Router/Tunnel: Handling Updates for Inbound Messages.

Eliminate the forwarding of messages in the Inbound Message Distributor.

The Inbound Message Distributor is the end point, and attempting
to handling forwarding instructions opens up too many possibilities
for potentially dangerous scenarios.

Typically, the messages with forwarding instructions are the result
of decrypting garlic messages that yield another I2NP message,
which is recursively handled.

It shouldn't be necessary to forward messages at this point.
The client should handle any decisions regarding forwarding, not
the router.

Normally, I don't clean up the code in a given commit, but there
were some remnants of commented-out code right in the middle
of the section being reworked, and this deprecated code would
have been out of context if not removed.

Signed-off-by: obscuratus <[email protected]>

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

@@ -51,7 +51,8 @@ public void distribute(I2NPMessage msg, Hash target) {
 
     public void distribute(I2NPMessage msg, Hash target, TunnelId tunnel) {
         if (_log.shouldLog(Log.DEBUG))
-            _log.debug("IBMD for " + _client + " to " + target + " / " + tunnel + " : " + msg);
+            _log.debug("IBMD for " + ((_client != null) ? _client.toBase32() : "null")
+                       + " to " + target + " / " + tunnel + " : " + msg);
 
         // allow messages on client tunnels even after client disconnection, as it may
         // include e.g. test messages, etc.  DataMessages will be dropped anyway
@@ -176,9 +177,12 @@ public void distribute(I2NPMessage msg, Hash target, TunnelId tunnel) {
             } // switch
         } // client != null
 
-        if ( (target == null) || ( (tunnel == null) && (_context.routerHash().equals(target) ) ) ) {
-            // targetting us either implicitly (no target) or explicitly (no tunnel)
-            // make sure we don't honor any remote requests directly (garlic instructions, etc)
+        if ( (target == null) && (tunnel == null) ) {
+            // Since the InboundMessageDistributor handles messages for the endpoint,
+            // most messages that arrive here have both target==null and tunnel==null.
+            // Messages with targeting instructions need careful handling, and will
+            // typically be dropped because we're the endpoint.  Especially when they
+            // specifically target this router (_context.routerHash().equals(target)).
             if (type == GarlicMessage.MESSAGE_TYPE) {
                 // in case we're looking for replies to a garlic message (cough load tests cough)
                 _context.inNetMessagePool().handleReplies(msg);
@@ -187,47 +191,37 @@ public void distribute(I2NPMessage msg, Hash target, TunnelId tunnel) {
                 _receiver.receive((GarlicMessage)msg);
             } else {
                 if (_log.shouldLog(Log.INFO))
-                    _log.info("distributing inbound tunnel message into our inNetMessagePool: " + msg);
+                    _log.info("distributing inbound tunnel message into our inNetMessagePool"
+                              + " (for client " + ((_client != null) ? _client.toBase32() : "null")
+                              + " to target=NULL/tunnel=NULL " + msg);
                 _context.inNetMessagePool().add(msg, null, null);
             }
-/****** latency measuring attack?
         } else if (_context.routerHash().equals(target)) {
-            // the want to send it to a tunnel, except we are also that tunnel's gateway
-            // dispatch it directly
-            if (_log.shouldLog(Log.INFO))
-                _log.info("distributing inbound tunnel message back out, except we are the gateway");
-            TunnelGatewayMessage gw = new TunnelGatewayMessage(_context);
-            gw.setMessage(msg);
-            gw.setTunnelId(tunnel);
-            gw.setMessageExpiration(_context.clock().now()+10*1000);
-            gw.setUniqueId(_context.random().nextLong(I2NPMessage.MAX_ID_VALUE));
-            _context.tunnelDispatcher().dispatch(gw);
-******/
+            if (type == GarlicMessage.MESSAGE_TYPE)
+                if (_log.shouldLog(Log.WARN))
+                    _log.warn("Dropping inbound garlic message TARGETED TO OUR ROUTER for client "
+                              + ((_client != null) ? _client.toBase32() : "null")
+                              + " to " + target + " / " + tunnel);
+            else
+                if (_log.shouldLog(Log.WARN))
+                    _log.warn("Dropping inbound message TARGETED TO OUR ROUTER for client "
+                              + ((_client != null) ? _client.toBase32() : "null")
+                              + " to " + target + " / " + tunnel + " : " + msg);
+            return;
         } else {
-            // ok, they want us to send it remotely, but that'd bust our anonymity,
-            // so we send it out a tunnel first
-            // TODO use the OCMOSJ cache to pick OB tunnel we are already using?
-            TunnelInfo out = _context.tunnelManager().selectOutboundTunnel(_client, target);
-            if (out == null) {
+            if (type == GarlicMessage.MESSAGE_TYPE)
                 if (_log.shouldLog(Log.WARN))
-                    _log.warn("no outbound tunnel to send the client message for " + _client + ": " + msg);
-                return;
-            }
-            if (_log.shouldLog(Log.DEBUG))
-                _log.debug("distributing IB tunnel msg type " + type + " back out " + out
-                          + " targetting " + target);
-            TunnelId outId = out.getSendTunnelId(0);
-            if (outId == null) {
-                if (_log.shouldLog(Log.ERROR))
-                    _log.error("strange? outbound tunnel has no outboundId? " + out 
-                               + " failing to distribute " + msg);
-                return;
-            }
-            long exp = _context.clock().now() + 20*1000;
-            if (msg.getMessageExpiration() < exp)
-                msg.setMessageExpiration(exp);
-            _context.tunnelDispatcher().dispatchOutbound(msg, outId, tunnel, target);
+                    _log.warn("Dropping targeted inbound garlic message for client "
+                              + ((_client != null) ? _client.toBase32() : "null")
+                              + " to " + target + " / " + tunnel);
+            else
+                if (_log.shouldLog(Log.WARN))
+                    _log.warn("Dropping targeted inbound message for client "
+                              + ((_client != null) ? _client.toBase32() : "null")
+                              + " to " + target + " / " + tunnel + " : " + msg);
+            return;
         }
+
     }
 
     /**
@@ -370,9 +364,14 @@ public void handleClove(DeliveryInstructions instructions, I2NPMessage data) {
 
             case DeliveryInstructions.DELIVERY_MODE_ROUTER: // fall through
             case DeliveryInstructions.DELIVERY_MODE_TUNNEL:
+                // Targeted messages are usually dropped, but it is safe to
+                // allow distribute() to evaluate the message.
                 if (_log.shouldLog(Log.INFO))
-                    _log.info("clove targetted " + instructions.getRouter() + ":" + instructions.getTunnelId()
-                               + ", treat recursively to prevent leakage");
+                    _log.info("Recursively handling message from targeted clove (for client:"
+                              + ((_client != null) ? _client.toBase32() : "null") + ", msg type: "
+                              + data.getClass().getSimpleName() + "): " + instructions.getRouter()
+                              + ":" + instructions.getTunnelId() + " msg: " + data);
+
                 distribute(data, instructions.getRouter(), instructions.getTunnelId());
                 return;