Added "qdnEnabled" setting (default: true) to allow users to opt out of QDN functionality.

src/main/java/org/qortal/arbitrary/ArbitraryDataReader.java

@@ -164,6 +164,7 @@ public class ArbitraryDataReader {
 
     private void preExecute() throws DataException {
         ArbitraryDataBuildManager.getInstance().setBuildInProgress(true);
+        this.checkEnabled();
         this.createWorkingDirectory();
         this.createUncompressedDirectory();
     }
@@ -172,6 +173,12 @@ public class ArbitraryDataReader {
         ArbitraryDataBuildManager.getInstance().setBuildInProgress(false);
     }
 
+    private void checkEnabled() throws DataException {
+        if (!Settings.getInstance().isQdnEnabled()) {
+            throw new DataException("QDN is disabled in settings");
+        }
+    }
+
     private void createWorkingDirectory() throws DataException {
         try {
             Files.createDirectories(this.workingPath);

src/main/java/org/qortal/arbitrary/ArbitraryDataRenderer.java

@@ -9,6 +9,8 @@ import org.qortal.arbitrary.ArbitraryDataFile.*;
 import org.qortal.arbitrary.exception.MissingDataException;
 import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.Controller;
+import org.qortal.repository.DataException;
+import org.qortal.settings.Settings;
 
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
@@ -64,6 +66,11 @@ public class ArbitraryDataRenderer {
             inPath = File.separator + inPath;
         }
 
+        // Don't render data if QDN is disabled
+        if (!Settings.getInstance().isQdnEnabled()) {
+            return ArbitraryDataRenderer.getResponse(response, 500, "QDN is disabled in settings");
+        }
+
         ArbitraryDataReader arbitraryDataReader = new ArbitraryDataReader(resourceId, resourceIdType, service, null);
         arbitraryDataReader.setSecret58(secret58); // Optional, used for loading encrypted file hashes only
         try {

src/main/java/org/qortal/arbitrary/ArbitraryDataWriter.java

@@ -81,6 +81,8 @@ public class ArbitraryDataWriter {
     }
 
     private void preExecute() throws DataException {
+        this.checkEnabled();
+
         // Enforce compression when uploading a directory
         File file = new File(this.filePath.toString());
         if (file.isDirectory() && compression == Compression.NONE) {
@@ -95,6 +97,12 @@ public class ArbitraryDataWriter {
         this.cleanupFilesystem();
     }
 
+    private void checkEnabled() throws DataException {
+        if (!Settings.getInstance().isQdnEnabled()) {
+            throw new DataException("QDN is disabled in settings");
+        }
+    }
+
     private void createWorkingDirectory() throws DataException {
         // Use the user-specified temp dir, as it is deterministic, and is more likely to be located on reusable storage hardware
         String baseDir = Settings.getInstance().getTempDataPath();

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

@@ -6,6 +6,7 @@ import java.util.*;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.api.resource.TransactionsResource.ConfirmationStatus;
+import org.qortal.arbitrary.ArbitraryDataRenderer;
 import org.qortal.controller.Controller;
 import org.qortal.data.network.ArbitraryPeerData;
 import org.qortal.data.transaction.ArbitraryTransactionData;
@@ -793,6 +794,11 @@ public class ArbitraryDataManager extends Thread {
 	// Network handlers
 
 	public void onNetworkArbitraryDataFileListMessage(Peer peer, Message message) {
+		// Don't process if QDN is disabled
+		if (!Settings.getInstance().isQdnEnabled()) {
+			return;
+		}
+
 		ArbitraryDataFileListMessage arbitraryDataFileListMessage = (ArbitraryDataFileListMessage) message;
 		LOGGER.info("Received hash list from peer {} with {} hashes", peer, arbitraryDataFileListMessage.getHashes().size());
 
@@ -880,6 +886,11 @@ public class ArbitraryDataManager extends Thread {
 	}
 
 	public void onNetworkGetArbitraryDataFileMessage(Peer 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);
@@ -949,6 +960,11 @@ public class ArbitraryDataManager extends Thread {
 	}
 
 	public void onNetworkGetArbitraryDataFileListMessage(Peer 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;
@@ -1040,6 +1056,11 @@ public class ArbitraryDataManager extends Thread {
 	}
 
 	public void onNetworkArbitrarySignaturesMessage(Peer peer, Message message) {
+		// Don't process if QDN is disabled
+		if (!Settings.getInstance().isQdnEnabled()) {
+			return;
+		}
+
 		LOGGER.info("Received arbitrary signature list from peer {}", peer);
 
 		ArbitrarySignaturesMessage arbitrarySignaturesMessage = (ArbitrarySignaturesMessage) message;

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

@@ -274,11 +274,13 @@ public class Settings {
 	private Long testNtpOffset = null;
 
 
-	// Data storage
+	// Data storage (QDN)
 
+	/** Data storage enabled/disabled*/
+	private boolean qdnEnabled = true;
 	/** Data storage path. */
 	private String dataPath = "data";
-	/** Data storage path (for temporary data). */
+	/** Data storage path (for temporary data). Defaults to {dataPath}/_temp */
 	private String tempDataPath = null;
 
 	/** Storage policy to indicate which data should be hosted */
@@ -831,6 +833,10 @@ public class Settings {
 	}
 
 
+	public boolean isQdnEnabled() {
+		return this.qdnEnabled;
+	}
+
 	public String getDataPath() {
 		return this.dataPath;
 	}