- Change secure Node ID requirements again

- Protect against null DHT races
- Add message about restarting tunnel when DHT config changes
- Add DHT size to table totals

apps/i2psnark/java/src/org/klomp/snark/PeerCheckerTask.java

@@ -28,6 +28,8 @@ import net.i2p.I2PAppContext;
 import net.i2p.data.DataHelper;
 import net.i2p.util.Log;
 
+import org.klomp.snark.dht.DHT;
+
 /**
  * TimerTask that checks for good/bad up/downloader. Works together
  * with the PeerCoordinator to select which Peers get (un)choked.
@@ -74,6 +76,7 @@ class PeerCheckerTask implements Runnable
         List<Peer> removed = new ArrayList();
         int uploadLimit = coordinator.allowedUploaders();
         boolean overBWLimit = coordinator.overUpBWLimit();
+        DHT dht = _util.getDHT();
         for (Peer peer : peerList) {
 
             // Remove dying peers
@@ -218,8 +221,8 @@ class PeerCheckerTask implements Runnable
             if (coordinator.getNeededLength() > 0 || !peer.isCompleted())
                 peer.keepAlive();
             // announce them to local tracker (TrackerClient does this too)
-            if (_util.getDHT() != null && (_runCount % 5) == 0) {
+            if (dht != null && (_runCount % 5) == 0) {
-                _util.getDHT().announce(coordinator.getInfoHash(), peer.getPeerID().getDestHash());
+                dht.announce(coordinator.getInfoHash(), peer.getPeerID().getDestHash());
             }
           }
 
@@ -267,8 +270,8 @@ class PeerCheckerTask implements Runnable
         }
 
         // announce ourselves to local tracker (TrackerClient does this too)
-        if (_util.getDHT() != null && (_runCount % 16) == 0) {
+        if (dht != null && (_runCount % 16) == 0) {
-            _util.getDHT().announce(coordinator.getInfoHash());
+            dht.announce(coordinator.getInfoHash());
         }
   }
 }

apps/i2psnark/java/src/org/klomp/snark/SnarkManager.java

@@ -577,6 +577,8 @@ public class SnarkManager implements Snark.CompleteListener {
                 addMessage(_("Enabled DHT."));
             else
                 addMessage(_("Disabled DHT."));
+            if (_util.connected())
+                addMessage(_("DHT change requires tunnel shutdown and reopen"));
             _util.setUseDHT(useDHT);
             changed = true;
         }

apps/i2psnark/java/src/org/klomp/snark/TrackerClient.java

@@ -43,6 +43,8 @@ import net.i2p.util.I2PAppThread;
 import net.i2p.util.Log;
 import net.i2p.util.SimpleTimer2;
 
+import org.klomp.snark.dht.DHT;
+
 /**
  * Informs metainfo tracker of events and gets new peers for peer
  * coordinator.
@@ -323,8 +325,9 @@ public class TrackerClient implements Runnable {
             }
 
             // Local DHT tracker announce
-            if (_util.getDHT() != null)
+            DHT dht = _util.getDHT();
-                _util.getDHT().announce(snark.getInfoHash());
+            if (dht != null)
+                dht.announce(snark.getInfoHash());
 
             long uploaded = coordinator.getUploaded();
             long downloaded = coordinator.getDownloaded();
@@ -372,9 +375,10 @@ public class TrackerClient implements Runnable {
                         snark.setTrackerSeenPeers(tr.seenPeers);
 
                     // pass everybody over to our tracker
-                    if (_util.getDHT() != null) {
+                    dht = _util.getDHT();
+                    if (dht != null) {
                         for (Peer peer : peers) {
-                            _util.getDHT().announce(snark.getInfoHash(), peer.getPeerID().getDestHash());
+                            dht.announce(snark.getInfoHash(), peer.getPeerID().getDestHash());
                         }
                     }
 
@@ -458,20 +462,21 @@ public class TrackerClient implements Runnable {
 
             // Get peers from DHT
             // FIXME this needs to be in its own thread
-            if (_util.getDHT() != null && (meta == null || !meta.isPrivate()) && !stop) {
+            dht = _util.getDHT();
+            if (dht != null && (meta == null || !meta.isPrivate()) && !stop) {
                 int numwant;
                 if (event.equals(STOPPED_EVENT) || !coordinator.needOutboundPeers())
                     numwant = 1;
                 else
                     numwant = _util.getMaxConnections();
-                List<Hash> hashes = _util.getDHT().getPeers(snark.getInfoHash(), numwant, 2*60*1000);
+                List<Hash> hashes = dht.getPeers(snark.getInfoHash(), numwant, 2*60*1000);
                 if (_log.shouldLog(Log.INFO))
                     _log.info("Got " + hashes + " from DHT");
                 // announce  ourselves while the token is still good
                 // FIXME this needs to be in its own thread
                 if (!stop) {
                     // announce only to the 1 closest
-                    int good = _util.getDHT().announce(snark.getInfoHash(), 1, 5*60*1000);
+                    int good = dht.announce(snark.getInfoHash(), 1, 5*60*1000);
                     if (_log.shouldLog(Log.INFO))
                         _log.info("Sent " + good + " good announces to DHT");
                 }
@@ -548,8 +553,9 @@ public class TrackerClient implements Runnable {
    */
   private void unannounce() {
       // Local DHT tracker unannounce
-      if (_util.getDHT() != null)
+      DHT dht = _util.getDHT();
-          _util.getDHT().unannounce(snark.getInfoHash());
+      if (dht != null)
+          dht.unannounce(snark.getInfoHash());
       int i = 0;
       for (Tracker tr : trackers) {
           if (_util.connected() &&

apps/i2psnark/java/src/org/klomp/snark/dht/DHT.java

@@ -89,4 +89,9 @@ public interface DHT {
      * Stop everything.
      */
     public void stop();
+
+    /**
+     * Known nodes, not estimated total network size.
+     */
+    public int size();
 }

apps/i2psnark/java/src/org/klomp/snark/dht/KRPC.java

@@ -158,7 +158,7 @@ public class KRPC implements I2PSessionMuxedListener, DHT {
         _qPort = 2555 + ctx.random().nextInt(61111);
         _rPort = _qPort + 1;
         if (SECURE_NID) {
-            _myNID = NodeInfo.generateNID(session.getMyDestination().calculateHash(), _qPort);
+            _myNID = NodeInfo.generateNID(session.getMyDestination().calculateHash(), _qPort, _context.random());
             _myID = _myNID.getData();
         } else {
             _myID = new byte[NID.HASH_LENGTH];
@@ -176,6 +176,13 @@ public class KRPC implements I2PSessionMuxedListener, DHT {
 
     ///////////////// Public methods
 
+    /**
+     * Known nodes, not estimated total network size.
+     */
+    public int size() {
+        return _knownNodes.size();
+    }
+
     /**
      *  @return The UDP query port
      */

apps/i2psnark/java/src/org/klomp/snark/dht/NodeInfo.java

@@ -9,6 +9,7 @@ import net.i2p.data.DataHelper;
 import net.i2p.data.Destination;
 import net.i2p.data.Hash;
 import net.i2p.data.SimpleDataStructure;
+import net.i2p.util.RandomSource;
 
 /*
  *  A Node ID, Hash, and port, and an optional Destination.
@@ -139,29 +140,35 @@ class NodeInfo extends SimpleDataStructure {
     }
 
     /**
-     * Generate a secure NID that matches the Hash and port
+     * Generate a secure NID that matches the Hash and port.
+     * Rules: First 4 bytes must match Hash.
+     * Next 2 bytes must match Hash ^ port.
+     * Remaining bytes may be random.
+     *
      * @throws IllegalArgumentException
      */
-    public static NID generateNID(Hash h, int p) {
+    public static NID generateNID(Hash h, int p, RandomSource random) {
         byte[] n = new byte[NID.HASH_LENGTH];
-        System.arraycopy(h.getData(), 0, n, 0, NID.HASH_LENGTH);
+        System.arraycopy(h.getData(), 0, n, 0, 6);
-        n[0] ^= (byte) (p >> 8);
+        n[4] ^= (byte) (p >> 8);
-        n[1] ^= (byte) p;
+        n[5] ^= (byte) p;
+        random.nextBytes(n, 6, NID.HASH_LENGTH - 6);
         return new NID(n);
     }
 
     /**
-     * Verify the NID matches the Hash
+     * Verify the NID matches the Hash.
-     * @throws IllegalArgumentException
+     * See generateNID() for requirements.
+     * @throws IllegalArgumentException on mismatch
      */
     private void verify() {
         if (!KRPC.SECURE_NID)
             return;
         byte[] nb = nID.getData();
         byte[] hb = hash.getData();
-        if ((!DataHelper.eq(nb, 2, hb, 2, NID.HASH_LENGTH - 2)) ||
+        if ((!DataHelper.eq(nb, 0, hb, 0, 4)) ||
-            ((nb[0] ^ (port >> 8)) & 0xff) != (hb[0] & 0xff) ||
+            ((nb[4] ^ (port >> 8)) & 0xff) != (hb[4] & 0xff) ||
-            ((nb[1] ^ port) & 0xff) != (hb[1] & 0xff))
+            ((nb[5] ^ port) & 0xff) != (hb[5] & 0xff))
             throw new IllegalArgumentException("NID/Hash mismatch");
     }
 

apps/i2psnark/java/src/org/klomp/snark/web/I2PSnarkServlet.java

@@ -42,6 +42,7 @@ import org.klomp.snark.SnarkManager;
 import org.klomp.snark.Storage;
 import org.klomp.snark.Tracker;
 import org.klomp.snark.TrackerClient;
+import org.klomp.snark.dht.DHT;
 
 import org.mortbay.jetty.servlet.DefaultServlet;
 import org.mortbay.resource.Resource;
@@ -470,6 +471,14 @@ public class I2PSnarkServlet extends DefaultServlet {
             out.write(", ");
             out.write(DataHelper.formatSize2(stats[5]) + "B, ");
             out.write(ngettext("1 connected peer", "{0} connected peers", (int) stats[4]));
+            DHT dht = _manager.util().getDHT();
+            if (dht != null) {
+                int dhts = dht.size();
+                if (dhts > 0) {
+                    out.write(", ");
+                    out.write(ngettext("1 DHT peer", "{0} DHT peers", dhts));
+                }
+            }
             out.write("</th>\n");
             if (_manager.util().connected()) {
                 out.write("    <th align=\"right\">" + formatSize(stats[0]) + "</th>\n" +