RNS mostly implemented. Todo - removing bytest from buffer when reading (threading issue?)

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

@@ -18,6 +18,7 @@ import org.qortal.controller.hsqldb.HSQLDBDataCacheManager;
 import org.qortal.controller.repository.NamesDatabaseIntegrityCheck;
 import org.qortal.controller.repository.PruneManager;
 import org.qortal.controller.tradebot.TradeBot;
+import org.qortal.controller.tradebot.RNSTradeBot;
 import org.qortal.data.account.AccountBalanceData;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
@@ -34,6 +35,7 @@ import org.qortal.gui.Gui;
 import org.qortal.gui.SysTray;
 import org.qortal.network.Network;
 import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
 import org.qortal.network.Peer;
 import org.qortal.network.PeerAddress;
 import org.qortal.network.message.*;
@@ -1245,20 +1247,20 @@ public class Controller extends Thread {
 	}
 
 	public void doRNSNetworkBroadcast() {
-		//if (Settings.getInstance().isLite()) {
+		if (Settings.getInstance().isLite()) {
-		//	// Lite nodes have nothing to broadcast
+			// Lite nodes have nothing to broadcast
-		//	return;
+			return;
-		//}
+		}
-		//RNSNetwork network = RNSNetwork.getInstance();
+		RNSNetwork network = RNSNetwork.getInstance();
 
-		//// Send our current height
+		// Send our current height
-		//network.broadcastOurChain();
+		network.broadcastOurChain();
 
-		//// Request unconfirmed transaction signatures, but only if we're up-to-date.
+		// Request unconfirmed transaction signatures, but only if we're up-to-date.
-		//// if we're not up-to-dat then priority is synchronizing first
+		// if we're not up-to-dat then priority is synchronizing first
-		//if (isUpToDate()) {
+		if (isUpToDateRNS()) {
-		//	network.broadcast(network::buildGetUnconfirmedTransactionsMessage);
+			network.broadcast(network::buildGetUnconfirmedTransactionsMessage);
-		//}
+		}
 
 	}
 
@@ -2193,4 +2195,688 @@ public class Controller extends Thread {
 	public StatsSnapshot getStatsSnapshot() {
 		return this.stats;
 	}
+
+	public void onRNSNetworkMessage(RNSPeer peer, Message message) {
+		LOGGER.trace(() -> String.format("Processing %s message from %s", message.getType().name(), peer));
+
+		// Ordered by message type value
+		switch (message.getType()) {
+			case GET_BLOCK:
+				onRNSNetworkGetBlockMessage(peer, message);
+				break;
+			
+			case GET_BLOCK_SUMMARIES:
+				onRNSNetworkGetBlockSummariesMessage(peer, message);
+				break;
+			
+			case GET_SIGNATURES_V2:
+				onRNSNetworkGetSignaturesV2Message(peer, message);
+				break;
+			
+			case HEIGHT_V2:
+				onRNSNetworkHeightV2Message(peer, message);
+				break;
+			
+			case BLOCK_SUMMARIES_V2:
+				onRNSNetworkBlockSummariesV2Message(peer, message);
+				break;
+			
+			case GET_TRANSACTION:
+				RNSTransactionImporter.getInstance().onNetworkGetTransactionMessage(peer, message);
+				break;
+			
+			case TRANSACTION:
+				RNSTransactionImporter.getInstance().onNetworkTransactionMessage(peer, message);
+				break;
+			
+			case GET_UNCONFIRMED_TRANSACTIONS:
+				RNSTransactionImporter.getInstance().onNetworkGetUnconfirmedTransactionsMessage(peer, message);
+				break;
+			
+			case TRANSACTION_SIGNATURES:
+				RNSTransactionImporter.getInstance().onNetworkTransactionSignaturesMessage(peer, message);
+				break;
+			
+			//case GET_ONLINE_ACCOUNTS_V3:
+			//	OnlineAccountsManager.getInstance().onNetworkGetOnlineAccountsV3Message(peer, message);
+			//	break;
+			//
+			//case ONLINE_ACCOUNTS_V3:
+			//	OnlineAccountsManager.getInstance().onNetworkOnlineAccountsV3Message(peer, message);
+			//	break;
+			
+			//// TODO: Compiles but much of the Manager details need to be rethought for Reticulum
+			//case GET_ARBITRARY_DATA:
+			//	// Not currently supported
+			//	break;
+			////
+			//case ARBITRARY_DATA_FILE_LIST:
+			//	RNSArbitraryDataFileListManager.getInstance().onNetworkArbitraryDataFileListMessage(peer, message);
+			//	break;
+			//
+			//case GET_ARBITRARY_DATA_FILE:
+			//	RNSArbitraryDataFileManager.getInstance().onNetworkGetArbitraryDataFileMessage(peer, message);
+			//	break;
+			//
+			//case GET_ARBITRARY_DATA_FILE_LIST:
+			//	RNSArbitraryDataFileListManager.getInstance().onNetworkGetArbitraryDataFileListMessage(peer, message);
+			//	break;
+			//
+			case ARBITRARY_SIGNATURES:
+				// Not currently supported
+				break;
+			
+			case GET_ARBITRARY_METADATA:
+				RNSArbitraryMetadataManager.getInstance().onNetworkGetArbitraryMetadataMessage(peer, message);
+				break;
+			
+			case ARBITRARY_METADATA:
+				RNSArbitraryMetadataManager.getInstance().onNetworkArbitraryMetadataMessage(peer, message);
+				break;
+			
+			case GET_TRADE_PRESENCES:
+				RNSTradeBot.getInstance().onGetTradePresencesMessage(peer, message);
+				break;
+			
+			case TRADE_PRESENCES:
+				RNSTradeBot.getInstance().onTradePresencesMessage(peer, message);
+				break;
+			
+			case GET_ACCOUNT:
+				onRNSNetworkGetAccountMessage(peer, message);
+				break;
+			
+			case GET_ACCOUNT_BALANCE:
+				onRNSNetworkGetAccountBalanceMessage(peer, message);
+				break;
+			
+			case GET_ACCOUNT_TRANSACTIONS:
+				onRNSNetworkGetAccountTransactionsMessage(peer, message);
+				break;
+			
+			case GET_ACCOUNT_NAMES:
+				onRNSNetworkGetAccountNamesMessage(peer, message);
+				break;
+			
+			case GET_NAME:
+				onRNSNetworkGetNameMessage(peer, message);
+				break;
+
+			default:
+				LOGGER.debug(() -> String.format("Unhandled %s message [ID %d] from peer %s", message.getType().name(), message.getId(), peer));
+				break;
+		}
+	}
+
+	private void onRNSNetworkGetBlockMessage(RNSPeer peer, Message message) {
+		GetBlockMessage getBlockMessage = (GetBlockMessage) message;
+		byte[] signature = getBlockMessage.getSignature();
+		this.stats.getBlockMessageStats.requests.incrementAndGet();
+
+		ByteArray signatureAsByteArray = ByteArray.wrap(signature);
+
+		CachedBlockMessage cachedBlockMessage = this.blockMessageCache.get(signatureAsByteArray);
+		int blockCacheSize = Settings.getInstance().getBlockCacheSize();
+
+		// Check cached latest block message
+		if (cachedBlockMessage != null) {
+			this.stats.getBlockMessageStats.cacheHits.incrementAndGet();
+
+			// We need to duplicate it to prevent multiple threads setting ID on the same message
+			CachedBlockMessage clonedBlockMessage = Message.cloneWithNewId(cachedBlockMessage, message.getId());
+
+			//if (!peer.sendMessage(clonedBlockMessage))
+			//	peer.disconnect("failed to send block");
+			peer.sendMessage(clonedBlockMessage);
+
+			return;
+		}
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			BlockData blockData = repository.getBlockRepository().fromSignature(signature);
+
+			if (blockData != null) {
+				if (PruneManager.getInstance().isBlockPruned(blockData.getHeight())) {
+					// If this is a pruned block, we likely only have partial data, so best not to sent it
+					blockData = null;
+				}
+			}
+
+			// If we have no block data, we should check the archive in case it's there
+			if (blockData == null) {
+				if (Settings.getInstance().isArchiveEnabled()) {
+					Triple<byte[], Integer, Integer> serializedBlock = BlockArchiveReader.getInstance().fetchSerializedBlockBytesForSignature(signature, true, repository);
+					if (serializedBlock != null) {
+						byte[] bytes = serializedBlock.getA();
+						Integer serializationVersion = serializedBlock.getB();
+
+						Message blockMessage;
+						switch (serializationVersion) {
+							case 1:
+								blockMessage = new CachedBlockMessage(bytes);
+								break;
+
+							case 2:
+								blockMessage = new CachedBlockV2Message(bytes);
+								break;
+
+							default:
+								return;
+						}
+						blockMessage.setId(message.getId());
+
+						// This call also causes the other needed data to be pulled in from repository
+						//if (!peer.sendMessage(blockMessage)) {
+						//	peer.disconnect("failed to send block");
+						//	// Don't fall-through to caching because failure to send might be from failure to build message
+						//	return;
+						//}
+						peer.sendMessage(blockMessage);
+
+						// Sent successfully from archive, so nothing more to do
+						return;
+					}
+				}
+			}
+
+			if (blockData == null) {
+				// We don't have this block
+				this.stats.getBlockMessageStats.unknownBlocks.getAndIncrement();
+
+				// 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)));
+
+				// Send generic 'unknown' message as it's very short
+				//Message blockUnknownMessage = peer.getPeersVersion() >= GenericUnknownMessage.MINIMUM_PEER_VERSION
+				//		? new GenericUnknownMessage()
+				//		: new BlockSummariesMessage(Collections.emptyList());
+				Message blockUnknownMessage = new GenericUnknownMessage();
+				blockUnknownMessage.setId(message.getId());
+				//if (!peer.sendMessage(blockUnknownMessage))
+				//	peer.disconnect("failed to send block-unknown response");
+				peer.sendMessage(blockUnknownMessage);
+				return;
+			}
+
+			Block block = new Block(repository, blockData);
+
+			//// V2 support
+			//if (peer.getPeersVersion() >= BlockV2Message.MIN_PEER_VERSION) {
+			//	Message blockMessage = new BlockV2Message(block);
+			//	blockMessage.setId(message.getId());
+			//	if (!peer.sendMessage(blockMessage)) {
+			//		peer.disconnect("failed to send block");
+			//		// Don't fall-through to caching because failure to send might be from failure to build message
+			//		return;
+			//	}
+			//	return;
+			//}
+
+			CachedBlockMessage blockMessage = new CachedBlockMessage(block);
+			blockMessage.setId(message.getId());
+
+			//if (!peer.sendMessage(blockMessage)) {
+			//	peer.disconnect("failed to send block");
+			//	// Don't fall-through to caching because failure to send might be from failure to build message
+			//	return;
+			//}
+			peer.sendMessage(blockMessage);
+
+			// If request is for a recent block, cache it
+			if (getChainHeight() - blockData.getHeight() <= blockCacheSize) {
+				this.stats.getBlockMessageStats.cacheFills.incrementAndGet();
+
+				this.blockMessageCache.put(ByteArray.wrap(blockData.getSignature()), blockMessage);
+			}
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while sending block %s to peer %s", Base58.encode(signature), peer), e);
+		} catch (TransformationException e) {
+			LOGGER.error(String.format("Serialization issue while sending block %s to peer %s", Base58.encode(signature), peer), e);
+		}
+	}
+
+	private void onRNSNetworkGetBlockSummariesMessage(RNSPeer peer, Message message) {
+		GetBlockSummariesMessage getBlockSummariesMessage = (GetBlockSummariesMessage) message;
+		final byte[] parentSignature = getBlockSummariesMessage.getParentSignature();
+		this.stats.getBlockSummariesStats.requests.incrementAndGet();
+
+		// If peer's parent signature matches our latest block signature
+		// 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 BlockSummariesV2Message(Collections.emptyList());
+
+			blockSummariesMessage.setId(message.getId());
+
+			//if (!peer.sendMessage(blockSummariesMessage))
+			//	peer.disconnect("failed to send block summaries");
+			peer.sendMessage(blockSummariesMessage);
+
+			return;
+		}
+
+		List<BlockSummaryData> blockSummaries = new ArrayList<>();
+
+		// Attempt to serve from our cache of latest blocks
+		synchronized (this.latestBlocks) {
+			blockSummaries = this.latestBlocks.stream()
+					.dropWhile(cachedBlockData -> !Arrays.equals(cachedBlockData.getReference(), parentSignature))
+					.map(BlockSummaryData::new)
+					.collect(Collectors.toList());
+		}
+
+		if (blockSummaries.isEmpty()) {
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				int numberRequested = Math.min(Network.MAX_BLOCK_SUMMARIES_PER_REPLY, getBlockSummariesMessage.getNumberRequested());
+
+				BlockData blockData = repository.getBlockRepository().fromReference(parentSignature);
+				if (blockData == null) {
+					// Try the archive
+					blockData = repository.getBlockArchiveRepository().fromReference(parentSignature);
+				}
+
+				if (blockData != null) {
+					if (PruneManager.getInstance().isBlockPruned(blockData.getHeight())) {
+						// If this request contains a pruned block, we likely only have partial data, so best not to sent anything
+						// We always prune from the oldest first, so it's fine to just check the first block requested
+						blockData = null;
+					}
+				}
+
+				while (blockData != null && blockSummaries.size() < numberRequested) {
+					BlockSummaryData blockSummary = new BlockSummaryData(blockData);
+					blockSummaries.add(blockSummary);
+
+					byte[] previousSignature = blockData.getSignature();
+					blockData = repository.getBlockRepository().fromReference(previousSignature);
+					if (blockData == null) {
+						// Try the archive
+						blockData = repository.getBlockArchiveRepository().fromReference(previousSignature);
+					}
+				}
+			} catch (DataException e) {
+				LOGGER.error(String.format("Repository issue while sending block summaries after %s to peer %s", Base58.encode(parentSignature), peer), e);
+			}
+		} else {
+			this.stats.getBlockSummariesStats.cacheHits.incrementAndGet();
+
+			if (blockSummaries.size() >= getBlockSummariesMessage.getNumberRequested())
+				this.stats.getBlockSummariesStats.fullyFromCache.incrementAndGet();
+		}
+
+		//Message blockSummariesMessage = peer.getPeersVersion() >= BlockSummariesV2Message.MINIMUM_PEER_VERSION
+		//		? new BlockSummariesV2Message(blockSummaries)
+		//		: new BlockSummariesMessage(blockSummaries);
+		Message blockSummariesMessage = new BlockSummariesV2Message(blockSummaries);
+		blockSummariesMessage.setId(message.getId());
+		//if (!peer.sendMessage(blockSummariesMessage))
+		//	peer.disconnect("failed to send block summaries");
+		peer.sendMessage(blockSummariesMessage);
+	}
+
+	private void onRNSNetworkGetSignaturesV2Message(RNSPeer peer, Message message) {
+		GetSignaturesV2Message getSignaturesMessage = (GetSignaturesV2Message) message;
+		final byte[] parentSignature = getSignaturesMessage.getParentSignature();
+		this.stats.getBlockSignaturesV2Stats.requests.incrementAndGet();
+
+		// If peer's parent signature matches our latest block signature
+		// then we can short-circuit with an empty response
+		BlockData chainTip = getChainTip();
+		if (chainTip != null && Arrays.equals(parentSignature, chainTip.getSignature())) {
+			Message signaturesMessage = new SignaturesMessage(Collections.emptyList());
+			signaturesMessage.setId(message.getId());
+			//if (!peer.sendMessage(signaturesMessage))
+			//	peer.disconnect("failed to send signatures (v2)");
+			peer.sendMessage(signaturesMessage);
+
+			return;
+		}
+
+		List<byte[]> signatures = new ArrayList<>();
+
+		// Attempt to serve from our cache of latest blocks
+		synchronized (this.latestBlocks) {
+			signatures = this.latestBlocks.stream()
+					.dropWhile(cachedBlockData -> !Arrays.equals(cachedBlockData.getReference(), parentSignature))
+					.map(BlockData::getSignature)
+					.collect(Collectors.toList());
+		}
+
+		if (signatures.isEmpty()) {
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				int numberRequested = getSignaturesMessage.getNumberRequested();
+				BlockData blockData = repository.getBlockRepository().fromReference(parentSignature);
+				if (blockData == null) {
+					// Try the archive
+					blockData = repository.getBlockArchiveRepository().fromReference(parentSignature);
+				}
+
+				while (blockData != null && signatures.size() < numberRequested) {
+					signatures.add(blockData.getSignature());
+
+					byte[] previousSignature = blockData.getSignature();
+					blockData = repository.getBlockRepository().fromReference(previousSignature);
+					if (blockData == null) {
+						// Try the archive
+						blockData = repository.getBlockArchiveRepository().fromReference(previousSignature);
+					}
+				}
+			} catch (DataException e) {
+				LOGGER.error(String.format("Repository issue while sending V2 signatures after %s to peer %s", Base58.encode(parentSignature), peer), e);
+			}
+		} else {
+			this.stats.getBlockSignaturesV2Stats.cacheHits.incrementAndGet();
+
+			if (signatures.size() >= getSignaturesMessage.getNumberRequested())
+				this.stats.getBlockSignaturesV2Stats.fullyFromCache.incrementAndGet();
+		}
+
+		Message signaturesMessage = new SignaturesMessage(signatures);
+		signaturesMessage.setId(message.getId());
+		//if (!peer.sendMessage(signaturesMessage))
+		//	peer.disconnect("failed to send signatures (v2)");
+		peer.sendMessage(signaturesMessage);
+	}
+
+	private void onRNSNetworkHeightV2Message(RNSPeer peer, Message message) {
+		HeightV2Message heightV2Message = (HeightV2Message) message;
+
+		if (!Settings.getInstance().isLite()) {
+			// 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.getIsInitiator() && peer.getChainTipData() == null) {
+				Message responseMessage = RNSNetwork.getInstance().buildHeightOrChainTipInfo(peer);
+				peer.sendMessage(responseMessage);
+			}
+		}
+
+		// Update peer chain tip data
+		BlockSummaryData newChainTipData = new BlockSummaryData(heightV2Message.getHeight(), heightV2Message.getSignature(), heightV2Message.getMinterPublicKey(), heightV2Message.getTimestamp());
+		peer.setChainTipData(newChainTipData);
+
+		// Potentially synchronize
+		Synchronizer.getInstance().requestSync();
+	}
+
+	private void onRNSNetworkBlockSummariesV2Message(RNSPeer 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.getIsInitiator() && peer.getChainTipData() == null) {
+				Message responseMessage = RNSNetwork.getInstance().buildHeightOrChainTipInfo(peer);
+				peer.sendMessage(responseMessage);
+			}
+		}
+
+		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.debug("Discarding late {} message with ID {} from {}", message.getType().name(), message.getId(), peer);
+			return;
+		}
+
+		// Update peer chain tip data
+		peer.setChainTipSummaries(blockSummariesV2Message.getBlockSummaries());
+
+		// Potentially synchronize
+		Synchronizer.getInstance().requestSync();
+	}
+
+	// ************
+
+	private void onRNSNetworkGetAccountMessage(RNSPeer peer, Message message) {
+		GetAccountMessage getAccountMessage = (GetAccountMessage) message;
+		String address = getAccountMessage.getAddress();
+		this.stats.getAccountMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountData accountData = repository.getAccountRepository().getAccount(address);
+
+			if (accountData == null) {
+				// We don't have this account
+				this.stats.getAccountMessageStats.unknownAccounts.getAndIncrement();
+
+				// 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));
+
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
+				accountUnknownMessage.setId(message.getId());
+				peer.sendMessage(accountUnknownMessage);
+				return;
+			}
+
+			AccountMessage accountMessage = new AccountMessage(accountData);
+			accountMessage.setId(message.getId());
+
+			// handle in timeout callback instead
+			//if (!peer.sendMessage(accountMessage)) {
+			//	peer.disconnect("failed to send account");
+			//}
+			peer.sendMessage(accountMessage);
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send account %s to peer %s", address, peer), e);
+		}
+	}
+
+	private void onRNSNetworkGetAccountBalanceMessage(RNSPeer peer, Message message) {
+		GetAccountBalanceMessage getAccountBalanceMessage = (GetAccountBalanceMessage) message;
+		String address = getAccountBalanceMessage.getAddress();
+		long assetId = getAccountBalanceMessage.getAssetId();
+		this.stats.getAccountBalanceMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			AccountBalanceData accountBalanceData = repository.getAccountRepository().getBalance(address, assetId);
+
+			if (accountBalanceData == null) {
+				// We don't have this account
+				this.stats.getAccountBalanceMessageStats.unknownAccounts.getAndIncrement();
+
+				// 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));
+
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
+				accountUnknownMessage.setId(message.getId());
+				peer.sendMessage(accountUnknownMessage);
+				return;
+			}
+
+			AccountBalanceMessage accountMessage = new AccountBalanceMessage(accountBalanceData);
+			accountMessage.setId(message.getId());
+
+			// handle in timeout callback instead
+			//if (!peer.sendMessage(accountMessage)) {
+			//	peer.disconnect("failed to send account balance");
+			//}
+			peer.sendMessage(accountMessage);
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send balance for account %s and asset ID %d to peer %s", address, assetId, peer), e);
+		}
+	}
+
+	private void onRNSNetworkGetAccountTransactionsMessage(RNSPeer peer, Message message) {
+		GetAccountTransactionsMessage getAccountTransactionsMessage = (GetAccountTransactionsMessage) message;
+		String address = getAccountTransactionsMessage.getAddress();
+		int limit = Math.min(getAccountTransactionsMessage.getLimit(), 100);
+		int offset = getAccountTransactionsMessage.getOffset();
+		this.stats.getAccountTransactionsMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<byte[]> signatures = repository.getTransactionRepository().getSignaturesMatchingCriteria(null, null, null,
+					null, null, null, address, TransactionsResource.ConfirmationStatus.CONFIRMED, limit, offset, false);
+
+			// Expand signatures to transactions
+			List<TransactionData> transactions = new ArrayList<>(signatures.size());
+			for (byte[] signature : signatures) {
+				transactions.add(repository.getTransactionRepository().fromSignature(signature));
+			}
+
+			if (transactions == null) {
+				// We don't have this account
+				this.stats.getAccountTransactionsMessageStats.unknownAccounts.getAndIncrement();
+
+				// 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));
+
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
+				accountUnknownMessage.setId(message.getId());
+				peer.sendMessage(accountUnknownMessage);
+				return;
+			}
+
+			TransactionsMessage transactionsMessage = new TransactionsMessage(transactions);
+			transactionsMessage.setId(message.getId());
+
+			// handle in timeout callback instead
+			//if (!peer.sendMessage(transactionsMessage)) {
+			//	peer.disconnect("failed to send account transactions");
+			//}
+			peer.sendMessage(transactionsMessage);
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while sending transactions for account %s %d to peer %s", address, peer), e);
+		} catch (MessageException e) {
+			LOGGER.error(String.format("Message serialization issue while sending transactions for account %s %d to peer %s", address, peer), e);
+		}
+	}
+
+	private void onRNSNetworkGetAccountNamesMessage(RNSPeer peer, Message message) {
+		GetAccountNamesMessage getAccountNamesMessage = (GetAccountNamesMessage) message;
+		String address = getAccountNamesMessage.getAddress();
+		this.stats.getAccountNamesMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			List<NameData> namesDataList = repository.getNameRepository().getNamesByOwner(address);
+
+			if (namesDataList == null) {
+				// We don't have this account
+				this.stats.getAccountNamesMessageStats.unknownAccounts.getAndIncrement();
+
+				// 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));
+
+				// Send generic 'unknown' message as it's very short
+				Message accountUnknownMessage = new GenericUnknownMessage();
+				accountUnknownMessage.setId(message.getId());
+				peer.sendMessage(accountUnknownMessage);
+				return;
+			}
+
+			NamesMessage namesMessage = new NamesMessage(namesDataList);
+			namesMessage.setId(message.getId());
+
+			// handle in timeout callback instead
+			//if (!peer.sendMessage(namesMessage)) {
+			//	peer.disconnect("failed to send account names");
+			//}
+			peer.sendMessage(namesMessage);
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send names for account %s to peer %s", address, peer), e);
+		}
+	}
+
+	private void onRNSNetworkGetNameMessage(RNSPeer peer, Message message) {
+		GetNameMessage getNameMessage = (GetNameMessage) message;
+		String name = getNameMessage.getName();
+		this.stats.getNameMessageStats.requests.incrementAndGet();
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			NameData nameData = repository.getNameRepository().fromName(name);
+
+			if (nameData == null) {
+				// We don't have this account
+				this.stats.getNameMessageStats.unknownAccounts.getAndIncrement();
+
+				// 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));
+
+				// Send generic 'unknown' message as it's very short
+				Message nameUnknownMessage = new GenericUnknownMessage();
+				nameUnknownMessage.setId(message.getId());
+				if (!peer.sendMessage(nameUnknownMessage))
+				peer.sendMessage(nameUnknownMessage);
+				return;
+			}
+
+			NamesMessage namesMessage = new NamesMessage(Arrays.asList(nameData));
+			namesMessage.setId(message.getId());
+
+			// handle in timeout callback instead
+			//if (!peer.sendMessage(namesMessage)) {
+			//	peer.disconnect("failed to send name data");
+			//}
+			peer.sendMessage(namesMessage);
+
+		} catch (DataException e) {
+			LOGGER.error(String.format("Repository issue while send name %s to peer %s", name, peer), e);
+		}
+	}
+
+	/**
+	 * Returns whether we think our node has up-to-date blockchain based on our info about other peers.
+	 * @param minLatestBlockTimestamp - the minimum block timestamp to be considered recent
+	 * @return boolean - whether our node's blockchain is up to date or not
+	 */
+	public boolean isUpToDateRNS(Long minLatestBlockTimestamp) {
+		if (Settings.getInstance().isLite()) {
+			// Lite nodes are always "up to date"
+			return true;
+		}
+
+		// Do we even have a vaguely recent block?
+		if (minLatestBlockTimestamp == null)
+			return false;
+
+		final BlockData latestBlockData = getChainTip();
+		if (latestBlockData == null || latestBlockData.getTimestamp() < minLatestBlockTimestamp)
+			return false;
+
+		if (Settings.getInstance().isSingleNodeTestnet())
+			// Single node testnets won't have peers, so we can assume up to date from this point
+			return true;
+
+		// Needs a mutable copy of the unmodifiableList
+		List<RNSPeer> peers = new ArrayList<>(RNSNetwork.getInstance().getImmutableLinkedPeers());
+		if (peers == null)
+			return false;
+
+		//// Disregard peers that have "misbehaved" recently
+		//peers.removeIf(hasMisbehaved);
+		//
+		//// Disregard peers that don't have a recent block
+		//peers.removeIf(hasNoRecentBlock);
+
+		// Check we have enough peers to potentially synchronize/mint
+		if (peers.size() < Settings.getInstance().getReticulumMinDesiredPeers())
+			return false;
+
+		// If we don't have any peers left then can't synchronize, therefore consider ourself not up to date
+		return !peers.isEmpty();
+	}
+
+	/**
+	 * Returns whether we think our node has up-to-date blockchain based on our info about other peers.
+	 * Uses the default minLatestBlockTimestamp value.
+	 * @return boolean - whether our node's blockchain is up to date or not
+	 */
+	public boolean isUpToDateRNS() {
+		final Long minLatestBlockTimestamp = getMinimumLatestBlockTimestamp();
+		return this.isUpToDate(minLatestBlockTimestamp);
+	}
 }

src/main/java/org/qortal/controller/RNSTransactionImporter.java

@@ -0,0 +1,460 @@
+package org.qortal.controller;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.data.block.BlockData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
+import org.qortal.network.message.GetTransactionMessage;
+import org.qortal.network.message.Message;
+import org.qortal.network.message.TransactionMessage;
+import org.qortal.network.message.TransactionSignaturesMessage;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.transaction.Transaction;
+import org.qortal.transform.TransformationException;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.util.*;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.stream.Collectors;
+
+public class RNSTransactionImporter extends Thread {
+
+    private static final Logger LOGGER = LogManager.getLogger(RNSTransactionImporter.class);
+
+    private static RNSTransactionImporter instance;
+    private volatile boolean isStopping = false;
+
+    private static final int MAX_INCOMING_TRANSACTIONS = 5000;
+
+    /** Minimum time before considering an invalid unconfirmed transaction as "stale" */
+    public static final long INVALID_TRANSACTION_STALE_TIMEOUT = 30 * 60 * 1000L; // ms
+    /** Minimum frequency to re-request stale unconfirmed transactions from peers, to recheck validity */
+    public static final long INVALID_TRANSACTION_RECHECK_INTERVAL = 60 * 60 * 1000L; // ms\
+    /** Minimum frequency to re-request expired unconfirmed transactions from peers, to recheck validity
+     * This mainly exists to stop expired transactions from bloating the list */
+    public static final long EXPIRED_TRANSACTION_RECHECK_INTERVAL = 10 * 60 * 1000L; // ms
+
+
+    /** Map of incoming transaction that are in the import queue. Key is transaction data, value is whether signature has been validated. */
+    private final Map<TransactionData, Boolean> incomingTransactions = Collections.synchronizedMap(new HashMap<>());
+
+    /** Map of recent invalid unconfirmed transactions. Key is base58 transaction signature, value is do-not-request expiry timestamp. */
+    private final Map<String, Long> invalidUnconfirmedTransactions = Collections.synchronizedMap(new HashMap<>());
+
+    /** Cached list of unconfirmed transactions, used when counting per creator. This is replaced regularly */
+    public static List<TransactionData> unconfirmedTransactionsCache = null;
+
+
+    public static synchronized RNSTransactionImporter getInstance() {
+        if (instance == null) {
+            instance = new RNSTransactionImporter();
+        }
+
+        return instance;
+    }
+
+    @Override
+    public void run() {
+        Thread.currentThread().setName("Transaction Importer");
+
+        try {
+            while (!Controller.isStopping()) {
+                Thread.sleep(500L);
+
+                // Process incoming transactions queue
+                validateTransactionsInQueue();
+                importTransactionsInQueue();
+
+                // Clean up invalid incoming transactions list
+                cleanupInvalidTransactionsList(NTP.getTime());
+            }
+        } catch (InterruptedException e) {
+            // Fall through to exit thread
+        }
+    }
+
+    public void shutdown() {
+        isStopping = true;
+        this.interrupt();
+    }
+
+
+    // Incoming transactions queue
+
+    private boolean incomingTransactionQueueContains(byte[] signature) {
+        synchronized (incomingTransactions) {
+            return incomingTransactions.keySet().stream().anyMatch(t -> Arrays.equals(t.getSignature(), signature));
+        }
+    }
+
+    private void removeIncomingTransaction(byte[] signature) {
+        incomingTransactions.keySet().removeIf(t -> Arrays.equals(t.getSignature(), signature));
+    }
+
+    /**
+     * Retrieve all pending unconfirmed transactions that have had their signatures validated.
+     * @return a list of TransactionData objects, with valid signatures.
+     */
+    private List<TransactionData> getCachedSigValidTransactions() {
+        synchronized (this.incomingTransactions) {
+            return this.incomingTransactions.entrySet().stream()
+                    .filter(t -> Boolean.TRUE.equals(t.getValue()))
+                    .map(Map.Entry::getKey)
+                    .collect(Collectors.toList());
+        }
+    }
+
+    /**
+     * Validate the signatures of any transactions pending import, then update their
+     * entries in the queue to mark them as valid/invalid.
+     *
+     * No database lock is required.
+     */
+    private void validateTransactionsInQueue() {
+        if (this.incomingTransactions.isEmpty()) {
+            // Nothing to do?
+            return;
+        }
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            // Take a snapshot of incomingTransactions, so we don't need to lock it while processing
+            Map<TransactionData, Boolean> incomingTransactionsCopy = Map.copyOf(this.incomingTransactions);
+
+            int unvalidatedCount = Collections.frequency(incomingTransactionsCopy.values(), Boolean.FALSE);
+            int validatedCount = 0;
+
+            if (unvalidatedCount > 0) {
+                LOGGER.debug("Validating signatures in incoming transactions queue (size {})...", unvalidatedCount);
+            }
+
+            // A list of all currently pending transactions that have valid signatures
+            List<Transaction> sigValidTransactions = new ArrayList<>();
+
+            // A list of signatures that became valid in this round
+            List<byte[]> newlyValidSignatures = new ArrayList<>();
+
+            boolean isLiteNode = Settings.getInstance().isLite();
+
+            // We need the latest block in order to check for expired transactions
+            BlockData latestBlock = Controller.getInstance().getChainTip();
+
+            // Signature validation round - does not require blockchain lock
+            for (Map.Entry<TransactionData, Boolean> transactionEntry : incomingTransactionsCopy.entrySet()) {
+                // Quick exit?
+                if (isStopping) {
+                    return;
+                }
+
+                TransactionData transactionData = transactionEntry.getKey();
+                Transaction transaction = Transaction.fromData(repository, transactionData);
+                String signature58 = Base58.encode(transactionData.getSignature());
+
+                Long now = NTP.getTime();
+                if (now == null) {
+                    return;
+                }
+
+                // Drop expired transactions before they are considered "sig valid"
+                if (latestBlock != null && transaction.getDeadline() <= latestBlock.getTimestamp()) {
+                    LOGGER.debug("Removing expired {} transaction {} from import queue", transactionData.getType().name(), signature58);
+                    removeIncomingTransaction(transactionData.getSignature());
+                    invalidUnconfirmedTransactions.put(signature58, (now + EXPIRED_TRANSACTION_RECHECK_INTERVAL));
+                    continue;
+                }
+
+                // Only validate signature if we haven't already done so
+                Boolean isSigValid = transactionEntry.getValue();
+                if (!Boolean.TRUE.equals(isSigValid)) {
+                    if (isLiteNode) {
+                        // Lite nodes can't easily validate transactions, so for now we will have to assume that everything is valid
+                        sigValidTransactions.add(transaction);
+                        newlyValidSignatures.add(transactionData.getSignature());
+                        // Add mark signature as valid if transaction still exists in import queue
+                        incomingTransactions.computeIfPresent(transactionData, (k, v) -> Boolean.TRUE);
+                        continue;
+                    }
+
+                    if (!transaction.isSignatureValid()) {
+                        LOGGER.debug("Ignoring {} transaction {} with invalid signature", transactionData.getType().name(), signature58);
+                        removeIncomingTransaction(transactionData.getSignature());
+
+                        // Also add to invalidIncomingTransactions map
+                        now = NTP.getTime();
+                        if (now != null) {
+                            Long expiry = now + INVALID_TRANSACTION_RECHECK_INTERVAL;
+                            LOGGER.trace("Adding invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
+                            // Add to invalidUnconfirmedTransactions so that we don't keep requesting it
+                            invalidUnconfirmedTransactions.put(signature58, expiry);
+                        }
+
+                        // We're done with this transaction
+                        continue;
+                    }
+
+                    // Count the number that were validated in this round, for logging purposes
+                    validatedCount++;
+
+                    // Add mark signature as valid if transaction still exists in import queue
+                    incomingTransactions.computeIfPresent(transactionData, (k, v) -> Boolean.TRUE);
+
+                    // Signature validated in this round
+                    newlyValidSignatures.add(transactionData.getSignature());
+
+                } else {
+                    LOGGER.trace(() -> String.format("Transaction %s known to have valid signature", Base58.encode(transactionData.getSignature())));
+                }
+
+                // Signature valid - add to shortlist
+                sigValidTransactions.add(transaction);
+            }
+
+            if (unvalidatedCount > 0) {
+                LOGGER.debug("Finished validating signatures in incoming transactions queue (valid this round: {}, total pending import: {})...", validatedCount, sigValidTransactions.size());
+            }
+
+        } catch (DataException e) {
+            LOGGER.error("Repository issue while processing incoming transactions", e);
+        }
+    }
+
+    /**
+     * Import any transactions in the queue that have valid signatures.
+     *
+     * A database lock is required.
+     */
+    private void importTransactionsInQueue() {
+        List<TransactionData> sigValidTransactions = this.getCachedSigValidTransactions();
+        if (sigValidTransactions.isEmpty()) {
+            // Don't bother locking if there are no new transactions to process
+            return;
+        }
+
+        if (Synchronizer.getInstance().isSyncRequested() || Synchronizer.getInstance().isSynchronizing()) {
+            // Prioritize syncing, and don't attempt to lock
+            return;
+        }
+
+        ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+        if (!blockchainLock.tryLock()) {
+            LOGGER.debug("Too busy to import incoming transactions queue");
+            return;
+        }
+
+        LOGGER.debug("Importing incoming transactions queue (size {})...", sigValidTransactions.size());
+
+        int processedCount = 0;
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Use a single copy of the unconfirmed transactions list for each cycle, to speed up constant lookups
+            // when counting unconfirmed transactions by creator.
+            List<TransactionData> unconfirmedTransactions = repository.getTransactionRepository().getUnconfirmedTransactions();
+            unconfirmedTransactions.removeIf(t -> t.getType() == Transaction.TransactionType.CHAT);
+            unconfirmedTransactionsCache = unconfirmedTransactions;
+
+            // A list of signatures were imported in this round
+            List<byte[]> newlyImportedSignatures = new ArrayList<>();
+
+            // Import transactions with valid signatures
+            try {
+                for (int i = 0; i < sigValidTransactions.size(); ++i) {
+                    if (isStopping) {
+                        return;
+                    }
+
+                    if (Synchronizer.getInstance().isSyncRequestPending()) {
+                        LOGGER.debug("Breaking out of transaction importing with {} remaining, because a sync request is pending", sigValidTransactions.size() - i);
+                        return;
+                    }
+
+                    TransactionData transactionData = sigValidTransactions.get(i);
+                    Transaction transaction = Transaction.fromData(repository, transactionData);
+
+                    Transaction.ValidationResult validationResult = transaction.importAsUnconfirmed();
+                    processedCount++;
+
+                    switch (validationResult) {
+                        case TRANSACTION_ALREADY_EXISTS: {
+                            LOGGER.trace(() -> String.format("Ignoring existing transaction %s", Base58.encode(transactionData.getSignature())));
+                            break;
+                        }
+
+                        case NO_BLOCKCHAIN_LOCK: {
+                            // Is this even possible considering we acquired blockchain lock above?
+                            LOGGER.trace(() -> String.format("Couldn't lock blockchain to import unconfirmed transaction %s", Base58.encode(transactionData.getSignature())));
+                            break;
+                        }
+
+                        case OK: {
+                            LOGGER.debug(() -> String.format("Imported %s transaction %s", transactionData.getType().name(), Base58.encode(transactionData.getSignature())));
+
+                            // Add to the unconfirmed transactions cache
+                            if (transactionData.getType() != Transaction.TransactionType.CHAT && unconfirmedTransactionsCache != null) {
+                                unconfirmedTransactionsCache.add(transactionData);
+                            }
+
+                            // Signature imported in this round
+                            newlyImportedSignatures.add(transactionData.getSignature());
+
+                            break;
+                        }
+
+                        // All other invalid cases:
+                        default: {
+                            final String signature58 = Base58.encode(transactionData.getSignature());
+                            LOGGER.debug(() -> String.format("Ignoring invalid (%s) %s transaction %s", validationResult.name(), transactionData.getType().name(), signature58));
+
+                            Long now = NTP.getTime();
+                            if (now != null && now - transactionData.getTimestamp() > INVALID_TRANSACTION_STALE_TIMEOUT) {
+                                Long expiryLength = INVALID_TRANSACTION_RECHECK_INTERVAL;
+
+                                if (validationResult == Transaction.ValidationResult.TIMESTAMP_TOO_OLD) {
+                                    // Use shorter recheck interval for expired transactions
+                                    expiryLength = EXPIRED_TRANSACTION_RECHECK_INTERVAL;
+                                }
+
+                                Long expiry = now + expiryLength;
+                                LOGGER.trace("Adding stale invalid transaction {} to invalidUnconfirmedTransactions...", signature58);
+                                // Invalid, unconfirmed transaction has become stale - add to invalidUnconfirmedTransactions so that we don't keep requesting it
+                                invalidUnconfirmedTransactions.put(signature58, expiry);
+                            }
+                        }
+                    }
+
+                    // Transaction has been processed, even if only to reject it
+                    removeIncomingTransaction(transactionData.getSignature());
+                }
+
+                if (!newlyImportedSignatures.isEmpty()) {
+                    LOGGER.debug("Broadcasting {} newly imported signatures", newlyImportedSignatures.size());
+                    Message newTransactionSignatureMessage = new TransactionSignaturesMessage(newlyImportedSignatures);
+                    RNSNetwork.getInstance().broadcast(broadcastPeer -> newTransactionSignatureMessage);
+                }
+            } finally {
+                LOGGER.debug("Finished importing {} incoming transaction{}", processedCount, (processedCount == 1 ? "" : "s"));
+                blockchainLock.unlock();
+
+                // Clear the unconfirmed transaction cache so new data can be populated in the next cycle
+                unconfirmedTransactionsCache = null;
+            }
+        } catch (DataException e) {
+            LOGGER.error("Repository issue while importing incoming transactions", e);
+        }
+    }
+
+    private void cleanupInvalidTransactionsList(Long now) {
+        if (now == null) {
+            return;
+        }
+        // Periodically remove invalid unconfirmed transactions from the list, so that they can be fetched again
+        invalidUnconfirmedTransactions.entrySet().removeIf(entry -> entry.getValue() == null || entry.getValue() < now);
+    }
+
+
+    // Network handlers
+
+    public void onNetworkTransactionMessage(RNSPeer peer, Message message) {
+        TransactionMessage transactionMessage = (TransactionMessage) message;
+        TransactionData transactionData = transactionMessage.getTransactionData();
+
+        if (this.incomingTransactions.size() < MAX_INCOMING_TRANSACTIONS) {
+            synchronized (this.incomingTransactions) {
+                if (!incomingTransactionQueueContains(transactionData.getSignature())) {
+                    this.incomingTransactions.put(transactionData, Boolean.FALSE);
+                }
+            }
+        }
+    }
+
+    public void onNetworkGetTransactionMessage(RNSPeer peer, Message message) {
+        GetTransactionMessage getTransactionMessage = (GetTransactionMessage) message;
+        byte[] signature = getTransactionMessage.getSignature();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            // Firstly check the sig-valid transactions that are currently queued for import
+            TransactionData transactionData = this.getCachedSigValidTransactions().stream()
+                    .filter(t -> Arrays.equals(signature, t.getSignature()))
+                    .findFirst().orElse(null);
+
+            if (transactionData == null) {
+                // Not found in import queue, so try the database
+                transactionData = repository.getTransactionRepository().fromSignature(signature);
+            }
+
+            if (transactionData == null) {
+                // Still not found - so we don't have this transaction
+                LOGGER.debug(() -> String.format("Ignoring GET_TRANSACTION request from peer %s for unknown transaction %s", peer, Base58.encode(signature)));
+                // Send no response at all???
+                return;
+            }
+
+            Message transactionMessage = new TransactionMessage(transactionData);
+            transactionMessage.setId(message.getId());
+            peer.sendMessage(transactionMessage);
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while sending transaction %s to peer %s", Base58.encode(signature), peer), e);
+        } catch (TransformationException e) {
+            LOGGER.error(String.format("Serialization issue while sending transaction %s to peer %s", Base58.encode(signature), peer), e);
+        }
+    }
+
+    public void onNetworkGetUnconfirmedTransactionsMessage(RNSPeer peer, Message message) {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            List<byte[]> signatures = Collections.emptyList();
+
+            // If we're NOT up-to-date then don't send out unconfirmed transactions
+            // as it's possible they are already included in a later block that we don't have.
+            if (Controller.getInstance().isUpToDate())
+                signatures = repository.getTransactionRepository().getUnconfirmedTransactionSignatures();
+
+            Message transactionSignaturesMessage = new TransactionSignaturesMessage(signatures);
+            peer.sendMessage(transactionSignaturesMessage);
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while sending unconfirmed transaction signatures to peer %s", peer), e);
+        }
+    }
+
+    public void onNetworkTransactionSignaturesMessage(RNSPeer peer, Message message) {
+        TransactionSignaturesMessage transactionSignaturesMessage = (TransactionSignaturesMessage) message;
+        List<byte[]> signatures = transactionSignaturesMessage.getSignatures();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            for (byte[] signature : signatures) {
+                String signature58 = Base58.encode(signature);
+                if (invalidUnconfirmedTransactions.containsKey(signature58)) {
+                    // Previously invalid transaction - don't keep requesting it
+                    // It will be periodically removed from invalidUnconfirmedTransactions to allow for rechecks
+                    continue;
+                }
+
+                // Ignore if this transaction is in the queue
+                if (incomingTransactionQueueContains(signature)) {
+                    LOGGER.trace(() -> String.format("Ignoring existing queued transaction %s from peer %s", Base58.encode(signature), peer));
+                    continue;
+                }
+
+                // Do we have it already? (Before requesting transaction data itself)
+                if (repository.getTransactionRepository().exists(signature)) {
+                    LOGGER.trace(() -> String.format("Ignoring existing transaction %s from peer %s", Base58.encode(signature), peer));
+                    continue;
+                }
+
+                // Check isInterrupted() here and exit fast
+                if (Thread.currentThread().isInterrupted())
+                    return;
+
+                // Fetch actual transaction data from peer
+                Message getTransactionMessage = new GetTransactionMessage(signature);
+                peer.sendMessage(getTransactionMessage);
+            }
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while processing unconfirmed transactions from peer %s", peer), e);
+        }
+    }
+
+}

src/main/java/org/qortal/controller/arbitrary/RNSArbitraryDataFileListManager.java

@@ -0,0 +1,731 @@
+package org.qortal.controller.arbitrary;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.arbitrary.ArbitraryDataFile;
+import org.qortal.arbitrary.ArbitraryDataFileChunk;
+import org.qortal.controller.Controller;
+import org.qortal.data.arbitrary.RNSArbitraryDirectConnectionInfo;
+import org.qortal.data.arbitrary.RNSArbitraryFileListResponseInfo;
+import org.qortal.data.arbitrary.RNSArbitraryRelayInfo;
+import org.qortal.data.transaction.ArbitraryTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
+import org.qortal.network.message.ArbitraryDataFileListMessage;
+import org.qortal.network.message.GetArbitraryDataFileListMessage;
+import org.qortal.network.message.Message;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.Base58;
+import org.qortal.utils.ListUtils;
+import org.qortal.utils.NTP;
+import org.qortal.utils.Triple;
+
+import java.util.*;
+
+import static org.qortal.controller.arbitrary.RNSArbitraryDataFileManager.MAX_FILE_HASH_RESPONSES;
+
+public class RNSArbitraryDataFileListManager {
+
+    private static final Logger LOGGER = LogManager.getLogger(RNSArbitraryDataFileListManager.class);
+
+    private static RNSArbitraryDataFileListManager instance;
+
+    private static String MIN_PEER_VERSION_FOR_FILE_LIST_STATS = "3.2.0";
+
+    /**
+     * Map of recent incoming requests for ARBITRARY transaction data file lists.
+     * <p>
+     * Key is original request's message ID<br>
+     * Value is Triple&lt;transaction signature in base58, first requesting peer, first request's timestamp&gt;
+     * <p>
+     * If peer is null then either:<br>
+     * <ul>
+     * <li>we are the original requesting peer</li>
+     * <li>we have already sent data payload to original requesting peer.</li>
+     * </ul>
+     * If signature is null then we have already received the file list and either:<br>
+     * <ul>
+     * <li>we are the original requesting peer and have processed it</li>
+     * <li>we have forwarded the file list</li>
+     * </ul>
+     */
+    public Map<Integer, Triple<String, RNSPeer, Long>> arbitraryDataFileListRequests = Collections.synchronizedMap(new HashMap<>());
+
+    /**
+     * Map to keep track of in progress arbitrary data signature requests
+     * Key: string - the signature encoded in base58
+     * Value: Triple<networkBroadcastCount, directPeerRequestCount, lastAttemptTimestamp>
+     */
+    private Map<String, Triple<Integer, Integer, Long>> arbitraryDataSignatureRequests = Collections.synchronizedMap(new HashMap<>());
+
+
+    /** Maximum number of seconds that a file list relay request is able to exist on the network */
+    public static long RELAY_REQUEST_MAX_DURATION = 5000L;
+    /** Maximum number of hops that a file list relay request is allowed to make */
+    public static int RELAY_REQUEST_MAX_HOPS = 4;
+
+    /** Minimum peer version to use relay */
+    public static String RELAY_MIN_PEER_VERSION = "3.4.0";
+
+
+    private RNSArbitraryDataFileListManager() {
+    }
+
+    public static RNSArbitraryDataFileListManager getInstance() {
+        if (instance == null)
+            instance = new RNSArbitraryDataFileListManager();
+
+        return instance;
+    }
+
+
+    public void cleanupRequestCache(Long now) {
+        if (now == null) {
+            return;
+        }
+        final long requestMinimumTimestamp = now - ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT;
+        arbitraryDataFileListRequests.entrySet().removeIf(entry -> entry.getValue().getC() == null || entry.getValue().getC() < requestMinimumTimestamp);
+    }
+
+
+    // Track file list lookups by signature
+
+    private boolean shouldMakeFileListRequestForSignature(String signature58) {
+        Triple<Integer, Integer, Long> request = arbitraryDataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        // Extract the components
+        Integer networkBroadcastCount = request.getA();
+        // Integer directPeerRequestCount = request.getB();
+        Long lastAttemptTimestamp = request.getC();
+
+        if (lastAttemptTimestamp == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        long timeSinceLastAttempt = NTP.getTime() - lastAttemptTimestamp;
+
+        // Allow a second attempt after 15 seconds, and another after 30 seconds
+        if (timeSinceLastAttempt > 15 * 1000L) {
+            // We haven't tried for at least 15 seconds
+
+            if (networkBroadcastCount < 3) {
+                // We've made less than 3 total attempts
+                return true;
+            }
+        }
+
+        // Then allow another 5 attempts, each 1 minute apart
+        if (timeSinceLastAttempt > 60 * 1000L) {
+            // We haven't tried for at least 1 minute
+
+            if (networkBroadcastCount < 8) {
+                // We've made less than 8 total attempts
+                return true;
+            }
+        }
+
+        // Then allow another 8 attempts, each 15 minutes apart
+        if (timeSinceLastAttempt > 15 * 60 * 1000L) {
+            // We haven't tried for at least 15 minutes
+
+            if (networkBroadcastCount < 16) {
+                // We've made less than 16 total attempts
+                return true;
+            }
+        }
+
+        // From then on, only try once every 6 hours, to reduce network spam
+        if (timeSinceLastAttempt > 6 * 60 * 60 * 1000L) {
+            // We haven't tried for at least 6 hours
+            return true;
+        }
+
+        return false;
+    }
+
+    private boolean shouldMakeDirectFileRequestsForSignature(String signature58) {
+        if (!Settings.getInstance().isDirectDataRetrievalEnabled()) {
+            // Direct connections are disabled in the settings
+            return false;
+        }
+
+        Triple<Integer, Integer, Long> request = arbitraryDataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        // Extract the components
+        //Integer networkBroadcastCount = request.getA();
+        Integer directPeerRequestCount = request.getB();
+        Long lastAttemptTimestamp = request.getC();
+
+        if (lastAttemptTimestamp == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        if (directPeerRequestCount == 0) {
+            // We haven't tried asking peers directly yet, so we should
+            return true;
+        }
+
+        long timeSinceLastAttempt = NTP.getTime() - lastAttemptTimestamp;
+        if (timeSinceLastAttempt > 10 * 1000L) {
+            // We haven't tried for at least 10 seconds
+            if (directPeerRequestCount < 5) {
+                // We've made less than 5 total attempts
+                return true;
+            }
+        }
+
+        if (timeSinceLastAttempt > 5 * 60 * 1000L) {
+            // We haven't tried for at least 5 minutes
+            if (directPeerRequestCount < 10) {
+                // We've made less than 10 total attempts
+                return true;
+            }
+        }
+
+        if (timeSinceLastAttempt > 60 * 60 * 1000L) {
+            // We haven't tried for at least 1 hour
+            return true;
+        }
+
+        return false;
+    }
+
+    public boolean isSignatureRateLimited(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        return !this.shouldMakeFileListRequestForSignature(signature58)
+                && !this.shouldMakeDirectFileRequestsForSignature(signature58);
+    }
+
+    public long lastRequestForSignature(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        Triple<Integer, Integer, Long> request = arbitraryDataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return 0;
+        }
+
+        // Extract the components
+        Long lastAttemptTimestamp = request.getC();
+        if (lastAttemptTimestamp != null) {
+            return  lastAttemptTimestamp;
+        }
+        return 0;
+    }
+
+    public void addToSignatureRequests(String signature58, boolean incrementNetworkRequests, boolean incrementPeerRequests) {
+        Triple<Integer, Integer, Long> request  = arbitraryDataSignatureRequests.get(signature58);
+        Long now = NTP.getTime();
+
+        if (request == null) {
+            // No entry yet
+            Triple<Integer, Integer, Long> newRequest = new Triple<>(0, 0, now);
+            arbitraryDataSignatureRequests.put(signature58, newRequest);
+        }
+        else {
+            // There is an existing entry
+            if (incrementNetworkRequests) {
+                request.setA(request.getA() + 1);
+            }
+            if (incrementPeerRequests) {
+                request.setB(request.getB() + 1);
+            }
+            request.setC(now);
+            arbitraryDataSignatureRequests.put(signature58, request);
+        }
+    }
+
+    public void removeFromSignatureRequests(String signature58) {
+        arbitraryDataSignatureRequests.remove(signature58);
+    }
+
+
+    // Lookup file lists by signature (and optionally hashes)
+
+    public boolean fetchArbitraryDataFileList(ArbitraryTransactionData arbitraryTransactionData) {
+        byte[] signature = arbitraryTransactionData.getSignature();
+        String signature58 = Base58.encode(signature);
+
+        // Require an NTP sync
+        Long now = NTP.getTime();
+        if (now == null) {
+            return false;
+        }
+
+        // If we've already tried too many times in a short space of time, make sure to give up
+        if (!this.shouldMakeFileListRequestForSignature(signature58)) {
+            // Check if we should make direct connections to peers
+            if (this.shouldMakeDirectFileRequestsForSignature(signature58)) {
+                return RNSArbitraryDataFileManager.getInstance().fetchDataFilesFromPeersForSignature(signature);
+            }
+
+            LOGGER.trace("Skipping file list request for signature {} due to rate limit", signature58);
+            return false;
+        }
+        this.addToSignatureRequests(signature58, true, false);
+
+        //List<Peer> handshakedPeers = Network.getInstance().getImmutableHandshakedPeers();
+        List<RNSPeer> handshakedPeers = RNSNetwork.getInstance().getLinkedPeers();
+        List<byte[]> missingHashes = null;
+
+        // Find hashes that we are missing
+        try {
+            ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromTransactionData(arbitraryTransactionData);
+            missingHashes = arbitraryDataFile.missingHashes();
+        } catch (DataException e) {
+            // Leave missingHashes as null, so that all hashes are requested
+        }
+        int hashCount = missingHashes != null ? missingHashes.size() : 0;
+
+        LOGGER.debug(String.format("Sending data file list request for signature %s with %d hashes to %d peers...", signature58, hashCount, handshakedPeers.size()));
+
+        //// Send our address as requestingPeer, to allow for potential direct connections with seeds/peers
+        //String requestingPeer = Network.getInstance().getOurExternalIpAddressAndPort();
+        String requestingPeer = null;
+
+        // Build request
+        Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, missingHashes, now, 0, requestingPeer);
+
+        // Save our request into requests map
+        Triple<String, RNSPeer, Long> requestEntry = new Triple<>(signature58, null, NTP.getTime());
+
+        // Assign random ID to this message
+        int id;
+        do {
+            id = new Random().nextInt(Integer.MAX_VALUE - 1) + 1;
+
+            // Put queue into map (keyed by message ID) so we can poll for a response
+            // If putIfAbsent() doesn't return null, then this ID is already taken
+        } while (arbitraryDataFileListRequests.put(id, requestEntry) != null);
+        getArbitraryDataFileListMessage.setId(id);
+
+        // Broadcast request
+        RNSNetwork.getInstance().broadcast(peer -> getArbitraryDataFileListMessage);
+
+        // Poll to see if data has arrived
+        final long singleWait = 100;
+        long totalWait = 0;
+        while (totalWait < ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT) {
+            try {
+                Thread.sleep(singleWait);
+            } catch (InterruptedException e) {
+                break;
+            }
+
+            requestEntry = arbitraryDataFileListRequests.get(id);
+            if (requestEntry == null)
+                return false;
+
+            if (requestEntry.getA() == null)
+                break;
+
+            totalWait += singleWait;
+        }
+        return true;
+    }
+
+    public boolean fetchArbitraryDataFileList(RNSPeer peer, byte[] signature) {
+        String signature58 = Base58.encode(signature);
+
+        // Require an NTP sync
+        Long now = NTP.getTime();
+        if (now == null) {
+            return false;
+        }
+
+        int hashCount = 0;
+        LOGGER.debug(String.format("Sending data file list request for signature %s with %d hashes to peer %s...", signature58, hashCount, peer));
+
+        // Build request
+        // Use a time in the past, so that the recipient peer doesn't try and relay it
+        // Also, set hashes to null since it's easier to request all hashes than it is to determine which ones we need
+        // This could be optimized in the future
+        long timestamp = now - 60000L;
+        List<byte[]> hashes = null;
+        Message getArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, hashes, timestamp, 0, null);
+
+        // Save our request into requests map
+        Triple<String, RNSPeer, Long> requestEntry = new Triple<>(signature58, null, NTP.getTime());
+
+        // Assign random ID to this message
+        int id;
+        do {
+            id = new Random().nextInt(Integer.MAX_VALUE - 1) + 1;
+
+            // Put queue into map (keyed by message ID) so we can poll for a response
+            // If putIfAbsent() doesn't return null, then this ID is already taken
+        } while (arbitraryDataFileListRequests.put(id, requestEntry) != null);
+        getArbitraryDataFileListMessage.setId(id);
+
+        // Send the request
+        peer.sendMessage(getArbitraryDataFileListMessage);
+
+        // Poll to see if data has arrived
+        final long singleWait = 100;
+        long totalWait = 0;
+        while (totalWait < ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT) {
+            try {
+                Thread.sleep(singleWait);
+            } catch (InterruptedException e) {
+                break;
+            }
+
+            requestEntry = arbitraryDataFileListRequests.get(id);
+            if (requestEntry == null)
+                return false;
+
+            if (requestEntry.getA() == null)
+                break;
+
+            totalWait += singleWait;
+        }
+        return true;
+    }
+
+    public void deleteFileListRequestsForSignature(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        for (Iterator<Map.Entry<Integer, Triple<String, RNSPeer, Long>>> it = arbitraryDataFileListRequests.entrySet().iterator(); it.hasNext();) {
+            Map.Entry<Integer, Triple<String, RNSPeer, Long>> entry = it.next();
+            if (entry == null || entry.getKey() == null || entry.getValue() != null) {
+                continue;
+            }
+            if (Objects.equals(entry.getValue().getA(), signature58)) {
+                // Update requests map to reflect that we've received all chunks
+                Triple<String, RNSPeer, Long> newEntry = new Triple<>(null, null, entry.getValue().getC());
+                arbitraryDataFileListRequests.put(entry.getKey(), newEntry);
+            }
+        }
+    }
+
+    // Network handlers
+
+    public void onNetworkArbitraryDataFileListMessage(RNSPeer peer, Message message) {
+        // Don't process if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        ArbitraryDataFileListMessage arbitraryDataFileListMessage = (ArbitraryDataFileListMessage) message;
+        LOGGER.debug("Received hash list from peer {} with {} hashes", peer, arbitraryDataFileListMessage.getHashes().size());
+
+        if (LOGGER.isDebugEnabled() && arbitraryDataFileListMessage.getRequestTime() != null) {
+            long totalRequestTime = NTP.getTime() - arbitraryDataFileListMessage.getRequestTime();
+            LOGGER.debug("totalRequestTime: {}, requestHops: {}, peerAddress: {}, isRelayPossible: {}",
+                    totalRequestTime, arbitraryDataFileListMessage.getRequestHops(),
+                    arbitraryDataFileListMessage.getPeerAddress(), arbitraryDataFileListMessage.isRelayPossible());
+        }
+
+        // Do we have a pending request for this data?
+        Triple<String, RNSPeer, Long> request = arbitraryDataFileListRequests.get(message.getId());
+        if (request == null || request.getA() == null) {
+            return;
+        }
+        boolean isRelayRequest = (request.getB() != null);
+
+        // Does this message's signature match what we're expecting?
+        byte[] signature = arbitraryDataFileListMessage.getSignature();
+        String signature58 = Base58.encode(signature);
+        if (!request.getA().equals(signature58)) {
+            return;
+        }
+
+        List<byte[]> hashes = arbitraryDataFileListMessage.getHashes();
+        if (hashes == null || hashes.isEmpty()) {
+            return;
+        }
+
+        ArbitraryTransactionData arbitraryTransactionData = null;
+
+        // Check transaction exists and hashes are correct
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
+            if (!(transactionData instanceof ArbitraryTransactionData))
+                return;
+
+            arbitraryTransactionData = (ArbitraryTransactionData) transactionData;
+
+//          // Load data file(s)
+//          ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromTransactionData(arbitraryTransactionData);
+//
+//			// Check all hashes exist
+//			for (byte[] hash : hashes) {
+//				//LOGGER.debug("Received hash {}", Base58.encode(hash));
+//				if (!arbitraryDataFile.containsChunk(hash)) {
+//					// Check the hash against the complete file
+//					if (!Arrays.equals(arbitraryDataFile.getHash(), hash)) {
+//						LOGGER.info("Received non-matching chunk hash {} for signature {}. This could happen if we haven't obtained the metadata file yet.", Base58.encode(hash), signature58);
+//						return;
+//					}
+//				}
+//			}
+
+            if (!isRelayRequest || !Settings.getInstance().isRelayModeEnabled()) {
+                Long now = NTP.getTime();
+
+                if (RNSArbitraryDataFileManager.getInstance().arbitraryDataFileHashResponses.size() < MAX_FILE_HASH_RESPONSES) {
+                    // Keep track of the hashes this peer reports to have access to
+                    for (byte[] hash : hashes) {
+                        String hash58 = Base58.encode(hash);
+
+                        // Treat null request hops as 100, so that they are able to be sorted (and put to the end of the list)
+                        int requestHops = arbitraryDataFileListMessage.getRequestHops() != null ? arbitraryDataFileListMessage.getRequestHops() : 100;
+
+                        RNSArbitraryFileListResponseInfo responseInfo = new RNSArbitraryFileListResponseInfo(hash58, signature58,
+                                peer, now, arbitraryDataFileListMessage.getRequestTime(), requestHops);
+
+                        RNSArbitraryDataFileManager.getInstance().arbitraryDataFileHashResponses.add(responseInfo);
+                    }
+                }
+
+                // Keep track of the source peer, for direct connections
+                if (arbitraryDataFileListMessage.getPeerAddress() != null) {
+                    RNSArbitraryDataFileManager.getInstance().addDirectConnectionInfoIfUnique(
+                            new RNSArbitraryDirectConnectionInfo(signature, arbitraryDataFileListMessage.getPeerAddress(), hashes, now));
+                }
+            }
+
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while finding arbitrary transaction data list for peer %s", peer), e);
+        }
+
+        // Forwarding
+        if (isRelayRequest && Settings.getInstance().isRelayModeEnabled()) {
+            boolean isBlocked = (arbitraryTransactionData == null || ListUtils.isNameBlocked(arbitraryTransactionData.getName()));
+            if (!isBlocked) {
+                RNSPeer requestingPeer = request.getB();
+                if (requestingPeer != null) {
+                    Long requestTime = arbitraryDataFileListMessage.getRequestTime();
+                    Integer requestHops = arbitraryDataFileListMessage.getRequestHops();
+
+                    // Add each hash to our local mapping so we know who to ask later
+                    Long now = NTP.getTime();
+                    for (byte[] hash : hashes) {
+                        String hash58 = Base58.encode(hash);
+                        RNSArbitraryRelayInfo relayInfo = new RNSArbitraryRelayInfo(hash58, signature58, peer, now, requestTime, requestHops);
+                        RNSArbitraryDataFileManager.getInstance().addToRelayMap(relayInfo);
+                    }
+
+                    // Bump requestHops if it exists
+                    if (requestHops != null) {
+                        requestHops++;
+                    }
+
+                    ArbitraryDataFileListMessage forwardArbitraryDataFileListMessage;
+
+                    //// TODO - rework for Reticulum
+                    //// Remove optional parameters if the requesting peer doesn't support it yet
+                    //// A message with less statistical data is better than no message at all
+                    //if (!requestingPeer.isAtLeastVersion(MIN_PEER_VERSION_FOR_FILE_LIST_STATS)) {
+                    //    forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+                    //} else {
+                    //    forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes, requestTime, requestHops,
+                    //            arbitraryDataFileListMessage.getPeerAddress(), arbitraryDataFileListMessage.isRelayPossible());
+                    //}
+                    forwardArbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes, requestTime, requestHops,
+                            arbitraryDataFileListMessage.getPeerAddress(), arbitraryDataFileListMessage.isRelayPossible());
+                    forwardArbitraryDataFileListMessage.setId(message.getId());
+
+                    // Forward to requesting peer
+                    LOGGER.debug("Forwarding file list with {} hashes to requesting peer: {}", hashes.size(), requestingPeer);
+                    //if (!requestingPeer.sendMessage(forwardArbitraryDataFileListMessage)) {
+                    //    requestingPeer.disconnect("failed to forward arbitrary data file list");
+                    //}
+                    requestingPeer.sendMessage(forwardArbitraryDataFileListMessage);
+                }
+            }
+        }
+    }
+
+    public void onNetworkGetArbitraryDataFileListMessage(RNSPeer peer, Message message) {
+        // Don't respond if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        Controller.getInstance().stats.getArbitraryDataFileListMessageStats.requests.incrementAndGet();
+
+        GetArbitraryDataFileListMessage getArbitraryDataFileListMessage = (GetArbitraryDataFileListMessage) message;
+        byte[] signature = getArbitraryDataFileListMessage.getSignature();
+        String signature58 = Base58.encode(signature);
+        Long now = NTP.getTime();
+        Triple<String, RNSPeer, Long> newEntry = new Triple<>(signature58, peer, now);
+
+        // If we've seen this request recently, then ignore
+        if (arbitraryDataFileListRequests.putIfAbsent(message.getId(), newEntry) != null) {
+            LOGGER.trace("Ignoring hash list request from peer {} for signature {}", peer, signature58);
+            return;
+        }
+
+        List<byte[]> requestedHashes = getArbitraryDataFileListMessage.getHashes();
+        int hashCount = requestedHashes != null ? requestedHashes.size() : 0;
+        String requestingPeer = getArbitraryDataFileListMessage.getRequestingPeer();
+
+        if (requestingPeer != null) {
+            LOGGER.debug("Received hash list request with {} hashes from peer {} (requesting peer {}) for signature {}", hashCount, peer, requestingPeer, signature58);
+        }
+        else {
+            LOGGER.debug("Received hash list request with {} hashes from peer {} for signature {}", hashCount, peer, signature58);
+        }
+
+        List<byte[]> hashes = new ArrayList<>();
+        ArbitraryTransactionData transactionData = null;
+        boolean allChunksExist = false;
+        boolean hasMetadata = false;
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Firstly we need to lookup this file on chain to get a list of its hashes
+            transactionData = (ArbitraryTransactionData)repository.getTransactionRepository().fromSignature(signature);
+            if (transactionData instanceof ArbitraryTransactionData) {
+
+                // Check if we're even allowed to serve data for this transaction
+                if (ArbitraryDataStorageManager.getInstance().canStoreData(transactionData)) {
+
+                    // Load file(s) and add any that exist to the list of hashes
+                    ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromTransactionData(transactionData);
+
+                    // If the peer didn't supply a hash list, we need to return all hashes for this transaction
+                    if (requestedHashes == null || requestedHashes.isEmpty()) {
+                        requestedHashes = new ArrayList<>();
+
+                        // Add the metadata file
+                        if (arbitraryDataFile.getMetadataHash() != null) {
+                            requestedHashes.add(arbitraryDataFile.getMetadataHash());
+                            hasMetadata = true;
+                        }
+
+                        // Add the chunk hashes
+                        if (!arbitraryDataFile.getChunkHashes().isEmpty()) {
+                            requestedHashes.addAll(arbitraryDataFile.getChunkHashes());
+                        }
+                        // Add complete file if there are no hashes
+                        else {
+                            requestedHashes.add(arbitraryDataFile.getHash());
+                        }
+                    }
+
+                    // Assume all chunks exists, unless one can't be found below
+                    allChunksExist = true;
+
+                    for (byte[] requestedHash : requestedHashes) {
+                        ArbitraryDataFileChunk chunk = ArbitraryDataFileChunk.fromHash(requestedHash, signature);
+                        if (chunk.exists()) {
+                            hashes.add(chunk.getHash());
+                            //LOGGER.trace("Added hash {}", chunk.getHash58());
+                        } else {
+                            LOGGER.trace("Couldn't add hash {} because it doesn't exist", chunk.getHash58());
+                            allChunksExist = false;
+                        }
+                    }
+                }
+            }
+
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while fetching arbitrary file list for peer %s", peer), e);
+        }
+
+        // If the only file we have is the metadata then we shouldn't respond. Most nodes will already have that,
+        // or can use the separate metadata protocol to fetch it. This should greatly reduce network spam.
+        if (hasMetadata && hashes.size() == 1) {
+            hashes.clear();
+        }
+
+        // We should only respond if we have at least one hash
+        if (!hashes.isEmpty()) {
+
+            // Firstly we should keep track of the requesting peer, to allow for potential direct connections later
+            RNSArbitraryDataFileManager.getInstance().addRecentDataRequest(requestingPeer);
+
+            // We have all the chunks, so update requests map to reflect that we've sent it
+            // There is no need to keep track of the request, as we can serve all the chunks
+            if (allChunksExist) {
+                newEntry = new Triple<>(null, null, now);
+                arbitraryDataFileListRequests.put(message.getId(), newEntry);
+            }
+
+            //String ourAddress = RNSNetwork.getInstance().getOurExternalIpAddressAndPort();
+            String ourAddress = RNSNetwork.getInstance().getBaseDestination().getHexHash();
+            ArbitraryDataFileListMessage arbitraryDataFileListMessage;
+
+            // TODO: rework for Reticulum
+            // Remove optional parameters if the requesting peer doesn't support it yet
+            // A message with less statistical data is better than no message at all
+            //if (!peer.isAtLeastVersion(MIN_PEER_VERSION_FOR_FILE_LIST_STATS)) {
+            //    arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+            //} else {
+            //    arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature,
+            //            hashes, NTP.getTime(), 0, ourAddress, true);
+            //}
+            arbitraryDataFileListMessage = new ArbitraryDataFileListMessage(signature, hashes);
+
+            arbitraryDataFileListMessage.setId(message.getId());
+
+            //if (!peer.sendMessage(arbitraryDataFileListMessage)) {
+            //    LOGGER.debug("Couldn't send list of hashes");
+            //    peer.disconnect("failed to send list of hashes");
+            //    return;
+            //}
+            peer.sendMessage(arbitraryDataFileListMessage);
+            LOGGER.debug("Sent list of hashes (count: {})", hashes.size());
+
+            if (allChunksExist) {
+                // Nothing left to do, so return to prevent any unnecessary forwarding from occurring
+                LOGGER.debug("No need for any forwarding because file list request is fully served");
+                return;
+            }
+
+        }
+
+        // We may need to forward this request on
+        boolean isBlocked = (transactionData == null || ListUtils.isNameBlocked(transactionData.getName()));
+        if (Settings.getInstance().isRelayModeEnabled() && !isBlocked) {
+            // In relay mode - so ask our other peers if they have it
+
+            long requestTime = getArbitraryDataFileListMessage.getRequestTime();
+            int requestHops = getArbitraryDataFileListMessage.getRequestHops() + 1;
+            long totalRequestTime = now - requestTime;
+
+            if (totalRequestTime < RELAY_REQUEST_MAX_DURATION) {
+                // Relay request hasn't timed out yet, so can potentially be rebroadcast
+                if (requestHops < RELAY_REQUEST_MAX_HOPS) {
+                    // Relay request hasn't reached the maximum number of hops yet, so can be rebroadcast
+
+                    Message relayGetArbitraryDataFileListMessage = new GetArbitraryDataFileListMessage(signature, hashes, requestTime, requestHops, requestingPeer);
+                    relayGetArbitraryDataFileListMessage.setId(message.getId());
+
+                    LOGGER.debug("Rebroadcasting hash list request from peer {} for signature {} to our other peers... totalRequestTime: {}, requestHops: {}", peer, Base58.encode(signature), totalRequestTime, requestHops);
+                    //Network.getInstance().broadcast(
+                    //        broadcastPeer ->
+                    //                !broadcastPeer.isAtLeastVersion(RELAY_MIN_PEER_VERSION) ? null :
+                    //                broadcastPeer == peer || Objects.equals(broadcastPeer.getPeerData().getAddress().getHost(), peer.getPeerData().getAddress().getHost()) ? null : relayGetArbitraryDataFileListMessage
+                    //);
+                    RNSNetwork.getInstance().broadcast(broadcastPeer -> relayGetArbitraryDataFileListMessage);
+
+                }
+                else {
+                    // This relay request has reached the maximum number of allowed hops
+                }
+            }
+            else {
+                // This relay request has timed out
+            }
+        }
+    }
+
+}

src/main/java/org/qortal/controller/arbitrary/RNSArbitraryDataFileManager.java

@@ -0,0 +1,639 @@
+package org.qortal.controller.arbitrary;
+
+import com.google.common.net.InetAddresses;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.arbitrary.ArbitraryDataFile;
+import org.qortal.controller.Controller;
+import org.qortal.data.arbitrary.RNSArbitraryDirectConnectionInfo;
+import org.qortal.data.arbitrary.RNSArbitraryFileListResponseInfo;
+import org.qortal.data.arbitrary.RNSArbitraryRelayInfo;
+import org.qortal.data.network.PeerData;
+import org.qortal.data.transaction.ArbitraryTransactionData;
+import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
+import org.qortal.network.message.*;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.ArbitraryTransactionUtils;
+import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
+
+import java.security.SecureRandom;
+import java.util.*;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.stream.Collectors;
+
+public class RNSArbitraryDataFileManager extends Thread {
+
+    private static final Logger LOGGER = LogManager.getLogger(RNSArbitraryDataFileManager.class);
+
+    private static RNSArbitraryDataFileManager instance;
+    private volatile boolean isStopping = false;
+
+
+    /**
+     * Map to keep track of our in progress (outgoing) arbitrary data file requests
+     */
+    public Map<String, Long> arbitraryDataFileRequests = Collections.synchronizedMap(new HashMap<>());
+
+    /**
+     * Map to keep track of hashes that we might need to relay
+     */
+    public final List<RNSArbitraryRelayInfo> arbitraryRelayMap = Collections.synchronizedList(new ArrayList<>());
+
+    /**
+     * List to keep track of any arbitrary data file hash responses
+     */
+    public final List<RNSArbitraryFileListResponseInfo> arbitraryDataFileHashResponses = Collections.synchronizedList(new ArrayList<>());
+
+    /**
+     * List to keep track of peers potentially available for direct connections, based on recent requests
+     */
+    private final List<RNSArbitraryDirectConnectionInfo> directConnectionInfo = Collections.synchronizedList(new ArrayList<>());
+
+    /**
+     * Map to keep track of peers requesting QDN data that we hold.
+     * Key = peer address string, value = time of last request.
+     * This allows for additional "burst" connections beyond existing limits.
+     */
+    private Map<String, Long> recentDataRequests = Collections.synchronizedMap(new HashMap<>());
+
+
+    public static int MAX_FILE_HASH_RESPONSES = 1000;
+
+
+    private RNSArbitraryDataFileManager() {
+    }
+
+    public static RNSArbitraryDataFileManager getInstance() {
+        if (instance == null)
+            instance = new RNSArbitraryDataFileManager();
+
+        return instance;
+    }
+
+    @Override
+    public void run() {
+        Thread.currentThread().setName("Arbitrary Data File Manager");
+
+        try {
+            // Use a fixed thread pool to execute the arbitrary data file requests
+            int threadCount = 5;
+            ExecutorService arbitraryDataFileRequestExecutor = Executors.newFixedThreadPool(threadCount);
+            for (int i = 0; i < threadCount; i++) {
+                arbitraryDataFileRequestExecutor.execute(new ArbitraryDataFileRequestThread());
+            }
+
+            while (!isStopping) {
+                // Nothing to do yet
+                Thread.sleep(1000);
+            }
+        } catch (InterruptedException e) {
+            // Fall-through to exit thread...
+        }
+    }
+
+    public void shutdown() {
+        isStopping = true;
+        this.interrupt();
+    }
+
+
+    public void cleanupRequestCache(Long now) {
+        if (now == null) {
+            return;
+        }
+        final long requestMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_REQUEST_TIMEOUT;
+        arbitraryDataFileRequests.entrySet().removeIf(entry -> entry.getValue() == null || entry.getValue() < requestMinimumTimestamp);
+
+        final long relayMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_RELAY_TIMEOUT;
+        arbitraryRelayMap.removeIf(entry -> entry == null || entry.getTimestamp() == null || entry.getTimestamp() < relayMinimumTimestamp);
+        arbitraryDataFileHashResponses.removeIf(entry -> entry.getTimestamp() < relayMinimumTimestamp);
+
+        final long directConnectionInfoMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_DIRECT_CONNECTION_INFO_TIMEOUT;
+        directConnectionInfo.removeIf(entry -> entry.getTimestamp() < directConnectionInfoMinimumTimestamp);
+
+        final long recentDataRequestMinimumTimestamp = now - ArbitraryDataManager.getInstance().ARBITRARY_RECENT_DATA_REQUESTS_TIMEOUT;
+        recentDataRequests.entrySet().removeIf(entry -> entry.getValue() < recentDataRequestMinimumTimestamp);
+    }
+
+
+
+    // Fetch data files by hash
+
+    public boolean fetchArbitraryDataFiles(Repository repository,
+                                           RNSPeer peer,
+                                           byte[] signature,
+                                           ArbitraryTransactionData arbitraryTransactionData,
+                                           List<byte[]> hashes) throws DataException {
+
+        // Load data file(s)
+        ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromTransactionData(arbitraryTransactionData);
+        boolean receivedAtLeastOneFile = false;
+
+        // Now fetch actual data from this peer
+        for (byte[] hash : hashes) {
+            if (isStopping) {
+                return false;
+            }
+            String hash58 = Base58.encode(hash);
+            if (!arbitraryDataFile.chunkExists(hash)) {
+                // Only request the file if we aren't already requesting it from someone else
+                if (!arbitraryDataFileRequests.containsKey(Base58.encode(hash))) {
+                    LOGGER.debug("Requesting data file {} from peer {}", hash58, peer);
+                    Long startTime = NTP.getTime();
+                    ArbitraryDataFile receivedArbitraryDataFile = fetchArbitraryDataFile(peer, null, arbitraryTransactionData, signature, hash, null);
+                    Long endTime = NTP.getTime();
+                    if (receivedArbitraryDataFile != null) {
+                        LOGGER.debug("Received data file {} from peer {}. Time taken: {} ms", receivedArbitraryDataFile.getHash58(), peer, (endTime-startTime));
+                        receivedAtLeastOneFile = true;
+
+                        // Remove this hash from arbitraryDataFileHashResponses now that we have received it
+                        arbitraryDataFileHashResponses.remove(hash58);
+                    }
+                    else {
+                        LOGGER.debug("Peer {} didn't respond with data file {} for signature {}. Time taken: {} ms", peer, Base58.encode(hash), Base58.encode(signature), (endTime-startTime));
+
+                        // Remove this hash from arbitraryDataFileHashResponses now that we have failed to receive it
+                        arbitraryDataFileHashResponses.remove(hash58);
+
+                        // Stop asking for files from this peer
+                        break;
+                    }
+                }
+                else {
+                    LOGGER.trace("Already requesting data file {} for signature {} from peer {}", arbitraryDataFile, Base58.encode(signature), peer);
+                }
+            }
+            else {
+                // Remove this hash from arbitraryDataFileHashResponses because we have a local copy
+                arbitraryDataFileHashResponses.remove(hash58);
+            }
+        }
+
+        if (receivedAtLeastOneFile) {
+            // Invalidate the hosted transactions cache as we are now hosting something new
+            ArbitraryDataStorageManager.getInstance().invalidateHostedTransactionsCache();
+
+            // Check if we have all the files we need for this transaction
+            if (arbitraryDataFile.allFilesExist()) {
+
+                // We have all the chunks for this transaction, so we should invalidate the transaction's name's
+                // data cache so that it is rebuilt the next time we serve it
+                ArbitraryDataManager.getInstance().invalidateCache(arbitraryTransactionData);
+            }
+        }
+
+        return receivedAtLeastOneFile;
+    }
+
+    private ArbitraryDataFile fetchArbitraryDataFile(RNSPeer peer, RNSPeer requestingPeer, ArbitraryTransactionData arbitraryTransactionData, byte[] signature, byte[] hash, Message originalMessage) throws DataException {
+        ArbitraryDataFile existingFile = ArbitraryDataFile.fromHash(hash, signature);
+        boolean fileAlreadyExists = existingFile.exists();
+        String hash58 = Base58.encode(hash);
+        ArbitraryDataFile arbitraryDataFile;
+
+        // Fetch the file if it doesn't exist locally
+        if (!fileAlreadyExists) {
+            LOGGER.debug(String.format("Fetching data file %.8s from peer %s", hash58, peer));
+            arbitraryDataFileRequests.put(hash58, NTP.getTime());
+            Message getArbitraryDataFileMessage = new GetArbitraryDataFileMessage(signature, hash);
+
+            Message response = null;
+            //// TODO - revisit (doesn't work with Reticulum)
+            //try {
+            //    response = peer.getResponseWithTimeout(getArbitraryDataFileMessage, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT);
+            //} catch (InterruptedException e) {
+            //    // Will return below due to null response
+            //}
+            arbitraryDataFileRequests.remove(hash58);
+            LOGGER.trace(String.format("Removed hash %.8s from arbitraryDataFileRequests", hash58));
+
+            // We may need to remove the file list request, if we have all the files for this transaction
+            this.handleFileListRequests(signature);
+
+            if (response == null) {
+                LOGGER.debug("Received null response from peer {}", peer);
+                return null;
+            }
+            if (response.getType() != MessageType.ARBITRARY_DATA_FILE) {
+                LOGGER.debug("Received response with invalid type: {} from peer {}", response.getType(), peer);
+                return null;
+            }
+
+            ArbitraryDataFileMessage peersArbitraryDataFileMessage = (ArbitraryDataFileMessage) response;
+            arbitraryDataFile = peersArbitraryDataFileMessage.getArbitraryDataFile();
+        } else {
+            LOGGER.debug(String.format("File hash %s already exists, so skipping the request", hash58));
+            arbitraryDataFile = existingFile;
+        }
+
+        if (arbitraryDataFile == null) {
+            // We don't have a file, so give up here
+            return null;
+        }
+
+        // We might want to forward the request to the peer that originally requested it
+        this.handleArbitraryDataFileForwarding(requestingPeer, new ArbitraryDataFileMessage(signature, arbitraryDataFile), originalMessage);
+
+        boolean isRelayRequest = (requestingPeer != null);
+        if (isRelayRequest) {
+            if (!fileAlreadyExists) {
+                // File didn't exist locally before the request, and it's a forwarding request, so delete it if it exists.
+                // It shouldn't exist on the filesystem yet, but leaving this here just in case.
+                arbitraryDataFile.delete(10);
+            }
+        }
+        else {
+            arbitraryDataFile.save();
+        }
+
+        // If this is a metadata file then we need to update the cache
+        if (arbitraryTransactionData != null && arbitraryTransactionData.getMetadataHash() != null) {
+            if (Arrays.equals(arbitraryTransactionData.getMetadataHash(), hash)) {
+                ArbitraryDataCacheManager.getInstance().addToUpdateQueue(arbitraryTransactionData);
+            }
+        }
+
+        return arbitraryDataFile;
+    }
+
+    private void handleFileListRequests(byte[] signature) {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Fetch the transaction data
+            ArbitraryTransactionData arbitraryTransactionData = ArbitraryTransactionUtils.fetchTransactionData(repository, signature);
+            if (arbitraryTransactionData == null) {
+                return;
+            }
+
+            boolean allChunksExist = ArbitraryTransactionUtils.allChunksExist(arbitraryTransactionData);
+
+            if (allChunksExist) {
+                // Update requests map to reflect that we've received all chunks
+                RNSArbitraryDataFileListManager.getInstance().deleteFileListRequestsForSignature(signature);
+            }
+
+        } catch (DataException e) {
+            LOGGER.debug("Unable to handle file list requests: {}", e.getMessage());
+        }
+    }
+
+    public void handleArbitraryDataFileForwarding(RNSPeer requestingPeer, Message message, Message originalMessage) {
+        // Return if there is no originally requesting peer to forward to
+        if (requestingPeer == null) {
+            return;
+        }
+
+        // Return if we're not in relay mode or if this request doesn't need forwarding
+        if (!Settings.getInstance().isRelayModeEnabled()) {
+            return;
+        }
+
+        LOGGER.debug("Received arbitrary data file - forwarding is needed");
+
+        // The ID needs to match that of the original request
+        message.setId(originalMessage.getId());
+
+        //if (!requestingPeer.sendMessageWithTimeout(message, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT)) {
+        //    LOGGER.debug("Failed to forward arbitrary data file to peer {}", requestingPeer);
+        //    requestingPeer.disconnect("failed to forward arbitrary data file");
+        //}
+        //else {
+        //    LOGGER.debug("Forwarded arbitrary data file to peer {}", requestingPeer);
+        //}
+        requestingPeer.sendMessageWithTimeout(message, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT);
+    }
+
+
+    // Fetch data directly from peers
+
+    private List<RNSArbitraryDirectConnectionInfo> getDirectConnectionInfoForSignature(byte[] signature) {
+        synchronized (directConnectionInfo) {
+            return directConnectionInfo.stream().filter(i -> Arrays.equals(i.getSignature(), signature)).collect(Collectors.toList());
+        }
+    }
+
+    /**
+     * Add an ArbitraryDirectConnectionInfo item, but only if one with this peer-signature combination
+     * doesn't already exist.
+     * @param connectionInfo - the direct connection info to add
+     */
+    public void addDirectConnectionInfoIfUnique(RNSArbitraryDirectConnectionInfo connectionInfo) {
+        boolean peerAlreadyExists;
+        synchronized (directConnectionInfo) {
+            peerAlreadyExists = directConnectionInfo.stream()
+                    .anyMatch(i -> Arrays.equals(i.getSignature(), connectionInfo.getSignature())
+                            && Objects.equals(i.getPeerAddress(), connectionInfo.getPeerAddress()));
+        }
+        if (!peerAlreadyExists) {
+            directConnectionInfo.add(connectionInfo);
+        }
+    }
+
+    private void removeDirectConnectionInfo(RNSArbitraryDirectConnectionInfo connectionInfo) {
+        this.directConnectionInfo.remove(connectionInfo);
+    }
+
+    public boolean fetchDataFilesFromPeersForSignature(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+
+        boolean success = false;
+
+        try {
+            while (!success) {
+                if (isStopping) {
+                    return false;
+                }
+                Thread.sleep(500L);
+
+                // Firstly fetch peers that claim to be hosting files for this signature
+                List<RNSArbitraryDirectConnectionInfo> connectionInfoList = getDirectConnectionInfoForSignature(signature);
+                if (connectionInfoList == null || connectionInfoList.isEmpty()) {
+                    LOGGER.debug("No remaining direct connection peers found for signature {}", signature58);
+                    return false;
+                }
+
+                LOGGER.debug("Attempting a direct peer connection for signature {}...", signature58);
+
+                // Peers found, so pick one with the highest number of chunks
+                Comparator<RNSArbitraryDirectConnectionInfo> highestChunkCountFirstComparator =
+                        Comparator.comparingInt(RNSArbitraryDirectConnectionInfo::getHashCount).reversed();
+                RNSArbitraryDirectConnectionInfo directConnectionInfo = connectionInfoList.stream()
+                        .sorted(highestChunkCountFirstComparator).findFirst().orElse(null);
+
+                if (directConnectionInfo == null) {
+                    return false;
+                }
+
+                // Remove from the list so that a different peer is tried next time
+                removeDirectConnectionInfo(directConnectionInfo);
+
+                //// TODO - rework this section (RNS network address?)
+                //String peerAddressString = directConnectionInfo.getPeerAddress();
+                //
+                //// Parse the peer address to find the host and port
+                //String host = null;
+                //int port = -1;
+                //String[] parts = peerAddressString.split(":");
+                //if (parts.length > 1) {
+                //    host = parts[0];
+                //    port = Integer.parseInt(parts[1]);
+                //} else {
+                //    // Assume no port included
+                //    host = peerAddressString;
+                //    // Use default listen port
+                //    port = Settings.getInstance().getDefaultListenPort();
+                //}
+                //
+                //String peerAddressStringWithPort = String.format("%s:%d", host, port);
+                //success = Network.getInstance().requestDataFromPeer(peerAddressStringWithPort, signature);
+                //
+                //int defaultPort = Settings.getInstance().getDefaultListenPort();
+                //
+                //// If unsuccessful, and using a non-standard port, try a second connection with the default listen port,
+                //// since almost all nodes use that. This is a workaround to account for any ephemeral ports that may
+                //// have made it into the dataset.
+                //if (!success) {
+                //    if (host != null && port > 0) {
+                //        if (port != defaultPort) {
+                //            String newPeerAddressString = String.format("%s:%d", host, defaultPort);
+                //            success = Network.getInstance().requestDataFromPeer(newPeerAddressString, signature);
+                //        }
+                //    }
+                //}
+                //
+                //// If _still_ unsuccessful, try matching the peer's IP address with some known peers, and then connect
+                //// to each of those in turn until one succeeds.
+                //if (!success) {
+                //    if (host != null) {
+                //        final String finalHost = host;
+                //        List<PeerData> knownPeers = Network.getInstance().getAllKnownPeers().stream()
+                //                .filter(knownPeerData -> knownPeerData.getAddress().getHost().equals(finalHost))
+                //                .collect(Collectors.toList());
+                //        // Loop through each match and attempt a connection
+                //        for (PeerData matchingPeer : knownPeers) {
+                //            String matchingPeerAddress = matchingPeer.getAddress().toString();
+                //            int matchingPeerPort = matchingPeer.getAddress().getPort();
+                //            // Make sure that it's not a port we've already tried
+                //            if (matchingPeerPort != port && matchingPeerPort != defaultPort) {
+                //                success = Network.getInstance().requestDataFromPeer(matchingPeerAddress, signature);
+                //                if (success) {
+                //                    // Successfully connected, so stop making connections
+                //                    break;
+                //                }
+                //            }
+                //        }
+                //    }
+                //}
+
+                if (success) {
+                    // We were able to connect with a peer, so track the request
+                    RNSArbitraryDataFileListManager.getInstance().addToSignatureRequests(signature58, false, true);
+                }
+
+            }
+        } catch (InterruptedException e) {
+            // Do nothing
+        }
+
+        return success;
+    }
+
+
+    // Relays
+
+    private List<RNSArbitraryRelayInfo> getRelayInfoListForHash(String hash58) {
+        synchronized (arbitraryRelayMap) {
+            return arbitraryRelayMap.stream()
+                    .filter(relayInfo -> Objects.equals(relayInfo.getHash58(), hash58))
+                    .collect(Collectors.toList());
+        }
+    }
+
+    private RNSArbitraryRelayInfo getOptimalRelayInfoEntryForHash(String hash58) {
+        LOGGER.trace("Fetching relay info for hash: {}", hash58);
+        List<RNSArbitraryRelayInfo> relayInfoList = this.getRelayInfoListForHash(hash58);
+        if (relayInfoList != null && !relayInfoList.isEmpty()) {
+
+            // Remove any with null requestHops
+            relayInfoList.removeIf(r -> r.getRequestHops() == null);
+
+            // If list is now empty, then just return one at random
+            if (relayInfoList.isEmpty()) {
+                return this.getRandomRelayInfoEntryForHash(hash58);
+            }
+
+            // Sort by number of hops (lowest first)
+            relayInfoList.sort(Comparator.comparingInt(RNSArbitraryRelayInfo::getRequestHops));
+
+            // FUTURE: secondary sort by requestTime?
+
+            RNSArbitraryRelayInfo relayInfo = relayInfoList.get(0);
+
+            LOGGER.trace("Returning optimal relay info for hash: {} (requestHops {})", hash58, relayInfo.getRequestHops());
+            return relayInfo;
+        }
+        LOGGER.trace("No relay info exists for hash: {}", hash58);
+        return null;
+    }
+
+    private RNSArbitraryRelayInfo getRandomRelayInfoEntryForHash(String hash58) {
+        LOGGER.trace("Fetching random relay info for hash: {}", hash58);
+        List<RNSArbitraryRelayInfo> relayInfoList = this.getRelayInfoListForHash(hash58);
+        if (relayInfoList != null && !relayInfoList.isEmpty()) {
+
+            // Pick random item
+            int index = new SecureRandom().nextInt(relayInfoList.size());
+            LOGGER.trace("Returning random relay info for hash: {} (index {})", hash58, index);
+            return relayInfoList.get(index);
+        }
+        LOGGER.trace("No relay info exists for hash: {}", hash58);
+        return null;
+    }
+
+    public void addToRelayMap(RNSArbitraryRelayInfo newEntry) {
+        if (newEntry == null || !newEntry.isValid()) {
+            return;
+        }
+
+        // Remove existing entry for this peer if it exists, to renew the timestamp
+        this.removeFromRelayMap(newEntry);
+
+        // Re-add
+        arbitraryRelayMap.add(newEntry);
+        LOGGER.debug("Added entry to relay map: {}", newEntry);
+    }
+
+    private void removeFromRelayMap(RNSArbitraryRelayInfo entry) {
+        arbitraryRelayMap.removeIf(relayInfo -> relayInfo.equals(entry));
+    }
+
+
+    // Peers requesting QDN data from us
+
+    /**
+     * Add an address string of a peer that is trying to request data from us.
+     * @param peerAddress
+     */
+    public void addRecentDataRequest(String peerAddress) {
+        if (peerAddress == null) {
+            return;
+        }
+
+        Long now = NTP.getTime();
+        if (now == null) {
+            return;
+        }
+
+        // Make sure to remove the port, since it isn't guaranteed to match next time
+        String[] parts = peerAddress.split(":");
+        if (parts.length == 0) {
+            return;
+        }
+        String host = parts[0];
+        if (!InetAddresses.isInetAddress(host)) {
+            // Invalid host
+            return;
+        }
+
+        this.recentDataRequests.put(host, now);
+    }
+
+    public boolean isPeerRequestingData(String peerAddressWithoutPort) {
+        return this.recentDataRequests.containsKey(peerAddressWithoutPort);
+    }
+
+    public boolean hasPendingDataRequest() {
+        return !this.recentDataRequests.isEmpty();
+    }
+
+
+    // Network handlers
+
+    public void onNetworkGetArbitraryDataFileMessage(RNSPeer peer, Message message) {
+        // Don't respond if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        GetArbitraryDataFileMessage getArbitraryDataFileMessage = (GetArbitraryDataFileMessage) message;
+        byte[] hash = getArbitraryDataFileMessage.getHash();
+        String hash58 = Base58.encode(hash);
+        byte[] signature = getArbitraryDataFileMessage.getSignature();
+        Controller.getInstance().stats.getArbitraryDataFileMessageStats.requests.incrementAndGet();
+
+        LOGGER.debug("Received GetArbitraryDataFileMessage from peer {} for hash {}", peer, Base58.encode(hash));
+
+        try {
+            ArbitraryDataFile arbitraryDataFile = ArbitraryDataFile.fromHash(hash, signature);
+            RNSArbitraryRelayInfo relayInfo = this.getOptimalRelayInfoEntryForHash(hash58);
+
+            if (arbitraryDataFile.exists()) {
+                LOGGER.trace("Hash {} exists", hash58);
+
+                // We can serve the file directly as we already have it
+                LOGGER.debug("Sending file {}...", arbitraryDataFile);
+                ArbitraryDataFileMessage arbitraryDataFileMessage = new ArbitraryDataFileMessage(signature, arbitraryDataFile);
+                arbitraryDataFileMessage.setId(message.getId());
+                //if (!peer.sendMessageWithTimeout(arbitraryDataFileMessage, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT)) {
+                //    LOGGER.debug("Couldn't send file {}", arbitraryDataFile);
+                //    peer.disconnect("failed to send file");
+                //}
+                //else {
+                //    LOGGER.debug("Sent file {}", arbitraryDataFile);
+                //}
+                peer.sendMessageWithTimeout(arbitraryDataFileMessage, (int) ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT);
+            }
+            //// TODO: rework (doesn't work with Reticulum)
+            //else if (relayInfo != null) {
+            //    LOGGER.debug("We have relay info for hash {}", Base58.encode(hash));
+            //    // We need to ask this peer for the file
+            //    Peer peerToAsk = relayInfo.getPeer();
+            //    if (peerToAsk != null) {
+            //
+            //        // Forward the message to this peer
+            //        LOGGER.debug("Asking peer {} for hash {}", peerToAsk, hash58);
+            //        // No need to pass arbitraryTransactionData below because this is only used for metadata caching,
+            //        // and metadata isn't retained when relaying.
+            //        this.fetchArbitraryDataFile(peerToAsk, peer, null, signature, hash, message);
+            //    }
+            //    else {
+            //        LOGGER.debug("Peer {} not found in relay info", peer);
+            //    }
+            //}
+            else {
+                LOGGER.debug("Hash {} doesn't exist and we don't have relay info", hash58);
+
+                // We don't have this file
+                Controller.getInstance().stats.getArbitraryDataFileMessageStats.unknownFiles.getAndIncrement();
+
+                // 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));
+
+                //// 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");
+                //    peer.disconnect("failed to send file-unknown response");
+                //}
+                //else {
+                //    LOGGER.debug("Sent file-unknown response for file {}", arbitraryDataFile);
+                //}
+                Message fileUnknownMessage = new GenericUnknownMessage();
+                peer.sendMessage(fileUnknownMessage);
+            }
+        }
+        catch (DataException e) {
+            LOGGER.debug("Unable to handle request for arbitrary data file: {}", hash58);
+        }
+    }
+
+}

src/main/java/org/qortal/controller/arbitrary/RNSArbitraryMetadataManager.java

@@ -0,0 +1,481 @@
+package org.qortal.controller.arbitrary;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.arbitrary.ArbitraryDataFile;
+import org.qortal.arbitrary.ArbitraryDataResource;
+import org.qortal.arbitrary.metadata.ArbitraryDataTransactionMetadata;
+import org.qortal.controller.Controller;
+import org.qortal.data.transaction.ArbitraryTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
+import org.qortal.network.message.ArbitraryMetadataMessage;
+import org.qortal.network.message.GetArbitraryMetadataMessage;
+import org.qortal.network.message.Message;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
+import org.qortal.utils.Base58;
+import org.qortal.utils.ListUtils;
+import org.qortal.utils.NTP;
+import org.qortal.utils.Triple;
+
+import java.io.IOException;
+import java.util.*;
+
+import static org.qortal.controller.arbitrary.ArbitraryDataFileListManager.*;
+
+public class RNSArbitraryMetadataManager {
+
+    private static final Logger LOGGER = LogManager.getLogger(ArbitraryMetadataManager.class);
+
+    private static RNSArbitraryMetadataManager instance;
+
+    /**
+     * Map of recent incoming requests for ARBITRARY transaction metadata.
+     * <p>
+     * Key is original request's message ID<br>
+     * Value is Triple&lt;transaction signature in base58, first requesting peer, first request's timestamp&gt;
+     * <p>
+     * If peer is null then either:<br>
+     * <ul>
+     * <li>we are the original requesting peer</li>
+     * <li>we have already sent data payload to original requesting peer.</li>
+     * </ul>
+     * If signature is null then we have already received the file list and either:<br>
+     * <ul>
+     * <li>we are the original requesting peer and have processed it</li>
+     * <li>we have forwarded the metadata</li>
+     * </ul>
+     */
+    public Map<Integer, Triple<String, RNSPeer, Long>> arbitraryMetadataRequests = Collections.synchronizedMap(new HashMap<>());
+
+    /**
+     * Map to keep track of in progress arbitrary metadata requests
+     * Key: string - the signature encoded in base58
+     * Value: Triple<networkBroadcastCount, directPeerRequestCount, lastAttemptTimestamp>
+     */
+    private Map<String, Triple<Integer, Integer, Long>> arbitraryMetadataSignatureRequests = Collections.synchronizedMap(new HashMap<>());
+
+
+    private RNSArbitraryMetadataManager() {
+    }
+
+    public static RNSArbitraryMetadataManager getInstance() {
+        if (instance == null)
+            instance = new RNSArbitraryMetadataManager();
+
+        return instance;
+    }
+
+    public void cleanupRequestCache(Long now) {
+        if (now == null) {
+            return;
+        }
+        final long requestMinimumTimestamp = now - ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT;
+        arbitraryMetadataRequests.entrySet().removeIf(entry -> entry.getValue().getC() == null || entry.getValue().getC() < requestMinimumTimestamp);
+    }
+
+
+    public ArbitraryDataTransactionMetadata fetchMetadata(ArbitraryDataResource arbitraryDataResource, boolean useRateLimiter) {
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            // Find latest transaction
+            ArbitraryTransactionData latestTransaction = repository.getArbitraryRepository()
+                    .getLatestTransaction(arbitraryDataResource.getResourceId(), arbitraryDataResource.getService(),
+                            null, arbitraryDataResource.getIdentifier());
+
+            if (latestTransaction != null) {
+                byte[] signature = latestTransaction.getSignature();
+                byte[] metadataHash = latestTransaction.getMetadataHash();
+                if (metadataHash == null) {
+                    // This resource doesn't have metadata
+                    throw new IllegalArgumentException("This resource doesn't have metadata");
+                }
+
+                ArbitraryDataFile metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+                if (!metadataFile.exists()) {
+                    // Request from network
+                    this.fetchArbitraryMetadata(latestTransaction, useRateLimiter);
+                }
+
+                // Now check again as it may have been downloaded above
+                if (metadataFile.exists()) {
+                    // Use local copy
+                    ArbitraryDataTransactionMetadata transactionMetadata = new ArbitraryDataTransactionMetadata(metadataFile.getFilePath());
+                    try {
+                        transactionMetadata.read();
+                    } catch (DataException e) {
+                        // Invalid file, so delete it
+                        LOGGER.info("Deleting invalid metadata file due to exception: {}", e.getMessage());
+                        transactionMetadata.delete();
+                        return null;
+                    }
+                    return transactionMetadata;
+                }
+            }
+
+        } catch (DataException | IOException e) {
+            LOGGER.error("Repository issue when fetching arbitrary transaction metadata", e);
+        }
+
+        return null;
+    }
+
+
+    // Request metadata from network
+
+    public byte[] fetchArbitraryMetadata(ArbitraryTransactionData arbitraryTransactionData, boolean useRateLimiter) {
+        byte[] metadataHash = arbitraryTransactionData.getMetadataHash();
+        if (metadataHash == null) {
+            return null;
+        }
+
+        byte[] signature = arbitraryTransactionData.getSignature();
+        String signature58 = Base58.encode(signature);
+
+        // Require an NTP sync
+        Long now = NTP.getTime();
+        if (now == null) {
+            return null;
+        }
+
+        // If we've already tried too many times in a short space of time, make sure to give up
+        if (useRateLimiter && !this.shouldMakeMetadataRequestForSignature(signature58)) {
+            LOGGER.trace("Skipping metadata request for signature {} due to rate limit", signature58);
+            return null;
+        }
+        this.addToSignatureRequests(signature58, true, false);
+
+        //List<Peer> handshakedPeers = Network.getInstance().getImmutableHandshakedPeers();
+        List<RNSPeer> handshakedPeers = RNSNetwork.getInstance().getLinkedPeers();
+        LOGGER.debug(String.format("Sending metadata request for signature %s to %d peers...", signature58, handshakedPeers.size()));
+
+        // Build request
+        Message getArbitraryMetadataMessage = new GetArbitraryMetadataMessage(signature, now, 0);
+
+        // Save our request into requests map
+        Triple<String, RNSPeer, Long> requestEntry = new Triple<>(signature58, null, NTP.getTime());
+
+        // Assign random ID to this message
+        int id;
+        do {
+            id = new Random().nextInt(Integer.MAX_VALUE - 1) + 1;
+
+            // Put queue into map (keyed by message ID) so we can poll for a response
+            // If putIfAbsent() doesn't return null, then this ID is already taken
+        } while (arbitraryMetadataRequests.put(id, requestEntry) != null);
+        getArbitraryMetadataMessage.setId(id);
+
+        // Broadcast request
+        RNSNetwork.getInstance().broadcast(peer -> getArbitraryMetadataMessage);
+
+        // Poll to see if data has arrived
+        final long singleWait = 100;
+        long totalWait = 0;
+        while (totalWait < ArbitraryDataManager.ARBITRARY_REQUEST_TIMEOUT) {
+            try {
+                Thread.sleep(singleWait);
+            } catch (InterruptedException e) {
+                break;
+            }
+
+            requestEntry = arbitraryMetadataRequests.get(id);
+            if (requestEntry == null)
+                return null;
+
+            if (requestEntry.getA() == null)
+                break;
+
+            totalWait += singleWait;
+        }
+
+        try {
+            ArbitraryDataFile metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+            if (metadataFile.exists()) {
+                return metadataFile.getBytes();
+            }
+        } catch (DataException e) {
+            // Do nothing
+        }
+
+        return null;
+    }
+
+
+    // Track metadata lookups by signature
+
+    private boolean shouldMakeMetadataRequestForSignature(String signature58) {
+        Triple<Integer, Integer, Long> request = arbitraryMetadataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        // Extract the components
+        Integer networkBroadcastCount = request.getA();
+        // Integer directPeerRequestCount = request.getB();
+        Long lastAttemptTimestamp = request.getC();
+
+        if (lastAttemptTimestamp == null) {
+            // Not attempted yet
+            return true;
+        }
+
+        long timeSinceLastAttempt = NTP.getTime() - lastAttemptTimestamp;
+
+        // Allow a second attempt after 60 seconds
+        if (timeSinceLastAttempt > 60 * 1000L) {
+            // We haven't tried for at least 60 seconds
+
+            if (networkBroadcastCount < 2) {
+                // We've made less than 2 total attempts
+                return true;
+            }
+        }
+
+        // Then allow another attempt after 60 minutes
+        if (timeSinceLastAttempt > 60 * 60 * 1000L) {
+            // We haven't tried for at least 60 minutes
+
+            if (networkBroadcastCount < 3) {
+                // We've made less than 3 total attempts
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public boolean isSignatureRateLimited(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        return !this.shouldMakeMetadataRequestForSignature(signature58);
+    }
+
+    public long lastRequestForSignature(byte[] signature) {
+        String signature58 = Base58.encode(signature);
+        Triple<Integer, Integer, Long> request = arbitraryMetadataSignatureRequests.get(signature58);
+
+        if (request == null) {
+            // Not attempted yet
+            return 0;
+        }
+
+        // Extract the components
+        Long lastAttemptTimestamp = request.getC();
+        if (lastAttemptTimestamp != null) {
+            return  lastAttemptTimestamp;
+        }
+        return 0;
+    }
+
+    public void addToSignatureRequests(String signature58, boolean incrementNetworkRequests, boolean incrementPeerRequests) {
+        Triple<Integer, Integer, Long> request  = arbitraryMetadataSignatureRequests.get(signature58);
+        Long now = NTP.getTime();
+
+        if (request == null) {
+            // No entry yet
+            Triple<Integer, Integer, Long> newRequest = new Triple<>(0, 0, now);
+            arbitraryMetadataSignatureRequests.put(signature58, newRequest);
+        }
+        else {
+            // There is an existing entry
+            if (incrementNetworkRequests) {
+                request.setA(request.getA() + 1);
+            }
+            if (incrementPeerRequests) {
+                request.setB(request.getB() + 1);
+            }
+            request.setC(now);
+            arbitraryMetadataSignatureRequests.put(signature58, request);
+        }
+    }
+
+    public void removeFromSignatureRequests(String signature58) {
+        arbitraryMetadataSignatureRequests.remove(signature58);
+    }
+
+
+    // Network handlers
+
+    public void onNetworkArbitraryMetadataMessage(RNSPeer peer, Message message) {
+        // Don't process if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        ArbitraryMetadataMessage arbitraryMetadataMessage = (ArbitraryMetadataMessage) message;
+        LOGGER.debug("Received metadata from peer {}", peer);
+
+        // Do we have a pending request for this data?
+        Triple<String, RNSPeer, Long> request = arbitraryMetadataRequests.get(message.getId());
+        if (request == null || request.getA() == null) {
+            return;
+        }
+        boolean isRelayRequest = (request.getB() != null);
+
+        // Does this message's signature match what we're expecting?
+        byte[] signature = arbitraryMetadataMessage.getSignature();
+        String signature58 = Base58.encode(signature);
+        if (!request.getA().equals(signature58)) {
+            return;
+        }
+
+        // Update requests map to reflect that we've received this metadata
+        Triple<String, RNSPeer, Long> newEntry = new Triple<>(null, null, request.getC());
+        arbitraryMetadataRequests.put(message.getId(), newEntry);
+
+        // Get transaction info
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            TransactionData transactionData = repository.getTransactionRepository().fromSignature(signature);
+            if (!(transactionData instanceof ArbitraryTransactionData)) {
+                return;
+            }
+            ArbitraryTransactionData arbitraryTransactionData = (ArbitraryTransactionData) transactionData;
+
+            // Check if the name is blocked
+            boolean isBlocked = (arbitraryTransactionData == null || ListUtils.isNameBlocked(arbitraryTransactionData.getName()));
+
+            // Save if not blocked
+            ArbitraryDataFile arbitraryMetadataFile = arbitraryMetadataMessage.getArbitraryMetadataFile();
+            if (!isBlocked && arbitraryMetadataFile != null) {
+                arbitraryMetadataFile.save();
+            }
+
+            // Forwarding
+            if (isRelayRequest && Settings.getInstance().isRelayModeEnabled()) {
+                if (!isBlocked) {
+                    RNSPeer requestingPeer = request.getB();
+                    if (requestingPeer != null) {
+
+                        ArbitraryMetadataMessage forwardArbitraryMetadataMessage = new ArbitraryMetadataMessage(signature, arbitraryMetadataMessage.getArbitraryMetadataFile());
+                        forwardArbitraryMetadataMessage.setId(arbitraryMetadataMessage.getId());
+
+                        // Forward to requesting peer
+                        LOGGER.debug("Forwarding metadata to requesting peer: {}", requestingPeer);
+                        //if (!requestingPeer.sendMessage(forwardArbitraryMetadataMessage)) {
+                        //    requestingPeer.disconnect("failed to forward arbitrary metadata");
+                        //}
+                        requestingPeer.sendMessage(forwardArbitraryMetadataMessage);
+                    }
+                }
+            }
+
+            // Add to resource queue to update arbitrary resource caches
+            if (arbitraryTransactionData != null) {
+                ArbitraryDataCacheManager.getInstance().addToUpdateQueue(arbitraryTransactionData);
+            }
+
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while saving arbitrary transaction metadata from peer %s", peer), e);
+        }
+    }
+
+    public void onNetworkGetArbitraryMetadataMessage(RNSPeer peer, Message message) {
+        // Don't respond if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return;
+        }
+
+        Controller.getInstance().stats.getArbitraryMetadataMessageStats.requests.incrementAndGet();
+
+        GetArbitraryMetadataMessage getArbitraryMetadataMessage = (GetArbitraryMetadataMessage) message;
+        byte[] signature = getArbitraryMetadataMessage.getSignature();
+        String signature58 = Base58.encode(signature);
+        Long now = NTP.getTime();
+        Triple<String, RNSPeer, Long> newEntry = new Triple<>(signature58, peer, now);
+
+        // If we've seen this request recently, then ignore
+        if (arbitraryMetadataRequests.putIfAbsent(message.getId(), newEntry) != null) {
+            LOGGER.debug("Ignoring metadata request from peer {} for signature {}", peer, signature58);
+            return;
+        }
+
+        LOGGER.debug("Received metadata request from peer {} for signature {}", peer, signature58);
+
+        ArbitraryTransactionData transactionData = null;
+        ArbitraryDataFile metadataFile = null;
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+
+            // Firstly we need to lookup this file on chain to get its metadata hash
+            transactionData = (ArbitraryTransactionData)repository.getTransactionRepository().fromSignature(signature);
+            if (transactionData instanceof ArbitraryTransactionData) {
+
+                // Check if we're even allowed to serve metadata for this transaction
+                if (ArbitraryDataStorageManager.getInstance().canStoreData(transactionData)) {
+
+                    byte[] metadataHash = transactionData.getMetadataHash();
+                    if (metadataHash != null) {
+
+                        // Load metadata file
+                        metadataFile = ArbitraryDataFile.fromHash(metadataHash, signature);
+                    }
+                }
+            }
+
+        } catch (DataException e) {
+            LOGGER.error(String.format("Repository issue while fetching arbitrary metadata for peer %s", peer), e);
+        }
+
+        // We should only respond if we have the metadata file
+        if (metadataFile != null && metadataFile.exists()) {
+
+            // We have the metadata file, so update requests map to reflect that we've sent it
+            newEntry = new Triple<>(null, null, now);
+            arbitraryMetadataRequests.put(message.getId(), newEntry);
+
+            ArbitraryMetadataMessage arbitraryMetadataMessage = new ArbitraryMetadataMessage(signature, metadataFile);
+            arbitraryMetadataMessage.setId(message.getId());
+            //if (!peer.sendMessage(arbitraryMetadataMessage)) {
+            //    LOGGER.debug("Couldn't send metadata");
+            //    peer.disconnect("failed to send metadata");
+            //    return;
+            //}
+            peer.sendMessage(arbitraryMetadataMessage);
+            LOGGER.debug("Sent metadata");
+
+            // Nothing left to do, so return to prevent any unnecessary forwarding from occurring
+            LOGGER.debug("No need for any forwarding because metadata request is fully served");
+            return;
+
+        }
+
+        // We may need to forward this request on
+        boolean isBlocked = (transactionData == null || ListUtils.isNameBlocked(transactionData.getName()));
+        if (Settings.getInstance().isRelayModeEnabled() && !isBlocked) {
+            // In relay mode - so ask our other peers if they have it
+
+            long requestTime = getArbitraryMetadataMessage.getRequestTime();
+            int requestHops = getArbitraryMetadataMessage.getRequestHops() + 1;
+            long totalRequestTime = now - requestTime;
+
+            if (totalRequestTime < RELAY_REQUEST_MAX_DURATION) {
+                // Relay request hasn't timed out yet, so can potentially be rebroadcast
+                if (requestHops < RELAY_REQUEST_MAX_HOPS) {
+                    // Relay request hasn't reached the maximum number of hops yet, so can be rebroadcast
+
+                    Message relayGetArbitraryMetadataMessage = new GetArbitraryMetadataMessage(signature, requestTime, requestHops);
+                    relayGetArbitraryMetadataMessage.setId(message.getId());
+
+                    LOGGER.debug("Rebroadcasting metadata request from peer {} for signature {} to our other peers... totalRequestTime: {}, requestHops: {}", peer, Base58.encode(signature), totalRequestTime, requestHops);
+                    //Network.getInstance().broadcast(
+                    //        broadcastPeer ->
+                    //                !broadcastPeer.isAtLeastVersion(RELAY_MIN_PEER_VERSION) ? null :
+                    //                broadcastPeer == peer || Objects.equals(broadcastPeer.getPeerData().getAddress().getHost(), peer.getPeerData().getAddress().getHost()) ? null : relayGetArbitraryMetadataMessage);
+                    RNSNetwork.getInstance().broadcast(broadcastPeer -> relayGetArbitraryMetadataMessage);
+
+                }
+                else {
+                    // This relay request has reached the maximum number of allowed hops
+                }
+            }
+            else {
+                // This relay request has timed out
+            }
+        }
+    }
+
+}

src/main/java/org/qortal/controller/tradebot/RNSTradeBot.java

@@ -0,0 +1,778 @@
+package org.qortal.controller.tradebot;
+
+import com.google.common.primitives.Longs;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bitcoinj.core.ECKey;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.api.model.crosschain.TradeBotCreateRequest;
+import org.qortal.controller.Controller;
+import org.qortal.controller.Synchronizer;
+import org.qortal.controller.tradebot.AcctTradeBot.ResponseResult;
+import org.qortal.crosschain.*;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.at.ATData;
+import org.qortal.data.crosschain.CrossChainTradeData;
+import org.qortal.data.crosschain.TradeBotData;
+import org.qortal.data.network.TradePresenceData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.gui.SysTray;
+import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
+import org.qortal.network.message.GetTradePresencesMessage;
+import org.qortal.network.message.Message;
+import org.qortal.network.message.TradePresencesMessage;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.repository.hsqldb.HSQLDBImportExport;
+import org.qortal.settings.Settings;
+import org.qortal.transaction.Transaction;
+import org.qortal.utils.ByteArray;
+import org.qortal.utils.NTP;
+
+import java.awt.TrayIcon.MessageType;
+import java.security.SecureRandom;
+import java.util.*;
+import java.util.function.Supplier;
+
+/**
+ * Performing cross-chain trading steps on behalf of user.
+ * <p>
+ * We deal with three different independent state-spaces here:
+ * <ul>
+ * 	<li>Qortal blockchain</li>
+ * 	<li>Foreign blockchain</li>
+ * 	<li>Trade-bot entries</li>
+ * </ul>
+ */
+public class RNSTradeBot implements Listener {
+
+	private static final Logger LOGGER = LogManager.getLogger(TradeBot.class);
+	private static final Random RANDOM = new SecureRandom();
+
+	/** Maximum lifetime of trade presence timestamp. 30 mins in ms. */
+	private static final long PRESENCE_LIFETIME = 30 * 60 * 1000L;
+	/** How soon before expiry of our own trade presence timestamp that we want to trigger renewal. 5 mins in ms. */
+	private static final long EARLY_RENEWAL_PERIOD = 5 * 60 * 1000L;
+	/** Trade presence timestamps are rounded up to this nearest interval. Bigger values improve grouping of entries in [GET_]TRADE_PRESENCES network messages. 15 mins in ms. */
+	private static final long EXPIRY_ROUNDING = 15 * 60 * 1000L;
+	/** How often we want to broadcast our list of all known trade presences to peers. 5 mins in ms. */
+	private static final long PRESENCE_BROADCAST_INTERVAL = 5 * 60 * 1000L;
+
+	public interface StateNameAndValueSupplier {
+		public String getState();
+		public int getStateValue();
+	}
+
+	public static class StateChangeEvent implements Event {
+		private final TradeBotData tradeBotData;
+
+		public StateChangeEvent(TradeBotData tradeBotData) {
+			this.tradeBotData = tradeBotData;
+		}
+
+		public TradeBotData getTradeBotData() {
+			return this.tradeBotData;
+		}
+	}
+
+	public static class TradePresenceEvent implements Event {
+		private final TradePresenceData tradePresenceData;
+
+		public TradePresenceEvent(TradePresenceData tradePresenceData) {
+			this.tradePresenceData = tradePresenceData;
+		}
+
+		public TradePresenceData getTradePresenceData() {
+			return this.tradePresenceData;
+		}
+	}
+
+	private static final Map<Class<? extends ACCT>, Supplier<AcctTradeBot>> acctTradeBotSuppliers = new HashMap<>();
+	static {
+		acctTradeBotSuppliers.put(BitcoinACCTv1.class, BitcoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(BitcoinACCTv3.class, BitcoinACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(LitecoinACCTv1.class, LitecoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(LitecoinACCTv3.class, LitecoinACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DogecoinACCTv1.class, DogecoinACCTv1TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DogecoinACCTv3.class, DogecoinACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(DigibyteACCTv3.class, DigibyteACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(RavencoinACCTv3.class, RavencoinACCTv3TradeBot::getInstance);
+		acctTradeBotSuppliers.put(PirateChainACCTv3.class, PirateChainACCTv3TradeBot::getInstance);
+	}
+
+	private static RNSTradeBot instance;
+
+	private final Map<ByteArray, Long> ourTradePresenceTimestampsByPubkey = Collections.synchronizedMap(new HashMap<>());
+	private final List<TradePresenceData> pendingTradePresences = Collections.synchronizedList(new ArrayList<>());
+
+	private final Map<ByteArray, TradePresenceData> allTradePresencesByPubkey = Collections.synchronizedMap(new HashMap<>());
+	private Map<ByteArray, TradePresenceData> safeAllTradePresencesByPubkey = Collections.emptyMap();
+	private long nextTradePresenceBroadcastTimestamp = 0L;
+
+	private Map<String, Long> failedTrades = new HashMap<>();
+	private Map<String, Long> validTrades = new HashMap<>();
+
+	private RNSTradeBot() {
+		EventBus.INSTANCE.addListener(event -> RNSTradeBot.getInstance().listen(event));
+	}
+
+	public static synchronized RNSTradeBot getInstance() {
+		if (instance == null)
+			instance = new RNSTradeBot();
+
+		return instance;
+	}
+
+	public ACCT getAcctUsingAtData(ATData atData) {
+		byte[] codeHash = atData.getCodeHash();
+		if (codeHash == null)
+			return null;
+
+		return SupportedBlockchain.getAcctByCodeHash(codeHash);
+	}
+
+	public CrossChainTradeData populateTradeData(Repository repository, ATData atData) throws DataException {
+		ACCT acct = this.getAcctUsingAtData(atData);
+		if (acct == null)
+			return null;
+
+		return acct.populateTradeData(repository, atData);
+	}
+
+	/**
+	 * Creates a new trade-bot entry from the "Bob" viewpoint,
+	 * i.e. OFFERing QORT in exchange for foreign blockchain currency.
+	 * <p>
+	 * Generates:
+	 * <ul>
+	 * 	<li>new 'trade' private key</li>
+	 * 	<li>secret(s)</li>
+	 * </ul>
+	 * Derives:
+	 * <ul>
+	 * 	<li>'native' (as in Qortal) public key, public key hash, address (starting with Q)</li>
+	 * 	<li>'foreign' public key, public key hash</li>
+	 *	<li>hash(es) of secret(s)</li>
+	 * </ul>
+	 * A Qortal AT is then constructed including the following as constants in the 'data segment':
+	 * <ul>
+	 * 	<li>'native' (Qortal) 'trade' address - used to MESSAGE AT</li>
+	 * 	<li>'foreign' public key hash - used by Alice's to allow redeem of currency on foreign blockchain</li>
+	 * 	<li>hash(es) of secret(s) - used by AT (optional) and foreign blockchain as needed</li>
+	 * 	<li>QORT amount on offer by Bob</li>
+	 * 	<li>foreign currency amount expected in return by Bob (from Alice)</li>
+	 * 	<li>trading timeout, in case things go wrong and everyone needs to refund</li>
+	 * </ul>
+	 * Returns a DEPLOY_AT transaction that needs to be signed and broadcast to the Qortal network.
+	 * <p>
+	 * Trade-bot will wait for Bob's AT to be deployed before taking next step.
+	 * <p>
+	 * @param repository
+	 * @param tradeBotCreateRequest
+	 * @return raw, unsigned DEPLOY_AT transaction
+	 * @throws DataException
+	 */
+	public byte[] createTrade(Repository repository, TradeBotCreateRequest tradeBotCreateRequest) throws DataException {
+		// Fetch latest ACCT version for requested foreign blockchain
+		ACCT acct = tradeBotCreateRequest.foreignBlockchain.getLatestAcct();
+
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null)
+			return null;
+
+		return acctTradeBot.createTrade(repository, tradeBotCreateRequest);
+	}
+
+	/**
+	 * Creates a trade-bot entry from the 'Alice' viewpoint,
+	 * i.e. matching foreign blockchain currency to an existing QORT offer.
+	 * <p>
+	 * Requires a chosen trade offer from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a foreign blockchain wallet via <tt>foreignKey</tt>.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeData chosen trade OFFER that Alice wants to match
+	 * @param foreignKey foreign blockchain wallet key
+	 * @throws DataException
+	 */
+	public ResponseResult startResponse(Repository repository, ATData atData, ACCT acct,
+			CrossChainTradeData crossChainTradeData, String foreignKey, String receivingAddress) throws DataException {
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null) {
+			LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot for AT %s", atData.getATAddress()));
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		// Check Alice doesn't already have an existing, on-going trade-bot entry for this AT.
+		if (repository.getCrossChainRepository().existsTradeWithAtExcludingStates(atData.getATAddress(), acctTradeBot.getEndStates()))
+			return ResponseResult.TRADE_ALREADY_EXISTS;
+
+		return acctTradeBot.startResponse(repository, atData, acct, crossChainTradeData, foreignKey, receivingAddress);
+	}
+
+	/**
+	 * Creates a trade-bot entries from the 'Alice' viewpoint,
+	 * i.e. matching foreign blockchain currency to existing QORT offers.
+	 * <p>
+	 * Requires chosen trade offers from Bob, passed by <tt>crossChainTradeData</tt>
+	 * and access to a foreign blockchain wallet via <tt>foreignKey</tt>.
+	 * <p>
+	 * @param repository
+	 * @param crossChainTradeDataList chosen trade OFFERs that Alice wants to match
+	 * @param receiveAddress Alice's Qortal address to receive her QORT
+	 * @param foreignKey foreign blockchain wallet key
+	 * @param bitcoiny
+	 * @throws DataException
+	 */
+	public ResponseResult startResponseMultiple(
+			Repository repository,
+			ACCT acct,
+			List<CrossChainTradeData> crossChainTradeDataList,
+			String receiveAddress,
+			String foreignKey,
+			Bitcoiny bitcoiny) throws DataException {
+		AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+		if (acctTradeBot == null) {
+			LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot for %s", acct.getBlockchain()));
+			return ResponseResult.NETWORK_ISSUE;
+		}
+
+		for( CrossChainTradeData tradeData : crossChainTradeDataList) {
+			// Check Alice doesn't already have an existing, on-going trade-bot entry for this AT.
+			if (repository.getCrossChainRepository().existsTradeWithAtExcludingStates(tradeData.qortalAtAddress, acctTradeBot.getEndStates()))
+				return ResponseResult.TRADE_ALREADY_EXISTS;
+		}
+		return TradeBotUtils.startResponseMultiple(repository, acct, crossChainTradeDataList, receiveAddress, foreignKey, bitcoiny);
+	}
+
+	public boolean deleteEntry(Repository repository, byte[] tradePrivateKey) throws DataException {
+		TradeBotData tradeBotData = repository.getCrossChainRepository().getTradeBotData(tradePrivateKey);
+		if (tradeBotData == null)
+			// Can't delete what we don't have!
+			return false;
+
+		boolean canDelete = false;
+
+		ACCT acct = SupportedBlockchain.getAcctByName(tradeBotData.getAcctName());
+		if (acct == null)
+			// We can't/no longer support this ACCT
+			canDelete = true;
+		else {
+			AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+			canDelete = acctTradeBot == null || acctTradeBot.canDelete(repository, tradeBotData);
+		}
+
+		if (canDelete) {
+			repository.getCrossChainRepository().delete(tradePrivateKey);
+			repository.saveChanges();
+		}
+
+		return canDelete;
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Synchronizer.NewChainTipEvent))
+			return;
+
+		// Don't process trade bots or broadcast presence timestamps if our chain is more than 60 minutes old
+		final Long minLatestBlockTimestamp = NTP.getTime() - (60 * 60 * 1000L);
+		if (!Controller.getInstance().isUpToDate(minLatestBlockTimestamp))
+			return;
+
+		synchronized (this) {
+			expireOldPresenceTimestamps();
+
+			List<TradeBotData> allTradeBotData;
+
+			try (final Repository repository = RepositoryManager.getRepository()) {
+				allTradeBotData = repository.getCrossChainRepository().getAllTradeBotData();
+			} catch (DataException e) {
+				LOGGER.error("Couldn't run trade bot due to repository issue", e);
+				return;
+			}
+
+			for (TradeBotData tradeBotData : allTradeBotData)
+				try (final Repository repository = RepositoryManager.getRepository()) {
+					// Find ACCT-specific trade-bot for this entry
+					ACCT acct = SupportedBlockchain.getAcctByName(tradeBotData.getAcctName());
+					if (acct == null) {
+						LOGGER.debug(() -> String.format("Couldn't find ACCT matching name %s", tradeBotData.getAcctName()));
+						continue;
+					}
+
+					AcctTradeBot acctTradeBot = findTradeBotForAcct(acct);
+					if (acctTradeBot == null) {
+						LOGGER.debug(() -> String.format("Couldn't find ACCT trade-bot matching name %s", tradeBotData.getAcctName()));
+						continue;
+					}
+
+					acctTradeBot.progress(repository, tradeBotData);
+				} catch (DataException e) {
+					LOGGER.error("Couldn't run trade bot due to repository issue", e);
+				} catch (ForeignBlockchainException e) {
+					LOGGER.warn(() -> String.format("Foreign blockchain issue processing trade-bot entry for AT %s: %s", tradeBotData.getAtAddress(), e.getMessage()));
+				}
+
+			broadcastPresenceTimestamps();
+		}
+	}
+
+	public static byte[] generateTradePrivateKey() {
+		// The private key is used for both Curve25519 and secp256k1 so needs to be valid for both.
+		// Curve25519 accepts any seed, so generate a valid secp256k1 key and use that.
+		return new ECKey().getPrivKeyBytes();
+	}
+
+	public static byte[] deriveTradeNativePublicKey(byte[] privateKey) {
+		return Crypto.toPublicKey(privateKey);
+	}
+
+	public static byte[] deriveTradeForeignPublicKey(byte[] privateKey) {
+		return ECKey.fromPrivate(privateKey).getPubKey();
+	}
+
+	/*package*/ public static byte[] generateSecret() {
+		byte[] secret = new byte[32];
+		RANDOM.nextBytes(secret);
+		return secret;
+	}
+
+	/*package*/ static void backupTradeBotData(Repository repository, List<TradeBotData> additional) {
+		// Attempt to backup the trade bot data. This an optional step and doesn't impact trading, so don't throw an exception on failure
+		try {
+			LOGGER.info("About to backup trade bot data...");
+			HSQLDBImportExport.backupTradeBotStates(repository, additional);
+		} catch (DataException e) {
+			LOGGER.info(String.format("Repository issue when exporting trade bot data: %s", e.getMessage()));
+		}
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData,
+			String newState, int newStateValue, Supplier<String> logMessageSupplier) throws DataException {
+		tradeBotData.setState(newState);
+		tradeBotData.setStateValue(newStateValue);
+		tradeBotData.setTimestamp(NTP.getTime());
+		repository.getCrossChainRepository().save(tradeBotData);
+		repository.saveChanges();
+
+		if (Settings.getInstance().isTradebotSystrayEnabled())
+			SysTray.getInstance().showMessage("Trade-Bot", String.format("%s: %s", tradeBotData.getAtAddress(), newState), MessageType.INFO);
+
+		if (logMessageSupplier != null)
+			LOGGER.info(logMessageSupplier.get());
+
+		LOGGER.debug(() -> String.format("new state for trade-bot entry based on AT %s: %s", tradeBotData.getAtAddress(), newState));
+
+		notifyStateChange(tradeBotData);
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData, StateNameAndValueSupplier newStateSupplier, Supplier<String> logMessageSupplier) throws DataException {
+		updateTradeBotState(repository, tradeBotData, newStateSupplier.getState(), newStateSupplier.getStateValue(), logMessageSupplier);
+	}
+
+	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
+	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData, Supplier<String> logMessageSupplier) throws DataException {
+		updateTradeBotState(repository, tradeBotData, tradeBotData.getState(), tradeBotData.getStateValue(), logMessageSupplier);
+	}
+
+	/*package*/ static void notifyStateChange(TradeBotData tradeBotData) {
+		StateChangeEvent stateChangeEvent = new StateChangeEvent(tradeBotData);
+		EventBus.INSTANCE.notify(stateChangeEvent);
+	}
+
+	/*package*/ static AcctTradeBot findTradeBotForAcct(ACCT acct) {
+		Supplier<AcctTradeBot> acctTradeBotSupplier = acctTradeBotSuppliers.get(acct.getClass());
+		if (acctTradeBotSupplier == null)
+			return null;
+
+		return acctTradeBotSupplier.get();
+	}
+
+	// PRESENCE-related
+
+	public Collection<TradePresenceData> getAllTradePresences() {
+		return this.safeAllTradePresencesByPubkey.values();
+	}
+
+	/** Trade presence timestamps expire in the 'future' so any that reach 'now' have expired and are removed. */
+	private void expireOldPresenceTimestamps() {
+		long now = NTP.getTime();
+
+		int allRemovedCount = 0;
+		synchronized (this.allTradePresencesByPubkey) {
+			int preRemoveCount = this.allTradePresencesByPubkey.size();
+			this.allTradePresencesByPubkey.values().removeIf(tradePresenceData -> tradePresenceData.getTimestamp() <= now);
+			allRemovedCount = this.allTradePresencesByPubkey.size() - preRemoveCount;
+		}
+
+		int ourRemovedCount = 0;
+		synchronized (this.ourTradePresenceTimestampsByPubkey) {
+			int preRemoveCount = this.ourTradePresenceTimestampsByPubkey.size();
+			this.ourTradePresenceTimestampsByPubkey.values().removeIf(timestamp -> timestamp < now);
+			ourRemovedCount = this.ourTradePresenceTimestampsByPubkey.size() - preRemoveCount;
+		}
+
+		if (allRemovedCount > 0)
+			LOGGER.debug("Removed {} expired trade presences, of which {} ours", allRemovedCount, ourRemovedCount);
+	}
+
+	/*package*/ void updatePresence(Repository repository, TradeBotData tradeBotData, CrossChainTradeData tradeData)
+			throws DataException {
+		String atAddress = tradeBotData.getAtAddress();
+
+		PrivateKeyAccount tradeNativeAccount = new PrivateKeyAccount(repository, tradeBotData.getTradePrivateKey());
+		String signerAddress = tradeNativeAccount.getAddress();
+
+		/*
+		* There's no point in Alice trying to broadcast presence for an AT that isn't locked to her,
+		* as other peers won't be able to verify as signing public key isn't yet in the AT's data segment.
+		*/
+		if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress)) {
+			// Signer is neither Bob, nor trade locked to Alice
+			LOGGER.trace("Can't provide trade presence for our AT {} as it's not yet locked to Alice", atAddress);
+			return;
+		}
+
+		long now = NTP.getTime();
+		long newExpiry = generateExpiry(now);
+		ByteArray pubkeyByteArray = ByteArray.wrap(tradeNativeAccount.getPublicKey());
+
+		// If map entry's timestamp is missing, or within early renewal period, use the new expiry - otherwise use existing timestamp.
+		synchronized (this.ourTradePresenceTimestampsByPubkey) {
+			Long currentTimestamp = this.ourTradePresenceTimestampsByPubkey.get(pubkeyByteArray);
+
+			if (currentTimestamp != null && currentTimestamp - now > EARLY_RENEWAL_PERIOD) {
+				// timestamp still good
+				LOGGER.trace("Current trade presence timestamp {} still good for our trade {}", currentTimestamp, atAddress);
+				return;
+			}
+
+			this.ourTradePresenceTimestampsByPubkey.put(pubkeyByteArray, newExpiry);
+		}
+
+		// Create signature
+		byte[] signature = tradeNativeAccount.sign(Longs.toByteArray(newExpiry));
+
+		// Add new trade presence to queue to be broadcast around network
+		TradePresenceData tradePresenceData = new TradePresenceData(newExpiry, tradeNativeAccount.getPublicKey(), signature, atAddress);
+		this.pendingTradePresences.add(tradePresenceData);
+
+		this.allTradePresencesByPubkey.put(pubkeyByteArray, tradePresenceData);
+		rebuildSafeAllTradePresences();
+
+		LOGGER.trace("New trade presence timestamp {} for our trade {}", newExpiry, atAddress);
+
+		EventBus.INSTANCE.notify(new TradePresenceEvent(tradePresenceData));
+	}
+
+	private void rebuildSafeAllTradePresences() {
+		synchronized (this.allTradePresencesByPubkey) {
+			// Collect into a *new* unmodifiable map.
+			this.safeAllTradePresencesByPubkey = Map.copyOf(this.allTradePresencesByPubkey);
+		}
+	}
+
+	private void broadcastPresenceTimestamps() {
+		// If we have new trade presences that are pending broadcast, send those as a priority
+		if (!this.pendingTradePresences.isEmpty()) {
+			// Create a copy for Network to safely use in another thread
+			List<TradePresenceData> safeTradePresences;
+			synchronized (this.pendingTradePresences) {
+				safeTradePresences = List.copyOf(this.pendingTradePresences);
+				this.pendingTradePresences.clear();
+			}
+
+			LOGGER.debug("Broadcasting {} new trade presences", safeTradePresences.size());
+
+			TradePresencesMessage tradePresencesMessage = new TradePresencesMessage(safeTradePresences);
+			RNSNetwork.getInstance().broadcast(peer -> tradePresencesMessage);
+
+			return;
+		}
+
+		// As we have no new trade presences, check whether it's time to do a general broadcast
+		Long now = NTP.getTime();
+		if (now == null || now < nextTradePresenceBroadcastTimestamp)
+			return;
+
+		nextTradePresenceBroadcastTimestamp = now + PRESENCE_BROADCAST_INTERVAL;
+
+		List<TradePresenceData> safeTradePresences = List.copyOf(this.safeAllTradePresencesByPubkey.values());
+
+		LOGGER.debug("Broadcasting all {} known trade presences. Next broadcast timestamp: {}",
+				safeTradePresences.size(), nextTradePresenceBroadcastTimestamp
+		);
+
+		GetTradePresencesMessage getTradePresencesMessage = new GetTradePresencesMessage(safeTradePresences);
+		RNSNetwork.getInstance().broadcast(peer -> getTradePresencesMessage);
+	}
+
+	// Network message processing
+
+	public void onGetTradePresencesMessage(RNSPeer peer, Message message) {
+		GetTradePresencesMessage getTradePresencesMessage = (GetTradePresencesMessage) message;
+
+		List<TradePresenceData> peersTradePresences = getTradePresencesMessage.getTradePresences();
+
+		// Create mutable copy from safe snapshot
+		Map<ByteArray, TradePresenceData> entriesUnknownToPeer = new HashMap<>(this.safeAllTradePresencesByPubkey);
+		int knownCount = entriesUnknownToPeer.size();
+
+		for (TradePresenceData peersTradePresence : peersTradePresences) {
+			ByteArray pubkeyByteArray = ByteArray.wrap(peersTradePresence.getPublicKey());
+
+			TradePresenceData ourEntry = entriesUnknownToPeer.get(pubkeyByteArray);
+
+			if (ourEntry != null && ourEntry.getTimestamp() == peersTradePresence.getTimestamp())
+				entriesUnknownToPeer.remove(pubkeyByteArray);
+		}
+
+		if (entriesUnknownToPeer.isEmpty())
+			return;
+
+		LOGGER.debug("Sending {} trade presences to peer {} after excluding their {} from known {}",
+				entriesUnknownToPeer.size(), peer, peersTradePresences.size(), knownCount
+		);
+
+		// Send complement to peer
+		List<TradePresenceData> safeTradePresences = List.copyOf(entriesUnknownToPeer.values());
+		Message responseMessage = new TradePresencesMessage(safeTradePresences);
+		//if (!peer.sendMessage(responseMessage)) {
+		//	peer.disconnect("failed to send TRADE_PRESENCES response");
+		//	return;
+		//}
+		peer.sendMessage(responseMessage);
+	}
+
+	public void onTradePresencesMessage(RNSPeer peer, Message message) {
+		TradePresencesMessage tradePresencesMessage = (TradePresencesMessage) message;
+
+		List<TradePresenceData> peersTradePresences = tradePresencesMessage.getTradePresences();
+
+		long now = NTP.getTime();
+		// Timestamps before this are too far into the past
+		long pastThreshold = now;
+		// Timestamps after this are too far into the future
+		long futureThreshold = now + PRESENCE_LIFETIME;
+
+		Map<ByteArray, Supplier<ACCT>> acctSuppliersByCodeHash = SupportedBlockchain.getAcctMap();
+
+		int newCount = 0;
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			for (TradePresenceData peersTradePresence : peersTradePresences) {
+				long timestamp = peersTradePresence.getTimestamp();
+
+				// Ignore if timestamp is out of bounds
+				if (timestamp < pastThreshold || timestamp > futureThreshold) {
+					if (timestamp < pastThreshold)
+						LOGGER.trace("Ignoring trade presence {} from peer {} as timestamp {} is too old vs {}",
+								peersTradePresence.getAtAddress(), peer, timestamp, pastThreshold
+								);
+					else
+						LOGGER.trace("Ignoring trade presence {} from peer {} as timestamp {} is too new vs {}",
+								peersTradePresence.getAtAddress(), peer, timestamp, pastThreshold
+						);
+
+					continue;
+				}
+
+				ByteArray pubkeyByteArray = ByteArray.wrap(peersTradePresence.getPublicKey());
+
+				// Ignore if we've previously verified this timestamp+publickey combo or sent timestamp is older
+				TradePresenceData existingTradeData = this.safeAllTradePresencesByPubkey.get(pubkeyByteArray);
+				if (existingTradeData != null && timestamp <= existingTradeData.getTimestamp()) {
+					if (timestamp == existingTradeData.getTimestamp())
+						LOGGER.trace("Ignoring trade presence {} from peer {} as we have verified timestamp {} before",
+								peersTradePresence.getAtAddress(), peer, timestamp
+						);
+					else
+						LOGGER.trace("Ignoring trade presence {} from peer {} as timestamp {} is older than latest {}",
+								peersTradePresence.getAtAddress(), peer, timestamp, existingTradeData.getTimestamp()
+						);
+
+					continue;
+				}
+
+				// Check timestamp signature
+				byte[] timestampSignature = peersTradePresence.getSignature();
+				byte[] timestampBytes = Longs.toByteArray(timestamp);
+				byte[] publicKey = peersTradePresence.getPublicKey();
+				if (!Crypto.verify(publicKey, timestampSignature, timestampBytes)) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as signature failed to verify",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				ATData atData = repository.getATRepository().fromATAddress(peersTradePresence.getAtAddress());
+				if (atData == null || atData.getIsFrozen() || atData.getIsFinished()) {
+					if (atData == null)
+						LOGGER.trace("Ignoring trade presence {} from peer {} as AT doesn't exist",
+								peersTradePresence.getAtAddress(), peer
+						);
+					else
+						LOGGER.trace("Ignoring trade presence {} from peer {} as AT is frozen or finished",
+								peersTradePresence.getAtAddress(), peer
+						);
+
+					continue;
+				}
+
+				ByteArray atCodeHash = ByteArray.wrap(atData.getCodeHash());
+				Supplier<ACCT> acctSupplier = acctSuppliersByCodeHash.get(atCodeHash);
+				if (acctSupplier == null) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as AT isn't a known ACCT?",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				CrossChainTradeData tradeData = acctSupplier.get().populateTradeData(repository, atData);
+				if (tradeData == null) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as trade data not found?",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				// Convert signer's public key to address form
+				String signerAddress = peersTradePresence.getTradeAddress();
+
+				// Signer's public key (in address form) must match Bob's / Alice's trade public key (in address form)
+				if (!signerAddress.equals(tradeData.qortalCreatorTradeAddress) && !signerAddress.equals(tradeData.qortalPartnerAddress)) {
+					LOGGER.trace("Ignoring trade presence {} from peer {} as signer isn't Alice or Bob?",
+							peersTradePresence.getAtAddress(), peer
+					);
+
+					continue;
+				}
+
+				// This is new to us
+				this.allTradePresencesByPubkey.put(pubkeyByteArray, peersTradePresence);
+				++newCount;
+
+				LOGGER.trace("Added trade presence {} from peer {} with timestamp {}",
+						peersTradePresence.getAtAddress(), peer, timestamp
+				);
+
+				EventBus.INSTANCE.notify(new TradePresenceEvent(peersTradePresence));
+			}
+		} catch (DataException e) {
+			LOGGER.error("Couldn't process TRADE_PRESENCES message due to repository issue", e);
+		}
+
+		if (newCount > 0) {
+			LOGGER.debug("New trade presences: {}, all trade presences: {}", newCount, allTradePresencesByPubkey.size());
+			rebuildSafeAllTradePresences();
+		}
+	}
+
+	public void bridgePresence(long timestamp, byte[] publicKey, byte[] signature, String atAddress) {
+		long expiry = generateExpiry(timestamp);
+		ByteArray pubkeyByteArray = ByteArray.wrap(publicKey);
+
+		TradePresenceData fakeTradePresenceData = new TradePresenceData(expiry, publicKey, signature, atAddress);
+
+		// Only bridge if trade presence expiry timestamp is newer
+		TradePresenceData computedTradePresenceData = this.allTradePresencesByPubkey.compute(pubkeyByteArray, (k, v) ->
+				v == null || v.getTimestamp() < expiry ? fakeTradePresenceData : v
+		);
+
+		if (computedTradePresenceData == fakeTradePresenceData) {
+			LOGGER.trace("Bridged PRESENCE transaction for trade {} with timestamp {}", atAddress, expiry);
+			rebuildSafeAllTradePresences();
+
+			EventBus.INSTANCE.notify(new TradePresenceEvent(fakeTradePresenceData));
+		}
+	}
+
+	/** Decorates a CrossChainTradeData object with Alice / Bob trade-bot presence timestamp, if available. */
+	public void decorateTradeDataWithPresence(CrossChainTradeData crossChainTradeData) {
+		// Match by AT address, then check for Bob vs Alice
+		this.safeAllTradePresencesByPubkey.values().stream()
+				.filter(tradePresenceData -> tradePresenceData.getAtAddress().equals(crossChainTradeData.qortalAtAddress))
+				.forEach(tradePresenceData -> {
+					String signerAddress = tradePresenceData.getTradeAddress();
+
+					// Signer's public key (in address form) must match Bob's / Alice's trade public key (in address form)
+					if (signerAddress.equals(crossChainTradeData.qortalCreatorTradeAddress))
+						crossChainTradeData.creatorPresenceExpiry = tradePresenceData.getTimestamp();
+					else if (signerAddress.equals(crossChainTradeData.qortalPartnerAddress))
+						crossChainTradeData.partnerPresenceExpiry = tradePresenceData.getTimestamp();
+				});
+	}
+
+	/** Removes any trades that have had multiple failures */
+	public List<CrossChainTradeData> removeFailedTrades(Repository repository, List<CrossChainTradeData> crossChainTrades) {
+		Long now = NTP.getTime();
+		if (now == null) {
+			return crossChainTrades;
+		}
+
+		List<CrossChainTradeData> updatedCrossChainTrades = new ArrayList<>(crossChainTrades);
+		int getMaxTradeOfferAttempts = Settings.getInstance().getMaxTradeOfferAttempts();
+
+		for (CrossChainTradeData crossChainTradeData : crossChainTrades) {
+			// We only care about trades in the OFFERING state
+			if (crossChainTradeData.mode != AcctMode.OFFERING) {
+				failedTrades.remove(crossChainTradeData.qortalAtAddress);
+				validTrades.remove(crossChainTradeData.qortalAtAddress);
+				continue;
+			}
+
+			// Return recently cached values if they exist
+			Long failedTimestamp = failedTrades.get(crossChainTradeData.qortalAtAddress);
+			if (failedTimestamp != null && now - failedTimestamp < 60 * 60 * 1000L) {
+				updatedCrossChainTrades.remove(crossChainTradeData);
+				//LOGGER.info("Removing cached failed trade AT {}", crossChainTradeData.qortalAtAddress);
+				continue;
+			}
+			Long validTimestamp = validTrades.get(crossChainTradeData.qortalAtAddress);
+			if (validTimestamp != null && now - validTimestamp < 60 * 60 * 1000L) {
+				//LOGGER.info("NOT removing cached valid trade AT {}", crossChainTradeData.qortalAtAddress);
+				continue;
+			}
+
+			try {
+				List<TransactionData> transactions = repository.getTransactionRepository().getUnconfirmedTransactions(Arrays.asList(Transaction.TransactionType.MESSAGE), null, null, null, null);
+
+				for (TransactionData transactionData : transactions) {
+					// Treat as failed if buy attempt was more than 60 mins ago (as it's still in the OFFERING state)
+					if (transactionData.getRecipient().equals(crossChainTradeData.qortalCreatorTradeAddress) && now - transactionData.getTimestamp() > 60*60*1000L) {
+						failedTrades.put(crossChainTradeData.qortalAtAddress, now);
+						updatedCrossChainTrades.remove(crossChainTradeData);
+					} else {
+						validTrades.put(crossChainTradeData.qortalAtAddress, now);
+					}
+				}
+
+			} catch (DataException e) {
+				LOGGER.info("Unable to determine failed state of AT {}", crossChainTradeData.qortalAtAddress);
+            }
+		}
+
+		return updatedCrossChainTrades;
+	}
+
+	public boolean isFailedTrade(Repository repository, CrossChainTradeData crossChainTradeData) {
+		List<CrossChainTradeData> results = removeFailedTrades(repository, Arrays.asList(crossChainTradeData));
+		return results.isEmpty();
+	}
+
+	private long generateExpiry(long timestamp) {
+		return ((timestamp - 1) / EXPIRY_ROUNDING) * EXPIRY_ROUNDING + PRESENCE_LIFETIME;
+	}
+
+}

src/main/java/org/qortal/data/arbitrary/RNSArbitraryDirectConnectionInfo.java

@@ -0,0 +1,59 @@
+package org.qortal.data.arbitrary;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+public class RNSArbitraryDirectConnectionInfo {
+
+    private final byte[] signature;
+    private final String peerAddress;
+    private final List<byte[]> hashes;
+    private final long timestamp;
+
+    public RNSArbitraryDirectConnectionInfo(byte[] signature, String peerAddress, List<byte[]> hashes, long timestamp) {
+        this.signature = signature;
+        this.peerAddress = peerAddress;
+        this.hashes = hashes;
+        this.timestamp = timestamp;
+    }
+
+    public byte[] getSignature() {
+        return this.signature;
+    }
+
+    public String getPeerAddress() {
+        return this.peerAddress;
+    }
+
+    public List<byte[]> getHashes() {
+        return this.hashes;
+    }
+    
+    public long getTimestamp() {
+        return this.timestamp;
+    }
+
+    public int getHashCount() {
+        if (this.hashes == null) {
+            return 0;
+        }
+        return this.hashes.size();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (other == this)
+            return true;
+
+        if (!(other instanceof ArbitraryDirectConnectionInfo))
+            return false;
+
+        ArbitraryDirectConnectionInfo otherDirectConnectionInfo = (ArbitraryDirectConnectionInfo) other;
+
+        return Arrays.equals(this.signature, otherDirectConnectionInfo.getSignature())
+                && Objects.equals(this.peerAddress, otherDirectConnectionInfo.getPeerAddress())
+                && Objects.equals(this.hashes, otherDirectConnectionInfo.getHashes())
+                && Objects.equals(this.timestamp, otherDirectConnectionInfo.getTimestamp());
+    }
+}

src/main/java/org/qortal/data/arbitrary/RNSArbitraryFileListResponseInfo.java

@@ -0,0 +1,11 @@
+package org.qortal.data.arbitrary;
+
+import org.qortal.network.RNSPeer;
+
+public class RNSArbitraryFileListResponseInfo extends  RNSArbitraryRelayInfo {
+
+    public RNSArbitraryFileListResponseInfo(String hash58, String signature58, RNSPeer peer, Long timestamp, Long requestTime, Integer requestHops) {
+        super(hash58, signature58, peer, timestamp, requestTime, requestHops);
+    }
+
+}

src/main/java/org/qortal/data/arbitrary/RNSArbitraryRelayInfo.java

@@ -0,0 +1,73 @@
+package org.qortal.data.arbitrary;
+
+import org.qortal.network.RNSPeer;
+
+import java.util.Objects;
+
+public class RNSArbitraryRelayInfo {
+
+    private final String hash58;
+    private final String signature58;
+    private final RNSPeer peer;
+    private final Long timestamp;
+    private final Long requestTime;
+    private final Integer requestHops;
+
+    public RNSArbitraryRelayInfo(String hash58, String signature58, RNSPeer peer, Long timestamp, Long requestTime, Integer requestHops) {
+        this.hash58 = hash58;
+        this.signature58 = signature58;
+        this.peer = peer;
+        this.timestamp = timestamp;
+        this.requestTime = requestTime;
+        this.requestHops = requestHops;
+    }
+
+    public boolean isValid() {
+        return this.getHash58() != null && this.getSignature58() != null
+                && this.getPeer() != null && this.getTimestamp() != null;
+    }
+
+    public String getHash58() {
+        return this.hash58;
+    }
+
+    public String getSignature58() {
+        return signature58;
+    }
+
+    public RNSPeer getPeer() {
+        return peer;
+    }
+
+    public Long getTimestamp() {
+        return timestamp;
+    }
+
+    public Long getRequestTime() {
+        return this.requestTime;
+    }
+
+    public Integer getRequestHops() {
+        return this.requestHops;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("%s = %s, %s, %d", this.hash58, this.signature58, this.peer, this.timestamp);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (other == this)
+            return true;
+
+        if (!(other instanceof ArbitraryRelayInfo))
+            return false;
+
+        RNSArbitraryRelayInfo otherRelayInfo = (RNSArbitraryRelayInfo) other;
+
+        return this.peer == otherRelayInfo.getPeer()
+                && Objects.equals(this.hash58, otherRelayInfo.getHash58())
+                && Objects.equals(this.signature58, otherRelayInfo.getSignature58());
+    }
+}

src/main/java/org/qortal/data/network/RNSPeerData.java

@@ -0,0 +1,117 @@
+package org.qortal.data.network;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import org.qortal.network.PeerAddress;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlTransient;
+import static org.apache.commons.codec.binary.Hex.encodeHexString;
+
+// All properties to be converted to JSON via JAXB
+@XmlAccessorType(XmlAccessType.FIELD)
+public class RNSPeerData {
+
+	//public static final int MAX_PEER_ADDRESS_SIZE = 255;
+
+	// Properties
+
+	//// Don't expose this via JAXB - use pretty getter instead
+	//@XmlTransient
+	//@Schema(hidden = true)
+	//private PeerAddress peerAddress;
+	private byte[] peerAddress;
+
+	private Long lastAttempted;
+	private Long lastConnected;
+	private Long lastMisbehaved;
+	private Long addedWhen;
+	private String addedBy;
+
+	/** The number of consecutive times we failed to sync with this peer */
+	private int failedSyncCount = 0;
+
+	// Constructors
+
+	// necessary for JAXB serialization
+	protected RNSPeerData() {
+	}
+
+	public RNSPeerData(byte[] peerAddress, Long lastAttempted, Long lastConnected, Long lastMisbehaved, Long addedWhen, String addedBy) {
+		this.peerAddress = peerAddress;
+		this.lastAttempted = lastAttempted;
+		this.lastConnected = lastConnected;
+		this.lastMisbehaved = lastMisbehaved;
+		this.addedWhen = addedWhen;
+		this.addedBy = addedBy;
+	}
+
+	public RNSPeerData(byte[] peerAddress, Long addedWhen, String addedBy) {
+		this(peerAddress, null, null, null, addedWhen, addedBy);
+	}
+
+	public RNSPeerData(byte[] peerAddress) {
+		this(peerAddress, null, null, null, null, null);
+	}
+
+	// Getters / setters
+
+	// Don't let JAXB use this getter
+	@XmlTransient
+	@Schema(hidden = true)
+	public byte[] getAddress() {
+		return this.peerAddress;
+	}
+
+	public Long getLastAttempted() {
+		return this.lastAttempted;
+	}
+
+	public void setLastAttempted(Long lastAttempted) {
+		this.lastAttempted = lastAttempted;
+	}
+
+	public Long getLastConnected() {
+		return this.lastConnected;
+	}
+
+	public void setLastConnected(Long lastConnected) {
+		this.lastConnected = lastConnected;
+	}
+
+	public Long getLastMisbehaved() {
+		return this.lastMisbehaved;
+	}
+
+	public void setLastMisbehaved(Long lastMisbehaved) {
+		this.lastMisbehaved = lastMisbehaved;
+	}
+
+	public Long getAddedWhen() {
+		return this.addedWhen;
+	}
+
+	public String getAddedBy() {
+		return this.addedBy;
+	}
+
+	public int getFailedSyncCount() {
+		return this.failedSyncCount;
+	}
+
+	public void setFailedSyncCount(int failedSyncCount) {
+		this.failedSyncCount = failedSyncCount;
+	}
+
+	public void incrementFailedSyncCount() {
+		this.failedSyncCount++;
+	}
+
+	// Pretty peerAddress getter for JAXB
+	@XmlElement(name = "address")
+	protected String getPrettyAddress() {
+		return encodeHexString(this.peerAddress);
+	}
+
+}

src/main/java/org/qortal/network/RNSNetwork.java

@@ -69,12 +69,24 @@ import java.util.concurrent.atomic.AtomicLong;
 //import java.util.concurrent.locks.Lock;
 //import java.util.concurrent.locks.ReentrantLock;
 import java.util.Objects;
+import java.util.function.Function;
 
 import org.apache.commons.codec.binary.Hex;
 import org.qortal.utils.ExecuteProduceConsume;
 import org.qortal.utils.ExecuteProduceConsume.StatsSnapshot;
 import org.qortal.utils.NTP;
 import org.qortal.utils.NamedThreadFactory;
+import org.qortal.network.message.Message;
+import org.qortal.network.message.BlockSummariesV2Message;
+import org.qortal.network.message.TransactionSignaturesMessage;
+import org.qortal.network.message.GetUnconfirmedTransactionsMessage;
+import org.qortal.network.task.RNSBroadcastTask;
+import org.qortal.controller.Controller;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.data.block.BlockData;
+import org.qortal.data.block.BlockSummaryData;
+import org.qortal.data.transaction.TransactionData;
 
 // logging
 import lombok.extern.slf4j.Slf4j;
@@ -90,12 +102,8 @@ public class RNSNetwork {
     static final String APP_NAME = Settings.getInstance().isTestNet() ? RNSCommon.TESTNET_APP_NAME: RNSCommon.MAINNET_APP_NAME;
     //static final String defaultConfigPath = ".reticulum"; // if empty will look in Reticulums default paths
     static final String defaultConfigPath = Settings.getInstance().isTestNet() ? RNSCommon.defaultRNSConfigPathTestnet: RNSCommon.defaultRNSConfigPath;
-    //static final String defaultConfigPath = RNSCommon.defaultRNSConfigPath;
+    private final int MAX_PEERS = Settings.getInstance().getReticulumMaxPeers();
-    //private final String defaultConfigPath = Settings.getInstance().getReticulumDefaultConfigPath();
+    private final int MIN_DESIRED_PEERS = Settings.getInstance().getReticulumMinDesiredPeers();
-    private static Integer MAX_PEERS = 12;
-    //private final Integer MAX_PEERS = Settings.getInstance().getReticulumMaxPeers();
-    private static Integer MIN_DESIRED_PEERS = 3;
-    //private final Integer MIN_DESIRED_PEERS = Settings.getInstance().getReticulumMinDesiredPeers();
     Identity serverIdentity;
     public Destination baseDestination;
     private volatile boolean isShuttingDown = false;
@@ -114,14 +122,18 @@ public class RNSNetwork {
 
     private final ExecuteProduceConsume rnsNetworkEPC;
     private static final long NETWORK_EPC_KEEPALIVE = 1000L; // 1 second
-    //private volatile boolean isShuttingDown = false;
     private int totalThreadCount = 0;
-    // TODO: settings - MaxReticulumPeers, MaxRNSNetworkThreadPoolSize (if needed)
+    private final int reticulumMaxNetworkThreadPoolSize = Settings.getInstance().getReticulumMaxNetworkThreadPoolSize();
 
     // replicating a feature from Network.class needed in for base Message.java,
     // just in case the classic TCP/IP Networking is turned off.
     private static final byte[] MAINNET_MESSAGE_MAGIC = new byte[]{0x51, 0x4f, 0x52, 0x54}; // QORT
     private static final byte[] TESTNET_MESSAGE_MAGIC = new byte[]{0x71, 0x6f, 0x72, 0x54}; // qorT
+    private static final int BROADCAST_CHAIN_TIP_DEPTH = 7; // Just enough to fill a SINGLE TCP packet (~1440 bytes)
+    /**
+     * How long between informational broadcasts to all ACTIVE peers, in milliseconds.
+     */
+    private static final long BROADCAST_INTERVAL = 30 * 1000L; // ms
 
     //private static final Logger logger = LoggerFactory.getLogger(RNSNetwork.class);
     
@@ -146,7 +158,7 @@ public class RNSNetwork {
 
         //        Settings.getInstance().getMaxRNSNetworkThreadPoolSize(),   // statically set to 5 below
         ExecutorService RNSNetworkExecutor = new ThreadPoolExecutor(1,
-                5,
+                reticulumMaxNetworkThreadPoolSize,
                 NETWORK_EPC_KEEPALIVE, TimeUnit.SECONDS,
                 new SynchronousQueue<Runnable>(),
                 new NamedThreadFactory("RNSNetwork-EPC", Settings.getInstance().getNetworkThreadPriority()));
@@ -228,6 +240,44 @@ public class RNSNetwork {
         }
     }
 
+    public void broadcast(Function<RNSPeer, Message> peerMessageBuilder) {
+        for (RNSPeer peer : getImmutableLinkedPeers()) {
+            if (this.isShuttingDown)
+                return;
+    
+            Message message = peerMessageBuilder.apply(peer);
+    
+            if (message == null) {
+                continue;
+            }
+    
+            peer.sendMessage(message);
+        }
+    }
+
+    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);
+
+            broadcast(broadcastPeer -> latestBlockSummariesMessage);
+        } catch (DataException e) {
+            log.warn("Couldn't broadcast our chain tip info", e);
+        }
+    }
+
+    public Message buildNewTransactionMessage(RNSPeer peer, TransactionData transactionData) {
+        // In V2 we send out transaction signature only and peers can decide whether to request the full transaction
+        return new TransactionSignaturesMessage(Collections.singletonList(transactionData.getSignature()));
+    }
+
+    public Message buildGetUnconfirmedTransactionsMessage(RNSPeer peer) {
+        return new GetUnconfirmedTransactionsMessage();
+    }
+
     public void shutdown() {
         isShuttingDown = true;
         log.info("shutting down Reticulum");
@@ -403,6 +453,8 @@ public class RNSNetwork {
         protected Task produceTask(boolean canBlock) throws InterruptedException {
             Task task;
 
+            //// TODO: enable this once we figure out how to add pending messages in RNSPeer
+            ///        (RNSPeer: pendingMessages.offer(message))
             //task = maybeProducePeerMessageTask();
             //if (task != null) {
             //    return task;
@@ -415,10 +467,10 @@ public class RNSNetwork {
                 return task;
             }
             
-            //task = maybeProduceBroadcastTask(now);
+            task = maybeProduceBroadcastTask(now);
-            //if (task != null) {
+            if (task != null) {
-            //    return task;
+                return task;
-            //}
+            }
             return null;
         }
 
@@ -430,12 +482,18 @@ public class RNSNetwork {
         //            .orElse(null);
         //}
         //private Task maybeProducePeerMessageTask() {
-        //    return getImmutableIncommingPeers().stream()
+        //    return getImmutableIncomingPeers().stream()
         //            .map(RNSPeer::getMessageTask)
         //            .filter(RNSPeer::isAvailable)
-        //            .findFirst*()
+        //            .findFirst()
         //            .orElse(null);
         //}
+        private Task maybeProducePeerMessageTask() {
+            return getImmutableIncomingPeers().stream()
+                    .map(RNSPeer::getMessageTask)
+                    .findFirst()
+                    .orElse(null);
+        }
 
         //private Task maybeProducePeerPingTask(Long now) {
         //    return getImmutableHandshakedPeers().stream()
@@ -461,14 +519,14 @@ public class RNSNetwork {
                     .orElse(null);
         }
         
-        //private Task maybeProduceBroadcastTask(Long now) {
+        private Task maybeProduceBroadcastTask(Long now) {
-        //    if (now == null || now < nextBroadcastTimestamp.get()) {
+            if (now == null || now < nextBroadcastTimestamp.get()) {
-        //        return null;
+                return null;
-        //    }
+            }
-        //
+        
-        //    nextBroadcastTimestamp.set(now + BROADCAST_INTERVAL);
+            nextBroadcastTimestamp.set(now + BROADCAST_INTERVAL);
-        //    return new BroadcastTask();
+            return new RNSBroadcastTask();
-        //}
+        }
     }
 
     private static class SingletonContainer {
@@ -713,5 +771,23 @@ public class RNSNetwork {
         return Settings.getInstance().isTestNet() ? TESTNET_MESSAGE_MAGIC : MAINNET_MESSAGE_MAGIC;
     }
 
+    // Network methods Reticulum implementation
+
+    /** Builds either (legacy) HeightV2Message or (newer) BlockSummariesV2Message, depending on peer version.
+     *
+     *  @return Message, or null if DataException was thrown.
+     */
+    public Message buildHeightOrChainTipInfo(RNSPeer peer) {
+        // peer only used for version check
+        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;
+        }
+    }
+
 }
 

src/main/java/org/qortal/network/RNSPeer.java

@@ -8,6 +8,8 @@ import static java.util.Objects.nonNull;
 //import java.io.IOException;
 import java.time.Instant;
 import java.util.Arrays;
+import java.util.List;
+import java.util.Collections;
 
 //import io.reticulum.Reticulum;
 //import org.qortal.network.RNSNetwork;
@@ -37,6 +39,7 @@ import static io.reticulum.utils.IdentityUtils.concatArrays;
 import org.qortal.controller.Controller;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.data.block.CommonBlockData;
+import org.qortal.data.network.RNSPeerData;
 import org.qortal.network.message.Message;
 import org.qortal.network.message.PingMessage;
 import org.qortal.network.message.*;
@@ -106,11 +109,22 @@ public class RNSPeer {
     private Long lastPing = null;      // last ping roundtrip time [ms]
     private Long lastPingSent = null;  // time last ping was sent, or null if not started.
     private Map<Integer, BlockingQueue<Message>> replyQueues;
-    //private LinkedBlockingQueue<Message> pendingMessages;    // we might not need this
+    private LinkedBlockingQueue<Message> pendingMessages;
     // Versioning
     public static final Pattern VERSION_PATTERN = Pattern.compile(Controller.VERSION_PREFIX
             + "(\\d{1,3})\\.(\\d{1,5})\\.(\\d{1,5})");
 
+    private RNSPeerData peerData = null;
+    /**
+     * Latest block info as reported by peer.
+     */
+    private List<BlockSummaryData> peersChainTipData = Collections.emptyList();
+    /**
+     * Our common block with this peer
+     */
+    private CommonBlockData commonBlockData;
+
+
     /**
      * Constructor for initiator peers
      */
@@ -122,6 +136,8 @@ public class RNSPeer {
         this.creationTimestamp = Instant.now();
         this.isVacant = true;
         this.replyQueues = new ConcurrentHashMap<>();
+        this.pendingMessages = new LinkedBlockingQueue<>();
+        this.peerData = new RNSPeerData(dhash);
     }
 
     /**
@@ -142,6 +158,7 @@ public class RNSPeer {
         //this.peerLink.setLinkEstablishedCallback(this::linkEstablished);
         //this.peerLink.setLinkClosedCallback(this::linkClosed);
         //this.peerLink.setPacketCallback(this::linkPacketReceived);
+        this.peerData = new RNSPeerData(this.destinationHash);
     }
     public void initPeerLink() {
         peerDestination = new Destination(
@@ -168,7 +185,8 @@ public class RNSPeer {
         var channel = this.peerLink.getChannel();
         if (nonNull(this.peerBuffer)) {
             log.trace("peerBuffer exists: {}, link status: {}", this.peerBuffer, this.peerLink.getStatus());
-            return this.peerBuffer;
+            log.info("peerBuffer exists: {}, link status: {}", this.peerBuffer, this.peerLink.getStatus());
+            //return this.peerBuffer;
             //try {
             //    this.peerBuffer.close();
             //    this.peerBuffer = Buffer.createBidirectionalBuffer(receiveStreamId, sendStreamId, channel, this::peerBufferReady);
@@ -185,7 +203,8 @@ public class RNSPeer {
             log.info("creating buffer - peerLink status: {}, channel: {}", this.peerLink.getStatus(), channel);
             this.peerBuffer = Buffer.createBidirectionalBuffer(receiveStreamId, sendStreamId, channel, this::peerBufferReady);
         }
-        return getPeerBuffer();
+        //return getPeerBuffer();
+        return this.peerBuffer;
     }
 
     public Link getOrInitPeerLink() {
@@ -223,6 +242,10 @@ public class RNSPeer {
         return getPeerLink().getChannel();
     }
 
+    public Boolean getIsInitiator() {
+        return this.isInitiator;
+    }
+
     /** Link callbacks */
     public void linkEstablished(Link link) {
         link.setLinkClosedCallback(this::linkClosed);
@@ -285,38 +308,40 @@ public class RNSPeer {
     public void peerBufferReady(Integer readyBytes) {
         // get the message data
         var data = this.peerBuffer.read(readyBytes);
+        log.info("data length, data: {}, {}", data.length, data);
         //var pureData = Arrays.copyOfRange(data, this.messageMagic.length - 1, data.length);
         log.trace("peerBufferReady - data bytes: {}", data.length);
 
         try {
             Message message = Message.fromByteBuffer(ByteBuffer.wrap(data));
+            log.info("received message - {}", message);
             log.info("type {} message received: {}", message.getType(), message);
             // TODO: Now what with message?
             switch (message.getType()) {
+                // Do we need this ? (seems like a TCP scenario only thing)
+                // Does any RNSPeer ever require an other RNSPeer's peer list?
                 //case GET_PEERS:
                 //    onGetPeersMessage(peer, message);
                 //    break;
                 
                 case PING:
                     onPingMessage(this, message);
-                    //PongMessage pongMessage = new PongMessage();
-                    //pongMessage.setId(message.getId());
-                    //this.peerBuffer.write(pongMessage.toBytes());
-                    //this.peerBuffer.flush();
                     break;
 
                 case PONG:
                     //log.info("PONG received");
                     //break;
 
+                // Do we need this ? (We don't have RNSPeer versions)
                 //case PEERS_V2:
                 //    onPeersV2Message(peer, message);
                 //    break;
-                //
+                
-                //default:
+                default:
-                //    // Bump up to controller for possible action
+                    // Bump up to controller for possible action
-                //    Controller.getInstance().onNetworkMessage(peer, message);
+                    //Controller.getInstance().onNetworkMessage(peer, message);
-                //    break;
+                    Controller.getInstance().onRNSNetworkMessage(this, message);
+                    break;
             }
         } catch (MessageException e) {
             //log.error("{} from peer {}", e.getMessage(), this);
@@ -569,6 +594,50 @@ public class RNSPeer {
         }
     }
 
+    protected Task getMessageTask() {
+        /*
+         * If our peerLink is not in ACTIVE node and there is a message yet to be
+         * processed then don't produce another message task.
+         * This allows us to process remaining messages sequentially.
+         */
+        if (this.peerLink.getStatus() != ACTIVE) {
+            return null;
+        }
+
+        final Message nextMessage = this.pendingMessages.poll();
+
+        if (nextMessage == null) {
+            return null;
+        }
+
+        // Return a task to process message in queue
+        return new RNSMessageTask(this, nextMessage);
+    }
+
+    /**
+     * Send a Qortal message using a Reticulum Buffer
+     * 
+     * @param message message to be sent
+     * @return <code>true</code> if message successfully sent; <code>false</code> otherwise
+     */
+    public boolean sendMessage(Message message) {
+        try {
+            log.trace("Sending {} message with ID {} to peer {}", message.getType().name(), message.getId(), this);
+            var peerBuffer = getOrInitPeerBuffer();
+            this.peerBuffer.write(message.toBytes());
+            this.peerBuffer.flush();
+            return true;
+        } catch (IllegalStateException e) {
+            this.peerLink.teardown();
+            this.peerBuffer = null;
+            log.error("IllegalStateException - can't write to buffer: {}", e);
+            return false;
+        } catch (MessageException e) {
+            log.error(e.getMessage(), e);
+            return false;
+        }
+    }
+
     protected void startPings() {
         log.trace("[{}] Enabling pings for peer {}",
                 peerLink.getDestination().getHexHash(), this);
@@ -600,4 +669,35 @@ public class RNSPeer {
 
         return new RNSPingTask(this, now);
     }
+
+    // Peer methods reticulum implementations
+    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(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() {
+        return this.commonBlockData;
+    }
+
+    public void setCommonBlockData(CommonBlockData commonBlockData) {
+        this.commonBlockData = commonBlockData;
+    }
 }

src/main/java/org/qortal/network/task/RNSBroadcastTask.java

@@ -0,0 +1,19 @@
+package org.qortal.network.task;
+
+import org.qortal.controller.Controller;
+import org.qortal.utils.ExecuteProduceConsume.Task;
+
+public class RNSBroadcastTask implements Task {
+    public RNSBroadcastTask() {
+    }
+
+    @Override
+    public String getName() {
+        return "BroadcastTask";
+    }
+
+    @Override
+    public void perform() throws InterruptedException {
+        Controller.getInstance().doRNSNetworkBroadcast();
+    }
+}

src/main/java/org/qortal/network/task/RNSMessageTask.java

@@ -0,0 +1,29 @@
+package org.qortal.network.task;
+
+import org.qortal.network.RNSNetwork;
+import org.qortal.network.RNSPeer;
+import org.qortal.network.message.Message;
+import org.qortal.utils.ExecuteProduceConsume.Task;
+
+public class RNSMessageTask implements Task {
+    private final RNSPeer peer;
+    private final Message nextMessage;
+    private final String name;
+
+    public RNSMessageTask(RNSPeer peer, Message nextMessage) {
+        this.peer = peer;
+        this.nextMessage = nextMessage;
+        this.name = "MessageTask::" + peer + "::" + nextMessage.getType();
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public void perform() throws InterruptedException {
+        //RNSNetwork.getInstance().onMessage(peer, nextMessage);
+        // TODO: what do we do in the Reticulum case? => implement
+    }
+}

src/main/java/org/qortal/settings/Settings.java

@@ -577,6 +577,15 @@ public class Settings {
 		}
 	}
 
+	// Related to Reticulum networking
+
+	/** Maximum number of Reticulum peers allowed. */
+	private int reticulumMaxPeers = 55;
+	/** Minimum number of Reticulum peers desired. */
+	private int reticulumMinDesiredPeers = 3;
+	/** Maximum number of task executor network threads */
+	private int reticulumMaxNetworkThreadPoolSize = 89;
+
 	// Constructors
 
 	private Settings() {
@@ -1333,4 +1342,16 @@ public class Settings {
 	public boolean isConnectionPoolMonitorEnabled() {
 		return connectionPoolMonitorEnabled;
 	}
+
+	public int getReticulumMaxPeers() {
+		return this.reticulumMaxPeers;
+	}
+
+	public int getReticulumMinDesiredPeers() {
+		return this.reticulumMinDesiredPeers;
+	}
+
+	public int getReticulumMaxNetworkThreadPoolSize() {
+		return this.reticulumMaxNetworkThreadPoolSize;
+	}
 }