/*
* Mojito Distributed Hash Table (Mojito DHT)
* Copyright (C) 2006-2007 LimeWire LLC
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.limewire.mojito.handler.request;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.limewire.mojito.Context;
import org.limewire.mojito.KUID;
import org.limewire.mojito.messages.FindNodeResponse;
import org.limewire.mojito.messages.LookupRequest;
import org.limewire.mojito.messages.RequestMessage;
import org.limewire.mojito.routing.Contact;
import org.limewire.mojito.routing.RouteTable.SelectMode;
import org.limewire.mojito.settings.KademliaSettings;
import org.limewire.mojito.util.CollectionUtils;
import org.limewire.mojito.util.ContactUtils;
/**
* Handles incoming FIND_NODE requests.
*/
public class FindNodeRequestHandler extends AbstractRequestHandler {
private static final Log LOG = LogFactory.getLog(FindNodeRequestHandler.class);
public FindNodeRequestHandler(Context context) {
super(context);
}
/**
* This method returns a list of nodes along with a SecurityToken generated for this node.
* The SecurityToken will can then be used by the querying node to store data at this node.
*
* If the local node is passive (e.g. firewalled), it returns a list of Most Recently Seen
* nodes instead of returning the closest nodes to the lookup key. The reason for this is that
* passive nodes do not have accurate routing tables.
*
* @param message the RequestMessage for this lookup
* @throws IOException
*/
@Override
protected void request(RequestMessage message) throws IOException {
// Cast to LookupRequest because FindValueRequestHandler
// is delegating requests to this class!
LookupRequest request = (LookupRequest)message;
KUID lookupId = request.getLookupID();
Contact node = request.getContact();
Collection<Contact> nodes = Collections.emptyList();
if (!context.isBootstrapping()) {
if(context.isFirewalled()) {
nodes = ContactUtils.sort(
context.getRouteTable().getContacts(),
KademliaSettings.REPLICATION_PARAMETER.getValue());
// If the external port is not set then make sure
// we're not in the list!
if (context.getExternalPort() == 0) {
nodes.remove(context.getLocalNode());
}
} else {
nodes = context.getRouteTable().select(lookupId,
KademliaSettings.REPLICATION_PARAMETER.getValue(), SelectMode.ALIVE);
}
}
if (LOG.isTraceEnabled()) {
if (!nodes.isEmpty()) {
LOG.trace("Sending back: " + CollectionUtils.toString(nodes) + " to: " + node);
} else {
LOG.trace("Sending back an empty list to: " + node);
}
}
FindNodeResponse response = context.getMessageHelper()
.createFindNodeResponse(request, nodes);
context.getMessageDispatcher().send(node, response);
}
}