Tunnel Endpoints:

- Reject type 3 (undefined) delivery instructions at both OBEP and IBEP,
     would be treated as LOCAL
   - Reject type 0 (LOCAL) delivery instructions at OBEP, no current usage,
     would cause NPE if handled

router/java/src/net/i2p/router/tunnel/FragmentHandler.java

@@ -277,10 +277,10 @@ class FragmentHandler {
     /** for subsequent fragments, which bits contain the fragment #? */
     private static final int MASK_FRAGMENT_NUM = (byte)((1 << 7) - 2); // 0x7E;
     
-    /** LOCAL isn't explicitly used anywhere, because the code knows that it is 0 */
     static final short TYPE_LOCAL = 0;
     static final short TYPE_TUNNEL = 1;
     static final short TYPE_ROUTER = 2;
+    static final short TYPE_UNDEF = 3;
     
     /** 
      * @return the offset for the next byte after the received fragment 
@@ -350,7 +350,15 @@ class FragmentHandler {
         int size = (int)DataHelper.fromLong(preprocessed, offset, 2);
         offset += 2;
         
-        if (fragmented) {
+        if (type == TYPE_UNDEF) {
+            // do this after the above since we have to return offset
+            // no uses for TYPE_LOCAL yet
+            // OutboundTunnelEndpoint doesn't check for null Hash, passes it
+            // to OutboundMessageDistributor.distribute() which will NPE
+            if (_log.shouldLog(Log.WARN))
+                _log.warn("Dropping msg at tunnel endpoint with unsupported delivery instruction type " +
+                          type + " rcvr: " + _receiver);
+        } else if (fragmented) {
             FragmentedMessage msg;
             synchronized (_fragmentedMessages) {
                 msg = _fragmentedMessages.get(Long.valueOf(messageId));

router/java/src/net/i2p/router/tunnel/OutboundTunnelEndpoint.java

@@ -47,6 +47,14 @@ class OutboundTunnelEndpoint {
     
     private class DefragmentedHandler implements FragmentHandler.DefragmentedReceiver {
         public void receiveComplete(I2NPMessage msg, Hash toRouter, TunnelId toTunnel) {
+            if (toRouter == null) {
+                // Delivery type LOCAL is not supported at the OBEP
+                // We don't have any use for it yet.
+                // Don't send to OutboundMessageDistributor.distribute() which will NPE or fail
+                if (_log.shouldLog(Log.WARN))
+                    _log.warn("Dropping msg at OBEP with unsupported delivery instruction type LOCAL");
+                return;
+            }
             if (_log.shouldLog(Log.DEBUG))
                 _log.debug("outbound tunnel " + _config + " received a full message: " + msg
                            + " to be forwarded on to "