = startIndex + summariesToReturn - 1;
-		if (endIndex > peerSummaries.size() - 1)
-			return null;
-
-		LOGGER.trace("Serving {} block summaries from cache", summariesToReturn);
-		return peerSummaries.subList(startIndex, endIndex);
-	}
-
 	private List<BlockSummaryData> getBlockSummaries(Peer peer, byte[] parentSignature, int numberRequested) throws InterruptedException {
-		// We might be able to shortcut the response if we already have the summaries in the peer's chain tip data
-		List<BlockSummaryData> cachedSummaries = this.getBlockSummariesFromCache(peer, parentSignature, numberRequested);
-		if (cachedSummaries != null && !cachedSummaries.isEmpty())
-			return cachedSummaries;
-
-		LOGGER.trace("Requesting {} block summaries from peer {}", numberRequested, peer);
-
 		Message getBlockSummariesMessage = new GetBlockSummariesMessage(parentSignature, numberRequested);
 
 		Message message = peer.getResponse(getBlockSummariesMessage);

From e6bb0b81cff21d2e713185c95b8962d4bb87e50e Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 9 Oct 2022 19:11:20 +0100
Subject: [PATCH 43/50] Revert "Reduce INITIAL_BLOCK_STEP from 8 to 7."

This reverts commit 0088ba8485a73c723a9ea4555e0435d42df20a3f.
---
 src/main/java/org/qortal/controller/Synchronizer.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index e4419249..0fe9a56b 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -43,7 +43,7 @@ public class Synchronizer extends Thread {
 	private static final int SYNC_BATCH_SIZE = 1000; // XXX move to Settings?
 
 	/** Initial jump back of block height when searching for common block with peer */
-	private static final int INITIAL_BLOCK_STEP = 7;
+	private static final int INITIAL_BLOCK_STEP = 8;
 	/** Maximum jump back of block height when searching for common block with peer */
 	private static final int MAXIMUM_BLOCK_STEP = 128;
 

From 2d58118d7cfa717a4a6521b9d2fa2bd325c7e5ea Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 9 Oct 2022 20:11:01 +0100
Subject: [PATCH 44/50] Always use BlockSummariesMessage V1 (instead of V2)
 when responding to GetBlockSummaries requests.

This should hopefully fix a potential issue where peer's chain tip data becomes contaminated with other summary data, causing incorrect sync decisions.
---
 src/main/java/org/qortal/controller/Controller.java | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index ce994757..1e028ebc 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -1430,9 +1430,7 @@ public class Controller extends Thread {
 		// then we have no blocks after that and can short-circuit with an empty response
 		BlockData chainTip = getChainTip();
 		if (chainTip != null && Arrays.equals(parentSignature, chainTip.getSignature())) {
-			Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
-					? new BlockSummariesV2Message(Collections.emptyList())
-					: new BlockSummariesMessage(Collections.emptyList());
+			Message blockSummariesMessage = new BlockSummariesMessage(Collections.emptyList());
 
 			blockSummariesMessage.setId(message.getId());
 
@@ -1491,9 +1489,7 @@ public class Controller extends Thread {
 				this.stats.getBlockSummariesStats.fullyFromCache.incrementAndGet();
 		}
 
-		Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
-				? new BlockSummariesV2Message(blockSummaries)
-				: new BlockSummariesMessage(blockSummaries);
+		Message blockSummariesMessage = new BlockSummariesMessage(blockSummaries);
 		blockSummariesMessage.setId(message.getId());
 		if (!peer.sendMessage(blockSummariesMessage))
 			peer.disconnect("failed to send block summaries");

From cb1eee8ff5f1f30e647cec69779cbf08dff91f94 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Sun, 9 Oct 2022 20:37:39 +0100
Subject: [PATCH 45/50] GenericUnknownMessage.MINIMUM_PEER_VERSION set to
 3.6.1.

This should ideally have been set in the 3.6.1 release, but not setting it is unlikely to have caused any problems.
---
 .../java/org/qortal/network/message/GenericUnknownMessage.java  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/network/message/GenericUnknownMessage.java b/src/main/java/org/qortal/network/message/GenericUnknownMessage.java
index 15faaa1b..dea9f2b8 100644
--- a/src/main/java/org/qortal/network/message/GenericUnknownMessage.java
+++ b/src/main/java/org/qortal/network/message/GenericUnknownMessage.java
@@ -4,7 +4,7 @@ import java.nio.ByteBuffer;
 
 public class GenericUnknownMessage extends Message {
 
-    public static final long MINIMUM_PEER_VERSION = 0x03000400cbL;
+    public static final long MINIMUM_PEER_VERSION = 0x0300060001L;
 
     public GenericUnknownMessage() {
         super(MessageType.GENERIC_UNKNOWN);

From 36fcd6792a55352b8d7753dd7d9b8cb16f42d9eb Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 10 Oct 2022 10:28:36 +0100
Subject: [PATCH 46/50] Discard BLOCK_SUMMARIES_V2 messages with an ID (thanks
 to @catbref for the code)

This is a better fix for the "contaminated chain tip summaries" issue. Need to reduce the logging level to debug before release.
---
 src/main/java/org/qortal/controller/Controller.java | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index 1e028ebc..2146c86b 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -1599,6 +1599,17 @@ public class Controller extends Thread {
 			}
 		}
 
+		if (message.hasId()) {
+			/*
+			 * Experimental proof-of-concept: discard messages with ID
+			 * These are 'late' reply messages received after timeout has expired,
+			 * having been passed upwards from Peer to Network to Controller.
+			 * Hence, these are NOT simple "here's my chain tip" broadcasts from other peers.
+			 */
+			LOGGER.info("Discarding late {} message with ID {} from {}", message.getType().name(), message.getId(), peer);
+			return;
+		}
+
 		// Update peer chain tip data
 		peer.setChainTipSummaries(blockSummariesV2Message.getBlockSummaries());
 

From 10d3176e70694808be0476a95d15804e31fcb948 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 10 Oct 2022 10:28:44 +0100
Subject: [PATCH 47/50] Revert "Always use BlockSummariesMessage V1 (instead of
 V2) when responding to GetBlockSummaries requests."

This reverts commit 2d58118d7cfa717a4a6521b9d2fa2bd325c7e5ea.
---
 src/main/java/org/qortal/controller/Controller.java | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/qortal/controller/Controller.java b/src/main/java/org/qortal/controller/Controller.java
index 2146c86b..93cbae92 100644
--- a/src/main/java/org/qortal/controller/Controller.java
+++ b/src/main/java/org/qortal/controller/Controller.java
@@ -1430,7 +1430,9 @@ public class Controller extends Thread {
 		// then we have no blocks after that and can short-circuit with an empty response
 		BlockData chainTip = getChainTip();
 		if (chainTip != null && Arrays.equals(parentSignature, chainTip.getSignature())) {
-			Message blockSummariesMessage = new BlockSummariesMessage(Collections.emptyList());
+			Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+					? new BlockSummariesV2Message(Collections.emptyList())
+					: new BlockSummariesMessage(Collections.emptyList());
 
 			blockSummariesMessage.setId(message.getId());
 
@@ -1489,7 +1491,9 @@ public class Controller extends Thread {
 				this.stats.getBlockSummariesStats.fullyFromCache.incrementAndGet();
 		}
 
-		Message blockSummariesMessage = new BlockSummariesMessage(blockSummaries);
+		Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+				? new BlockSummariesV2Message(blockSummaries)
+				: new BlockSummariesMessage(blockSummaries);
 		blockSummariesMessage.setId(message.getId());
 		if (!peer.sendMessage(blockSummariesMessage))
 			peer.disconnect("failed to send block summaries");

From d4aaba2293105e63deeb784b87a8dbe566d25724 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Mon, 10 Oct 2022 19:06:08 +0100
Subject: [PATCH 48/50] Bump version to 3.6.2

---
 pom.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pom.xml b/pom.xml
index 3be7fff3..591801e9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.6.1</version>
+	<version>3.6.2</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>

From 7c15d88cbc23dd45d8c090d286a628c05974af01 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Wed, 12 Oct 2022 08:52:58 +0100
Subject: [PATCH 49/50] Fix for issue in BLOCK_SUMMARIES_V2 when sending an
 empty array of summaries.

The BLOCK_SUMMARIES message type would differentiate between an empty response and a missing/invalid response. However, in V2, a response with empty summaries would throw a BufferUnderflowException and be treated by the caller as a null message.

This caused problems when trying to find a common block with peers that have diverged by more than 8 blocks. With V1 the caller would know to search back further (e.g. 16 blocks) but in V2 it was treated as "no response" and so the caller would give up instead of increasing the look-back threshold.

This fix will identify BLOCK_SUMMARIES_V2 messages with no content, and return an empty array of block summaries instead of a null message.

Should be enough to recover any stuck nodes, as long as they haven't diverged more than 240 blocks from the main chain.
---
 .../qortal/network/message/BlockSummariesV2Message.java    | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java b/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
index 6ed6c8aa..62428cc0 100644
--- a/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
+++ b/src/main/java/org/qortal/network/message/BlockSummariesV2Message.java
@@ -68,13 +68,18 @@ public class BlockSummariesV2Message extends Message {
 	}
 
 	public static Message fromByteBuffer(int id, ByteBuffer bytes) {
+		List<BlockSummaryData> blockSummaries = new ArrayList<>();
+
+		// If there are no bytes remaining then we can treat this as an empty array of summaries
+		if (bytes.remaining() == 0)
+			return new BlockSummariesV2Message(id, blockSummaries);
+
 		int height = bytes.getInt();
 
 		// Expecting bytes remaining to be exact multiples of BLOCK_SUMMARY_V2_LENGTH
 		if (bytes.remaining() % BLOCK_SUMMARY_V2_LENGTH != 0)
 			throw new BufferUnderflowException();
 
-		List<BlockSummaryData> blockSummaries = new ArrayList<>();
 		while (bytes.hasRemaining()) {
 			byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
 			bytes.get(signature);

From 7c7f071eba29240e1b8045df978d1b6fc3f11f60 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Wed, 12 Oct 2022 08:54:27 +0100
Subject: [PATCH 50/50] Bump version to 3.6.3

---
 pom.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pom.xml b/pom.xml
index 591801e9..5f439cad 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>3.6.2</version>
+	<version>3.6.3</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>